- New assay method based on Raman spectroscopy for enzymes reacting with gaseous substrates
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Enzyme activity is typically assayed by quantitatively measuring the initial and final concentrations of the substrates and/or products over a defined time period. For enzymatic reactions involving gaseous substrates, the substrate concentrations can be estimated either directly by gas chromatography or mass spectrometry, or indirectly by absorption spectroscopy, if the catalytic reactions involve electron transfer with electron mediators that exhibit redox-dependent spectral changes. We have developed a new assay system for measuring the time course of enzymatic reactions involving gaseous substrates based on Raman spectroscopy. This system permits continuous monitoring of the gas composition in the reaction cuvette in a non-invasive manner over a prolonged time period. We have applied this system to the kinetic study of the [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F. This enzyme physiologically catalyzes the reversible oxidation of H2 and also possesses the nonphysiological functions of H/D exchange and nuclear spin isomer conversion reactions. The proposed system has the additional advantage of enabling us to measure all of the hydrogenase-mediated reactions simultaneously. Using the proposed system, we confirmed that H2 (the fully exchanged product) is concomitantly produced alongside HD by the H/D exchange reaction in the D2/H2O system. Based on a kinetic model, the ratio of the rate constants of the H/D exchange reaction (k) at the active site and product release rate (kout) was estimated to be 1.9 ± 0.2. The proposed assay method based on Raman spectroscopy can be applied to the investigation of other enzymes involving gaseous substrates.
- Kawahara-Nakagawa, Yuka,Nishikawa, Koji,Nakashima, Satoru,Inoue, Shota,Ohta, Takehiro,Ogura, Takashi,Shigeta, Yasuteru,Fukutani, Katsuyuki,Yagi, Tatsuhiko,Higuchi, Yoshiki
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- Visible-light-driven methane formation from CO2 with a molecular iron catalyst
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Converting CO2 into fuel or chemical feedstock compounds could in principle reduce fossil fuel consumption and climate-changing CO2 emissions. One strategy aims for electrochemical conversions powered by electricity from renewable sources, but photochemical approaches driven by sunlight are also conceivable. A considerable challenge in both approaches is the development of efficient and selective catalysts, ideally based on cheap and Earth-abundant elements rather than expensive precious metals. Of the molecular photo- and electrocatalysts reported, only a few catalysts are stable and selective for CO2 reduction; moreover, these catalysts produce primarily CO or HCOOH, and catalysts capable of generating even low to moderate yields of highly reduced hydrocarbons remain rare. Here we show that an iron tetraphenylporphyrin complex functionalized with trimethylammonio groups, which is the most efficient and selective molecular electro- catalyst for converting CO2 to CO known, can also catalyse the eight-electron reduction of CO2 to methane upon visible light irradiation at ambient temperature and pressure. We find that the catalytic system, operated in an acetonitrile solution containing a photosensitizer and sacrificial electron donor, operates stably over several days. CO is the main product of the direct CO2 photoreduction reaction, but a two-pot procedure that first reduces CO2 and then reduces CO generates methane with a selectivity of up to 82 per cent and a quantum yield (light-to-product efficiency) of 0.18 per cent. However, we anticipate that the operating principles of our system may aid the development of other molecular catalysts for the production of solar fuels from CO2 under mild conditions.
- Rao, Heng,Schmidt, Luciana C.,Bonin, Julien,Robert, Marc
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- Formal Kinetic Description of Photocatalytic Hydrogen Evolution from Ethanol Aqueous Solutions in the Presence of Sodium Hydroxide
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Abstract: The dependences of the rate of the photocatalytic hydrogen production in ethanol aqueous solutions on the concentration of ethanol and sodium hydroxide on the 1% Pt/10% Ni(OH)2/Cd0.3Zn0.7S photocatalyst under vis
- Markovskaya,Kozlova
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- Surface modification of Ni/Al2O3 with Pt: Highly efficient catalysts for H2 generation via selective decomposition of hydrous hydrazine
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Hydrous hydrazine, such as hydrazine monohydrate (N2H 4·H2O), is a promising hydrogen carrier material due to its high content of hydrogen (8.0 wt%). The decomposition of hydrous hydrazine to H2 with a high selectivity and a high activity under mild conditions is the key to its potential usage as a hydrogen carrier material. Platinum-modified Ni/Al2O3 catalysts (NiPt x/Al2O3) were prepared starting from Ni-Al hydrotalcite and tested in the decomposition of hydrous hydrazine. Compared with Ni/Al2O3, the TOF was enhanced sevenfold over NiPt 0.057/Al2O3; meanwhile, the selectivity to H2 was increased to 98%. Characterization results by means of HAADF-STEM, XRD, and EXAFS revealed the presence of surface Pt-Ni alloy in this Pt-promoted catalyst. The formation of Pt-Ni alloy could significantly weaken the interaction between adspecies produced (including H2 and NH x) and surface Ni atoms, which is confirmed by microcalorimetry and TPD results. The weakening effect could account for the greatly enhanced reaction rate, as well as H2 selectivity on NiPtx/Al 2O3 catalysts.
- He, Lei,Huang, Yanqiang,Wang, Aiqin,Liu, Yu,Liu, Xiaoyan,Chen, Xiaowei,Delgado, Juan Jose,Wang, Xiaodong,Zhang, Tao
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- Tribarium tetrahedro-tetragermanide acetylenide, Ba3[Ge4][C2]: Synthesis, structure, and properties
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Ba3Ge4C2 is formed at 1530 K from the elements or by reaction of BaC2 with BaGe2 (corundum crucible; steel ampoule). The compound is a semiconductor (grey colour; Eg = 1.1 eV), brittle, very sensitive to moisture, and reacts with NH4Cl at about 400 K forming acetylene and germanes up to Ge4Hn. The new Ba3Ge4C2 structure type (space group I4/mcm, No. 140; a = 8.840(1) ?, c = 12.466(1) ?; Z = 4, Pearson code tI36), contains two kinds of isolated polyanions, namely tetrahedro-tetragermanide [Ge4]4- and acetylenide [C2]2- anions. The bond lengths are d(Ge-Ge) = 2.517 ? (4x) and 2.641 ? (2x), and d(C≡C) = 1.20 ?. The Ba3[Ge4][C2] structure is a hierarchical derivative of the perovskite (CaTiO3) generated by a partial atom/cluster replacement ([Ge4] for Ca, [C2] for Ti and Ba for O). The Raman spectrum shows bands at 168, 199 and 280 cm-1, and at 1796 cm-1 characteristic for [Ge4]4- and [C2]2 polyanions, respectively.
- Curda, Jan,Carrillo-Cabrera, Wilder,Schmeding, André,Peters, Karl,Somer, Mehmet,Von Schnering, Hans Georg
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- A simple glucose route to nickel and cobalt phosphide catalysts
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In this work, we have developed a simple one-step synthesis of Ni2P and CoP phosphides based on a carbonization process. The current approach uses glucose as a reductant instead of H2 and employs inert gas as feed gas. The Ni2P/C and CoP/C obtained by the glucose route showed higher CH4-CO2 reforming performance than corresponding phosphides prepared by traditional H2 reduction method, which should be attributed to the fact that the phosphides prepared by glucose route had higher surface areas and smaller particle sizes than the ones prepared by traditional method.
- Zhang, Wanting,Ding, Wei,Yao, Zhiwei,Shi, Yan,Sun, Yue,Kang, Xiaoxue
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- Photochemical In Situ Exfoliation of Metal–Organic Frameworks for Enhanced Visible-Light-Driven CO2 Reduction
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Two novel two-dimensional metal–organic frameworks (2D MOFs), 2D-M2TCPE (M=Co or Ni, TCPE=1,1,2,2-tetra(4-carboxylphenyl)ethylene), which are composed of staggered (4,4)-grid layers based on paddlewheel-shaped dimers, serve as heterogeneous photocatalysts for efficient reduction of CO2 to CO. During the visible-light-driven catalysis, these structures undergo in situ exfoliation to form nanosheets, which exhibit excellent stability and improved catalytic activity. The exfoliated 2D-M2TCPE nanosheets display a high CO evolution rate of 4174 μmol g?1 h?1 and high selectivity of 97.3 % for M=Co and Ni, and thus are superior to most reported MOFs. The performance differences and photocatalytic mechanisms have been studied with theoretical calculations and photoelectric experiments. This study provides new insight for the controllable synthesis of effective crystalline photocatalysts based on structural and morphological coregulation.
- Chen, Er-Xia,He, Liang,Huang, Shan-Lin,Lin, Qipu,Luo, Ming-Bu,Wei, Qin,Zheng, Hui-Li
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- Effect of the preparation method of support on the aqueous phase reforming of ethylene glycol over 2 wt% Pt/Ce0.15Zr0.85O2 Catalysts
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The effect of catalyst support on the aqueous phase reforming of ethylene glycol over supported 2 wt% Pt/Ce0.15Zr0.85O2 catalysts have been investigated. Various types of Ce0.15Zr0.85O2 mixed oxides were prepared by hydrothermal prec
- Kim, Jung-Hyun,Jeong, Kwang-Eun,Kim, Tae-Wan,Chae, Ho-Jeong,Jeong, Soon-Yong,Kim, Chu-Ung,Lee, Kwan-Young
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- Synthetic Metallodithiolato Ligands as Pendant Bases in [FeIFeI], [FeI[Fe(NO)]II], and [(μ-H)FeIIFeII] Complexes
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The development of ligands with specific stereo- and electrochemical requirements that are necessary for catalyst design challenges synthetic chemists in academia and industry. The crucial aza-dithiolate linker in the active site of [FeFe]-H2ase has inspired the development of synthetic analogues that utilize ligands which serve as conventional σ donors with pendant base features for H+ binding and delivery. Several MN2S2 complexes (M = Ni2+, [Fe(NO)]2+, [Co(NO)]2+, etc.) utilize these cis-dithiolates to bind low valent metals and also demonstrate the useful property of hemilability, i.e., alternate between bi- and monodentate ligation. Herein, synthetic efforts have led to the isolation and characterization of three heterotrimetallics that employ metallodithiolato ligand binding to di-iron scaffolds in three redox levels, (μ-pdt)[Fe(CO)3]2, (μ-pdt)[Fe(CO)3][(Fe(NO))II(IMe)(CO)]+, and (μ-pdt)(μ-H)[FeII(CO)2(PMe3)]2+ to generate (μ-pdt)[(FeI(CO)3][FeI(CO)2·NiN2S2] (1), (μ-pdt)[FeI(CO)3][(Fe(NO))II(IMe)(CO)]+ (2), and (μ-pdt)(μ-H)[FeII(CO)2(PMe3)][FeII(CO)(PMe3)·NiN2S2]+ (3) complexes (pdt = 1,3-propanedithiolate, IMe = 1,3-dimethylimidazole-2-ylidene, NiN2S2 = [N,N′-bis(2-mercaptidoethyl)-1,4-diazacycloheptane] nickel(II)). These complexes display efficient metallodithiolato binding to the di-iron scaffold with one thiolate-S, which allows the free unbound thiolate to potentially serve as a built-in pendant base to direct proton binding, promoting a possible Fe-H-···+H-S coupling mechanism for the electrocatalytic hydrogen evolution reaction (HER) in the presence of acids. Ligand substitution studies on 1 indicate an associative/dissociative type reaction mechanism for the replacement of the NiN2S2 ligand, providing insight into the Fe-S bond strength.
