- Synthesis, characterization, and photocatalytic activity of stannum-doped MgIn2S4 microspheres
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A series of Sn2+ doped MgIn2S4 photocatalysts were prepared via a facial hydrothermal method. The Sn dopants substitute the sites of Mg atom in MgIn2S4 unit cell, but not alter the crystal structure, demonstrated by the results of XRD and XPS. Compared to pristine MgIn2S4, Sn-doped MgIn2S4 samples exhibit significantly enhanced photocatalytic CO2 reduction activity. With increasing the Sn dopant content, the CO2 conversion rate first ascends, achieving the maximum rate at Sn-MgIn2S4-2 sample, and then decreases. After illumination for 4 h, the highest yield of CO and CH4 for Sn-MgIn2S4-2 sample reaches about 3.35 and 3.33 times higher than that of pristine MgIn2S4. The theoretical results based on density functional theory calculations reveal that Sn doping in MgIn2S4 tunes the band structure from the direct-transition of MgIn2S4 to indirect-transition, diminishes band gap and extends the light absorption range, reduces the effective masses of holes and promotes the migration of photoinduced carriers. The experimental results also demonstrate the positive role of Sn dopant in accelerating the separation and transportation of charges, and improving CO2 adsorption ability. This work systematically investigates and discusses the Sn2+ doping effect in MgIn2S4 on crystal structure, lattice variations, electronic band structures, CO2 adsorption ability, and photocatalytic CO2 reduction activity, which can provide a new hint for the fabrication of efficient photocatalyst by metal ion doping.
- Yang, Wenhong,Dong, Yujing,Wang, Zhipeng,Li, Yuqin,Dai, Chunhui,Ma, Dongwei,Jia, Yu,Yang, Zhen,Zeng, Chao
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- Engineering a CsPbBr3-based nanocomposite for efficient photocatalytic CO2 reduction: Improved charge separation concomitant with increased activity sites
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Metal-halide perovskite nanocrystals have emerged as one of the promising photocatalysts in the photocatalysis field owing to their low-cost and excellent optoelectronic properties. However, this type of nanocrystals generally displays low activity in photocatalytic CO2 reduction owing to the lack of intrinsic catalytic sites and insufficient charge separation. Herein, we functionalized CsPbBr3 nanocrystals with graphitic carbon nitride, containing titanium-oxide species (TiO-CN) to develop an efficient composite catalyst system for photocatalytic CO2 reduction using water as the electron source. Compared to its congener with pristine CsPbBr3, the introduction of TiO-CN could not only increase the number of active sites, but also led to a swift interfacial charge separation between CsPbBr3 and TiO-CN due to their favorable energy-offsets and strong chemical bonding behaviors, which endowed this composite system with an obviously enhanced photocatalytic activity in the reduction of CO2 to CO with water as the sacrificial reductant. Over 3-fold and 6-fold higher activities than those of pristine CsPbBr3 nanocrystals and TiO-CN nanosheets, respectively, were observed under visible light irradiation. Our study provides an effective strategy for improving the photocatalytic activity of metal-halide perovskite nanocrystals, thus promoting their photocatalytic application in the field of artificial photosynthesis.
- Guo, Xiao-Xuan,Tang, Shang-Feng,Mu, Yan-Fei,Wu, Li-Yuan,Dong, Guang-Xing,Zhang, Min
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- N-heterocyclic carbene-functionalized magic-number gold nanoclusters
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Magic-number gold nanoclusters are atomically precise nanomaterials that have enabled unprecedented insight into structure–property relationships in nanoscience. Thiolates are the most common ligand, binding to the cluster via a staple motif in which only
- Narouz, Mina R.,Osten, Kimberly M.,Unsworth, Phillip J.,Man, Renee W. Y.,Salorinne, Kirsi,Takano, Shinjiro,Tomihara, Ryohei,Kaappa, Sami,Malola, Sami,Dinh, Cao-Thang,Padmos, J. Daniel,Ayoo, Kennedy,Garrett, Patrick J.,Nambo, Masakazu,Horton, J. Hugh,Sargent, Edward H.,H?kkinen, Hannu,Tsukuda, Tatsuya,Crudden, Cathleen M.
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- A porous hybrid material based on calixarene dye and TiO2 demonstrating high and stable photocatalytic performance
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A highly robust hybrid material based on calixarene dye (HO-TPA) and titanium dioxide with a micro/mesoporous structure and a large surface area (denoted as HO-TPA-TiO2) has been prepared by a facile sol-gel method. When Pt nanoparticles (Pt NP
- Chen, Yi-Fan,Huang, Jian-Feng,Shen, Min-Hui,Liu, Jun-Min,Huang, Li-Bo,Zhong, Yu-Hui,Qin, Su,Guo, Jing,Su, Cheng-Yong
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- A cyanide-bridged di-manganese carbonyl complex that photochemically reduces CO2 to CO
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Manganese(i) tricarbonyl complexes such as [Mn(bpy)(CO)3L] (L = Br, or CN) are known to be electrocatalysts for CO2 reduction to CO. However, due to their rapid photodegradation under UV and visible light, these monomeric manganese complexes have not been considered as photocatalysts for CO2 reduction without the use of a photosensitizer. In this paper, we report a cyanide-bridged di-manganese complex, {[Mn(bpy)(CO)3]2(μ-CN)}ClO4, which is both electrocatalytic and photochemically active for CO2 reduction to CO. Compared to the [Mn(bpy)(CO)3CN] electrocatalyst, our CN-bridged binuclear complex is a more efficient electrocatalyst for CO2 reduction using H2O as a proton source. In addition, we report a photochemical CO2 reduction to CO using the dimanganese complex under 395 nm irradiation.
- Kuo, Hsin-Ya,Lee, Tia S.,Chu, An T.,Tignor, Steven E.,Scholes, Gregory D.,Bocarsly, Andrew B.
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- Constructed Z-Scheme g-C3N4/Ag3VO4/rGO Photocatalysts with Multi-interfacial Electron-Transfer Paths for High Photoreduction of CO2
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Z-scheme g-C3N4/Ag3VO4/reduced graphene oxide (rGO) photocatalysts with multi-interfacial electron-transfer paths enhancing CO2 photoreduction under UV-vis light irradiation were successfully prepared by a hydrothermal process. Transmission electron microscope images displayed that the prepared photocatalysts have a unique 2D-0D-2D ternary sandwich structure. Photoelectrochemical characterizations including TPR, electrochemical impedance spectroscopy, photoluminescence, and linear sweep voltammetry explained that the multi-interfacial structure effectively improved the separation and transmission capabilities of photogenerated carriers. Electron spin resonance spectroscopy and band position analysis proved that the electron-transfer mode of g-C3N4/Ag3VO4 meets the Z-scheme mechanism. The introduction of rGO provided more electron-transfer paths for the photocatalysts and enhanced the stability of Ag-based semiconductors. In addition, the π-πconjugation effect between g-C3N4 and rGO further improved the generation and separation efficiency of photogenerated electron-hole pairs. Then, the multiple channels (Ag3VO4 → CN, Ag3VO4 → rGO → CN, and rGO → CN) due to the 2D-0D-2D structure greatly improving the photocatalytic CO2 reduction ability have been discussed in detail.
- Gao, Ming,Sun, Linlin,Ma, Changchang,Li, Xin,Jiang, Haopeng,Shen, Dong,Wang, Huiqin,Huo, Pengwei
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- Ultrasmall C-TiO2?x nanoparticle/g-C3N4 composite for CO2 photoreduction with high efficiency and selectivity
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The photoreduction of CO2 to CO offers a promising sustainable and clean approach for a global new energy program. Coupling this reductive process with a matched water photo-oxidation pathway is an attractive avenue to accelerate the half-reaction of CO2 reduction. Herein, we propose a three-component photocatalyst design strategy for reducing CO2 to CO coupled with water oxidation via a two-electron/two-step pathway. Employing polyoxotitanium ([Ti17O24(OPri)20]) as a titanium source, ultrasmall TiO2?x nanoparticles coated with ultrathin carbon layers (C-TiO2?x) were fabricated and loaded on to a g-C3N4 matrix through chemical bonding (C-TiO2?x@g-C3N4) for the first time. The optimized C-TiO2?x@g-C3N4 photocatalyst showed a very high activity of 12.30 mmol g?1 (204.96 mmol gTiO2?1) CO generation within 60 h visible-light irradiation, which represents the highest CO production rate to date among the reported TiO2-based materials under similar conditions. The excellent adsorption capability of C-TiO2?x@g-C3N4 for photons, H+ protons, and CO2 molecules together with efficient charge separation and the two-electron/two-step oxidative pathway lead to the high reactivity.
- Zhou, Jie,Wu, Han,Sun, Chun-Yi,Hu, Cheng-Ying,Wang, Xin-Long,Kang, Zhen-Hui,Su, Zhong-Min
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- Activity and selectivity regulation through varying the size of cobalt active sites in photocatalytic CO2 reduction
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The development of efficient and economical catalysts for photocatalytic reduction of CO2 into chemical feedstocks is highly desirable for addressing both the global energy crisis and carbon emission problem. Herein, a series of carbonized coba
- Mu, Qiaoqiao,Zhu, Wei,Yan, Gangbin,Lian, Yuebin,Yao, Yuanzhou,Li, Qin,Tian, Yuyu,Zhang, Peng,Deng, Zhao,Peng, Yang
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- A Bioinspired Disulfide/Dithiol Redox Switch in a Rhenium Complex as Proton, H Atom, and Hydride Transfer Reagent
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The transfer of multiple electrons and protons is of crucial importance in many reactions relevant in biology and chemistry. Natural redox-active cofactors are capable of storing and releasing electrons and protons under relatively mild conditions and thus serve as blueprints for synthetic proton-coupled electron transfer (PCET) reagents. Inspired by the prominence of the 2e-/2H+ disulfide/dithiol couple in biology, we investigate herein the diverse PCET reactivity of a Re complex equipped with a bipyridine ligand featuring a unique SH···-S moiety in the backbone. The disulfide bond in fac-[Re(S-Sbpy)(CO)3Cl] (1, S-Sbpy = [1,2]dithiino[4,3-b:5,6-b′]dipyridine) undergoes two successive reductions at equal potentials of-1.16 V vs Fc+|0 at room temperature forming [Re(S2bpy)(CO)3Cl]2- (12-, S2bpy = [2,2′-bipyridine]-3,3′-bis(thiolate)). 12- has two adjacent thiolate functions at the bpy periphery, which can be protonated forming the S-H···-S unit, 1H-. The disulfide/dithiol switch exhibits a rich PCET reactivity and can release a proton (G°H+ = 34 kcal mol-1, pKa = 24.7), an H atom (? G°H = 59 kcal mol-1), or a hydride ion (G°H- = 60 kcal mol-1) as demonstrated in the reactivity with various organic test substrates.
- Hua, Shao-An,Paul, Lucas A.,Oelschlegel, Manuel,Dechert, Sebastian,Meyer, Franc,Siewert, Inke
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- Photoelectrochemical CO2Reduction by a Molecular Cobalt(II) Catalyst on Planar and Nanostructured Si Surfaces
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In the presence of a molecular CoIIcatalyst, CO2reduction occurred at much less negative potentials on Si photoelectrodes than on an Au electrode. The addition of 1 % H2O significantly improved the performance of the CoIIcatalyst. Photovoltages of 580 and 320 mV were obtained on Si nanowires and a planar Si photoelectrode, respectively. This difference likely originated from the fact that the multifaceted Si nanowires are better in light harvesting and charge transfer than the planar Si surface.
- He, Da,Jin, Tong,Li, Wei,Pantovich, Sebastian,Wang, Dunwei,Li, Gonghu
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- Selective Photocatalytic CO2 Reduction in Water through Anchoring of a Molecular Ni Catalyst on CdS Nanocrystals
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Photocatalytic conversion of CO2 into carbonaceous feedstock chemicals is a promising strategy to mitigate greenhouse gas emissions and simultaneously store solar energy in chemical form. Photocatalysts for this transformation are typically based on precious metals and operate in nonaqueous solvents to suppress competing H2 generation. In this work, we demonstrate selective visible-light-driven CO2 reduction in water using a synthetic photocatalyst system that is entirely free of precious metals. We present a series of self-assembled nickel terpyridine complexes as electrocatalysts for the reduction of CO2 to CO in organic media. Immobilization on CdS quantum dots allows these catalysts to be active in purely aqueous solution and photocatalytically reduce CO2 with >90% selectivity under UV-filtered simulated solar light irradiation (AM 1.5G, 100 mW cm-2, λ > 400 nm, pH 6.7, 25 °C). Correlation between catalyst immobilization efficiency and product selectivity shows that anchoring the molecular catalyst on the semiconductor surface is key in controlling the selectivity for CO2 reduction over H2 evolution in aqueous solution.
- Kuehnel, Moritz F.,Orchard, Katherine L.,Dalle, Kristian E.,Reisner, Erwin
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- Pulse-response TAP studies of the reverse water-gas shift reaction over a Pt/CeO2 catalyst
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The temporal analysis of products (TAP) technique was successfully applied for the first time to investigate the reverse water-gas shift (RWGS) reaction over a 2% Pt/CeO2 catalyst. The adsorption/desorption rate constants for CO2 and H2 were determined in separate TAP pulse-response experiments, and the number of H-containing exchangeable species was determined using D2 multipulse TAP experiments. This number is similar to the amount of active sites observed in previous SSITKA experiments. The CO production in the RWGS reaction was studied in a TAP experiment using separate (sequential) and simultaneous pulsing of CO2 and H 2. A small yield of CO was observed when CO2 was pulsed alone over the reduced catalyst, whereas a much higher CO yield was observed when CO2 and H2 were pulsed consecutively. The maximum CO yield was observed when the CO2 pulse was followed by a H2 pulse with only a short (1 s) delay. Based on these findings, we conclude that an associative reaction mechanism dominates the RWGS reaction under these experimental conditions. The rate constants for several elementary steps can be determined from the TAP data. In addition, using a difference in the time scale of the separate reaction steps identified in the TAP experiments, it is possible to distinguish a number of possible reaction pathways.
- Goguet,Shekhtman,Burch,Hardacre,Meunier,Yablonsky
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- Surface activation of cobalt oxide nanoparticles for photocatalytic carbon dioxide reduction to methane
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Cobalt oxide nanoparticles, by surface activation, successfully promoted photocatalytic CO2 reduction with a high efficiency and selectivity in aqueous media. Treatment with N-bromosuccinimide (NBS) resulted in the formation of an active form of Co3O4, removed surfactants, and coordinated Br on the surface, thereby enhancing the catalytic efficiency of CO2 reduction to methane.
- Choi, Ji Yong,Lim, Chan Kyu,Park, Bumjin,Kim, Minjun,Jamal, Aqil,Song, Hyunjoon
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- Eosin Y-Functionalized Conjugated Organic Polymers for Visible-Light-Driven CO2 Reduction with H2O to CO with High Efficiency
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Visible-light-driven photoreduction of CO2 to energy-rich chemicals in the presence of H2O without any sacrifice reagent is of significance, but challenging. Herein, Eosin Y-functionalized porous polymers (PEosinY-N, N=1–3), with high surface areas up to 610 m2 g?1, are reported. They exhibit high activity for the photocatalytic reduction of CO2 to CO in the presence of gaseous H2O, without any photosensitizer or sacrifice reagent, and under visible-light irradiation. Especially, PEosinY-1 derived from coupling of Eosin Y with 1,4-diethynylbenzene shows the best performance for the CO2 photoreduction, affording CO as the sole carbonaceous product with a production rate of 33 μmol g?1 h?1 and a selectivity of 92 %. This work provides new insight for designing and fabricating photocatalytically active polymers with high efficiency for solar-energy conversion.
- Yu, Xiaoxiao,Yang, Zhenzhen,Qiu, Bing,Guo, Shien,Yang, Peng,Yu, Bo,Zhang, Hongye,Zhao, Yanfei,Yang, Xinzheng,Han, Buxing,Liu, Zhimin
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- Porous boron nitride for combined CO2 capture and photoreduction
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Porous and amorphous materials are typically not employed for photocatalytic purposes, like CO2 photoreduction, as their high number of defects can lead to low charge mobility and favour bulk electron-hole recombination. Yet, with a disordered nature can come porosity, which in turn promotes catalyst/reactant interactions and fast charge transfer to reactants. Here, we demonstrate that moving from h-BN, a well-known crystalline insulator, to amorphous BN, we create a semiconductor, which is able to photoreduce CO2 in the gas/solid phase, under both UV-vis and pure visible light and ambient conditions, without the need for cocatalysts. The material selectively produces CO and maintains its photocatalytic stability over several catalytic cycles. The performance of this un-optimized material is on par with that of TiO2, the benchmark in the field. For the first time, we map out experimentally the band edges of porous BN on the absolute energy scale vs. vacuum to provide fundamental insight into the reaction mechanism. Owing to the chemical and structural tunability of porous BN, these findings highlight the potential of porous BN-based structures for photocatalysis particularly solar fuel production.
- Shankar, Ravi,Sachs, Michael,Francàs, Laia,Lubert-Perquel, Daphné,Kerherve, Gwilherm,Regoutz, Anna,Petit, Camille
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- Photoelectrochemical Reduction of CO2 Coupled to Water Oxidation Using a Photocathode with a Ru(II)-Re(I) Complex Photocatalyst and a CoOx/TaON Photoanode
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Photoelectrochemical CO2 reduction activity of a hybrid photocathode, based on a Ru(II)-Re(I) supramolecular metal complex photocatalyst immobilized on a NiO electrode (NiO-RuRe), was confirmed in an aqueous electrolyte solution. Under half-reaction conditions, the NiO-RuRe photocathode generated CO with high selectivity, and its turnover number for CO formation reached 32 based on the amount of immobilized RuRe. A photoelectrochemical cell comprising a NiO-RuRe photocathode and a CoOx/TaON photoanode showed activity for visible-light-driven CO2 reduction using water as a reductant to generate CO and O2, with the assistance of an external electrical (0.3 V) and chemical (0.10 V) bias produced by a pH difference. This is the first example of a molecular and semiconductor photocatalyst hybrid-constructed photoelectrochemical cell for visible-light-driven CO2 reduction using water as a reductant.
- Sahara, Go,Kumagai, Hiromu,Maeda, Kazuhiko,Kaeffer, Nicolas,Artero, Vincent,Higashi, Masanobu,Abe, Ryu,Ishitani, Osamu
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- Highly Efficient Photocatalytic System Constructed from CoP/Carbon Nanotubes or Graphene for Visible-Light-Driven CO2 Reduction
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Visible-light-driven conversion of CO2 to CO and high-value-added carbon products is a promising strategy for mitigating CO2 emissions and reserving solar energy in chemical form. We report an efficient system for CO2 transformation to CO catalyzed by bare CoP, hybrid CoP/carbon nanotubes (CNTs), and CoP/reduced graphene oxide (rGO) in mixed aqueous solutions containing a Ru-based photosensitizer, under visible-light irradiation. The in situ prepared hybrid catalysts CoP/CNT and CoP/rGO show excellent catalytic activities in CO2 reduction to CO, with a catalytic rates of up to 39 510 and 47 330 μmol h?1 g?1 in the first 2 h of reaction, respectively; a high CO selectivity of 73.1 % for the former was achieved in parallel competing reactions in the photoreduction of CO2 and H2O. A combination of experimental and computational studies clearly shows that strong interactions between CoP and carbon-supported materials and partially adsorbed H2O molecules on the catalyst surface significantly improve CO-generating rates.
- Fu, Zi-Cheng,Xu, Rong-Chen,Moore, Joshua T.,Liang, Fei,Nie, Xiao-Cun,Mi, Chen,Mo, Jiang,Xu, Yong,Xu, Quan-Qing,Yang, Zhi,Lin, Zhe-Shuai,Fu, Wen-Fu
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- Photocatalytic reduction of CO2 by CuxO nanocluster loaded SrTiO3 nanorod thin film
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Photocatalytic carbon dioxide (CO2) conversion into carbon monoxide (CO) using H2O as an electron donor was achieved by the strontium titanate (SrTiO3: STO) nanorod thin films loaded with amorphous copper oxide (CuxO) nanoclusters. The loading of the CuxO-cocatalysts onto STO nanorods clearly improved the photocatalytic activity compared to bare STO nanorods. The CuxO-cocatalysts are composed of abundant and non-toxic elements, and can be loaded by using a simple and economical method. Our findings demonstrate that CuxO nanoclusters function as a general cocatalyst and can be used in combination with various semiconductors to construct low-cost and efficient photocatalytic CO2 reduction systems.
- Shoji, Shusaku,Yin, Ge,Nishikawa, Masami,Atarashi, Daiki,Sakai, Etsuo,Miyauchi, Masahiro
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- Plasmonic Hot Electrons from Oxygen Vacancies for Infrared Light-Driven Catalytic CO2 Reduction on Bi2O3?x
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Current plasmonic photocatalysts are mainly based on noble metal nanoparticles and rarely work in the infrared (IR) light range. Herein, cost-effective Bi2O3?x with oxygen vacancies was formed in situ on commercial bismuth powder by calcination at 453.15 K in atmosphere. Interestingly, defects introduced into Bi2O3?x simultaneously induced a localized surface plasmon resonance (LSPR) in the wavelength range of 600–1400 nm and enhanced the adsorption for CO2 molecules, which enabled efficient photocatalysis of CO2-to-CO (ca. 100 % selectivity) even under low-intensity near-IR light irradiation. Significantly, the apparent quantum yield for CO evolution at 940 nm reached 0.113 %, which is approximately 4 times that found at 450 nm. We also showed that the unique LSPR allows for the realization of a nearly linear dependence of photocatalytic CO production rate on light intensity and operating temperature. Finally, based on an IR spectroscopy study, an oxygen-vacancy induced Mars-van Krevlen mechanism was proposed to understand the CO2 reduction reactions.
- Li, Yingxuan,Wen, Miaomiao,Wang, Ying,Tian, Guang,Wang, Chuanyi,Zhao, Jincai
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- Constructing Ordered Three-Dimensional TiO2 Channels for Enhanced Visible-Light Photocatalytic Performance in CO2 Conversion Induced by Au Nanoparticles
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As a typical photocatalyst for CO2 reduction, practical applications of TiO2 still suffer from low photocatalytic efficiency and limited visible-light absorption. Herein, a novel Au-nanoparticle (NP)-decorated ordered mesoporous TiO
- Xue, Hairong,Wang, Tao,Gong, Hao,Guo, Hu,Fan, Xiaoli,Gao, Bin,Feng, Yaya,Meng, Xianguang,Huang, Xianli,He, Jianping
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- Defect-Rich Bi12O17Cl2 Nanotubes Self-Accelerating Charge Separation for Boosting Photocatalytic CO2 Reduction
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Solar-driven reduction of CO2, which converts inexhaustible solar energy into value-added fuels, has been recognized as a promising sustainable energy conversion technology. However, the overall conversion efficiency is significantly limited by the inefficient charge separation and sluggish interfacial reaction dynamics, which resulted from a lack of sufficient active sites. Herein, Bi12O17Cl2 superfine nanotubes with a bilayer thickness of the tube wall are designed to achieve structural distortion for the creation of surface oxygen defects, thus accelerating the carrier migration and facilitating CO2 activation. Without cocatalyst and sacrificing reagent, Bi12O17Cl2 nanotubes deliver high selectivity CO evolution rate of 48.6 μmol g?1 h?1 in water (16.8 times than of bulk Bi12O17Cl2), while maintaining stability even after 12 h of testing. This paves the way to design efficient photocatalysts with collaborative optimizing charge separation and CO2 activation towards CO2 photoreduction.
- Di, Jun,Zhu, Chao,Ji, Mengxia,Duan, Meilin,Long, Ran,Yan, Cheng,Gu, Kaizhi,Xiong, Jun,She, Yuanbin,Xia, Jiexiang,Li, Huaming,Liu, Zheng
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- Photochemical CO2 splitting by metal-to-metal charge-transfer excitation in mesoporous ZrCu(l)-MCM-41 silicate sieve
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Binuclear redox sites consisting of a Zr oxo-bridged to a Cu(I) center have been obtained on the pore surface of MCM-41 silicate sieve by a stepwise grafting procedure, along with isolated metal centers. The bimetallic site features a Zr(IV)-O-Cu(I) to Zr(III)-O-Cu(II) metal-to-metal charge-transfer (MMCT) absorption extending from the UV region to about 500 nm. The Zr-O-Cu linkage is revealed by a Cu(I)-O infrared stretch mode at 643 cm-1. Irradiation of the MMCT chromophore of ZrCu(I)-MCM-41 loaded with 1 atm of CO2 gas at room temperature resulted in growth of CO (2150 cm-1) and H2O (1600 cm-1). Photolysis experiments using 13CO2 and C18O2 demonstrate that carbon monoxide and the oxygen atom of the water product originate from CO2. This indicates splitting of the CO2 by the excited MMCT moiety to CO and a surface OH radical, followed by trapping of the products at Cu(I) centers (OH is reduced to H2O). This is the first observation of CO2 photoreduction at a binuclear MMCT site at the gas-solid interface. Copyright
- Lin, Wenyong,Frei, Heinz
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- Selective photoelectrochemical reduction of aqueous CO2 to CO by solvated electrons
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Reduction of CO2 by direct one-electron activation is extraordinarily difficult because of the -1.9 V reduction potential of CO 2. Demonstrated herein is reduction of aqueous CO2 to CO with greater than 90 % product selectivity by direct one-electron reduction to CO2.- by solvated electrons. Illumination of inexpensive diamond substrates with UV light leads to the emission of electrons directly into water, where they form solvated electrons and induce reduction of CO 2 to CO2.-. Studies using diamond were supported by studies using aqueous iodide ion (I-), a chemical source of solvated electrons. Both sources produced CO with high selectivity and minimal formation of H2. The ability to initiate reduction reactions by emitting electrons directly into solution without surface adsorption enables new pathways which are not accessible using conventional electrochemical or photochemical processes.
- Zhang, Linghong,Zhu, Di,Nathanson, Gilbert M.,Hamers, Robert J.
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- The main factor to improve the performance of CoSe2 for photocatalytic CO2 reduction: Element doping or phase transformation
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In this work, orthorhombic CoSe2 is fabricated by nitrogen doping into a cubic CoSe2 structure, in which the crystalline phase undergoes transformation. The doped atoms lead to the rotation of the Se22- group, and then the faults of phase change can be observed. Thus, the reverse phase transformation provides an opportunity to study the aspects of element doping and phase change on photocatalytic CO2 reduction simultaneously. The phase change material of N-doped orthorhombic CoSe2 shows high activity toward the photoconversion of CO2 to CO, and the average production rate of CO is up to 1.66 × 104 μmol h-1 g-1 in the first 3 hours, being twice as efficient as that of cubic CoSe2. Intermediate COOH? is detected by in situ infrared spectroscopy and theoretical calculations are also conducted to reveal the intrinsic impact of the doping element on the photosplitting of CO2
- Ding, Shujiang,Mo, Jiang,Wang, Xiaoxia,Xie, Guanqun,Xu, Yong
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- A photo-activated process cascaded electrocatalysis for the highly efficient CO2reduction over a core-shell ZIF-8?Co/C
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Light irradiation can affect electronic properties of catalysts and the introduction of appropriate light into electrocatalysts may have a significant impact on the electrocatalytic process; however, this has not been fully studied. Herein, we propose a photo-activated process cascaded electrocatalysis for CO2 reduction to produce syngas over a core-shell ZIF-8?Co/C catalyst. Under light irradiation, the onset potential and overpotential of ZIF-8?Co/C positively shift by 40 and 200 mV, and the syngas production is enhanced 5.2-fold at a bias potential of -0.9 V vs. RHE. It is noteworthy that the electric energy efficiency is enhanced by 30%. Deducting syngas generated by electricity, the solar-to-syngas conversion efficiency (joule to joule) is as high as 5.38%, which outperforms reported photoelectrochemical systems. These devices also relatively maintain high efficiency in neutral pH aqueous solution. Dedicated experiments and in situ transient photovoltage studies demonstrate that the cascaded photo-activation of CO2 and H+ in electrocatalysis accounts for the outstanding catalytic performance. This journal is
- Gu, Jian-Xia,Kang, Zhen-Hui,Su, Zhong-Min,Sun, Chun-Yi,Sun, Yue,Wang, Xin-Long,Zhao, Xue,Zhou, Jie
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- A Highly Selective and Robust Co(II)-Based Homogeneous Catalyst for Reduction of CO2 to CO in CH3CN/H2O Solution Driven by Visible Light
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Visible-light driven reduction of CO2 into chemical fuels has attracted enormous interest in the production of sustainable energy and reversal of the global warming trend. The main challenge in this field is the development of efficient, selective, and economic photocatalysts. Herein, we report a Co(II)-based homogeneous catalyst, [Co(NTB)CH3CN](ClO4)2 (1, NTB = tris(benzimidazolyl-2-methyl)amine), which shows high selectivity and stability for the catalytic reduction of CO2 to CO in a water-containing system driven by visible light, with turnover number (TON) and turnover frequency (TOF) values of 1179 and 0.032 s-1, respectively, and selectivity to CO of 97%. The high catalytic activity of 1 for photochemical CO2-to-CO conversion is supported by the results of electrochemical investigations and DFT calculations.
- Ouyang, Ting,Hou, Cheng,Wang, Jia-Wei,Liu, Wen-Ju,Zhong, Di-Chang,Ke, Zhuo-Feng,Lu, Tong-Bu
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- Absolute Templating of M(111) Cluster Surrogates by Galvanic Exchange
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The precise preparation of monodisperse nanomaterials is among the most fundamental tasks in inorganic synthesis and materials science. Achieving this goal by galvanic exchange is hardly predictable and often results in major structural changes and polydisperse mixtures. Taking advantage of the enhanced stability imparted by ambiphilic carbenes, we report and rationalize the absolute templating, the complete exchange of metals in a template, of group 11 clusters across the entire coinage metal family by means of galvanic exchange. We further delineate that these species provide a molecular model for better understanding the reduction of CO2 at M(111) coinage metal surfaces.