- Bhuvanesh, Nattamai,Darensbourg, Donald J.,Darensbourg, Marcetta Y.,Elrod, Lindy Chase,Ghosh, Pokhraj,Hsieh, Chung-H.,Kariyawasam Pathirana, Kavindu Dilshan
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- Photocatalytic Formic Acid Conversion on CdS Nanocrystals with Controllable Selectivity for H2 or CO
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Formic acid is considered a promising energy carrier and hydrogen storage material for a carbon-neutral economy. We present an inexpensive system for the selective room-temperature photocatalytic conversion of formic acid into either hydrogen or carbon monoxide. Under visible-light irradiation (λ>420 nm, 1 sun), suspensions of ligand-capped cadmium sulfide nanocrystals in formic acid/sodium formate release up to 116±14 mmolH2gcat-1h-1 with >99% selectivity when combined with a cobalt co-catalyst; the quantum yield at λ=460 nm was 21.2±2.7%. In the absence of capping ligands, suspensions of the same photocatalyst in aqueous sodium formate generate up to 102±13 mmolCOgcat-1h-1 with >95% selectivity and 19.7±2.7% quantum yield. H2 and CO production was sustained for more than one week with turnover numbers greater than 6×105 and 3×106, respectively.
- Kuehnel, Moritz F.,Wakerley, David W.,Orchard, Katherine L.,Reisner, Erwin
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- Large Current Density CO2 Reduction under High Pressure Using Gas Diffusion Electrodes
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Electrochemical reduction of CO2 was studied under high pressure on Co, Rh, Ni, Pd, Pt, Ag, and Cu electrocatalysts supported in the gas diffusion electrode (GDE). CO was produced on Pd and Ag catalysts at faradaic efficiencies of 58 and 86%, respectively, at 300 mA cm-2 under CO2 20 atm. In the case of Cu-GDE, CO and formic acid were produced as the main reduction products. Hydrogen was the predominant reduction product in the electrolyses using other GDEs. Effects of the CO2 pressure, the current density, and the passed charge in the electrochemical reduction of CO2 using Pd and Ag-GDEs were investigated in detail. The maximum partial current density of CO formed on the Pd-GDE under CO2 20 atm was 450 mA cm-2. A very large partial current density of CO formation of 3.05 A cm-2 was achieved in the electrolysis under 30 atm on the Ag-GDE.
- Hara, Kohjiro,Sakata, Tadayoshi
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- Hydrogen generation from highly activated Al-Ce composite materials in pure water
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The reaction of aluminum with pure water is an eco-friendly approach to generate hydrogen. The main difficulty associated with this approach is that an oxide or hydroxide protective film around aluminum particles prohibit the hydrogen generation. In this
- Luo, Hui,Liu, Jie,Pu, Xuxin,Liang, Jie,Wang, Zhengjun,Wang, Feijiu,Zhang, Kun,Peng, Yingjie,Xu, Bo,Li, Jihong,Yu, Xibin
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- Electroreduction of a CoII coordination complex producing a metal-organic film with high performance toward electrocatalytic hydrogen evolution
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This paper describes the synthesis and structural characterization of a novel, cheap and simple CoII complex (CoII(L)2Cl2) based on the 1,3,5-trisubstituted-pyrazoline ligand along with the electrochemical production of metal-organic electroactive films derived from this new complex. These systems were applied as electrocatalysts for hydrogen production (ACN/ACA or ACN/TFA medium) where both materials presented high performance toward hydrogen evolution. Compared to the CoII complex, the electroactive films exhibited significant electroactivity toward hydrogen evolution, presenting a remarkable TOF for H2 production (312:900 s-1, corrected by Faraday efficiency) in the presence of TFA. In addition, the generated metal-organic film showed high stability toward the electrocatalytic hydrogen production, supporting at least 1000 cycles at 20 mV s-1 in the large potential range investigated, as well as good performance and stability in the presence of 0.5 M H2SO4. Relevant insights into the mechanistic details and the role played by the CoII complex and the films during the catalytic hydrogen production are also discussed in light of the structural features and electrochemical experiments.
- Bezerra, Leticia S.,Rosa, Persiely P.,Fortunato, Guilherme V.,Pizzuti, Lucas,Casagrande, Gleison A.,Maia, Gilberto
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- Hydrolysis of Ammonia-Borane over Ni/ZIF-8 Nanocatalyst: High Efficiency, Mechanism, and Controlled Hydrogen Release
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Non-noble metal nanoparticles are notoriously difficult to prepare and stabilize with appropriate dispersion, which in turn severely limits their catalytic functions. Here, using zeolitic imidazolate framework (ZIF-8) as MOF template, catalytically remark
- Wang, Changlong,Tuninetti, Jimena,Wang, Zhao,Zhang, Chen,Ciganda, Roberto,Salmon, Lionel,Moya, Sergio,Ruiz, Jaime,Astruc, Didier
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- Unsymmetrical dirhodium single molecule photocatalysts for H2production with low energy light
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New axially blocked unsymmetrical dirhodium complexes photocatalyze the production of H2under red light irradiation with a turnover number (TON) of 23 ± 3 in the presence of acid and a sacrificial donor. The presence of multiple metal/ligand-to-ligand charge transfer transitions improves their absorption of light into the near-IR.
- Millet, Agustin,Xue, Congcong,Turro, Claudia,Dunbar, Kim R.
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- Optical analyses (SE and ATR) and other properties of LPCVD Si3N4 thin films
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Thin silicon nitride films (less than 20 nm) deposited on (100) silicon substrates via low pressure chemical vapor deposition (LPCVD) at three temperature (730, 760, and 825°C) were analyzed by spectroscopic ellipsometry (SE), attenuated total reflection (ATR), and other tools. Films appeared to have similar optical bandgaps (～5 eV), and the values decreased slightly with the higher deposition temperature. Second ionic mass spectroscopy results showed that a similar amount of oxygen exists in the interface between silicon and silicon nitride. ATR spectra showed no sign of Si-H bonds and decreasing N-H bonds at higher deposition temperature in the thin films. The electrical properties of the films are also discussed.
- Wu, Yun,Zhong, Huicai,Romero, Jeremias,Tabery, Cyrus,Cheung, Cristina,MacDonald, Brian,Bhakta, Jay,Halliyal, Arvind,Cheung, Fred,Ogle, Robert
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- Photocatalytic H2 evolution from NADH with carbon quantum dots/Pt and 2-phenyl-4-(1-naphthyl)quinolinium ion
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Carbon quantum dots (CQDs) were simply blended with platinum salts (K2PtCl4 and K2PtCl6) and converted into a hydrogen-evolution co-catalyst in situ, wherein Pt salts were dispersed on the surface of CQDs under photoirradiation of an aqueous solution of NADH (an electron and proton source) and 2-phenyl-4-(1-naphthyl)quinolinium ion (QuPh+-NA) employed as an organic photocatalyst. The co-catalyst (CQDs/Pt) exhibits similar catalytic reactivity in H2 evolution as that of pure Pt nanoparticles (PtNPs) although the Pt amount of CQDs/Pt was only 1/200 that of PtNPs previously reported. CQDs were able to capture the Pt salt acting as Pt supports. Meanwhile, CQDs act as electron reservoir, playing an important role to enhance electron transfer from QuPh+-NA to the Pt salt, which was confirmed by kinetic studies, XPS and HRTEM.
- Wu, Wenting,Zhan, Liying,Ohkubo, Kei,Yamada, Yusuke,Wu, Mingbo,Fukuzumi, Shunichi
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- In situ preparation of a novel organo-inorganic 6,13-pentacenequinone-TiO2 coupled semiconductor nanosystem: A new visible light active photocatalyst for hydrogen generation
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Previous studies related to the synthesis of stable UV-visible light active photocatalysts for hydrogen generation have been limited to inorganic semiconductors and their nano- and hetero-structures. We demonstrate here the use of an organo-inorganic 6,13-pentacenequinone (PQ)-TiO2 coupled semiconductor nanosystem as an efficient photocatalyst active in visible light for the production of hydrogen. Anatase TiO2 nanoparticles (3-5 nm) were uniformly decorated on thin sheets of monoclinic PQ by an in situ solvothermal method. These as-prepared PQ-TiO2 coupled semiconductor nanosystems had a band gap in the range 2.7-2.8 eV. The strong emission at 590 nm can be attributed to the transfer of electrons from the LUMO energy level of TiO2 to combine with the holes present in the HOMO level of PQ. This electron-hole recombination makes availability of electrons and holes in LUMO of PQ and HOMO of TiO2, respectively. This hybrid semiconductor coupled nanosystem resulted in a rate of hydrogen evolution of 36 456 μmol h-1 g-1 from H2S under UV-visible light; this is four times higher than the rate obtained with TiO2 in earlier reports of UV-visible light active photocatalysts. These results open up a new path to explore inorganic systems coupled with PQ as new photoactive hybrid catalysts in a number of chemical and physicochemical processes. This journal is
- Pandit, Vikram,Arbuj, Sudhir,Hawaldar, Ranjit,Kshirsagar, Pradnya,Mulik, Uttam,Gosavi, Suresh,Park, Chan-Jin,Kale, Bharat
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- The mechanism of methane reforming with carbon dioxide: Comparison of supported Pt and Ni (Co) catalysts
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CH4 reforming with CO2 is one of the promising processes for natural gas conversion. Since the chemical properties of Pt radically differs from those of Ni/Co, the interaction of the catalyst 5.16 wt % Pt/α-Al2O3 with CH4, O2, CO2, and CH4 + CO2 pulses was investigated. CH4 activation occurred via a common pathway via dissociative chemisorption on the metal surface with the formation of H2 and carbon on all the catalysts. CO2 activation on Pt/Al2O3 differed from its activation on Ni(Co)/Al2O3. Pt/Al2O3 was graphite-like in contrast to carbide carbon on Ni(Co)/Al2O3. This graphite carbon was more stable and less reactive. This prevented it from being an active intermediate of CO2 reforming of CH4.
- Bychkov,Tyulenin,Korchak
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- Electrochemical reduction of carbon dioxide at various series of copper single crystal electrodes
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Electrochemical reduction of carbon dioxide was studied with various series of copper single crystal electrodes in 0.1 M KHCO3 aqueous solution at constant current density 5 mA cm-2; the electrodes employed are Cu(S)-[n(1 0 0) x (1 1
- Hori,Takahashi,Koga,Hoshi
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- Enhanced hydrogen production by carbon-doped TiO2 decorated with reduced graphene oxide (rGO) under visible light irradiation
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Enhancing visible light utilization by photocatalysts, avoiding electron-hole recombination, and facilitating charge transfer are three major challenges to the success of sustainable photocatalytic systems. In our study, carbon-doped TiO2 was s
- Kuang, Liyuan,Zhang, Wen
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- Micro-/Mesoporous Platinum–SiCN Nanocomposite Catalysts (Pt@SiCN): From Design to Catalytic Applications
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The synthesis, characterization, and catalytic studies of platinum (Pt) nanoparticles (NPs) supported by a polymer-derived SiCN matrix are reported. In the first step and under mild conditions (110 °C), a block copolymer (BCP) based on hydroxyl-group-terminated linear polyethylene (PEOH) and a commercially available polysilazane (PSZ: HTT 1800) were synthesized. Afterwards, the BCP was microphase separated, modified with an aminopyridinato (Ap) ligand-stabilized Pt complex, and cross-linked. The green bodies thus obtained were pyrolyzed at 1000 °C under nitrogen and provided porous Pt@SiCN nanocomposite via decomposition of the PEOH block while Pt nanoparticles grew in situ within the SiCN matrix. Powder X-ray diffraction (PXRD) studies confirmed the presence of the cubic Pt phase in the amorphous SiCN matrix whereas transmission electron microscopy (TEM) measurements revealed homogeneously distributed Pt nanoparticles in the size of 0.9 to 1.9 nm. N2sorption studies indicated the presence of micro- and mesopores. Pt@SiCN appears to be an active and robust catalyst in the hydrolysis of sodium borohydride under harsh conditions.
- Sachau, Sabrina M.,Zaheer, Muhammad,Lale, Abhijeet,Friedrich, Martin,Denner, Christine E.,Demirci, Umit B.,Bernard, Samuel,Motz, Günter,Kempe, Rhett
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- Improved hydrogen release from ammonia borane confined in microporous carbon with narrow pore size distribution
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Ammonia borane is a promising hydrogen storage candidate due to its high hydrogen capacity and good stability at room temperature, but there are still some barriers to be overcome before it can be used for practical applications. We present the hydrogen release from ammonia borane confined in templated microporous carbon with extremely narrow pore size distribution. Compared with neat ammonia borane, the hydrogen release temperature of ammonia borane confined in microporous carbon with a pore size of 1.05 nm is significantly reduced, starting at 50 °C and with the peak dehydrogenation temperature centred at 86 °C. The dehydrogenation kinetics of ammonia borane confined in templated microporous carbon is significantly improved and by-products including ammonia and diborane are also completely prohibited without any catalysts involved. The remarkably fast hydrogen release rate and high hydrogen storage capacity from ammonia borane confined in microporous carbon are due to the dramatic decrease in the activation energy of ammonia borane. This has been so far the best performance among porous carbon materials used as the confinement scaffolds for ammonia borane in hydrogen storage, making AB confined in microporous carbon a very promising candidate for hydrogen storage.
- Yang, Zhuxian,Zhou, Dan,Chen, Binling,Liu, Zongjian,Xia, Qinghua,Zhu, Yanqiu,Xia, Yongde
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- Catalytic activity of mesoporous Ni/CNT, Ni/SBA-15 and (Cu, Ca, Mg, Mn, Co)-Ni/SBA-15 catalysts for CO2 reforming of CH4
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The CO2 reforming of CH4 to H2 over a catalyst is an effective method for renewable energy generation. In this study, SBA-15 and CNT were chosen as supports for the Ni-based catalysts prepared by the impregnation method. The FESEM images demonstrated that NiO particles were rhombic and well distributed on the SBA-15 surface. The XRD patterns showed that the chemical state of Ni changed after the reforming reaction; the main crystals on the fresh and spent Ni/SBA-15 were found to be NiO and Ni0. The catalytic performance of Ni/SBA-15 in CO2/CH4 reforming was found to be superior to that of Ni/CNT. The results of the TGA and BET analysis demonstrated that spent Ni/SBA-15 (at 600 °C) showed no catalytic decay as an insignificant amount of coke was deposited on the catalyst supports. Moreover, Ni-based bimetallic catalysts were studied for the reforming reaction, and the activity of the catalysts with respect to metals was observed to follow a particular order: Cu-Ni > Mg-Ni > Co-Ni > Ca-Ni > Mn-Ni. The Cu-Ni/SBA-15 catalyst exhibited higher catalytic activity at a reaction temperature of 650 °C as compared to the others; the H2 yield (40%) was not decreased as the reaction time increased, and the conversion of CO2 and CH4 is 77% and 75%, respectively.
- Dai, Yong-Ming,Lu, Chi-Yuan,Chang, Chi-Jen
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- Conformational Effects of [Ni2(μ-ArS)2] Cores on Their Electrocatalytic Activity
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Two nickel complexes supported by tridentate NS2 ligands, [Ni2(κ-N,S,S,S′-NPh{CH2(MeC6H2R′)S}2)2] (1; R′=3,5-(CF3)2C6H3) and [Ni2(κ-N,S,S,S′-NiBu{CH2C6H4S}2)2] (2), were prepared as bioinspired models of the active site of [NiFe] hydrogenases. The solid-state structure of 1 reveals that the [Ni2(μ-ArS)2] core is bent, with the planes of the nickel centers at a hinge angle of 81.3(5)°, whereas 2 shows a coplanar arrangement between both nickel(II) ions in the dimeric structure. Complex 1 electrocatalyzes proton reduction from CF3COOH at ?1.93 (overpotential of 1.04 V, with icat/ip≈21.8) and ?1.47 V (overpotential of 580 mV, with icat/ip≈5.9) versus the ferrocene/ferrocenium redox couple. The electrochemical behavior of 1 relative to that of 2 may be related to the bent [Ni2(μ-ArS)2] core, which allows proximity of the two Ni???Ni centers at 2.730(8) ?; thus possibly favoring H+ reduction. In contrast, the planar [Ni2(μ-ArS)2] core of 2 results in a Ni???Ni distance of 3.364(4) ? and is unstable in the presence of acid.
- Mondragón-Díaz, Alexander,Robles-Marín, Elvis,Murueta-Cruz, Brenda A.,Aquite, Juan C.,Martínez-Alanis, Paulina R.,Flores-Alamo, Marcos,Aullón, Gabriel,Benítez, Luis Norberto,Castillo, Ivan
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- Ruthenium-catalyzed dehydrogenation of ammonia boranes
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The dehydrogenation of ammonia borane (AB) and methylammonia borane (MeAB) is shown to be catalyzed by several Ru-amido complexes. Up to 1 equiv of H2 (1.0 system wt %) is released from AB by as little as 0.03 mol % Ru within 5 min, and up to 2 equiv of H2 (3.0 system wt %) are released from MeAB with 0.5 mol % Ru in under 10 min at room temperature, the first equivalent emerging within 10 s. Also, a mixture of AB/MeAB yields up to 3.6 system wt % H2 within 1 h with 0.1 mol % Ru. Computational studies were performed to elucidate the mechanism of dehydrogenation of AB. Finally, it was shown that alkylamine-boranes can serve as a source of H2 in the Ru-catalyzed reduction of ketones and imines. Copyright
- Blaquiere, Nicole,Diallo-Garcia, Sarah,Gorelsky, Serge I.,Black, Daniel A.,Fagnou, Keith
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- Hydrogenation properties of Mg2AlNi2 and mechanical alloying in the Mg-Al-Ni system
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Samples with MgmAlNin composition (m, n ≤ 3) were synthesized by ball milling in form of crystalline nanoparticles, and were found to be a single phase with partially disordered CsCl-type cubic structure. For compositions with large
- Parente,Nale,Catti,Kopnin,Caracino
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- Trans-(Cl)-[Ru(5,5′-diamide-2,2′-bipyridine)(CO)2Cl2]: Synthesis, Structure, and Photocatalytic CO2 Reduction Activity
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A series of trans-(Cl)-[Ru(L)(CO)2Cl2]-type complexes, in which the ligands L are 2,2′-bipyridyl derivatives with amide groups at the 5,5′-positions, are synthesized. The C-connected amide group bound to the bipyridyl ligand through
- Kuramochi, Yusuke,Fukaya, Kyohei,Yoshida, Makoto,Ishida, Hitoshi
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- B-methyl amine borane derivatives: Synthesis, characterization, and hydrogen release
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We describe the synthesis of MeH2N-BH2Me (3) and H3N-BH2Me (4) as potential hydrogen storage materials with 6.8wt-% and 8.9wt-% capacity, respectively. Compounds 3 and 4 readily release 2 equivalents of H2 at 80°C in the presence of a CoCl2 catalyst to furnish the corresponding trimerized borazine derivatives. Regeneration of 3 from its spent fuel material can be accomplished using a simple two-step process: activation with formic acid followed by reduction with LiAlH4. CSIRO 2014.
- Campbell, Patrick G.,Ishibashi, Jacob S.A.,Zakharov, Lev N.,Liu, Shih-Yuan
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- Capacity enhancement of aqueous borohydride fuels for hydrogen storage in liquids
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Abstract In this work we demonstrate enhanced hydrogen storage capacities through increased solubility of sodium borate product species in aqueous media achieved by adjusting the sodium (NaOH) to boron (B(OH)3) ratio, i.e., M/B, to obtain a distribution of polyborate anions. For a 1:1 mol ratio of NaOH to B(OH)3, M/B = 1, the ratio of the hydrolysis product formed from NaBH4 hydrolysis, the sole borate species formed and observed by 11B NMR is sodium metaborate, NaB(OH)4. When the ratio is 1:3 NaOH to B(OH)3, M/B = 0.33, a mixture of borate anions is formed and observed as a broad peak in the 11B NMR spectrum. The complex polyborate mixture yields a metastable solution that is difficult to crystallize. Given the enhanced solubility of the polyborate mixture formed when M/B = 0.33 it should follow that the hydrolysis of sodium octahydrotriborate, NaB3H8, can provide a greater storage capacity of hydrogen for fuel cell applications compared to sodium borohydride while maintaining a single phase. Accordingly, the hydrolysis of a 23 wt.% NaB3H8 solution in water yields a solution having the same complex polyborate mixture as formed by mixing a 1:3 M ratio of NaOH and B(OH)3 and releases >8 eq of H2. By optimizing the M/B ratio a complex mixture of soluble products, including B3O3(OH)52-, B4O5(OH)42-, B3O3(OH)4-, B5O6(OH)4- and B(OH)3, can be maintained as a single liquid phase throughout the hydrogen release process. Consequently, hydrolysis of NaB3H8 can provide a 40% increase in H2 storage density compared to the hydrolysis of NaBH4 given the decreased solubility of sodium metaborate.
- Schubert, David,Neiner, Doinita,Bowden, Mark,Whittemore, Sean,Holladay, Jamie,Huang, Zhenguo,Autrey, Tom
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- Temperature effect on hydrogen generation by the reaction of γ-Al2O3-modified Al powder with distilled water
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The effect of temperature on the reaction of γ-Al2O 3-modified Al powders with distilled water was investigated. It was found that by increasing the temperature up to 40°C, the hydrogen generation speed can be enhanced one to two ord
- Deng, Zhen-Yan,Liu, Yu-Fu,Tanaka, Yoshihisa,Zhang, Hong-Wang,Ye, Jinhua,Kagawa, Yutaka
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- Immobilizing cobalt phthalocyanine into a porous carbonized wood membrane as a self-supported heterogenous electrode for selective and stable CO2electroreduction in water
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Immobilizing a cobalt phthalocyanine (CoPc) molecular electrocatalyst into a porous carbonized wood membrane (CoPc/CWM) results in a self-supported heterogenous electrode. The CoPc/CWM electrode with an ultralow CoPc loading of 8.2 × 10-6 mol cm-2 exhibits a faradaic efficiency (FE) over 90% for CO production at a wide potential range from-0.59 to-0.78 V versus reversible hydrogen electrode (RHE) and excellent long-term durability during a 12 h electrolysis reaction. This journal is
- Min, Shixiong,Wang, Fang,Zhang, Haidong,Zhang, Zhengguo
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- Clean Donor Oxidation Enhances the H2Evolution Activity of a Carbon Quantum Dot–Molecular Catalyst Photosystem
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Carbon quantum dots (CQDs) are new-generation light absorbers for photocatalytic H2evolution in aqueous solution, but the performance of CQD-molecular catalyst systems is currently limited by the decomposition of the molecular component. Clean oxidation of the electron donor by donor recycling prevents the formation of destructive radical species and non-innocent oxidation products. This approach allowed a CQD-molecular nickel bis(diphosphine) photocatalyst system to reach a benchmark lifetime of more than 5 days and a record turnover number of 1094±61 molH2(molNi)?1for a defined synthetic molecular nickel catalyst in purely aqueous solution under AM1.5G solar irradiation.