- Peltier, Jesse L.,Soleilhavoup, Michele,Martin, David,Jazzar, Rodolphe,Bertrand, Guy
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- Enhancement of CO Evolution by Modification of Ga2O3 with Rare-Earth Elements for the Photocatalytic Conversion of CO2 by H2O
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Modification of the surface of Ga2O3 with rare-earth elements enhanced the evolution of CO as a reduction product in the photocatalytic conversion of CO2 using H2O as an electron donor under UV irradiation in aqueous NaHCO3 as a pH buffer, with the rare-earth species functioning as a CO2 capture and storage material. Isotope experiments using 13CO2 as a substrate clearly revealed that CO was generated from the introduced gaseous CO2. In the presence of the NaHCO3 additive, the rare-earth (RE) species on the Ga2O3 surface are transformed into carbonate hydrates (RE2(CO3)3·nH2O) and/or hydroxycarbonates (RE2(OH)2(3-x)(CO3)x) which are decomposed upon photoirradiation. Consequently, Ag-loaded Yb-modified Ga2O3 exhibits much higher activity (209 μmol h-1 of CO) than the pristine Ag-loaded Ga2O3. The further modification of the surface of the Yb-modified Ga2O3 with Zn afforded a selectivity toward CO evolution of 80%. Thus, we successfully achieved an efficient Ag-loaded Yb- and Zn-modified Ga2O3 photocatalyst with high activity and controllable selectivity, suitable for use in artificial photosynthesis.
- Tatsumi, Hiroyuki,Teramura, Kentaro,Huang, Zeai,Wang, Zheng,Asakura, Hiroyuki,Hosokawa, Saburo,Tanaka, Tsunehiro
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- Highly efficient visible-light-driven CO2 reduction to CO using a Ru(ii)-Re(i) supramolecular photocatalyst in an aqueous solution
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In an aqueous solution, [Ru(dmb)2-(BL)-Re(CO)3Cl]2+ (BL = bridging ligand) most efficiently photocatalyzed the reduction of CO2 to CO under visible-light irradiation using 2-(1,3-dimethyl-2,3-dihydro-1H-benzimidazol-2-yl)benzoic acid (BI(CO2H)H) as a water-soluble sacrificial reductant (ΦCO = 13%, TON = 130). Since BI(CO2H)H could efficiently produce one-electron-reduced species of [Ru(diimine)3]2+-type complexes under visible-light irradiation even in an aqueous solution, that is one of the main reasons why the photocatalytic system induced the highly efficient CO2 reduction. This result strongly indicates that BI(CO2H)H should be a useful reductant for evaluating the real abilities of various photocatalytic systems in water as well.
- Nakada, Akinobu,Koike, Kazuhide,Maeda, Kazuhiko,Ishitani, Osamu
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- Efficient Photocatalytic CO2 Reduction by a Ni(II) Complex Having Pyridine Pendants through Capturing a Mg2+ Ion as a Lewis-Acid Cocatalyst
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We have synthesized a new Ni(II) complex having an S2N2-tetradentate ligand with two noncoordinating pyridine pendants as binding sites of Lewis-acidic metal ions in the vicinity of the Ni center, aiming at efficient CO production in photocatalytic CO2 reduction. In the presence of Mg2+ ions, enhancement of selective CO formation was observed in photocatalytic CO2 reduction by the Ni complex with the pyridine pendants through the formation of a Mg2+-bound species, as compared to the previously reported Ni complex without the Lewis-acid capturing sites. A higher quantum yield of CO evolution for the Mg2+-bound Ni complex was determined to be 11.1percent. Even at lower CO2 concentration (5percent), the Ni complex with the pendants exhibited comparable CO production to that at the CO2-saturated concentration (100percent). The Mg2+-bound Ni complex was evidenced by mass spectrometry and 1H NMR measurements. The enhancement of CO2 reduction by the Mg2+-bound species should be derived from cooperativity between the Ni and Mg centers for the stabilization of a Ni-CO2 intermediate by a Lewis-acidic Mg2+ ion captured in the vicinity of the Ni center, as supported by DFT calculations. The detailed mechanism of photocatalytic CO2 reduction by the Ni complex with the pyridine pendants in the presence of Mg2+ ions is discussed based on spectroscopic detection of the intermediate and kinetic analysis.
- Hong, Dachao,Kawanishi, Takuya,Tsukakoshi, Yuto,Kotani, Hiroaki,Ishizuka, Tomoya,Kojima, Takahiko
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- Metallic Cobalt–Carbon Composite as Recyclable and Robust Magnetic Photocatalyst for Efficient CO2 Reduction
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CO2 conversion into value-added chemical fuels driven by solar energy is an intriguing approach to address the current and future demand of energy supply. Currently, most reported surface-sensitized heterogeneous photocatalysts present poor activity and selectivity under visible light irradiation. Here, photosensitized porous metallic and magnetic 1200 Co?C composites (PMMCoCC-1200) are coupled with a [Ru(bpy)3]Cl2 photosensitizer to efficiently reduce CO2 under visible-light irradiation in a selective and sustainable way. As a result, the CO production reaches a high yield of 1258.30 μL with selectivity of 64.21% in 6 h, superior to most reported heterogeneous photocatalysts. Systematic investigation demonstrates that the central metal cobalt is the active site for activating the adsorbed CO2 molecules and the surficial graphite carbon coating on cobalt metal is crucial for transferring the electrons from the triplet metal-to-ligand charge transfer of the photosensitizer Ru(bpy)32+, which gives rise to significant enhancement for CO2 reduction efficiency. The fast electron injection from the excited Ru(bpy)32+ to PMMCoCC-1200 and the slow backward charge recombination result in a long-lived, charge-separated state for CO2 reduction. More impressively, the long-time stability and easy magnetic recycling ability of this metallic photocatalyst offer more benefits to the photocatalytic field.
- Zhao, Kun,Zhao, Shenlong,Gao, Chao,Qi, Jian,Yin, Huajie,Wei, Ding,Mideksa, Megasia Feyissa,Wang, Xiaoli,Gao, Yan,Tang, Zhiyong,Yu, Ranbo
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- Direct Z-Scheme Heterojunction of SnS2/Sulfur-Bridged Covalent Triazine Frameworks for Visible-Light-Driven CO2 Photoreduction
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Solar-driven reduction of CO2 into renewable carbon forms is considered as an alternative approach to address global warming and the energy crisis but suffers from low efficiency of the photocatalysts. Herein, a direct Z-Scheme SnS2/sulfur-bridged covalent triazine frameworks (S-CTFs) photocatalyst (denoted as SnS2/S-CTFs) was developed, which could efficiently adsorb CO2 owing to the CO2-philic feature of S-CTFs and promote separation of photoinduced electron–hole pairs. Under visible-light irradiation, SnS2/S-CTFs exhibited excellent performance for CO2 photoreduction, yielding CO and CH4 with evolution rates of 123.6 and 43.4 μmol g?1 h?1, respectively, much better than the most catalysts reported to date. This inorganic/organic hybrid with direct Z-Scheme structure for visible-light-driven CO2 photoreduction provides new insights for designing photocatalysts with high efficiency for solar-to-fuel conversion.
- Guo, Shien,Yang, Peng,Zhao, Yanfei,Yu, Xiaoxiao,Wu, Yunyan,Zhang, Hongye,Yu, Bo,Han, Buxing,George, Michael W.,Liu, Zhimin
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- Boosting CO2-To-CO conversion on a robust single-Atom copper decorated carbon catalyst by enhancing intermediate binding strength
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The ability to manipulate the binding strengths of intermediates on a catalyst is extremely challenging but essential for active and selective CO2 electroreduction (CO2RR). Single-Atom copper anchored on a nitrogenated carbon (Cu-N-C) structure is still rarely unexplored for efficient CO production. Herein, we demonstrate a plausible hydrogen-bonding promoted strategy that significantly enhances the ?COOH adsorption and facilitates the ?CO desorption on a Cu-N-C catalyst. The as-prepared Cu-N-C catalyst with Cu-N3 coordination achieves a high CO faradaic efficiency (FE) of 98% at-0.67 V (vs. reversible hydrogen electrode) as well as superior stability (FE remains above 90% over 20 h). Notably, in a three-phase flow cell configuration, a remarkable CO2 to CO FE of 99% at-0.67 V accompanying a large CO partial current density of 131.1 mA cm-2 at-1.17 V was observed. Density functional theory calculations reveal that the Cu-N3 coordination is potentially stabilized by an extended carbon plane with six nitrogen vacancies, while three unoccupied N sites are spontaneously saturated by protons during the CO2RR. Therefore, the hydrogen bonds formed between the adsorbed ?COOH and adjacent protons significantly reduce the energy barrier of ?COOH formation. After the first proton-coupled electron transfer process, the adsorbed ?CO species are easily released to boost the CO production.
- Chen, Shixia,Li, Yuewei,Bu, Zhuogang,Yang, Fangqi,Luo, Junhui,An, Qizheng,Zeng, Zheling,Wang, Jun,Deng, Shuguang
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- Visible-light-driven conversion of CO2 from air to CO using an ionic liquid and a conjugated polymer
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A metal-free and highly efficient catalytic system involving a task-specific ionic liquid, [P4444][p-2-O], and a pyrene-based conjugated polymer was developed for direct CO2 capture from air and its further photoreduction to CO under visible light irradiation, affording a CO production rate of 47.37 μmol g-1 h-1 with a selectivity of 98.3%.
- Chen, Yu,Ji, Guipeng,Guo, Shien,Yu, Bo,Zhao, Yanfei,Wu, Yunyan,Zhang, Hongye,Liu, Zhenghui,Han, Buxing,Liu, Zhimin
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- Covalent Organic Framework Nanosheets Embedding Single Cobalt Sites for Photocatalytic Reduction of Carbon Dioxide
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Covalent organic framework nanosheets (CONs), fabricated from two-dimensional covalent organic frameworks (COFs), present a promising strategy for incorporating atomically distributed catalytic metal centers into well-defined pore structures with desirable chemical environments. Here, a series of CONs was synthesized by embedding single cobalt sites that were then evaluated for photocatalytic carbon dioxide reduction. A partially fluorinated, cobalt-loaded CON produced 10.1 μmol carbon monoxide with a selectivity of 76%, over 6 hours irradiation under visible light (TON = 28.1), and a high external quantum efficiency (EQE) of 6.6% under 420 nm irradiation in the presence of an iridium dye. The CONs appear to act as a semiconducting support, facilitating charge carrier transfer between the dye and the cobalt centers, and this results in a performance comparable with that of the state-of-the-art heterogeneous catalysts in the literature under similar conditions. The ultrathin CONs outperformed their bulk counterparts in all cases, suggesting a general strategy to enhance the photocatalytic activities of COF materials.
- Wang, Xiaoyan,Fu, Zhiwei,Zheng, Lirong,Zhao, Chengxi,Wang, Xue,Chong, Samantha Y.,McBride, Fiona,Raval, Rasmita,Bilton, Matthew,Liu, Lunjie,Wu, Xiaofeng,Chen, Linjiang,Sprick, Reiner Sebastian,Cooper, Andrew I.
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- Conductive Two-Dimensional Phthalocyanine-based Metal–Organic Framework Nanosheets for Efficient Electroreduction of CO2
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The electrocatalytic conversion of CO2 into value-added chemicals is a promising approach to realize a carbon-energy balance. However, low current density still limits the application of the CO2 electroreduction reaction (CO2RR). Metal–organic frameworks (MOFs) are one class of promising alternatives for the CO2RR due to their periodically arranged isolated metal active sites. However, the poor conductivity of traditional MOFs usually results in a low current density in CO2RR. We have prepared conductive two-dimensional (2D) phthalocyanine-based MOF (NiPc-NiO4) nanosheets linked by nickel-catecholate, which can be employed as highly efficient electrocatalysts for the CO2RR to CO. The obtained NiPc-NiO4 has a good conductivity and exhibited a very high selectivity of 98.4 % toward CO production and a large CO partial current density of 34.5 mA cm?2, outperforming the reported MOF catalysts. This work highlights the potential of conductive crystalline frameworks in electrocatalysis.
- Cao, Rong,Chai, Guo-Liang,Huang, Yuan-Biao,Si, Duan-Hui,Wu, Qiao,Xie, Ruikuan,Yi, Jun-Dong,Yin, Qi,Zhang, Meng-Di
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- Flower-like CoAl layered double hydroxides modified with CeO2 and RGO as efficient photocatalyst towards CO2 reduction
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In this article, a simple yet effective in situ hydrothermal method has been developed to synthesize a series of CeO2 and reduced graphene oxide (RGO) stepwise-doped CoAl-LDH (CACR) composites with CoAl-LDH/CeO2 (CAC) as the intermediate. The smart design well integrates the photo-electrochemical merits of CoAl-LDHs and CeO2 with conductive RGO to form an optimized formula with high light-harvesting ability, efficient charge separation, and rapid electron transfer. Owing to these features, the sample of CAC-5-R-10 containing 5 wt% CeO2 and 10 wt% RGO, is found to be the most efficient one as the catalyst for CO2 photoreduction with a high average CO evolution rate of 5.5 μmol·g?1·h?1 at 25 °C without sacrifice reagent or extra photosensitizer under ultraviolet light, which surpasses those of the single CeO2, CoAl-LDHs, the intermediate of CAC, and many reported LDH-based counterparts. With the assistance of Mott–Schottky curves, the Z-scheme mechanism is proposed for the significantly enhanced photo-activity of the CAC-5-R-10. The present work provides a good sample for integrating LDHs with a second semiconductor and conductive RGO for collaborative optimization of photoelectric characteristics towards enhanced CO2 photoreduction.
- Li, Yang,Li, Zhao,Liu, Zhi,Wang, Qiu
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- Direct detection of key reaction intermediates in photochemical CO 2 reduction sensitized by a rhenium bipyridine complex
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Photochemical CO2 reduction sensitized by rhenium-bipyridyl complexes has been studied through multiple approaches during the past several decades. However, a key reaction intermediate, the CO2-coordinated Re-bipyridyl complex, which should govern the activity of CO2 reduction in the photocatalytic cycle, has never been detected in a direct way. In this study on photoreduction of CO2 catalyzed by the 4,4′-dimethyl-2,2′-bipyridine (dmbpy) complex, [Re(dmbpy)(CO) 3Cl] (1), we successfully detect the solvent-coordinated Re complex [Re(dmbpy)(CO)3DMF] (2) as the light-absorbing species to drive photoreduction of CO2. The key intermediate, the CO 2-coordinated Re-bipyridyl complex, [Re(dmbpy)(CO) 3(COOH)], is also successfully detected for the first time by means of cold-spray ionization spectrometry (CSI-MS). Mass spectra for a reaction mixture with isotopically labeled 13CO2 provide clear evidence for the incorporation of CO2 into the Re-bipyridyl complex. It is revealed that the starting chloride complex 1 was rapidly transformed into the DMF-coordinated Re complex 2 through the initial cycle of photoreduction of CO2. The observed induction period in the time profile of the CSI-MS signals can well explain the subsequent formation of the CO2- coordinated intermediate from the solvent-coordinated Re-bipyridyl complex. An FTIR study of the reaction mixture in dimethyl sulfoxide clearly shows the appearance of a signal at 1682 cm-1, which shifts to 1647 cm -1 for the 13CO2-labeled counterpart; this is assigned as the CO2-coordinated intermediate, ReII-COOH. Thus, a detailed understanding has now been obtained for the mechanism of the archetypical photochemical CO2 reduction sensitized by a Re-bipyridyl complex.