- Martindale, Benjamin C. M.,Joliat, Evelyne,Bachmann, Cyril,Alberto, Roger,Reisner, Erwin
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- Carbon quantum dot sensitized integrated Fe2O3@g-C3N4 core-shell nanoarray photoanode towards highly efficient water oxidation
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The construction of integrated heterojunction system photoelectrodes for solar energy conversion is indubitably an efficient alternative due to their effectiveness in charge separation and optimizing the ability for reduction and oxidation reactions. Here, an integrated photoanode constructed with carbon quantum dot (CQD) sensitized Ti:Fe2O3@GCNN (where GCNNs are graphitic carbon nitride nanosheets) core-shell nanoarrays is demonstrated, showing an excellent photocurrent density as high as 3.38 mA cm-2 at 1.23 V versus a reversible hydrogen electrode (VRHE), 2-fold higher than that of pristine Ti:Fe2O3, which is superior over that of recently reported promising photoanodes. In this ternary system (Ti:Fe2O3@GCNN-CQDs), each component plays a specific role in the process towards superior PEC water oxidation: (i) the vectorial hole transfer of Ti:Fe2O3 → g-C3N4 → CQDs; (ii) the introduction of CQDs leads to high catalytic activity for H2O2 decomposition contributing a high rate activity for water oxidation via a two-step-two-electron water-splitting process; (iii) the favorable electron transport behavior of CQDs. This controlled structure design represents one scalable alternative toward the development of photoanodes for high-efficiency water splitting.
- Yi, Sha-Sha,Yan, Jun-Min,Jiang, Qing
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- Polyacrylamide-Mediated Silver Nanoparticles for Selectively Enhancing Electroreduction of CO2 towards CO in Water
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Conversion of the greenhouse gas CO2 to value-added products is an important challenge for sustainable energy research. Here, a durably nanohybrid composed of Ag nanoparticles and polyacrylamide was constructed for the selectively electroreduction of CO2 to CO. The nanohybrid exhibited an outstanding CO faradaic efficiency of 97.2±0.2 % at ?0.89 VRHE (vs. the reversible hydrogen electrode) with a desirable CO partial current density of ?22.0±2.3 mA cm?2 and maintained the CO faradaic efficiency above 95 % over a wide potential range (?0.79 to ?1.09 VRHE), showing excellent stability during a 48 h prolonged electrolysis. The origins of selective enhancement of CO2 reduction over the nanohybrid stemmed from the activation of CO2 via hydrogen bond and the low basicity of the amide. DFT calculations implied that the synergy of Ag nanoparticles and amide could better stabilize the key intermediate (*COOH) and effectively lower the overpotential of CO2 reduction. These results establish the synergistic effects of organic/inorganic hybrid as a complementary method for tuning selectivity in CO2-to-fuels catalysis.
- Han, Xiaofei,Liu, Lin,Yuan, Jiayi,Zhang, Xinsheng,Niu, Dongfang
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- Remedying Defects in Carbon Nitride to Improve both Photooxidation and H2 Generation Efficiencies
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The outstanding visible light response of carbon nitride has aroused intense expectations regarding its photocatalysis, but it is impeded by the inevitable defects. Here, we report on a facile melamine-based defect-remedying strategy and resultant carbon
- Wu, Wenting,Zhang, Jinqiang,Fan, Weiyu,Li, Zhongtao,Wang, Lizhuo,Li, Xiaoming,Wang, Yang,Wang, Ruiqin,Zheng, Jingtang,Wu, Mingbo,Zeng, Haibo
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- A novel (μ-OAc)2 bridged unsymmetric coordinated binuclear Mn(II) macrocyclic complex with ligating pendant-arm
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A novel binuclear manganese Mn(II) macrocyclic complex with two pyridylmethyl pendant arms, [Mn2II(H2L)(μ-OAc)2](ClO4)2 · H2O, has been synthesized and characterized crystallographically and magnetically. The crystal structure of the complex shows that two manganese ions locate in the same head of the macrocycle, leaving an uncoordinating cavity to catch protons through oxide of phenolate and the nearby imine groups in another head. The electrochemical study demonstrates that the complex gives two couples of redox peaks with E1/2 of 0.3775 V and 0.8409 V, respectively. The variable temperature magnetic susceptibility measurement on the sample displays weak antiferromagnetic interaction between two manganese (II) with the J = -3.733(7) cm-1. This complex exhibits a moderate activity for catalyzing disproportionation of H2O2 to O2.
- Pan, Zhi-Quan,Ni, Wen-Hao,Zhou, Hong,Hu, Xue-Lei,Huang, Qi-Mao,Kong, Juan
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- HYDROGEN AND OXYGEN EVOLUTION ON GRAPHITE FIBER-EPOXY MATRIX COMPOSITE ELECTRODES.
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The electrochemical behavior of three graphite fiber-epoxy matrix composite materials containing various fiber orientations and fiber loadings was studied. Cyclic voltammetry was used to detect surface functionalities and to determine the electrochemically active surface areas of each material in 1 N H//2SO//4 and 30 weight percent (w/o) KOH. Hydrogen and oxygen evolution were studied on each electrode in 1 N H//2SO//4 and 30 w/o KOH, respectively. Tafel slopes for the hydrogen evolution reaction on the composite electrodes ranged from 0. 14 to 0. 18 V decade** minus **1 while exchange current densities ranged from 4 to 11 multiplied by 10** minus **7 A cm** minus **2. Tafel slopes for the oxygen evolution reaction on the composite materials were high, ranging from 0. 25 to 0. 28 V decade** minus **1.
- Lipka, S. M.,Cahen, G. L. Jr.,Stoner, G. E.,Scribner, L. L. Jr.,Gileadi, E.
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- Non-solvated aluminum hydride. Crystallization from diethyl ether-benzene solutions
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Crystallization of non-solvated aluminum hydride from a diethyl ether-benzene mixed solvent was studied. The desolvation of AlH 3?(Et2O)x etherate in solution and the crystallization of α-AlH3 during polythermal heating of the solution occur only in the presence of >10 wt.% LiAlH4. The process is multistage, and the crystallization begins with the formation of the AlH3?0.25Et2O solvate, which recrystallizes in the solid phase into γ-AlH3 and then α-AlH3. Four crystalline modifications of aluminum hydride were characterized by X-ray diffraction and electron microscopy.
- Bulychev,Verbetskii,Sizov,Zvukova,Genchel,Fokin
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- Photocatalytic Carbon Dioxide Reduction at p-Type Copper(I) Iodide
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A p-type semiconductor, CuI, has been synthesized, characterized, and tested as a photocatalyst for CO2 reduction under UV/Vis irradiation in presence of isopropanol as a hole scavenger. Formation of CO, CH4, and/or HCOOH was observed. The photocatalytic activity of CuI was attributed to the very low potential of the conduction band edge (i.e., ?2.28 V vs. NHE). Photocurrents generated by the studied material confirm a high efficiency of the photoinduced interfacial electrontransfer processes. Our studies show that p-type semiconductors may be effective photocatalysts for CO2 reduction, even better than extensively studied n-type titanium dioxide, owing to the low potential of the conduction band edge.
- Baran, Tomasz,Wojty?a, Szymon,Dibenedetto, Angela,Aresta, Michele,Macyk, Wojciech
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- Reversible hydrogen storage in Ti-Zr-codoped NaAlH4 under realistic operation conditions
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Ti-Zr-codoped NaAlH4 exhibits improved hydrogen desorption and reabsorption properties compared with sole Ti- or Zr-doped alanate. This contribution aims on reversible hydrogen storage in such material under realistic operation conditions. Results on isothermal dehydrogenation-rehydrogenation cycles at 125 °C and desorption at 4 bar hydrogen back-pressure are presented, proving NaAlH4 to be a suitable hydrogen material in combination with proton exchange membrane fuel cells.
- Schmidt, Thomas,R?ntzsch, Lars
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- CuZnCoOx multifunctional catalyst for in situ hydrogenation of 5-hydroxymethylfurfural with ethanol as hydrogen carrier
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Catalytic in situ hydrogenation of 5-hydroxymethylfurfural (5-HMF) to 2,5-dimethylfuran (DMF) has received a great interest in recent years. However, the issue of the consumption of expensive hydrogen donors, such as secondary alcohols, limits its applica
- Zhang, Zihao,Yao, Siyu,Wang, Changxue,Liu, Miaomiao,Zhang, Feng,Hu, Xiaobing,Chen, Hao,Gou, Xin,Chen, Kequan,Zhu, Yimei,Lu, Xiuyang,Ouyang, Pingkai,Fu, Jie
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- Manganese complexes as models for manganese-containing pseudocatalase enzymes: Synthesis, structural and catalytic activity studies
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Manganese complexes of the type [TpMn(X)] and [TpMn(μ-N3)(μ-X)MnTp] (X = acetylacetonate, acac; picolinate, pic and Tp = TpPh,Me for acac, Tp = Tpipr2 for pic complexes) having TpPh,Me (hydrotris(3-phenyl,5-methyl-pyrazol-1-yl)borate)/Tpipr2 (hydrotris(3,5-diisopropyl-pyrazol-1-yl)borate) as a supporting ligand have been synthesized and structurally characterized. IR and X-ray structures suggest that complexes 7 and 9 are binuclear with azido and bidentate ligands (acac/pic) bridging, whereas complexes 6 and 8 are mononuclear with a 5-coordinated metal center. In complex 9 the picolinate is coordinated as tridentate in a η3-fashion, but in complex 7 acac behaves as bidentate, whereas azide is coordinated in a bridging bidentate μ-1,3-manner in both 7 and 9. Since the coordination geometry of the manganese ions in complex 9 is very similar to the active site structure of manganese-containing pseudocatalase, we have tested the catalytic activity of the same towards the disproportionation of hydrogen peroxide. The catalytic results indicated that complex 9 has reasonably good catalase activity and may be suitable, structurally as well as functionally, as a model for the pseudocatalase enzyme.
- Singh, Udai P.,Tyagi, Pooja,Upreti, Shailesh
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- Formation of a Highly Reactive Cobalt Nanocluster Crystal within a Highly Negatively Charged Porous Coordination Cage
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Earth-abundant first-row transition-metal nanoclusters (NCs) have been extensively investigated as catalysts. However, their catalytic activity is relatively low compared with noble metal NCs. Enhanced catalytic activity of cobalt NCs can be achieved by encapsulating Co NCs in soluble porous coordination cages (PCCs). Two cages, PCC-2a and 2b, possess almost identical cavity in shape and size, while PCC-2a has five times more net charges than PCC-2b. Co2+ cations were accumulated in PCC-2a and reduced to ultra-small Co NCs in situ, while for PCC-2b, only bulky Co particles were formed. As a result, Co NCs@PCC-2a accomplished the highest catalytic activity in the hydrolysis of ammonium borane among all the first-row transition-metals NCs. Based on these results, it is envisioned that confining in the charged porous coordination cage could be a novel route for the synthesis of ultra-small NCs with extraordinary properties.