- Kou, Youki,Nabetani, Yu,Masui, Dai,Shimada, Tetsuya,Takagi, Shinsuke,Tachibana, Hiroshi,Inoue, Haruo
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- Building a Bridge from Papermaking to Solar Fuels
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Black liquor, an industrial waste product of papermaking, is primarily used as a low-grade combustible energy source. Despite its high lignin content, the potential utility of black liquor as a feedstock in products manufacturing, remains to be exploited. Demonstrated here in is the use of black liquor as a primary feed-stock for synthesizing graphene quantum dots that exhibit both up-conversion and photoluminescence when excited using visible/near-infrared radiation, thereby enabling the photosensitization of ultraviolet-absorbing TiO2 nanosheets. In addition, these graphene quantum dots can trap photo-generated electrons to realize the effective separation of electron-hole pairs. Together, these two processes facilitate the solar-powered generation of H2 from H2O, and CO from H2O–CO2, using broadband solar radiation.
- Jiang, Zaiyong,Zhang, Xinhan,Sun, Wei,Yang, Deren,Duchesne, Paul N.,Gao, Yugang,Wang, Zeyan,Yan, Tingjiang,Yuan, Zhimin,Yang, Guihua,Ji, Xingxiang,Chen, Jiachuan,Huang, Baibiao,Ozin, Geoffrey A.
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- Palladium-catalyzed carbonylative α-arylation of 2-oxindoles with (Hetero)aryl bromides: Efficient and complementary approach to 3-acyl-2-oxindoles
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An efficient Pd-catalyzed carbonylative α-arylation of 2-oxindoles with aryl and heteroaryl bromides for the one-step synthesis of 3-acyl-2-oxindoles has been developed. This reaction proceeds efficiently under mild conditions and is complementary to the
- Lian, Zhong,Friis, Stig D.,Skrydstrup, Troels
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- ZnSe quantum dots modified with a Ni(cyclam) catalyst for efficient visible-light driven CO2 reduction in water
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A precious metal and Cd-free photocatalyst system for efficient CO2 reduction in water is reported. The hybrid assembly consists of ligand-free ZnSe quantum dots (QDs) as a visible-light photosensitiser combined with a phosphonic acid-functiona
- Kuehnel, Moritz F.,Sahm, Constantin D.,Neri, Gaia,Lee, Jonathan R.,Orchard, Katherine L.,Cowan, Alexander J.,Reisner, Erwin
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- Ultrathin and Small-Size Graphene Oxide as an Electron Mediator for Perovskite-Based Z-Scheme System to Significantly Enhance Photocatalytic CO2 Reduction
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The judicious design of efficient electron mediators to accelerate the interfacial charge transfer in a Z-scheme system is one of the viable strategies to improve the performance of photocatalysts for artificial photosynthesis. Herein, ultrathin and small-size graphene oxide (USGO) nanosheets are constructed and employed as the electron mediator to elaborately exploit an efficient CsPbBr3-based all-solid-state Z-scheme system in combination with α-Fe2O3 for visible-light-driven CO2 reduction with water as the electron source. CsPbBr3 and α-Fe2O3 can be closely anchored on USGO nanosheets, owing to the existence of interfacial strong chemical bonding behaviors, which can significantly accelerate the photogenerated carrier transfer between CsPbBr3 and α-Fe2O3. The resultant improved charge separation efficiency endows the Z-scheme system exhibiting a record-high electron consumption rate of 147.6 μmol g?1 h?1 for photocatalytic CO2-to-CO conversion concomitant with stoichiometric O2 from water oxidation, which is over 19 and 12 times higher than that of pristine CsPbBr3 nanocrystals and the mixture of CsPbBr3 and α-Fe2O3, respectively. This work provides a novel and effective strategy for improving the catalytic activity of halide-perovskite-based photocatalysts, promoting their practical applications in the field of artificial photosynthesis.
- Mu, Yan-Fei,Zhang, Wen,Dong, Guang-Xing,Su, Ke,Zhang, Min,Lu, Tong-Bu
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- Edge activation of an inert polymeric carbon nitride matrix with boosted absorption kinetics and near-infrared response for efficient photocatalytic CO2reduction
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The reduction of CO2 into C1 feedstocks (e.g., CO) by utilizing solar energy has attracted increasing attention for the efficient production of renewable energy. However, a significant challenge in the reduction of CO2 is achieving high conversion efficiency due to the high CO dissociation energy of CO2 and difficultly in accessing the surface of photocatalysts. Herein, we fabricated a polymeric carbon nitride (PCN) catalyst with hydroxyethyl groups grafted on its edge via a facile bottom-up strategy, facilitating the efficient surface absorption of CO2 and lowering the CO2 transformation energy barrier; this was accompanied with exceptional extended optical absorption ability to the near-infrared region and increase in the density of states at the Fermi level. Thus, concentrated CO2 molecules could contact the surface of PCN and be easily activated; this resulted in an excellent CO production rate of up to 209.24 μmol h-1 g-1 in the modified PCN (i.e., 39.5-fold increase compared to that of pristine PCN) and a selectivity of 98.5% under white LED illumination, exceeding that of most PCN-based energy conversion systems reported to date. Notably, this PCN matrix also exhibited photocatalytic activity for the production of CO in the near-infrared region from 780 to 850 nm. These results pave the way for the development of structured photocatalysts with easy accessibility for CO2 and broadband spectral response for the efficient photocatalytic reduction of CO2. This journal is
- Liu, Qiong,Chen, Zhongxin,Tao, Weijian,Zhu, Haiming,Wang, Fuxian,Zhong, Linxin,Zou, Ren,Lei, Yongqian,Liu, Cuibo,Peng, Xinwen
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- The Homogeneous Reduction of CO2 by [Ni(cyclam)]+: Increased Catalytic Rates with the Addition of a CO Scavenger
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The homogeneous electrochemical reduction of CO2 by the molecular catalyst [Ni(cyclam)]2+ is studied by electrochemistry and infrared spectroelectrochemistry. The electrochemical kinetics are probed by varying CO2 substrate and proton concentrations. Products of CO2 reduction are observed in infrared spectra obtained from spectroelectrochemical experiments. The two major species observed are a Ni(I) carbonyl, [Ni(cyclam)(CO)]+, and a Ni(II) coordinated bicarbonate, [Ni(cyclam)(CO2OH)]+. The rate-limiting step during electrocatalysis is determined to be CO loss from the deactivated species, [Ni(cyclam)(CO)]+, to produce the active catalyst, [Ni(cyclam)]+. Another macrocyclic complex, [Ni(TMC)]+, is deployed as a CO scavenger in order to inhibit the deactivation of [Ni(cyclam)]+ by CO. Addition of the CO scavenger is shown to dramatically increase the catalytic current observed for CO2 reduction. Evidence for the [Ni(TMC)]+ acting as a CO scavenger includes the observation of [Ni(TMC)(CO)]+ by IR. Density functional theory (DFT) calculations probing the optimized geometry of the [Ni(cyclam)(CO)]+ species are also presented.
- Froehlich, Jesse D.,Kubiak, Clifford P.
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- Partially Oxidized SnS2 Atomic Layers Achieving Efficient Visible-Light-Driven CO2 Reduction
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Unraveling the role of surface oxide on affecting its native metal disulfide's CO2 photoreduction remains a grand challenge. Herein, we initially construct metal disulfide atomic layers and hence deliberately create oxidized domains on their surfaces. As an example, SnS2 atomic layers with different oxidation degrees are successfully synthesized. In situ Fourier transform infrared spectroscopy spectra disclose the COOH? radical is the main intermediate, whereas density-functional-theory calculations reveal the COOH? formation is the rate-limiting step. The locally oxidized domains could serve as the highly catalytically active sites, which not only benefit for charge-carrier separation kinetics, verified by surface photovoltage spectra, but also result in electron localization on Sn atoms near the O atoms, thus lowering the activation energy barrier through stabilizing the COOH? intermediates. As a result, the mildly oxidized SnS2 atomic layers exhibit the carbon monoxide formation rate of 12.28 μmol g-1 h-1, roughly 2.3 and 2.6 times higher than those of the poorly oxidized SnS2 atomic layers and the SnS2 atomic layers under visible-light illumination. This work uncovers atomic-level insights into the correlation between oxidized sulfides and CO2 reduction property, paving a new way for obtaining high-efficiency CO2 photoreduction performances.
- Jiao, Xingchen,Li, Xiaodong,Jin, Xiuyu,Sun, Yongfu,Xu, Jiaqi,Liang, Liang,Ju, Huanxin,Zhu, Junfa,Pan, Yang,Yan, Wensheng,Lin, Yue,Xie, Yi
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- A hexanuclear cobalt metal-organic framework for efficient CO2 reduction under visible light
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Increasing global challenges including climate warming and energy shortage have stimulated worldwide explorations for efficient materials for applications in the capture of CO2 and its conversion to chemicals. In this study, a novel pillared-layer porous metal-organic framework (Co6-MOF) with high nuclearity CoII clusters has been synthesized. This material exhibited a CO2 adsorption capacity of up to 55.24 cm3 g-1 and 38.17 cm3 g-1 at 273 K and 298 K, respectively. In a heterogeneous photocatalytic system of CO2 reduction, this material, co-operated with a ruthenium-based photosensitizer, can efficiently realize CO2 to CO conversion. Under visible-light irradiation for 3 hours, 39.36 μmol CO and 28.13 μmol H2 were obtained. This result is higher than those of most of the reported MOF materials under similar conditions and to the best of our knowledge, this is the first example of a high nuclear MOF used in CO2 reduction. The rooted reasons behind the high reactivity were studied through theoretical calculation studies. The results showed that electrons on reduced [Ru(bpy)3]Cl2·6H2O (bpy = 4,4′-bipyridine) could transfer to the Co6-MOF and the adsorbed CO2 molecule on the charged Co6-MOF could be activated more facilely. This work not only clarifies the reasons for high efficiency of the CO2 photoreduction system but also points out to us the direction for designing more effective MOF materials as photocatalysts for artificial CO2 photoreduction.
- Zhao, Jiao,Wang, Qi,Sun, Chunyi,Zheng, Tiantian,Yan, Likai,Li, Mengting,Shao, Kuizhan,Wang, Xinlong,Su, Zhongmin
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- Dependence of the intrinsic phase structure of Bi2O3catalysts on photocatalytic CO2reduction
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Rapid recombination of charge carriers and the low efficiency of surface catalysis limit the photocatalytic CO2reduction performance. Herein, models of Bi2O3with different phase structures were investigated to achieve in-depth understanding of the role that phase structure plays in the photocatalytic CO2process. The gamma phase of Bi2O3(γ-Bi2O3) exhibited significantly enhanced charge separation ability compared with that of the alpha phase (α-Bi2O3) and beta phase (β-Bi2O3). Charge-carrier dynamics revealed that the decay lifetime was increased in γ-Bi2O3, indicating the enhanced charge carrier separation and migration ability in the γ phase of Bi2O3. As expected, the γ-Bi2O3photocatalyst exhibited a remarkably improved photocatalytic CO2reduction activity of 48.10 μmol h?1g?1, which was nearly 3.19 and 1.62 times higher than that of α-Bi2O3and β-Bi2O3, respectively. This work indicates how phase structure affects charge separation and photocatalytic activity, and could open new opportunities for achieving highly efficient photocatalysts and reaction systems.
- Wei, Liujin,Huang, Guan,Zhang, Yajun
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- Transition-Metal Single Atoms in a Graphene Shell as Active Centers for Highly Efficient Artificial Photosynthesis
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Utilizing solar energy to fix CO2 with water into chemical fuels and oxygen, a mimic process of photosynthesis in nature, is becoming increasingly important but still challenged by low selectivity and activity, especially in CO2 electrocatalytic reduction. Here, we report transition-metal atoms coordinated in a graphene shell as active centers for aqueous CO2 reduction to CO with high faradic efficiencies over 90% under significant currents up to ～60 mA/mg. We employed three-dimensional atom probe tomography to directly identify the single Ni atomic sites in graphene vacancies. Theoretical simulations suggest that compared with metallic Ni, the Ni atomic sites present different electronic structures that facilitate CO2-to-CO conversion and suppress the competing hydrogen evolution reaction dramatically. Coupled with Li+-tuned Co3O4 oxygen evolution catalyst and powered by a triple-junction solar cell, our artificial photosynthesis system achieves a peak solar-to-CO efficiency of 12.7% by using earth-abundant transition-metal electrocatalysts in a pH-equal system. Using clean electricity to reduce CO2 to chemicals or fuels is becoming increasingly important to renewable energy applications and environmental protection. The challenge comes from the strong competition with the hydrogen evolution reaction in aqueous solutions, especially for those earth-abundant transition metals such as Ni, which dramatically lowers the CO2 reduction selectivity. Isolating the transition-metal single atoms into a graphene matrix can significantly tune their catalytic behaviors to favor the CO2-to-CO reduction pathway, reaching a high CO selectivity of more than 90%. This work creates an important platform in designing active and low-cost CO2 reduction catalysts with high selectivity toward fuels, opening up great opportunities for both technological applications in renewable energies and fundamental mechanism studies in catalysis. State-of-the-art three-dimensional atom probe tomography provides direct evidence of Ni single atoms coordinated in graphene vacancies for highly selective CO2 reduction to CO and suppressed hydrogen evolution in water.
- Jiang, Kun,Siahrostami, Samira,Akey, Austin J.,Li, Yanbin,Lu, Zhiyi,Lattimer, Judith,Hu, Yongfeng,Stokes, Chris,Gangishetty, Mahesh,Chen, Guangxu,Zhou, Yawei,Hill, Winfield,Cai, Wen-Bin,Bell, David,Chan, Karen,N?rskov, Jens K.,Cui, Yi,Wang, Haotian
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- Visible-Light Photochemical Reduction of CO2 to CO Coupled to Hydrocarbon Dehydrogenation
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Research on the photochemical reduction of CO2, initiated already 40 years ago, has with few exceptions been performed by using amines as sacrificial reductants. Hydrocarbons are high-volume chemicals whose dehydrogenation is of interest, so the coupling of a CO2 photoreduction to a hydrocarbon-photodehydrogenation reaction seems a worthwhile concept to explore. A three-component construct was prepared including graphitic carbon nitride (g-CN) as a visible-light photoactive semiconductor, a polyoxometalate (POM) that functions as an electron acceptor to improve hole–electron charge separation, and an electron donor to a rhenium-based CO2 reduction catalyst. Upon photoactivation of g-CN, a cascade is initiated by dehydrogenation of hydrocarbons coupled to the reduction of the polyoxometalate. Visible-light photoexcitation of the reduced polyoxometalate enables electron transfer to the rhenium-based catalyst active for the selective reduction of CO2 to CO. The construct was characterized by zeta potential, IR spectroscopy, thermogravimetry, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). An experimental Z-scheme diagram is presented based on electrochemical measurements and UV/Vis spectroscopy. The conceptual advance should promote study into more active systems.