- Fang, Yu,Xiao, Zhifeng,Li, Jialuo,Lollar, Christina,Liu, Lujia,Lian, Xizhen,Yuan, Shuai,Banerjee, Sayan,Zhang, Peng,Zhou, Hong-Cai
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- A readily accessible ruthenium catalyst for the solvolytic dehydrogenation of amine-borane adducts
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The use of the readily available complex [Ru(p-Cym)(bipy)Cl]Cl as an efficient and robust precatalyst for homogeneously catalysed solvolysis of amine-borane adducts to liberate the hydrogen content of the borane almost quantitatively is being presented. The reactions can be carried out in tap water, and in aqueous mixtures with non-deoxygenated solvents. The system is also efficient for the dehydrocoupling of dimethylamine-borane under solvent-free conditions. This journal is the Partner Organisations 2014.
- Munoz-Olasagasti, Martin,Telleria, Ainara,Perez-Miqueo, Jorge,Garralda, Maria A.,Freixa, Zoraida
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- Photochemical hydrogen evolution catalyzed by trimetallic [Re-Fe] complexes
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In order to conduct photoactive catalysts for hydrogen production, a novel trimetallic [Re-Fe] complex 1, consisting of the phenanthroline rhenium photosensitizer and the [2Fe2S] complex (connected by the axial coordination of a pyridyl group), was prepared and spectroscopically characterized. The apparent fluorescence quenching of the complex 1 was observed in comparison with the reference complex 1b, suggesting the possibility for an electron transfer from the excited state of the rhenium moiety to the [2Fe2S] moiety. Visible light-driven H2 generation was achieved by using triethylamine (sacrificial electron donor) in the presence of the complex 1 (catalyst) in CH3CN/H2O, with a turnover number reaching to 1.5. This is by far as we know the highest for the [Re-Fe] photocatalysts. In contrast to the molecular device, the multicomponent catalyst of complexes 1b and 1c, no H2 was detected by GC analysis in the same experimental condition. The plausible mechanism for the photochemical H2-evolution with this molecular device is discussed.
- Jiang, Weina,Liu, Jianhui,Li, Cheng
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- Direct Coupling of Thermo- and Photocatalysis for Conversion of CO2–H2O into Fuels
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Photocatalytic CO2 reduction into renewable hydrocarbon solar fuels is considered as a promising strategy to simultaneously address global energy and environmental issues. This study focused on the direct coupling of photocatalytic water splitting and thermocatalytic hydrogenation of CO2 in the conversion of CO2–H2O into fuels. Specifically, it was found that direct coupling of thermo- and photocatalysis over Au?Ru/TiO2 leads to activity 15 times higher (T=358 K; ca. 99 % CH4 selectivity) in the conversion of CO2–H2O into fuels than that of photocatalytic water splitting. This is ascribed to the promoting effect of thermocatalytic hydrogenation of CO2 by hydrogen atoms generated in situ by photocatalytic water splitting.
- Zhang, Li,Kong, Guoguo,Meng, Yaping,Tian, Jinshu,Zhang, Lijie,Wan, Shaolong,Lin, Jingdong,Wang, Yong
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- Surface stoichiometry manipulation enhances solar hydrogen evolution of CdSe quantum dots
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Surface stoichiometry is a sensitive parameter affecting the decay dynamics of photogenerated hole-electron pairs of QDs. However, the effect of this manipulation on artificial photocatalytic H2 evolution is unclear. Here, we report that surface stoichiometry manipulation is a facile and feasible approach for enhancing H2 photogeneration of QDs. In the absence of an external cocatalyst, a decrease in the surface Se ratio of CdSe QDs from ～16.7% to ～4.9% gives a more than 10-fold increase in solar H2 evolution. Taking Ni(ii) as an external cocatalyst, CdSe QDs with a surface Se ratio of ～4.9% can produce ～1600 ± 151 μmol H2 gas during 27 h of visible-light irradiation, giving a total turnover number of (1.24 ± 0.12) × 105 on CdSe QDs and an apparent quantum yield of 10.1%, which is about 8 times that of CdSe QDs with a surface Se ratio of ～16.7% under the same conditions. Mechanistic insights obtained by a combination of steady-state and time-resolved spectroscopic techniques indicate that surface stoichiometry exerts a significant influence on the exciton kinetics of CdSe QDs: a higher ratio of surface Se would increase the possibility of exciton recombination through hole trapping, thus depressing the performance of solar H2 evolution.
- Huang, Mao-Yong,Li, Xu-Bing,Gao, Yu-Ji,Li, Jian,Wu, Hao-Lin,Zhang, Li-Ping,Tung, Chen-Ho,Wu, Li-Zhu
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- 1T-2H MoSe2 modified MAPbI3 for effective photocatalytic hydrogen evolution
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Organic-inorganic perovskites such as iodine methylamine lead (MAPbI3) shows superb photocatalytic prospect in the field of solar energy driven photocatalysis. However, its catalytic performance is insufficient due to serious charge recombination. In this article, 1T-2H MoSe2/MAPbI3 composites were obtained by simple electrostatic adsorption method. The results of photocatalytic hydrogen production showed that 10 wt% 1T-2H MoSe2/MAPbI3 performed the best hydrogen evolution rate of 552.93 μmol·h?1·g?1, which was 23 times than that of pure MAPbI3 (23.13 μmol·h?1·g?1). The long-term cyclic stability test also indicated that 1T-2H MoSe2/MAPbI3 composites have good stability. The excellent hydrogen evolution rate activity is thoroughly investigated by optical/optoelectrochemical measurements, showing that 1T-2H MoSe2 as a co-catalyst can effectively transfer electrons and promote the separation of photogenerated charge. This study provided a reference for further exploration of MAPbI3-based catalysts with excellent catalytic activity.
- Cai, Yifei,Chen, Jinxi,Lou, Yongbing,Zhang, Tiantian
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- Oxygen-vacancy generation in MgFe2O4 by high temperature calcination and its improved photocatalytic activity for CO2 reduction
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MgFe2O4 spinel with abundant oxygen vacancy was synthesized by a simple precipitation method, and tested in photocatalytic reduction of CO2 with water vapor as reductant. A series of characterization including XRD, XPS, EPR, PL spectrum, UV–vis DRS and TPD-CO2 were performed to investigate the influence of calcination temperature on morphology, optical and electronic properties of MgFe2O4 spinel. The results demonstrated that the oxygen vacancy concentration increases first and then decreases with the increase of calcination temperature. By introducing oxygen vacancies, the recombination of photogenerated electron-hole pairs was significantly suppressed, visible light absorption and chemisorption capacity of CO2 were dramatically boosted. Mg-Fe-750 with the richest oxygen vacancies exhibits the highest photocatalytic activity, for which the production rate of CO and H2 was 24.4 and 34.3 μmol/gcat/h, respectively.
- Chen, Haowen,Fu, Liming,Wang, Kang,Wang, Xitao
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- Copper phthalocyanine@graphene oxide as a cocatalyst of TiO2 in hydrogen generation
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Hydrogen is among the most commonly discussed types of novel energies since it generates high energy in a green manner. Thus, hydrogen production under visible light has been studied with a novel hybrid catalyst including copper(II) phthalocyanine (CuPc) supported on graphene oxide (GO) and TiO2 in a pathway involving formic acid degradation. The homogenous distribution of CuPc on GO has been obtained through synthesis of CuPc in the presence of GO. CuPc@GO carried out the decomposition reaction of formic acid in the presence of TiO2 to afford H2 with TOF of up to 79 h?1 at room temperature. The catalyst indicated 103% and 39% enhancements in H2 generation compared to CuPc/TiO2 and CuPc@GO, respectively.
- Keshipour, Sajjad,Mohammad-Alizadeh, Shima,Razeghi, Mohammad Hossein
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- Synthesis, evaluation, and kinetic assessment of Co-based catalyst for enhanced methane decomposition reaction for hydrogen production
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In this work, the development of 10, 30, and 50?wt.% Co/TiO2–Al2O3 catalysts for catalytic methane decomposition reaction has been reported to produce pure hydrogen. The synthesis of Co particles on the surface of mesoporo
- Al Mesfer, Mohammed K.,Danish, Mohd,Shah, Mumtaj
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- An ultrahigh-loading single-site Zn catalyst for efficient and ambient hydrogen generation from silanes
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A nitrogen-doped carbon-supported ultrahigh-loading single-site Zn catalyst (Zn1-N-C, 28.3 wt%) was facilely constructed by using a ball milling strategy. With atomically dispersed ZnN3O sites, the catalyst showed superior catalytic properties for the generation of H2 from silane/alcohol pairs, and scale-up and recycling tests demonstrated its great potential in practical applications.
- Chen, Hongyu,He, Qian,He, Xiaohui,Ji, Hongbing,Wang, Pengbo
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supporting information
p. 3828 - 3832
(2022/03/31)
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- Few-Atom Pt Ensembles Enable Efficient Catalytic Cyclohexane Dehydrogenation for Hydrogen Production
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Identification of catalytic active sites is pivotal in the design of highly effective heterogeneous metal catalysts, especially for structure-sensitive reactions. Downsizing the dimension of the metal species on the catalyst increases the dispersion, which is maximized when the metal exists as single atoms, namely, single-atom catalysts (SACs). SACs have been reported to be efficient for various catalytic reactions. We show here that the Pt SACs, although with the highest metal atom utilization efficiency, are totally inactive in the cyclohexane (C6H12) dehydrogenation reaction, an important reaction that could enable efficient hydrogen transportation. Instead, catalysts enriched with fully exposed few-atom Pt ensembles, with a Pt-Pt coordination number of around 2, achieve the optimal catalytic performance. The superior performance of a fully exposed few-atom ensemble catalyst is attributed to its high d-band center, multiple neighboring metal sites, and weak binding of the product.
- Cai, Xiangbin,Deng, Yuchen,Diao, Jiangyong,Dong, Chunyang,Guo, Jinqiu,Guo, Yu,Jia, Zhimin,Jiang, Zheng,Li, Chengyu,Li, Jun,Liu, Hongyang,Liu, Jin-Cheng,Ma, Ding,Wang, Meng,Wang, Ning,Xiao, Hai,Xie, Jinglin,Xu, Bingjun,Zhang, Hongbo
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supporting information
p. 3535 - 3542
(2022/02/16)
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- Ethanol Steam Reforming by Ni Catalysts for H2 Production: Evaluation of Gd Effect in CeO2 Support
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Abstract: Ni-based catalysts supported on CeO2 doped with Gd were prepared in this work to investigate the role of gadolinium on ethanol conversion, H2 selectivity, and carbon formation on ethanol steam reforming reaction. For this, catalysts containing 5 wt% of Ni impregnated on supports of ceria modified with different amounts of Gd (1, 5, and 10 wt%) were used. Ex-situ studies of XRPD suggest an increase of the lattice parameters, indicating a solid solution formation between Gd and Ce. Results of TPR showed an increase in metal-support interactions as the content of Gd increased. In situ XRPD studies indicated the formation of a GdNiO ternary phase for the catalysts containing Gd, which is in agreement with the results obtained by XANES. The catalysts were tested at three temperatures: 400?°C, 500?°C, and 600?°C. The conversion and productivity showed dependence with the Gd content and also with the temperature of the reaction. After the catalytic tests, catalysts containing Gd presented filamentous carbon possible due to a change in the reaction pathway. The highest ethanol conversion and H2 productivity were obtained at 600?°C for all catalysts and the best catalyst at this temperature was 5Ni_5GdCeO2. The promising performance of this catalyst may be associate with the lowest formation of GdNiO ternary phase, among the catalysts containing Gd, which means more Ni0 active species available to convert ethanol. Graphical Abstract: [Figure not available: see fulltext.]