- Haviv, Eynat,Neumann, Ronny,Yu, Huijun
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- Visible-light-induced transition metal and photosensitizer free decarbonylative addition of amino-arylaldehydes to ketones
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The decarbonylative-coupling reaction is generally promoted by transition metals (via organometallic complexes) or peroxides (via radical intermediates), often at high temperatures to facilitate the CO release. Herein, a visible-light-induced, transition metal and external photosensitizer free decarbonylative addition of benzaldehydes to ketones/aldehydes at room temperature is reported. Tertiary/secondary alcohols were obtained in moderate to excellent yields promoted by using CsF under mild conditions. The detailed mechanistic investigation showed that the reaction proceeded through photoexcitation–decarbonylation of the aldehyde to generate an aromatic anion, followed by its addition to ketones/aldehydes. The reaction mechanism was verified by the density functional theory (DFT) calculations.
- Lang, Yatao,Li, Chao-Jun,Wang, Yi,Zeng, Huiying
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p. 698 - 703
(2022/02/01)
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- Ultra-fast construction of CuBi2O4 films supported Bi2O3 with dominant (0 2 0) facets for efficient CO2 photoreduction in water vapor
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CuBi2O4/Bi2O3 thin film was synthesized on the commercial glass by a spray pyrolysis-calcination method. The monoclinic phase Bi2O3 with dominant (0 2 0) facets was grown on the surface of tetragonal phase CuBi2O4 by the temperature control of spraying process. Photocatalytic activities of the synthesized materials for CO2 reduction were measured in the presence of water vapor under visible light irradiation (λ > 400 nm). The CO, CH4 and O2 yields of the optimal composite film reached 247.62, 119.27 and 418.00 μmol/m2 after 12 h of irradiation. The composite film resisted physical damage and showed good photocatalytic activity in the cycling tests. Moreover, it was found that the types of main products changed with the light intensity and their yields varied with the light wavelength. The exposed (0 2 0) facets efficiently improved the adsorbed ability for H2O molecules. Meanwhile, the hydrophobicity of the film surface ensured that the adsorbed sites of CO2 were unoccupied by abundant H2O molecules. The S-scheme charge transfer mechanism was further confirmed by the interlaced band alignment of the CuBi2O4/Bi2O3 heterostructure and the controlled experiment with different light conditions. The results gained in this report may open up an avenue to design advanced S-scheme heterostructures with suitable transitional-metal oxides for photoreduction CO2 to solar fuels.
- Shi, Weina,Wang, Ji-Chao,Guo, Xiaowei,Tian, Hong-Ling,Zhang, Wanqing,Gao, Huiling,Han, Huijuan,Li, Renlong,Hou, Yuxia
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supporting information
(2021/09/20)
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- Highly Durable and Fully Dispersed Cobalt Diatomic Site Catalysts for CO2 Photoreduction to CH4
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Dual-atom-site catalysts (DACs) have emerged as a new frontier in heterogeneous catalysis because the synergistic effect between adjacent metal atoms can promote their catalytic activity while maintaining the advantages of single-atom-site catalysts, such as almost 100 % atomic efficiency and excellent hydrocarbon selectivity. In this study, cobalt-based atom site catalysts with a Co2–N coordination structure were synthesized and used for photodriven CO2 reduction. The resulting CoDAC containing 3.5 % Co atoms demonstrated a superior atom ratio for CO2 reduction catalytic performance, with 65.0 % CH4 selectivity, which far exceeds that of cobalt-based single-atom-site catalysts (CoSACs). The intrinsic reason for the superior activity of CoDACs is the excellent adsorption strength of CO2 and CO* intermediates at dimeric Co active sites.
- Wang, Jinming,Kim, Eunhyo,Kumar, Dharani Praveen,Rangappa, Akkammagari Putta,Kim, Yujin,Zhang, Yuexing,Kim, Tae Kyu
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supporting information
(2021/12/30)
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- Syntheses of ZnTi-LDH sensitized by tetra (4-carboxyphenyl) porphyrin for accerlating photocatalytic reduction of carbon dioxide
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A strategy of covalently combining layered double hydroxides (LDHs) with photosensitizer was designed to construct organic-inorganic heterojunction for prompting photocatalytic reduction of CO2. A series of tetra (4-carboxyphenyl) porphyrin sensitized ZnTi-LDH (TCPP/ZT) were prepared by an in site hydrothermal method to uniformly load the TCPP molecules on the ZnTi-LDH scaffold, on which the incorporation of TCPP not only broadens the light absorption range, but also facilitates separation and migration of the photogenerated charge carriers, thereby leads to enhancement of the photocatalytic activity. Among the TCPP/ZT, 2 ?wt% TCPP on ZT exhibited a superior photocatalytic performance in CO2 and the cumulative output of CH4 and CO in 5 ?h reached 8.65 ?μmol/g and 1.72 ?μmol/g, respectively, which are 2.50 and 1.56 times higher than those on ZnTi-LDH. The XPS spectra, photoelectrochemical tests and density functional theory (DFT) calculations proved the covalently binding TCPP with ZnTi-LDH through the carboxyl group in TCPP and hydroxyl group on ZnTi-LDH to form ester. Meanwhile the photo-induced electrons are transferred from TCPP to ZnTi-LDH. This work attempted and realized to apply tetra(4-carboxyphenyl)porphyrin sensitized ZnTi-LDH as photocatalyst in photocatalytic CO2 reduction.
- Guo, JiaQing,Li, JiaMin,Mu, Manman,Shen, Haochen,Wu, Guang,Yin, Xiaohong
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- Core-shell Cu@Cu2O nanoparticles embedded in 3D honeycomb-like N-doped graphitic carbon for photocatalytic CO2reduction
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A facile polymer thermal treatment method has been employed to fabricate 3D honeycomb-like nitrogen-doped graphitic carbons (N-GCs) with embedded core-shell Cu@Cu2O nanoparticles (NPs). The 3D honeycomb-like N-GC architectures can not only serve as an excellent carrier for core-shell Cu@Cu2O NPs, but also provide sufficient active sites and fast electron transmission channels. Under visible light irradiation, the Cu@Cu2O/N-GC-600 catalyst has the highest yields of CH4 and CO at 38.89 μmol g-1 and 27.78 μmol g-1, respectively. The excellent photocatalytic activity is attributed to the synergistic effects between the unique N-GC framework and core-shell Cu@Cu2O NPs, which accelerates the transfer of charge carriers and promotes the accumulation of photogenerated electrons on core-shell Cu@Cu2O. The results of this study may be beneficial for the design and synthesis of high-efficiency core-shell photocatalysts. This journal is
- He, Lang,Liu, Sheng,Zhang, Wenyuan,Zhao, Kristin,Zhao, Yan
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supporting information
p. 4758 - 4769
(2022/03/15)
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- Tailored Linker Defects in UiO-67 with High Ligand-to-Metal Charge Transfer toward Efficient Photoreduction of CO2
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Defect engineering can be used as a potential tool to activate metal-organic frameworks by regulating the pore structure, electronic properties, and catalytic activity. Herein, linker defects were effectively controlled by adjusting the amount of formic acid, and UiO-67 with different CO2 reduction capabilities was obtained. Among them, UiO-67-200 had the highest ability to selectively reduce CO2 to CO (12.29 μmol g-1 h-1). On the one hand, the results based on time-resolved photoluminescence decay curves and photochemical experiments revealed that UiO-67-200 had the highest charge separation efficiency. On the other hand, the linker defects affected the band structure of UiO-67 by changing the lowest unoccupied molecular orbital (LUMO) based on the density functional theory and UV-vis spectra. Hence, the proper linker defects enhanced the ligand-to-metal charge transfer process by promoting the transfer of electrons between the highest occupied molecular orbital and LUMO. Additionally, in situ Fourier transform infrared spectra and 13CO2 labeling experiments also indicated that COOH? was an important intermediate for CO formation and that CO originated from the photoreduction of CO2.
- Zhao, Xiaoxue,Xu, Mengyang,Song, Xianghai,Liu, Xin,Zhou, Weiqiang,Wang, Huiqin,Huo, Pengwei
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p. 1765 - 1777
(2022/01/27)
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- Metallization-Prompted Robust Porphyrin-Based Hydrogen-Bonded Organic Frameworks for Photocatalytic CO2 Reduction
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Under topological guidance, the self-assembly process based on a tetratopic porphyrin synthon results in a hydrogen-bonded organic framework (HOF) with the predicted square layers topology (sql) but unsatisfied stability. Strikingly, simply introducing a transition metal in the porphyrin center does not change the network topology but drastically causes noticeable change on noncovalent interaction, orbital overlap, and molecular geometry, therefore ultimately giving rise to a series of metalloporphyrinic HOFs with high surface area, and excellent stability (intact after being soaked in boiling water, concentrated HCl, and heated to 270 °C). On integrating both photosensitizers and catalytic sites into robust backbones, this series of HOFs can effectively catalyze the photoreduction of CO2 to CO, and their catalytic performances greatly depend on the chelated metal species in the porphyrin centers. This work enriches the library of stable functional HOFs and expands their applications in photocatalytic CO2 reduction.
- Alexandrov, Eugeny V.,Fang, Zhi-Bin,Huang, Qian-Qian,Li, Yu-Lin,Liu, Tian-Fu,Proserpio, Davide M.,Qin, Wei-Kang,Si, Duan-Hui,Yin, Qi,Zhang, An-An,Zhang, Yuan
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supporting information
(2021/12/24)
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- Developing Atomically Thin Li1.81H0.19Ti2O5·2H2O Nanosheets for Selective Photocatalytic CO2Reduction to CO
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Solar-driven CO2 conversion to carbon-based fuels is an attractive approach to alleviate the worsening global climate change and increasing energy issues. However, exploring and designing efficient photocatalysts with excellent activity and stability still remain challenging. Herein, layered Li1.81H0.19Ti2O5·2H2O (LHTO) nanosheets were explored as the photocatalyst for photocatalytic CO2 reduction, and atomically thin LHTO nanosheets with one-unit-cell thickness were successfully constructed for photocatalytic CO2 reduction. The atomically thin LHTO nanosheets exhibited excellent performance for CO2 photoreduction to CO, with a yield rate of 4.0 μmol g-1 h-1, a selectivity of 93%, and over 25 h photostability, dramatically outperforming the bulk LHTO. The better performance of the atomically thin LHTO nanosheets was experimentally verified to benefit from more sites for CO2 adsorption, faster electron transfer rate, and a more negative conduction band edge compared with bulk LHTO. This work provided a methodological basis for designing more efficient photocatalytic CO2 reduction catalysts.
- Gao, Shan,Gui, Jiaojiao,Jin, Xin,Li, Yunkai,Song, Jimei,Xie, Yi,Xue, Jingyu,Yang, Chen,Yu, Yu,Zhan, Xiaowen,Zhang, Kaifu
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p. 523 - 530
(2022/01/08)
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- An unprecedented polyoxometalate-encapsulated organo-metallophosphate framework as a highly efficient cocatalyst for CO2photoreduction
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The photocatalytic reduction of CO2 to chemical fuels is attractive for addressing both the greenhouse effect and the energy crisis, but the key challenge is the design and synthesis of photocatalysts with remarkable performance under visible-light irradiation. Herein, we present two novel polyoxometalate-based organo-metallophosphate frameworks (POMPOs), formulated as [Zn4(PO4)(C7H8N4)6][BW12O40]·2H2O (1) and [Co4(PO4)(C7H8N4)6][BW12O40]·1.5H2O (2). According to the single crystal analysis, both compounds possess host organo-metallophosphate (OMPO) frameworks constructed with PO43- anions, with the Keggin-type polyoxometalate H5BW12O40 (BW12) as a guest encapsulated in these size-matched frameworks. Due to the synergistic combination of the POMs and OMPO frameworks in the system of photocatalytic CO2 reduction, compound 2 could act as a highly efficient cocatalyst in combination with the [Ru(bpy)3]Cl2 complex. The CO generation rate over compound 2 is 10?852 μmol g-1 h-1 with a high selectivity of 93.4%, which is superior to that of most reported POM-based or MOF-based catalysts for CO2 photoreduction. To our knowledge, this is the first report of OMPO frameworks functionally combined with Keggin-type POMs being extended for the photoreduction of CO2 and this affords a new pathway for the efficient photoconversion of CO2 to CO.
- Du, Ze-Yu,Li, Ning-Fang,Liu, Xiao-Mei,Mei, Hua,Wang, Ji-Lei,Xu, Yan,Xue, Ying-Nan
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p. 3469 - 3477
(2022/02/25)
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- Insights into Transformation of Icosahedral PdRu Nanocrystals into Lattice-Expanded Nanoframes with Strain Enhancement in Electrochemical Redox Reactions
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Bimetallic icosahedral nanoframes have three-dimensional open structures, a high surface-area-to-volume ratio, and high surface site availability. Twin boundaries in these structures cause surface lattice expansion that leads to tensile strain over the nanoframes, which can improve their catalytic activity; however, robust methods for their synthesis in most metal systems are still lacking. In this work, we demonstrate a one-step synthetic strategy for the synthesis of both closed solid and hollow frame icosahedral PdRu nanoparticles (INPs) via a two-stage process of growth and dissolution. By extraction at different reaction times, INPs, concave-faceted icosahedral PdRu nanoparticles (CINPs), and icosahedral PdRu nanoframes (INFs) are obtained. High-angle annular dark-field scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy and inductively coupled plasma-optical emission spectrometry analyses show that the icosahedral nanostructures are PdRu alloys with ～5 at. % Ru relative to Pd. We also carried out the electrochemical ethanol oxidation reaction (EOR) and CO2reduction reaction over three types of catalysts, PdRu INPs, PdRu CINPs, and PdRu INFs, as well as commercial Pd NPs, to examine their catalytic properties. PdRu INFs showed a much higher mass activity than PdRu INPs, PdRu CINPs, and Pd NPs in the EOR. PdRu INFs exhibited the highest Faradaic efficiency of CO gas (34%), which suggests that the expansive strain in the framework catalyst structure improves selectivity and activity for CO2conversion.