- Assaf, Elisabete M.,Ferreira, Gabriella R.,Lucrédio, Alessandra F.,Nogueira, Francisco G. E.
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- Introducing Water-Network-Assisted Proton Transfer for Boosted Electrocatalytic Hydrogen Evolution with Cobalt Corrole
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Proton transfer is vital for many biological and chemical reactions. Hydrogen-bonded water-containing networks are often found in enzymes to assist proton transfer, but similar strategy has been rarely presented by synthetic catalysts. We herein report the Co corrole 1 with an appended crown ether unit and its boosted activity for the hydrogen evolution reaction (HER). Crystallographic and 1H NMR studies proved that the crown ether of 1 can grab water via hydrogen bonds. By using protic acids as proton sources, the HER activity of 1 was largely boosted with added water, while the activity of crown-ether-free analogues showed very small enhancement. Inhibition studies by adding 1) external 18-crown-6-ether to extract water molecules and 2) potassium ion or N-benzyl-n-butylamine to block the crown ether of 1 further confirmed its critical role in assisting proton transfer via grabbed water molecules. This work presents a synthetic example to boost HER through water-containing networks.
- Li, Xialiang,Lv, Bin,Zhang, Xue-Peng,Jin, Xiaotong,Guo, Kai,Zhou, Dexia,Bian, Hongtao,Zhang, Wei,Apfel, Ulf-Peter,Cao, Rui
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supporting information
(2022/01/11)
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- Efficient splitting of alcohols into hydrogen and C–C coupled products over ultrathin Ni-doped ZnIn2S4 nanosheet photocatalyst
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Integrating selective organic synthesis with hydrogen (H2) evolution in one photocatalytic redox reaction system sheds light on the underlying approach for concurrent employment of photogenerated electrons and holes towards efficient production of solar fuels and chemicals. In this work, a facile one-pot oil bath method has been proposed to fabricate a noble metal-free ultrathin Ni-doped ZnIn2S4 (ZIS/Ni) composite nanosheet for effective solar-driven selective dehydrocoupling of benzyl alcohol into value-added C–C coupled hydrobenzoin and H2 fuel, which exhibits higher performance than pure ZIS nanosheet. The remarkably improved photoredox activity of ZIS/Ni is mainly attributed to the optimized electron structure featuring narrower band gap and suitable energy band position, which facilitates the ability of light harvesting and photoexcited charge carrier separation and transfer. Furthermore, it has been demonstrated that it is feasible to employ ZIS/Ni for various aromatic alcohols dehydrocoupling to the corresponding C–C coupled products. It is expected that this work can stimulate further interest on the establishment of innovative photocatalytic redox platform coupling clean solar fuels synthesis and selective organic conversion in a sustainable manner.
- Li, Jing-Yu,Qi, Ming-Yu,Xu, Yi-Jun
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p. 1084 - 1091
(2022/03/15)
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- Stabilized open metal sites in bimetallic metal-organic framework catalysts for hydrogen production from alcohols
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Liquid organic hydrogen carriers such as alcohols and polyols are a high-capacity means of transporting and reversibly storing hydrogen that demands effective catalysts to drive the (de)hydrogenation reactions under mild conditions. We employed a combined theory/experiment approach to develop MOF-74 catalysts for alcohol dehydrogenation and examine the performance of the open metal sites (OMS), which have properties analogous to the active sites in high-performance single-site catalysts and homogeneous catalysts. Methanol dehydrogenation was used as a model reaction system for assessing the performance of five monometallic M-MOF-74 variants (M = Co, Cu, Mg, Mn, Ni). Co-MOF-74 and Ni-MOF-74 give the highest H2 productivity. However, Ni-MOF-74 is unstable under reaction conditions and forms metallic nickel particles. To improve catalyst activity and stability, bimetallic (NixMg1-x)-MOF-74 catalysts were developed that stabilize the Ni OMS and promote the dehydrogenation reaction. An optimal composition exists at (Ni0.32Mg0.68)-MOF-74 that gives the greatest H2 productivity, up to 203 mL gcat-1 min-1 at 300 °C, and maintains 100% selectivity to CO and H2 between 225-275 °C. The optimized catalyst is also active for the dehydrogenation of other alcohols. DFT calculations reveal that synergistic interactions between the open metal site and the organic linker lead to lower reaction barriers in the MOF catalysts compared to the open metal site alone. This work expands the suite of hydrogen-related reactions catalyzed by MOF-74 which includes recent work on hydroformulation and our earlier reports of aryl-ether hydrogenolysis. Moreover, it highlights the use of bimetallic frameworks as an effective strategy for stabilizing a high density of catalytically active open metal sites. This journal is
- Snider, Jonathan L.,Su, Ji,Verma, Pragya,El Gabaly, Farid,Sugar, Joshua D.,Chen, Luning,Chames, Jeffery M.,Talin, A. Alec,Dun, Chaochao,Urban, Jeffrey J.,Stavila, Vitalie,Prendergast, David,Somorjai, Gabor A.,Allendorf, Mark D.
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p. 10869 - 10881
(2021/05/14)
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- Catalytic effect of SrTiO3 on the dehydrogenation properties of LiAlH4
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Lithium alanate (LiAlH4) is regarded as one of the potential materials for on-board hydrogen storage applications because of its high hydrogen capacity. However, this advantage is restricted by several obstacles such as high decomposition temperature and slow desorption kinetics that deny its marketability. Hence, efforts such as decreasing the particle size by the mechanical milling technique and by adding dopants/catalysts have been investigated widely to overcome these drawbacks. In this work, the influences of strontium titanate (SrTiO3) on the dehydrogenation properties of LiAlH4 have been investigated for the first time. The onset decomposition temperature of the 10 wt% SrTiO3-doped LiAlH4 sample decreased from 145 °C to 80 °C in the first dehydrogenation step and from 178 °C to 120 °C in the second dehydrogenation step. For the desorption kinetic measurements at 90 °C, the 10 wt% SrTiO3-doped LiAlH4 sample could desorb about 3.0 wt% of H2 in 20 min compared to 0.2 wt% by the as-milled LiAlH4. The activation energies calculated by Kissinger analysis in the two-step dehydrogenation process of LiAlH4 were lowered after the addition of SrTiO3. From the X-ray diffraction analysis, we found that SrTiO3 did not react during the mechanical milling and heating (desorption) processes. SrTiO3 is believed to play a catalytic role by reducing the physical size of LiAlH4 during the mechanical milling process thereby improving the dehydrogenation storage properties of LiAlH4.
- Ali, N. A.,Ismail, M.,Sazelee, N. A.,Suwarno, S.
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- Selectivity in UV photocatalytic CO2 conversion over bare and silver-decorated niobium-tantalum perovskites
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The hydrothermal synthesis of the perovskites NaNbO3, NaTaO3 and the intermediate composition NaNb0.5Ta0.5O3, as CO2 conversion photocatalysts is reported. Among them, the niobate shows the most promising performance under UV irradiation not only in terms of conversion and light utilization ability, but also regarding the selectivity towards CO2 reduction against hydrogen evolution from water protons. Further modification of NaNbO3 with silver as co-catalyst results in an increase of the selectivity towards highly reduced products, primarily methanol, against the carbon monoxide production mainly observed with the bare semiconductor. A thorough structural, electronic, electrochemical characterization, together with in-situ surface analysis by APXPS, was undertaken to gain deeper insight into the reasons that account for such changes. On the one hand, for the bare semiconductors, increased light absorption and the sole presence of Nb in +4 state at the surface seem to drive the superior activity of NaNbO3. On the other hand, electronic and surface chemistry modifications induced by 0.1 wt.% silver deposition are proposed to govern the higher selectivity towards methanol. Excessive metal loading, in turn, enhances the selectivity effect but at the expense of conversion, in such a way that light utilization becomes poorer than with the bare niobate.
- Fresno, Fernando,Galdón, Sandra,Barawi, Mariam,Alfonso-González, Elena,Escudero, Carlos,Pérez-Dieste, Virginia,Huck-Iriart, Cristián,de la Pe?a O'Shea, Víctor A.
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- Encapsulation of Cobalt Oxide into Metal-Organic Frameworks for an Improved Photocatalytic CO2 Reduction
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The increased emission of CO2 has negative impacts on the environment. Among the strategies, photocatalytic reduction is promising to convert the CO2 into chemicals. In this report, CoOx nanoparticles were loaded in the channels of MIL-101(Cr), a kind of metal-organic frameworks (MOF), to construct a novel CoOx/MIL-101(Cr) system to facilitate CO2 photoreduction. Under the optimal conditions, the CoOx/MIL-101(Cr) showed a significantly enhanced performance for photocatalytic CO2 reduction compared with bare CoOx and MIL-101(Cr). Our findings provide a pathway for a rational design of efficient MOF systems for the photocatalytic reduction of CO2.
- Ma, Yiwen,Du, Juan,Fang, Yuanxing,Wang, Xinchen
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p. 946 - 951
(2020/12/13)
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- Ammonium ion-promoted electrochemical production of synthetic gas from water and carbon dioxide on a fluorine-doped tin oxide electrode
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In situgenerated Sn nanoparticles on fluorine-doped tin oxide act as an electrocatalyst for the CO2reduction reaction to efficiently and stably produce synthetic gas from water and carbon dioxide with the reaction rate drastically enhanced by the addition of ammonium ions.
- Naya, Shin-Ichi,Yoshioka, Hisayoshi,Tada, Hiroaki
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supporting information
p. 1438 - 1441
(2021/02/21)
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- Light-Driven Syngas Production over Defective ZnIn2S4 Nanosheets
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Photocatalytic syngas (CO and H2) production with CO2 as gas source not only ameliorates greenhouse effect, but also produces valuable chemical feedstocks. However, traditional photocatalytic systems require noble metal or suffers fr
- Wang, Xuanwei,Chen, Jianfeng,Li, Qiuyun,Li, Lingyun,Zhuang, Zanyong,Chen, Fei-Fei,Yu, Yan
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p. 3786 - 3792
(2021/02/16)
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- Isolated Cobalt Centers on W18O49Nanowires Perform as a Reaction Switch for Efficient CO2Photoreduction
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Isolated cobalt atoms have been successfully decorated onto the surface of W18O49 ultrathin nanowires. The Co-atom-decorated W18O49 nanowires (W18O49@Co) greatly accelerate the charge carrier separation and electron transport in the catalytic system. Moreover, the surface decoration with Co atoms modifies the energy configuration of the W18O49@Co hybrid and thus boosts the redox capability of photoexcited electrons for CO2 reduction. The decorated Co atoms work as the real active sites and, perhaps more importantly, perform as a reaction switch to enable the reaction to proceed. The optimized catalyst delivers considerable activity for photocatalytic CO2 reduction, yielding an impressive CO generation rate of 21.18 mmol g-1 h-1.
- Zhang, Huabin,Wang, Yan,Zuo, Shouwei,Zhou, Wei,Zhang, Jing,Lou, Xiong Wen David
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supporting information
p. 2173 - 2177
(2021/02/16)
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- Preparation of a ZnIn2S4-ZnAlOxnanocomposite for photoreduction of CO2to CO
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Solar-driven CO2conversion into fuels and sustainable energy has attracted increasing attention around the world. However, the efficiency of the transformation remains relatively low due to the rapid recombination of photogenerated charge carriers. In this work, we prepared a ZnIn2S4-ZnAlOxnanocomposite for visible light driven CO2reduction. The thin layered structure facilitated the photoinduced charge carrier separation and transfer, and also gave excellent adsorption ability towards CO2molecules. Such a nanocatalyst exhibited excellent activity in visible-light driven CO2reduction with a CO optimal formation rate of 1100 μmol g?1h?1, which is 5 times that over bulk ZnIn2S4, and the CO/H2ratio was increased from 0.2 over bulk ZnIn2S4to 1.5 over the ZnIn2S4-ZnAlOxcomposite.In situFT-IR experiments indicated that CO2was reduced on ZnIn2S4-ZnAlOxfollowing a COOH* pathway. This work gives insights into the mechanism of the photocatalytic CO2reduction reaction and inspiration to construct novel heterostructure materials for application in energy and environmental catalysis.
- Dou, Zhaolin,Ji, Min,Liang, Xiaoyu,Pang, Min,Shao, Yuqing,Wang, Min,Wang, Xinkui,Xu, Qiang,Zhang, Xinxin
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p. 3422 - 3427
(2021/06/06)
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- Mechanistic insight into electrocatalytic CO2 reduction using Lewis acid-base pairs
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In this study, fac-[Re(bpy)(CO)3Cl] (bpy = 2,2′-bipyridine) is used as a Lewis base catalyst and [Zn(cyclam)]2+(cyclam = 1,4,8,11-tetraazacyclotetradecane) is used as a Lewis acid co-catalyst. The thermodynamic effect of the [Zn(cyclam)]2+ on the redox activity of the ReI(bpy) catalyst for CO2 reduction has been investigated experimentally using cyclic voltammetry and computationally using density functional theory (DFT). Both experimental and computational results reveal that [Zn(cyclam)]2+ facilitates the Cl? ion dissociation by forming an inner-sphere interaction. As a result, the addition of [Zn(cyclam)]2+ shifts the ReI(bpy) first reduction to less negative potential, enabling the catalyst to be activated with less energy input. Moreover, we are proposing that [Zn(cyclam)]2+ decreases the CO2 reduction overpotential by the ReI(bpy) complex by stabilizing the CO2 binding energy.
- Boraghi, Mahsasadat,White, Travis A.
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- Competition between electrocatalytic CO2 reduction and H+ reduction by Cu(II), Co(II) complexes containing redox-active ligand
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A benzimidazole derivative ligand (L1) and its corresponding transition metal complexes ML1Cl2 (M = Cu (1), Co (2)) have been synthesized and characterized by a combination of X-ray crystallography, PXRD, electrochemistry, spectral (IR, UV–vis) techniques and DFT calculations. The electrocatalytic activity of the two complexes for CO2 reduction was investigated without and with proton source. Bulk electrolysis of the two compounds demonstrates that there is a competition between CO2 and H+ reduction during the electrocatalytic process, leading to a low Faradaic efficiency for CO evolution but a high FE for H2 evolution. The reason of the serious competition reaction of hydrogen generation in the process of catalytic CO2 reduction have been investigated. Studies show that the catalytic effect could be due to a synergy effect between the redox active ligand L1 and metal ions (Cu (II) (1) and Co (II) (2)), while the formation of hydride complex [M(I)L1??H??]1- might be the crux in the selectivity between CO2 reduction and H2 evolution, and the process of electrocatalytic reduction of CO2 could have promoted H+ reduction.
- Fan, Yu-Hua,Gao, Wei-Song,Shi, Ning-Ning,Wang, Jin-Miao,Wang, Mei,Yin, Xiao-Meng,Zhang, Shi-Fu
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- Anchoring metal ions in amine-functionalized boron imidazolate framework for photocatalytic reduction of CO2
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The photocatalytic reduction of CO2 to energy-rich chemicals is highly appealing for alleviation of energy crisis and environment pollution. The introduction of different active sites is a key factor to determine the reaction activity and selectivity. Here, we demonstrate the metal ion-dependent performance for photocatalytic CO2 reduction by anchoring transition metal ions (Co2+ and Ni2+) in an amine-functionalized boron imidazolate framework (BIF-43). As a result, Ni@BIF-43 realized a high selectivity of 90.2% for the CO2-to-CO, while Co@BIF-43 achieved more efficient conversion with a high CO production rate of 2036.0 μmol g?1 h?1. Significantly, precise control of isolated metal site on a well-defined structure through coordination-assisted strategies enables us to better understand the specific effects of different metal-ion species on photoreduction of CO2 as well as the catalytic mechanism.
- Hong, Qin-Long,Liu, Meng,Sun, Yayong,Xu, Guilan,Zhang, Hai-Xia,Zhang, Jian
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supporting information
(2021/12/30)
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- One-pot preparation of multicomponent photocatalyst with (Zn, Co, Ni)(O, S)/Ga2O3nanocomposites to significantly enhance hydrogen production
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To enhance the production of hydrogen as an alternative energy to fossil fuel, multicomponent photocatalyst (Zn, Co, Ni)(O, S)/Ga2O3nanocomposites were synthesized and optimized with different amounts of Ga precursor in a relatively low-temperature process. The as-prepared nanocomposites were characterized by XRD, SEM, TEM, XPS, DRS, PL, EIS, TPC, CV, and MS techniques, and tested for their photocatalytic activities toward hydrogen evolution reactions (HERs). Zn(O, S) phase formation with low amounts of Ni and Co dopants and a Ga2O3secondary phase were confirmed. The HER catalytic activity of the as-prepared nanocomposite could achieve ～9 mmol g?1h?1without any noble metal as a cocatalyst under low-power UV-light-illuminated conditions. Ethanol was used as the hole scavenger to enhance the photocarrier separation during the photocatalytic HER. It was found that Ni-Co codopants played an essential role in improving HER activities of Zn(O, S). Although the wide-bandgap Ga2O3is not active for photoexcitation under 365 nm light irradiation, it is believed that oxygen vacancies in Ga2O3induce the electron transfer from the conduction band of (Zn, Ni, Co)(O, S). This charge transfer contributes to the photocarrier separation, leading to a higher photocatalytic activity. Moreover, based on XPS results, the trivalent Ni dopant also generated positively charged antisite defects, which also helps electron trapping, reducing the electron-hole recombination rate. This work demonstrated a nanomaterial-design strategy involving simultaneously using dopants and nanocomposite concepts to enhance hydrogen production with an aim to solve the global energy issue.
- Abdullah, Hairus,Ginting, Riski Titian,Gultom, Noto Susanto,Kuo, Dong-Hau,Sembiring, Anita Christine,Shuwanto, Hardy
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p. 19889 - 19902
(2021/11/12)
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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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- Dehydrogenation of sodium borohydride using cobalt embedded zeolitic imidazolate frameworks
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In the last decades were witnesses that hydrogen is in the limelight as an environmentally benign and alternative energy source to fossil fuels. The hydrolysis of sodium borohydride (NaBH4) is promising for the synthesis of materials/chemical compounds and on-demand hydrogen generation-based applications. Herein, cobalt embedded zeolitic imidazolate frameworks (Co@ZIF-8) were synthesized at ambient temperature via a one-pot method (within 60 ?min). X-ray diffraction (XRD) pattern ensures the successful synthesis of a pure phase of Co@ZIF-8 crystals. Transmission electron microscope (TEM) and nitrogen (N2) adsorption-desorption isotherm reveal that Co@ZIF-8 has a hierarchical porous structure. Co@ZIF-8 exhibited high catalytic activity for the hydrolysis of NaBH4 with a hydrogen generation rate (HGR) of 7230 ?mL?gcat?1?min?1 (18 ?× ?106 ?mL?gCo?1?min?1). The high catalytic performance and the simple synthesis procedure of Co@ZIF-8 endow the material's high potential to be a catalyst for hydrogen generation via the hydrolysis of hydrides such as NaBH4.
- Abdelhamid, Hani Nasser
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- Synergistical photo-thermal-catalysis of Zn2GeO4:xFe3+ for H2 evolution in NaBH4 hydrolysis reaction
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Herein, we reported the systematic investigation of synergistic photo-thermal-catalysis for NaBH4 hydrolysis reaction based on zinc orthogermanate. A series of Zn2GeO4:xFe3+ (x = 0 to 0.10) catalysts were prepared via solvothermal method. The H2 evolution experiments demonstrated that the photogenerated holes trap OH? not only shifted the equilibrium of NaBH4 hydrolysis reaction toward the direction of H2 evolution, but also inhibited the recombination of photogenerated carriers. With the remarkable photo-thermal synergism for the as-prepared catalysts, the H2 evolution rate in photo-thermal-driven condition had witnessed several times higher than that in mono-energy driven condition. The catalysts remained stable after circulation tests.
- Li, Qiaoqi,Wang, Fei,Zhou, Xin,Chen, Jianmei,Tang, Chao,Zhang, Lili
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- Cobalt ion redox and conductive polymers boosted the photocatalytic activity of the graphite carbon nitride-Co3O4Z-scheme heterostructure
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The enhanced photocatalytic hydrogen evolution performance of g-C3N4-Co3O4 2D-1D Z-scheme heterojunctions was achieved by employing the cobalt ion redox and conductive polymers (polyaniline, PANi) for the first time. Specifically, a Co3O4 1D nanobelt acting as the Z-scheme heterostructure component could promote the separation of photo-excited charge carriers and increased the redox capacity, and the conductive PANi brought about the boosted transport efficiency of the charge carriers. Notably, cobalt ions were adopted as the intermediate of the electron transfer between two components for boosting the carrier transport and utilization efficiency. Consequently, the Co3O4 nanobelt, PANi and cobalt ions exhibited a synergistic effect on facilitating the photocatalytic HER performance of the g-C3N4-based heterostructure, and the optimal ternary heterostructure (g-C3N4-PANi-Co3O4) exhibited a photocatalytic H2-evolution rate of 4.61 μmol h-1 under visible light, which further increased to 9.95 μmol h-1 by adding Co2+ solution owing to the further facilitated transport of charge carriers through the redox reaction of cobalt ions. Moreover, even in the absence of sacrificial agents, this Z-scheme system exhibited a photocatalytic hydrogen production activity of 3.35 μmol h-1 in the Co2+ aqueous solution under UV-visible light.
- Li, Tao,Cui, Jiandong,Lin, Yezhan,Liu, Kecheng,Li, Rui,Wang, Bo,Xie, Haiquan,Li, Kui
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supporting information
p. 162 - 168
(2021/01/11)
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- Ultrathin Porous Carbon Nitride Bundles with an Adjustable Energy Band Structure toward Simultaneous Solar Photocatalytic Water Splitting and Selective Phenylcarbinol Oxidation
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Actiniae-like carbon nitride (ACN) bundles were synthesized by the pyrolysis of an asymmetric supramolecular precursor prepared from L-arginine (L-Arg) and melamine. ACN has adjustable band gaps (2.25 eV–2.75 eV) and hollow microtubes with ultrathin pore
- Wu, Baogang,Zhang, Liping,Jiang, Baojiang,Li, Qi,Tian, Chungui,Xie, Ying,Li, Weizuo,Fu, Honggang
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supporting information
p. 4815 - 4822
(2021/01/20)
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- Single-atom nickel terminating sp2and sp3nitride in polymeric carbon nitride for visible-light photocatalytic overall water splitting
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Polymeric carbon nitride (PCN) has been widely used as a metal-free photocatalyst for solar hydrogen generation from water. However, rapid charge carrier recombination and sluggish water catalysis kinetics have greatly limited its photocatalytic performance for overall water splitting. Herein, a single-atom Ni terminating agent was introduced to coordinate with the heptazine units of PCN to create new hybrid orbitals. Both theoretical calculation and experimental evidence revealed that the new hybrid orbitals synergistically broadened visible light absorptionviaa metal-to-ligand charge transfer (MLCT) process, and accelerated the separation and transfer of photoexcited electrons and holes. The obtained single-atom Ni terminated PCN (PCNNi), without an additional cocatalyst loading, realized efficient photocatalytic overall water splitting into easily-separated gas-product H2and liquid-product H2O2under visible light, with evolution rates reaching 26.6 and 24.0 μmol g?1h?1, respectively. It was indicated that single-atom Ni and the neighboring C atom served as water oxidation and reduction active sites, respectively, for overall water splittingviaa two-electron reaction pathway.