- Kao, Chen-Rui,Yeh, Ai-Hsuan,Chen, Bo-Hao,Lyu, Lian-Ming,Chuang, Yu-Chun,Sneed, Brian T.,Kuo, Chun-Hong
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p. 2282 - 2291
(2022/03/01)
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- Ordered heterogeneity of molecular photosensitizer toward enhanced photocatalysis
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Ordered heterogeneity is significant for molecular photosensitizers to enhance their practical applications. However, the ordered heterogeneity of molecular photosensitizers is still a great challenge. In this article, we describe a supramolecular assembly method for the heterogeneity of molecular photosensitizers, with which a mononuclear Zn(II) molecular photosensitizer in solution was orderly assembled in long range via π-π stacking interactions, affording a cheap, solid photocatalyst (π-1) with a porous structure. With Co(II), Fe(III), or Ni(II) as a cocatalyst, π-1 shows noticeably better photocatalytic activity for CO2reduction than in a homogeneous system. The definite crystal structure and precise position of the catalytic center in π-1 were determined by single-crystal X-ray diffraction combined with X-ray diffraction adsorption spectra, based on which the enhanced activity of π-1 for photocatalytic CO2reduction was revealed by theoretical calculation. Thus, the reduced energy gap after ordered heterogeneity accelerates the electron transfer, greatly boosting the photocatalytic CO2reduction activity. This work demonstrates a method for developing crystalline, heterogeneous photocatalysts with definite structures and enhanced, catalytic performance.
- Zhang, Ji-Hong,Gong, Yun-Nan,Wang, Hong-Juan,Wang, Yu-Chen,Yang, Wei,Mei, Jian-Hua,Zhong, Di-Chang,Lu, Tong-Bu
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- Dissection of Light-Induced Charge Accumulation at a Highly Active Iron Porphyrin: Insights in the Photocatalytic CO2 Reduction
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Iron porphyrins are among the best molecular catalysts for the electrocatalytic CO2 reduction reaction. Powering these catalysts with the help of photosensitizers comes along with a couple of unsolved challenges that need to be addressed with much vigor. We have designed an iron porphyrin catalyst decorated with urea functions (UrFe) acting as a multipoint hydrogen bonding scaffold towards the CO2 substrate. We found a spectacular photocatalytic activity reaching unreported TONs and TOFs as high as 7270 and 3720 h?1, respectively. While the Fe0 redox state has been widely accepted as the catalytically active species, we show here that the FeI species is already involved in the CO2 activation, which represents the rate-determining step in the photocatalytic cycle. The urea functions help to dock the CO2 upon photocatalysis. DFT calculations bring support to our experimental findings that constitute a new paradigm in the catalytic reduction of CO2.
- Aukauloo, Ally,Boitrel, Bernard,Gotico, Philipp,Ha-Thi, Minh-Huong,Halime, Zakaria,Leibl, Winfried,Pino, Thomas,Pugliese, Eva,Quaranta, Annamaria,Sircoglou, Marie,Wehrung, Iris
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supporting information
(2022/02/17)
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- Covalent Microporous Polymer Nanosheets for Efficient Photocatalytic CO2 Conversion with H2O
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It is still a challenging target to achieve photocatalytic CO2 conversion to valuable chemicals with H2O as an electron donor. Herein, 2D imide-based covalent organic polymer nanosheets (CoPcPDA-CMP NSs), which integrate cobalt phthalocyanine (CoPc) moiety for reduction half-reaction and 3,4,9,10-perylenetetracarboxylic diimide moiety for oxidation half-reaction, are constructed as a Z-scheme artificial photosynthesis system to complete the overall CO2 reduction reaction. Owing to the outstanding light absorption capacity, charge separation efficiency, and electronic conductivity, CoPcPDA-CMP NSs exhibit excellent photocatalytic activity to reduce CO2 to CO using H2O as a sacrificial agent with a CO production rate of 14.27?μmol g?1 h?1 and a CO selectivity of 92%, which is competitive to the state-of-the-art visible-light-driven organic photocatalysts towards the overall CO2 reduction reaction. According to a series of spectroscopy experiments, the authors also verify the photoexcited electron transfer processes in the CoPcPDA-CMP NSs photocatalytic system, confirming the Z-scheme photocatalytic mechanism. The present results should be helpful for fabricating high-performance organic photocatalysts for CO2 conversion.
- Gong, Lei,Jiang, Jianzhuang,Liu, Heyuan,Liu, Wenbo,Liu, Wenping,Wang, Kang,Zhi, Qianjun,Zhou, Jun
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- Neighboring Zn-Zr Sites in a Metal-Organic Framework for CO2Hydrogenation
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ZrZnOx is active in catalyzing carbon dioxide (CO2) hydrogenation to methanol (MeOH) via a synergy between ZnOx and ZrOx. Here we report the construction of Zn2+-O-Zr4+ sites in a metal-organic framework (MOF) to reveal insights into the structural requirement for MeOH production. The Zn2+-O-Zr4+ sites are obtained by postsynthetic treatment of Zr6(μ3-O)4(μ3-OH)4 nodes of MOF-808 by ZnEt2 and a mild thermal treatment to remove capping ligands and afford exposed metal sites for catalysis. The resultant MOF-808-Zn catalyst exhibits >99% MeOH selectivity in CO2 hydrogenation at 250 °C and a high space-time yield of up to 190.7 mgMeOH gZn-1 h-1. The catalytic activity is stable for at least 100 h. X-ray absorption spectroscopy (XAS) analyses indicate the presence of Zn2+-O-Zr4+ centers instead of ZnmOn clusters. Temperature-programmed desorption (TPD) of hydrogen and H/D exchange tests show the activation of H2 by Zn2+ centers. Open Zr4+ sites are also critical, as Zn2+ centers supported on Zr-based nodes of other MOFs without open Zr4+ sites fail to produce MeOH. TPD of CO2 reveals the importance of bicarbonate decomposition under reaction conditions in generating open Zr4+ sites for CO2 activation. The well-defined local structures of metal-oxo nodes in MOFs provide a unique opportunity to elucidate structural details of bifunctional catalytic centers.
- An, Bing,Cao, Yonghua,Dai, Yiheng,Li, Zhe,Lin, Wenbin,Wang, Cheng,Wang, Wangyang,Zeng, Lingzhen,Zhang, Jingzheng
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supporting information
p. 8829 - 8837
(2021/06/28)
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- Secondary Coordination Effect on Monobipyridyl Ru(II) Catalysts in Photochemical CO2Reduction: Effective Proton Shuttle of Pendant Br?nsted Acid/Base Sites (OH and N(CH3)2) and Its Mechanistic Investigation
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While the incorporation of pendant Br?nsted acid/base sites in the secondary coordination sphere is a promising and effective strategy to increase the catalytic performance and product selectivity in organometallic catalysis for CO2reduction, the control of product selectivity still faces a great challenge. Herein, we report two newtrans(Cl)-[Ru(6-X-bpy)(CO)2Cl2] complexes functionalized with a saturated ethylene-linked functional group (bpy = 2,2′-bipyridine; X = ?(CH2)2-OH or ?(CH2)2-N(CH3)2) at theortho(6)-position of bpy ligand, which are named Ru-bpyOHand Ru-bpydiMeN, respectively. In the series of photolysis experiments, compared to nontethered case, the asymmetric attachment of tethering ligand to the bpy ligand led to less efficient but more selective formate production with inactivation of CO2-to-CO conversion route during photoreaction. From a series ofin situFTIR analyses, it was found that the Ru-formate intermediates are stabilized by a highly probable hydrogen bonding between pendent proton donors (?diMeN+H or ?OH) and the oxygen atom of metal-bound formate (RuI-OCHO···H-E-(CH2)2-,E= O or diMeN+). Under such conformation, the liberation of formate from the stabilized RuI-formate becomes less efficient compared to the nontethered case, consequently lowering the CO2-to-formate conversion activities during photoreaction. At the same time, such stabilization of Ru-formate species prevents the dehydration reaction route (η1-OCHO → η1-COOH on Ru metal) which leads toward the generation of Ru-CO species (key intermediate for CO production), eventually leading to the reduction of CO2-to-CO conversion activity.
- Back, Changhyun,Seo, Yunjeong,Choi, Sunghan,Choe, Min Su,Lee, Daehan,Baeg, Jin-Ook,Son, Ho-Jin,Kang, Sang Ook
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p. 14151 - 14164
(2021/09/20)
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- Stabilization of ultra-small gold nanoparticles in a photochromic organic cage: modulating photocatalytic CO2reduction by tuning light irradiation
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Synthesis and stabilization of ultra-small metal nanoparticles (MNPs) composed of a few atoms are of paramount importance in modulating their material properties based on quantum confinement effects. The highly reactive surface of small MNPs tends to aggregate, resulting in bigger particles and subsequent deterioration of the catalytic activity. In this work, we exploited a dithienylethene (DTE) based photochromic organic cage (TAE-DTE) for thein situstabilization of ultra-small Au NPs (Au@TAE-DTE) (2reduction to CO. Importantly, irradiating with light of the full range (λ= 250-750 nm) allowed for co-existence of both photoisomers which thereby showed wide spectrum absorption as compared to individual photoisomers, consequently displaying substantially enhanced performance for the photocatalytic CO2reduction. Further, the real-time progress of the CO2reduction reaction and corresponding reaction intermediates was detected by anin situDRIFT experiment.
- Singh, Ashish,Verma, Parul,Samanta, Debabrata,Dey, Anupam,Dey, Jyotirmoy,Maji, Tapas Kumar
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supporting information
p. 5780 - 5786
(2021/03/16)
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- In situ α-Fe2O3modified La2Ti2O7with enhanced photocatalytic CO2reduction activity
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Developing high-efficiency photocatalysts for CO2 photoreduction is one of the potential solutions to address both energy and pollution issues. In this study, α-Fe2O3 modified La2Ti2O7 was successfully synthesized with intimate contact between La2Ti2O7 an
- Zhang, Zifan,Lin, Yuan,Liu, Qianwen,Wang, Xuxu,Fu, Xianzhi,Su, Wenyue
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p. 6438 - 6444
(2021/10/12)
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- In-situ growth of PbI2 on ligand-free FAPbBr3 nanocrystals to significantly ameliorate the stability of CO2 photoreduction
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Excellent optical properties involving strong visible light response and superior carrier transport endow metal halide perovskites (MHP) with a fascinating prospect in the field of photocatalysis. Nevertheless, the poor stability of MHP nanocrystals (NCs) in water-contained system, especially without the protection of long alkyl chain ligands, severely restricts their photocatalytic performance. In this context, we report an effortless strategy for the generation of ligand-free MHP NCs based photocatalyst with high water tolerance, by coating PbI2 on the surface of ligand-free formamidinium lead bromide (FAPbBr3) NCs via the facile procedure of in-situ conversion with the aid of ZnI2. Under the protection of PbI2 layer, the resultant FAPbBr3/PbI2 composite exhibits significantly ameliorated stability in an artificial photosynthesis system with CO2 and H2O vapor as feedstocks. Moreover, the formation of compact PbI2 layer can accelerate the separation of photogenerated carriers in FAPbBr3 NCs, bringing forth a remarkable improvement of CO2 photoreduction efficiency with an impressive electron consumption yield of 2053 μmol/g in the absence of organic sacrificial agents, which is 7-fold over that of pristine FAPbBr3 NCs.
- Guo, Ning-Na,Liu, Zhao-Lei,Lu, Tong-Bu,Mu, Yan-Fei,Yao, Yuan,Zhang, Meng-Ran,Zhang, Min
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supporting information
(2021/12/02)
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- A Nickel(II)-Mediated Thiocarbonylation Strategy for Carbon Isotope Labeling of Aliphatic Carboxamides
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A series of pharmaceutically relevant small molecules and biopharmaceuticals bearing aliphatic carboxamides have been successfully labeled with carbon-13. Key to the success of this novel carbon isotope labeling technique is the observation that 13C-labeled NiII-acyl complexes, formed from a 13CO insertion step with NiII-alkyl intermediates, rapidly react in less than one minute with 2,2’-dipyridyl disulfide to quantitatively form the corresponding 2-pyridyl thioesters. Either the use of 13C-SilaCOgen or 13C-COgen allows for the stoichiometric addition of isotopically labeled carbon monoxide. Subsequent one-pot acylation of a series of structurally diverse amines provides the desired 13C-labeled carboxamides in good yields. A single electron transfer pathway is proposed between the NiII-acyl complexes and the disulfide providing a reactive NiIII-acyl sulfide intermediate, which rapidly undergoes reductive elimination to the desired thioester. By further optimization of the reaction parameters, reaction times down to only 11 min were identified, opening up the possibility of exploring this chemistry for carbon-11 isotope labeling. Finally, this isotope labeling strategy could be adapted to the synthesis of 13C-labeled liraglutide and insulin degludec, representing two antidiabetic drugs.
- Pedersen, Simon S.,Donslund, Aske S.,Mikkelsen, Jesper H.,Bakholm, Oskar S.,Papp, Florian,Jensen, Kim B.,Gustafsson, Magnus B. F.,Skrydstrup, Troels
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supporting information
p. 7114 - 7123
(2021/03/03)
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- Synthesis and [*C]CO-labelling of (C,N)gem-dimethylbenzylamine-palladium complexes for potential applications in positron emission tomography
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Various aryl-palladium complexes were synthesised fromgem-dimethylbenzylamine derivatives by C-H activation under extremely mild conditions. Interestingly, these highly stable structures reacted with [13C]carbon monoxide to produce the desired labelled lactams in 29% to 51% yields over the C-H activation/carbonylation steps. As representative examples, a non-natural amino acid and an estradiol-based conjugate were prepared and labelled in model experiments with [13C]CO in homogeneous or heterogeneous conditions. Especially, the latter was radiolabelled with [11C]CO using a convenient procedure from the resin-supported palladium complex precursor. Thus, these results strongly suggest that cyclometallated palladium complexes obtained fromgem-dimethylbenzylamine moieties are promising precursors for the practical synthesis of new [11C]tracers for Positron Emission Tomography.
- Audrain, Hélène,Christine, Thifanie,Cormier, Morgan,Fouquet, Eric,Hermange, Philippe,Tabey, Alexis
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supporting information
p. 10608 - 10614
(2021/08/09)
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- Practical Gas Cylinder-Free Preparations of Important Transition Metal-Based Precatalysts Requiring Gaseous Reagents
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A simple and safe setup for the synthesis of a selection of important transition metal-based precatalysts is reported, all requiring low-molecular weight gaseous reagents for their preparation. Hydrogen, carbon monoxide, ethylene, and acetylene are each liberated in a controlled manner from a corresponding easy-to-handle precursor in a closed two-chamber reactor. Gas cylinders and elaborate setups/techniques connected to handling toxic and/or flammable gases as reported in the literature can thus be avoided. The corresponding precatalysts are of high relevance in the active research fields of C-H bond activation, dehydrogenation, hydrogenation, and coupling reactions. The selection of complexes shown is meant to serve as examples for the usefulness and broadness of the presented methods, allowing precatalysts requiring gaseous reagents to become available for the research community.
- Ahrens, Alexander,Donslund, Bjarke S.,Gausas, Laurynas,Kristensen, Steffan K.,Skrydstrup, Troels,Sun, Hongwei
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supporting information
p. 2300 - 2307
(2021/09/28)
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- Transition-Metal-Modified Vanadoborate Clusters as Stable and Efficient Photocatalysts for CO2Reduction
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Photocatalytic carbon dioxide reduction (CO2RR) is considered to be a promising sustainable and clean approach to solve environmental issues. Polyoxometalates (POMs), with advantages in fast, reversible, and stepwise multiple-electron transfer without changing their structures, have been promising catalysts in various redox reactions. However, their performance is often restricted by poor thermal or chemical stability. In this work, two transition-metal-modified vanadoborate clusters, [Co(en)2]6[V12B18O54(OH)6]·17H2O (V12B18-Co) and [Ni(en)2]6[V12B18O54(OH)6]·17H2O (V12B18-Ni), are reported for photocatalytic CO2 reduction. V12B18-Co and V12B18-Ni can preserve their structures to 200 and 250 °C, respectively, and remain stable in polar organic solvents and a wide range of pH solutions. Under visible-light irradiation, CO2 can be converted into syngas and HCOO- with V12B18-Co or V12B18-Ni as catalysts. The total amount of gaseous products and liquid products for V12B18-Co is up to 9.5 and 0.168 mmol g-1 h-1. Comparing with V12B18-Co, the yield of CO for V12B18-Ni declines by 1.8-fold, while that of HCOO- increases by 35%. The AQY of V12B18-Co and V12B18-Ni is 1.1% and 0.93%, respectively. These values are higher than most of the reported POM materials under similar conditions. The density functional theory (DFT) calculations illuminate the active site of CO2RR and the reduction mechanism. This work provides new insights into the design of stable, high-performance, and low-cost photocatalysts for CO2 reduction.
- Yu, Xiang,Zhao, Cong-Cong,Gu, Jian-Xia,Sun, Chun-Yi,Zheng, Hai-Yan,Yan, Li-Kai,Sun, Min,Wang, Xin-Long,Su, Zhong-Min
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supporting information
p. 7364 - 7371
(2021/05/31)
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- Homogeneous electrocatalytic CO2 reduction by hexacarbonyl diiron dithiolate complex bearing hydroquinone
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Recently, the hexacarbonyl diiron dithiolate complex ((bdt)Fe2(CO)6, bdt = benzene-1,2-dithiolate) was reported for electrochemical CO2 reduction in CH3OH/CH3CN solution. To further simulate the [NiFe] carbon monoxide dehydrogenase (CODH) active center, another diiron dithiolate complex (1) with phenolic hydroxyl as second coordination sphere group was introduced to catalyze CO2 reduction electrochemically. Cyclic voltammetry measurements revealed that the phenolic hydroxyl group of 1 could lower the onset potential of electrochemical CO2 reduction. Under the best conditions, the maximum turnover frequency (TOFmax) of about 35 s?1 and an almost equal amount of HCOOH, CO, and H2 were obtained. Fourier transform infrared reflectance spectroelectrochemistry (IR-SEC) experiments illuminated the intermediate with terminal coordinated –COOH and the changes of intermolecular hydrogen bonds during the catalytic cycle.
- Cheng, Minglun,Fan, Fenglan,Liu, Jinyu,Wang, Lingjuan
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- A stable ring-expanded NHC-supported copper boryl and its reactivity towards heterocumulenes
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Reaction of bis(pinacolato)diboron with (6-Dipp)CuOtBu generates a ring-expanded N-heterocyclic carbene supported copper(i) boryl, (6-Dipp)CuBpin. This compound showed remarkable stability and was characterised by NMR spectroscopy and X-ray crystallography. (6-Dipp)CuBpin readily dechalcogenated a range of heterocumulenes such as CO2, isocyanates and isothiocyanates to yield (6-Dipp)CuXBpin (X = O, S). In the case of CO2 catalytic reduction to CO is viable in the presence of excess bis(pinacolato)diboron. In contrast, in the case of iso(thio)cyanates, the isocyanide byproduct of dechalcogenation reacted with (6-Dipp)CuBpin to generate a copper(i) borylimidinate, (6-Dipp)CuC(NR)Bpin, which went on to react with heterocumulenes. This off-cycle reactivity gives selective access to a range of novel boron-containing heterocycles bonded to copper, but precludes catalytic reactivity.
- Charman, Rex S. C.,Hall, Jonathan W.,Horsley Downie, Thomas M.,Liptrot, David J.,Lowe, John P.,Mahon, Mary F.
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p. 16336 - 16342
(2021/11/30)
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- Stable Dioxin-Linked Metallophthalocyanine Covalent Organic Frameworks (COFs) as Photo-Coupled Electrocatalysts for CO2 Reduction
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In this work, we rationally designed a series of crystalline and stable dioxin-linked metallophthalocyanine covalent organic frameworks (COFs; MPc-TFPN COF, M=Ni, Co, Zn) under the guidance of reticular chemistry. As a novel single-site catalysts (SSCs), NiPc/CoPc-TFPN COF exhibited outstanding activity and selectivity for electrocatalytic CO2 reduction (ECR; Faradaic efficiency of CO (FECO)=99.8(±1.24) %/ 96.1(±1.25) % for NiPc/CoPc-TFPN COF). More importantly, when coupled with light, the FECO and current density (jCO) were further improved across the applied potential range (?0.6 to ?1.2 V vs. RHE) compared to the dark environment for NiPc-TFPN COF (jCO increased from 14.1 to 17.5 A g?1 at ?0.9 V; FECO reached up to ca. 100 % at ?0.8 to ?0.9 V). Furthermore, an in-depth mechanism study was established by density functional theory (DFT) simulation and experimental characterization. For the first time, this work explored the application of COFs as photo-coupled electrocatalysts to improve ECR efficiency, which showed the potential of using light-sensitive COFs in the field of electrocatalysis.
- Lu, Meng,Zhang, Mi,Liu, Chun-Guang,Liu, Jiang,Shang, Lin-Jie,Wang, Min,Chang, Jia-Nan,Li, Shun-Li,Lan, Ya-Qian
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supporting information
p. 4864 - 4871
(2021/01/12)
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- Modulation of Self-Assembly Enhances the Catalytic Activity of Iron Porphyrin for CO2 Reduction
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Electrochemical reduction of CO2 in aqueous media is an important reaction to produce value-added carbon products in an environmentally and economically friendly manner. Various molecule-based catalytic systems for the reaction have been reported thus far. The key features of state-of-the-art catalytic systems in this field can be summarized as follows: 1) an iron-porphyrin-based scaffold as a catalytic center, 2) a dinuclear active center for the efficient activation of a CO2 molecule, and 3) a hydrophobic channel for the accumulation of CO2. This article reports a novel approach to construct a catalytic system for CO2 reduction with the aforementioned three key substructures. The self-assembly of a newly designed iron-porphyrin complex bearing bulky substituents with noncovalent interaction ability forms a highly ordered crystalline solid with adjacent catalytically active sites and hydrophobic pores. The obtained crystalline solid serves as an electrocatalyst for CO2 reduction in aqueous media. Note that a relevant iron-porphyrin complex without bulky substituents cannot form a porous structure with adjacent active sites, and the catalytic performance of the crystals of this relevant iron-porphyrin complex is substantially lower than that of the newly developed catalytic system. The present study provides a novel strategy for constructing porous crystalline solids for small-molecule conversions.
- Tasaki, Masahiro,Okabe, Yuki,Iwami, Hikaru,Akatsuka, Chiharu,Kosugi, Kento,Negita, Kohei,Kusaka, Sinpei,Matsuda, Ryotaro,Kondo, Mio,Masaoka, Shigeyuki
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- Water-Assisted Highly Efficient Photocatalytic Reduction of CO2to CO with Noble Metal-Free Bis(terpyridine)iron(II) Complexes and an Organic Photosensitizer
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Photocatalytic CO2 reduction reaction is believed to be a promising approach for CO2 utilization. In this work, a noble metal-free photocatalytic system, composed of bis(terpyridine)iron(II) complexes and an organic thermally activated delayed fluorescence compound, has been developed for selective reduction of CO2 to CO with a maximum turnover number up to 6320, 99.4% selectivity, and turnover frequency of 127 min-1 under visible-light irradiation in dimethylformamide/H2O solution. More than 0.3 mmol CO was generated using 0.05 μmol catalyst after 2 h of light irradiation. The apparent quantum yield was found to be 9.5% at 440 nm (180 mW cm-2). Control experiments and UV-vis-NIR spectroscopy studies further demonstrated that water strongly promoted the photocatalytic cycle and terpyridine ligands rather than Fe(II) were initially reduced during the photocatalytic process.
- Wang, Yanan,Liu, Ting,Chen, Longxin,Chao, Duobin
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supporting information
p. 5590 - 5597
(2021/03/08)
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- Automated and Continuous-Flow Platform to Analyze Semiconductor-Metal Complex Hybrid Systems for Photocatalytic CO2Reduction
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Sunlight-driven CO2reduction is increasingly considered as a promising approach to contribute toward a carbon-neutral fuel cycle, but most photocatalyst systems are currently studied individually under batch conditions with manual, labor-intensive analytical procedures. Here, we present the advantages of a continuous-flow setup to study photocatalytic CO2to CO reduction systems, which also benefits from aspects of automation (using programmed in-line gas quantification of multiple samples in parallel). The capabilities of the methodology are demonstrated using a state-of-the-art light absorber platform based on ZnSe quantum dots (QDs) in combination with a series of molecular co-catalysts based on Ni and Co for visible-light-driven CO2reduction in aqueous ascorbate solution. A newly synthesized Co-tetraphenylporphyrin featuring three sulfonate groups and one amine group (Co(tppS3N1)) is identified to exhibit a benchmark photocatalytic activity (18.6 μmol of CO, 79.7 mmol of CO gZnSe-1, TONCo(CO) of 619, external quantum efficiency (EQE) >5%). The utility of our methodology is further shown by applying the setup to study the photocatalyst systems under lower light intensities, low CO2concentration, and aerobic conditions, which impact the photocatalytic activity and selectivity. Overall, this work reports an improved methodology for studying photocatalytic CO2reduction alongside advancing the understanding of QD molecular co-catalyst hybrids using ZnSe QDs as a versatile light absorber based on earth-abundant components that operate under fully aqueous conditions.
- Sahm, Constantin D.,Ucoski, Geani M.,Roy, Souvik,Reisner, Erwin
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p. 11266 - 11277
(2021/09/14)
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- Quantum Dot-Sensitized Photoreduction of CO2 in Water with Turnover Number > 80,000
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Climate change and global energy demands motivate the search for sustainable transformations of carbon dioxide (CO2) to storable liquid fuels. Photocatalysis is a pathway for direct conversion of CO2 to CO, one step within light-powered reaction networks that could, if efficient enough, transform the solar energy conversion landscape. To date, the best performing photocatalytic CO2 reduction systems operate in nonaqueous solvents, but technologically viable solar fuels networks will likely operate in water. Here we demonstrate catalytic photoreduction of CO2 to CO in pure water at pH 6-7 with an unprecedented combination of performance parameters: turnover number (TON(CO)) = 72,484-84,101, quantum yield (QY) = 0.96-3.39%, and selectivity (SCO) > 99%, using CuInS2 colloidal quantum dots (QDs) as photosensitizers and a Co-porphyrin catalyst. At higher catalyst concentration, the system reaches QY = 3.53-5.23%. The performance of the QD-driven system greatly exceeds that of the benchmark aqueous system (926 turnovers with a quantum yield of 0.81% and selectivity of 82%), due primarily to (i) electrostatic attraction of the QD to the catalyst, which promotes fast multielectron delivery and colocalization of protons, CO2, and catalyst at the source of photoelectrons, and (ii) termination of the QD's ligand shell with free amines, which capture CO2 as carbamic acid that serves as a reservoir for CO2, effectively increasing its solubility in water, and lowers the onset potential for catalytic CO2 reduction by the Co-porphyrin. The breakthrough efficiency achieved in this work represents a nonincremental step in the realization of reaction networks for direct solar-to-fuel conversion.
- Arcudi, Francesca,Dordevi?, Luka,Nagasing, Benjamin,Stupp, Samuel I.,Weiss, Emily A.
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supporting information
p. 18131 - 18138
(2021/11/12)
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- Lowering Electrocatalytic CO2Reduction Overpotential Using N-Annulated Perylene Diimide Rhenium Bipyridine Dyads with Variable Tether Length
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We report the design, synthesis, and characterization of four N-annulated perylene diimide (NPDI) functionalized rhenium bipyridine [Re(bpy)] supramolecular dyads. The Re(bpy) scaffold was connected to the NPDI chromophore either directly [Re(py-C0-NPDI)] or via an ethyl [Re(bpy-C2-NPDI)], butyl [Re(bpy-C4-NPDI)], or hexyl [Re(bpy-C6-NPDI)] alkyl-chain spacer. Upon electrochemical reduction in the presence of CO2 and a proton source, Re(bpy-C2/4/6-NPDI) all exhibited significant current enhancement effects, while Re(py-C0-NPDI) did not. During controlled potential electrolysis (CPE) experiments at Eappl = -1.8 V vs Fc+/0, Re(bpy-C2/4/6-NPDI) all achieved comparable activity (TONco ～25) and Faradaic efficiency (FEco ～94%). Under identical CPE conditions, the standard catalyst Re(dmbpy) was inactive for electrocatalytic CO2 reduction; only at Eappl = -2.1 V vs Fc+/0 could Re(dmbpy) achieve the same catalytic performance, representing a 300 mV lowering in overpotential for Re(bpy-C2/4/6-NPDI). At higher overpotentials, Re(bpy-C4/6-NPDI) both outperformed Re(bpy-C2-NPDI), indicating the possibility of coinciding electrocatalytic CO2 reduction mechanisms that are dictated by tether-length and overpotential. Using UV-vis-nearIR spectroelectrochemistry (SEC), FTIR SEC, and chemical reduction experiments, it was shown that the NPDI-moiety served as an electron-reservoir for Re(bpy), thereby allowing catalytic activity at lower overpotentials. Density functional theory studies probing the optimized geometries and frontier molecular orbitals of various catalytic intermediates revealed that the geometric configuration of NPDI relative to the Re(bpy)-moiety plays a critical role in accessing electrons from the electron-reservoir. The improved performance of Re(bpy-C2/4/6-NPDI)dyads at lower overpotentials, relative to Re(dmbpy), highlights the utility of chromophore electron-reservoirs as a method for lowering the overpotential for CO2 conversion.
- Dubrawski, Zachary S.,Gelfand, Benjamin S.,Koenig, Josh D. B.,Piers, Warren E.,Rao, Keerthan R.,Risko, Chad,Welch, Gregory C.,Willkomm, Janina
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supporting information
p. 16849 - 16864
(2021/10/20)
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- A metal-free covalent organic framework as a photocatalyst for CO2reduction at low CO2concentration in a gas-solid system
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A β-ketoenamine-based COF is used as a photocatalyst to convert CO2 and H2O into CO and O2 under visible-light irradiation without using additional photosensitizers and sacrificial agents in a gas-solid system. When CO2 concentration was controlled at 30.0% at 80 °C, TpBb-COF exhibited a CO production rate of 89.9 μmol g-1 h-1, which was higher than that (52.8 μmol g-1 h-1) in pure CO2, indicating that low concentrations of CO2 are conducive to the photocatalytic reduction of CO2. DFT calculations indicate that the adsorption of H2O on TpBb-COF was more preferential, which promoted the adsorption and reduction of CO2. In light of this finding, the mechanism or reaction pathway was explored. The rate equation of CO2 photocatalytic reduction was derived to correlate the association of the CO2 concentration and CO production rate, which is consistent with the experimental results and theoretical calculations.
- Cui, Jin-Xian,Feng, Liu,Liu, Shaomin,Meng, Bo,Su, Zhong-Min,Wang, Kai,Wang, Lu-Jie,Zhou, Zi-Yan
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supporting information
p. 24895 - 24902
(2021/11/27)
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- A Water Soluble Cobalt(II) Complex with 1,10-Phenanthroline, a Catalyst for Visible-Light-Driven Reduction of CO2 to CO with High Selectivity
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In the presence of KCN, the reaction of 1,10-phenanthroline (phen) with Co (ClO4)2 affords a cobalt(II) complex, [(phen)2Co(CN)2], a co-catalyst for photochemical driven CO2 reduction to CO. Under visible light (λ = 469?nm), together with [Ru(phen)3](PF6)2] as a photosensitizer and triethanolamine (TEOA) as a sacrificial electron donor, [(phen)2Co(CN)2] shows a high selectivity (95%) for the catalytic reduction of CO2 to CO with a turnover number (TON) of 1450 during 10?h irradiation. The photocatalytic mechanism for CO2 reduction by [Co(phen)2(CN)2] is afforded. I hope that these findings can afford a new chemical paradigm for the design of catalysts for CO2 reduction that is highly active and selective. Graphic Abstract: Co(phen)2(CN)2, a catalyst for visible-light-driven driven CO2 reduction to CO with a high selectivity.[Figure not available: see fulltext.]
- Wang, Chun-Li,Du, Juan,Yang, Hao,Zhan, Shu-Zhong
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- Engineering the Cu/Mo2CTx (MXene) interface to drive CO2 hydrogenation to methanol
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Development of efficient catalysts for the direct hydrogenation of CO2 to methanol is essential for the valorization of this abundant feedstock. Here we show that a silica-supported Cu/Mo2CTx (MXene) catalyst achieves a higher intrinsic methanol formation rate per mass Cu than the reference Cu/SiO2 catalyst with a similar Cu loading. The Cu/Mo2CTx interface can be engineered due to the higher affinity of Cu for the partially reduced MXene surface (in preference to the SiO2 surface) and the mobility of Cu under H2 at 500 °C. With increasing reduction time, the Cu/Mo2CTx interface becomes more Lewis acidic due to the higher amount of Cu+ sites dispersed onto the reduced Mo2CTx and this correlates with an increased rate of CO2 hydrogenation to methanol. The critical role of the interface between Cu and Mo2CTx is further highlighted by density functional theory calculations that identify formate and methoxy species as stable reaction intermediates. [Figure not available: see fulltext.]
- Abdala, Paula M.,Chen, Zixuan,Comas-Vives, Aleix,Copéret, Christophe,Donat, Felix,Fedorov, Alexey,Kierzkowska, Agnieszka,Kuznetsov, Denis A.,López, Anna Vidal,López, Estefanía Díaz,Lam, Erwin,Müller, Christoph R.,Mance, Deni,Tsoukalou, Athanasia,Willinger, Elena,Zhou, Hui
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p. 860 - 871
(2021/10/27)
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- Tridecaboron diphosphide: a new infrared light active photocatalyst for efficient CO2photoreduction under mild reaction conditions
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The search for efficient infrared (IR) light responsive photocatalysts for photocatalytic CO2reduction is highly desirable but remains a huge challenge. Herein, tridecaboron diphosphide (B13P2) is demonstrated as an effect
- Shi, Li,Ren, Xiaohui,Wang, Qi,Zhou, Wei,Ye, Jinhua
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p. 2421 - 2428
(2021/02/09)
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- Promotion of photocatalytic steam reforming of methane over Ag0/Ag+-SrTiO3
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Methane (CH4) is not only used as a fuel but also as a promising clean energy source for hydrogen generation. The steam reforming of CH4 (SRM) using photocatalysts can realize the production of syngas (CO + H2) with low energy consumption. In this work, Ag0/Ag+-loaded SrTiO3 nanocomposites were successfully prepared through a photodeposition method. When the loading amount of Ag is 0.5 mol%, the atom ratio of Ag+ to Ag0 was found to be 51:49. In this case, a synergistic effect of Ag0 and Ag+ was observed, in which Ag0 was proposed to improve the adsorption of H2O to produce hydroxyl radicals and enhance the utilization of light energy as well as the separation of charge carriers. Meanwhile, Ag0 was regarded as the reduction reaction site with the function of an electron trapping agent. In addition, Ag+ adsorbed the CH4 molecules and acted as the oxidation reaction sites in the process of photocatalytic SRM to further promote electron-hole separation. As a result, 0.5 mol% Ag-SrTiO3 exhibited enhancement of photocatalytic activity for SRM with the highest CO production rate of 4.3 μmol g?1 h?1, which is ca. 5 times higher than that of pure SrTiO3. This work provides a facile route to fabricate nanocomposite with cocatalyst featuring different functions in promoting photocatalytic activity for SRM.
- Tan, Bingqing,Ye, Yinghao,Huang, Zeai,Ye, Liqun,Ma, Minzhi,Zhou, Ying
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p. 1530 - 1534
(2020/07/30)
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- Palladium-Catalyzed Oxidative C≡C Triple Bond Cleavage of 2-Alkynyl Carbonyl Compounds Toward 1,2-Dicarbonyl Compounds?
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A new, general palladium-catalyzed oxidative strategy for the cleavage of the C≡C triple bond is presented. By employing PdCl2, CuBr2, TEMPO and air as the catalytic system and H2O as the carbonyl oxygen atom source, a wide range of 2-alkynyl carbonyl compounds, including 1,3-disubstituted prop-2-yn-1-ones, propiolamides and propiolates, lost an alkynyl carbon to access various 1,2-dicarbonyl compounds, e.g., 1,2-diones, 2-keto amides and 2-keto esters, through Wacker oxidation, intramolecular cyclization and C—C bond cleavage cascades.
- Hu, Ming,Li, Jin-Heng,Luo, Mu-Jia,Zhou, Ming-Bo
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p. 553 - 558
(2020/04/20)
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- A Metal-Free Donor–Acceptor Covalent Organic Framework Photocatalyst for Visible-Light-Driven Reduction of CO2 with H2O
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Visible-light-driven CO2 reduction to valuable chemicals without sacrificial agents and cocatalysts remains challenging, especially for metal-free photocatalytic systems. Herein, a novel donor–acceptor (D–A) covalent organic framework (CT-COF) was constructed by the Schiff-base reaction of carbazole-triazine based D–A monomers and possessed a suitable energy band structure, strong visible-light-harvesting, and abundant nitrogen sites. CT-COF as a metal-free photocatalyst could reduce CO2 with gaseous H2O to CO as the main carbonaceous product with approximately stoichiometric O2 evolution under visible-light irradiation and without cocatalyst. The CO evolution rate (102.7 μmol g?1 h?1) was 68.5 times that of g-C3N4 under the same conditions. In situ Fourier-transform (FT)IR analysis indicated that CT-COF could adsorb and activate the CO2 and H2O molecules and that COOH* species may be a key intermediate. DFT calculations suggested that nitrogen atoms in the triazine rings may be photocatalytically active sites.
- Lei, Kai,Wang, Di,Ye, Liqun,Kou, Mingpu,Deng, Yu,Ma, Zhaoyu,Wang, Li,Kong, Yan
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p. 1725 - 1729
(2020/03/11)
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- Hydrogenation of CO2 to Methanol by Pt Nanoparticles Encapsulated in UiO-67: Deciphering the Role of the Metal-Organic Framework
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Metal-organic frameworks (MOFs) show great prospect as catalysts and catalyst support materials. Yet, studies that address their dynamic, kinetic, and mechanistic role in target reactions are scarce. In this study, an exceptionally stable MOF catalyst consisting of Pt nanoparticles (NPs) embedded in a Zr-based UiO-67 MOF was subject to steady-state and transient kinetic studies involving H/D and 13C/12C exchange, coupled with operando infrared spectroscopy and density functional theory (DFT) modeling, targeting methanol formation from CO2/H2 feeds at 170 °C and 1-8 bar pressure. The study revealed that methanol is formed at the interface between the Pt NPs and defect Zr nodes via formate species attached to the Zr nodes. Methanol formation is mechanistically separated from the formation of coproducts CO and methane, except for hydrogen activation on the Pt NPs. Careful analysis of transient data revealed that the number of intermediates was higher than the number of open Zr sites in the MOF lattice around each Pt NP. Hence, additional Zr sites must be available for formate formation. DFT modeling revealed that Pt NP growth is sufficiently energetically favored to enable displacement of linkers and creation of open Zr sites during pretreatment. However, linker displacement during formate formation is energetically disfavored, in line with the excellent catalyst stability observed experimentally. Overall, the study provides firm evidence that methanol is formed at the interface of Pt NPs and linker-deficient Zr6O8 nodes resting on the Pt NP surface.
- Gutter?d, Emil S.,Lazzarini, Andrea,Fjermestad, Torstein,Kaur, Gurpreet,Manzoli, Maela,Bordiga, Silvia,Svelle, Stian,Lillerud, Karl P.,Skúlason, Egill,?ien-?Degaard, Sigurd,Nova, Ainara,Olsbye, Unni
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supporting information
p. 999 - 1009
(2020/02/20)
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- A bimetallic-MOF catalyst for efficient CO2photoreduction from simulated flue gas to value-added formate
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Direct CO2 conversion from flue gas into high-value products is of great significance not only in relieving environmental burden but alleviating the energy crisis by a low-cost and energy-saving avenue, yet few studies in this aspect have been reported. Herein, we report metal-node-dependent catalytic performance for solar-energy-powered CO2 reduction to formate in simulated flue gas by bimetallic Ni/Mg-MOF-74. The yield of HCOO- with Ni0.75Mg0.25-MOF-74 as a catalyst in pure CO2 is 0.64 mmol h-1 gMOF-1 which is higher than that of Ni-MOF-74 (0.29 mmol h-1 gMOF-1) and Ni0.87Mg0.13-MOF-74 (0.54 mmol h-1 gMOF-1), whereas monometallic Mg-MOF-74 is almost inactive, indicating that reactivity relies on metal nodes. In simulated flue gas without water vapor at 20 °C, ～80percent of the reactivity in pure CO2 is retained, with HCOO- generation reaching 0.52 mmol h-1 gMOF-1. This activity is comparable to that of the best MOF catalysts in pure CO2, demonstrating that Ni/Mg-MOF-74 not only overcomes the limitation from CO2 concentration, but also has good resistance to other gas components in flue gas at 20 °C. DFT calculations reveal the high output for HCOO- from two crucial factors: strong CO2 binding affinity of Mg sites, and the synergistic effect of Mg and Ni leading to the stabilization of the key ?OCOH intermediate with an appropriate energy barrier. This work paves a new route for double-metal MOFs to enhance the CO2 photoreduction reactivity in flue gas. This journal is
- Dong, Man,Guo, Shao-Hong,Qi, Xiang-Juan,Su, Zhong-Min,Sun, Chun-Yi,Wang, Xiao-Hui,Wang, Xin-Long,Zhao, Xue,Zhou, Hui-Min,Zhou, Jie
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supporting information
p. 11712 - 11718
(2020/07/03)
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- Boosting Photocatalytic CO2 Reduction on CsPbBr3 Perovskite Nanocrystals by Immobilizing Metal Complexes
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Converting CO2 into chemical fuels with a photocatalyst and sunlight is an appealing approach to address climate deterioration and energy crisis. Metal complexes are superb candidates for CO2 reduction due to their tunable catalytic sites with high activity. The coupling of metal complexes with organic photosensitizers is regarded as a common strategy for establishing photocatalytic systems for visible-light-driven CO2 reduction. While most of the organic photosensitizers generally contain precious metals and are available through onerous synthetic routes, their large-scale application in the photocatalysis is limited. Halide perovskite nanocrystals (NCs) have been considered as one of the most promising light-harvesting materials to replace the organic photosensitizers due to their tunable light absorption range, low cost, abundant surface sites, and high molar extinction coefficient. Herein, we demonstrate a facile strategy to immobilize [Ni(terpy)2]2+ (Ni(tpy)) on inorganic ligand-capped CsPbBr3 NCs and to apply this hybrid as a catalyst for visible-light-driven CO2 reduction. In this hybrid photocatalytic system, the Ni(tpy) can provide specific catalytic sites and serve as electron sinks to suppress electron-hole recombination in the CsPbBr3 NCs. The CsPbBr3-Ni(tpy) catalytic system achieves a high yield (1724 μmol/g) in the reduction of CO2 to CO/CH4, which is approximately 26-fold higher than that achieved with the pristine CsPbBr3 NCs. This work has developed a method for enhancing the performance of photocatalytic CO2 reduction by immobilizing metal complexes on perovskite NCs. The methodology we present here provides a new platform for utilizing halide perovskite NCs for photocatalytic applications.
- Bai, Yu,Chen, Zhoujie,Ding, Chao,Gaponik, Nikolai,Hu, Yangguang,Jiang, Guocan,Li, Zhengquan,Shen, Qing,Wang, Jin,Zhang, Yaohong
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p. 1517 - 1525
(2020/03/13)
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- A green approach to the fabrication of a TiO2/NiAl-LDH core-shell hybrid photocatalyst for efficient and selective solar-powered reduction of CO2 into value-added fuels
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Exploring promising photocatalysts with high efficiency and selectivity for CO2 reduction holds paramount significance for resolving the energy crisis and various environmental problems associated with traditional fossil fuels. Here, we rationally design a core-shell hybrid photocatalyst in which anatase TiO2 hollow spheres serve as the core component and NiAl layered double hydroxide (LDH) nanoflakes serve as the shell component. The synthesis of the TiO2/LDH core-shell hybrid involves hydrothermal and calcination treatments without the use of environmentally toxic solvents or surfactants. Assorted experimental results demonstrate that the TiO2/LDH core-shell hybrid exhibits a strong light-harvesting ability, large surface area, porous structure, and extraordinary CO2 adsorption capability. In addition, the unique core-shell geometric structure of the TiO2/LDH hybrid results in a large interfacial contact area and thus provides a broader platform for efficient charge transfer. Benefiting from these structural and compositional features, the TiO2/LDH core-shell hybrid exhibits remarkable CO2 reduction activity, high selectivity (against water reduction), and more importantly, good stability during consecutive test cycles. Therefore, this work offers a promising approach to the rational design and fabrication of core-shell hybrid photocatalysts with potential applications in solar energy conversion and environmental protection.
- Jo, Wan-Kuen,Moru, Satyanarayana,Tonda, Surendar
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supporting information
p. 8020 - 8032
(2020/05/08)
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