- Li, Yanrui,Wang, Yiqing,Dong, Chung-Li,Huang, Yu-Cheng,Chen, Jie,Zhang, Zhen,Meng, Fanqi,Zhang, Qinghua,Huangfu, Yiliang,Zhao, Daming,Gu, Lin,Shen, Shaohua
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p. 3633 - 3643
(2021/03/24)
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- Surface Sulfate Ion on CdS Catalyst Enhances Syngas Generation from Biopolyols
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Photocatalytic biomass conversion represents an ideal way of generating syngas because of the sustainable use of biomass carbon and solar energy. However, the lack of efficient electron-proton transfer limits its efficiency. We here report an unprecedente
- Wang, Feng,Wang, Min,Zhang, Zhe,Zhou, Hongru
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p. 6533 - 6541
(2021/05/29)
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- Synthesis of ternary nanoparticles using the complexation-reduction method and their catalytic activities for hydrogen generation from formic acid
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A complex-reduction method was used for the synthesis of glycine-capped copper nanoparticles (Gly-CuNPs). Glycine-Cu2+ was prepared at room temperature, and the resulting complex was treated with NaBH4. Gly-Cu/Ag and Gly-Cu/Ag/MnO2 were prepared by using the stepwise metal displacement plating method. Gly-Cu, Gly-Cu/Ag and Gly-Cu/Ag/MnO2 were employed as catalysts for hydrogen generation from the decomposition of formic acid. The alkaline barium hydroxide solution was employed to trap CO2 formation, and pseudo-first-order rate constants were calculated by using the kobs = 2.303/t log(Aα-A0/Aα-At) relation. Hydrogen generation followed fractional order kinetics with formic acid, and various kinetic parameters were calculated for various concentrations of promoter (sodium format), catalyst and temperature. The catalytic activity was found to increase with an increasing number of incorporated metals, and the order of reactivity was as follows: Gly-Cu/Ag/MnO2 > Gly-Cu/Ag > Gly-Cu. For Gly-Cu/Ag/MnO2, the values of activation parameters (Ea = 56 kJ/mol, ?HNo. = 53 kJ/mol, ?SNo. = ? 68 J/K/mol) were determined with the Arrhenius and Eyring equations, which show higher catalytic efficiency than that of Gly-Cu/Ag (Ea = 69 kJ/mol, ?HNo. = 66 kJ/mol, ?SNo. = ? 25 J/K/mol) due to the synergistic effect and strong interactions between the three metals. The catalytic stability and recyclability were excellent for five consecutive cycles, but the stability and recyclability decreased due to the higher reactivity of MnO2 NPs.
- AL-Thabaiti, Shaeel Ahmad,Bashir, Ommer,Khan, Zaheer,Rafiquee, M. Z. A.
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- Plasmon Coupling-Induced Hot Electrons for Photocatalytic Hydrogen Generation
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We present the fabrication of core-shell-satellite Au@SiO2-Pt nanostructures and demonstrate that LSPR excitation of the core Au nanoparticle can induce plasmon coupling effect to initiate photocatalytic hydrogen generation from decomposition of formic acid. Further studies suggest that the plasmon coupling effect induces a strong local electric field between the Au core and Pt nanoparticles on the SiO2 shell, which enables creation of hot electrons on the non-plasmonic-active Pt nanoparticles to participate hydrogen evolution reaction on the Pt surface. In addition, small SiO2 shell thickness is required in order to obtain a strong plamon coupling effect and achieve efficient photocatalytic activities for hydrogen generation.
- Yuan, Xu,Zhen, Wenlong,Yu, Sijia,Xue, Can
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p. 3683 - 3688
(2021/10/01)
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- Quasi-continuous synthesis of cobalt single atom catalysts for transfer hydrogenation of quinoline
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Improving the transfer hydrogenation of N-heteroarenes is of key importance for various industrial processes and remains a challenge so far. We reported here a microcapsule-pyrolysis strategy to quasi-continuous synthesis S, N co-doped carbon supported Co single atom catalysts (Co/SNC), which was used for transfer hydrogenation of quinoline with formic acid as the hydrogen donor. Given the unique geometric and electronic properties of the Co single atoms, the excellent catalytic activity, selectivity and stability were observed. Benefiting from the quasi-continuous synthesis method, the as-obtained catalysts provide a reference for the large-scale preparation of single atom catalysts without amplification effect. Highly catalytic performances and quasi-continuous preparation process, demonstrating a new and promising approach to rational design of atomically dispersed catalysts with maximum atomic efficiency in industrial.
- Cheng, Yujie,Gan, Tao,He, Qian,He, Xiaohui,Huang, Liyun,Ji, Hongbing,Sun, Qingdi,Zhang, Hao
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supporting information
(2021/12/02)
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- Steam reforming for syngas production over Ni and Ni-promoted catalysts
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In this article, nanocrystalline γ-alumina with high surface area (309 m2 g?1) and mesoporous structure with an average pore size of 4.3?nm was synthesized and employed as a carrier for the synthesis of Ni catalysts in steam reformin
- Andache, Mahmood,Rezaei, Mehran,Taherkhani, Zohre
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p. 3661 - 3672
(2021/06/02)
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- One-pot synthesis of a highly mesoporous Ni/MgAl2O4spinel catalyst for efficient steam methane reforming: influence of inert annealing
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A highly mesoporous Ni/MgAl2O4spinel catalyst was facilely synthesized by a scalable one-pot strategy and employed in the steam methane reforming (SMR) reaction. The influence of annealing the catalyst in a N2atmosphere on
- Eissa, Ahmed Al-Shahat,Kim, Hyunjoung,Kim, Seung Bo,Kim, Woohyun,Lee, Hongjin,Lee, Kyubock,Seo, Dong Joo,Yoon, Wang Lai
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p. 4447 - 4458
(2021/07/12)
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- Insights into the Nonthermal Effects of Light in Dry Reforming of Methane to Enhance the H2/CO Ratio near Unity over Ni/Ga2O3
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Photothermal catalysis, which couples both solar and thermal energies, has burgeoned as a promising approach to drive catalytic reactions. However, the utilization of light irradiation to tune the reaction paths to obtain ideal product distribution in pho
- Rao, Zhiqiang,Cao, Yuehan,Huang, Zeai,Yin, Zihang,Wan, Wenchao,Ma, Minzhi,Wu, Yanxin,Wang, Junbu,Yang, Guidong,Cui, Yi,Gong, Zhongmiao,Zhou, Ying
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p. 4730 - 4738
(2021/05/04)
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- Atomically Dispersed Ni/α-MoC Catalyst for Hydrogen Production from Methanol/Water
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Methanol-water reforming is a promising solution for H2 production/transportation in stationary and mobile hydrogen applications. Developing inexpensive catalysts with sufficiently high activity, selectivity, and stability remains challenging. In this paper, nickel-supported over face-centered cubic (fcc) phase α-MoC has been discovered to exhibit extraordinary hydrogen production activity in the aqueous-phase methanol reforming reaction. Under optimized condition, the hydrogen production rate of 2% Ni/α-MoC is about 6 times higher than that of conventional noble metal 2% Pt/Al2O3 catalyst. We demonstrate that Ni is atomically dispersed over α-MoC via carbon bridge bonds, forming a Ni1-Cx motif on the carbide surface. Such Ni1-Cx motifs can effectively stabilize the isolated Ni1 sites over the α-MoC substrate, rendering maximized active site density and high structural stability. In addition, the synergy between Ni1-Cx motif and α-MoC produces an active interfacial structure for water dissociation, methanol activation, and successive reforming processes with compatible activity.
- Lin, Lili,Yu, Qiaolin,Peng, Mi,Li, Aowen,Yao, Siyu,Tian, Shuheng,Liu, Xi,Li, Ang,Jiang, Zheng,Gao, Rui,Han, Xiaodong,Li, Yong-Wang,Wen, Xiao-Dong,Zhou, Wu,Ma, Ding
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supporting information
p. 309 - 317
(2021/01/12)
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- Insights into the Mechanism of Methanol Steam Reforming Tandem Reaction over CeO2Supported Single-Site Catalysts
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We demonstrated how the special synergy between a noble metal single site and neighboring oxygen vacancies provides an "ensemble reaction pool"for high hydrogen generation efficiency and carbon dioxide (CO2) selectivity of a tandem reaction: methanol steam reforming. Specifically, the hydrogen generation rate over single site Ru1/CeO2 catalyst is up to 9360 mol H2 per mol Ru per hour (579 mLH2 gRu-1 s-1) with 99.5% CO2 selectivity. Reaction mechanism study showed that the integration of metal single site and O vacancies facilitated the tandem reaction, which consisted of methanol dehydrogenation, water dissociation, and the subsequent water gas shift (WGS) reaction. In addition, the strength of CO adsorption and the reaction activation energy difference between methanol dehydrogenation and WGS reaction play an important role in determining the activity and CO2 selectivity. Our study paves the way for the further rational design of single site catalysts at the atomic scale. Furthermore, the development of such highly efficient and selective hydrogen evolution systems promises to deliver highly desirable economic and ecological benefits.
- Chen, Jeng-Lung,Chen, Luning,Dun, Chaochao,Guo, Jinghua,Pao, Chih-Wen,Peng, Xinxing,Prendergast, David,Qi, Zhiyuan,Somorjai, Gabor A.,Su, Ji,Urban, Jeffrey J.,Young, Melissa,Zhang, Xibo
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p. 12074 - 12081
(2021/08/23)
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- PtSe2/Pt Heterointerface with Reduced Coordination for Boosted Hydrogen Evolution Reaction
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PtSe2 is a typical noble metal dichalcogenide (NMD) that holds promising possibility for next-generation electronics and photonics. However, when applied in hydrogen evolution reaction (HER), it exhibits sluggish kinetics due to the insufficient capability of absorbing active species. Here, we construct PtSe2/Pt heterointerface to boost the reaction dynamics of PtSe2, enabled by an in situ electrochemical method. It is found that Se vacancies are induced around the heterointerface, reducing the coordination environment. Correspondingly, the exposed Pt atoms at the very vicinity of Se vacancies are activated, with enhanced overlap with H 1s orbital. The adsorption of H. intermediate is thus strengthened, achieving near thermoneutral free energy change. Consequently, the as-prepared PtSe2/Pt exhibits extraordinary HER activity even superior to Pt/C, with an overpotential of 42 mV at 10 mA cm?2 and a Tafel slope of 53 mV dec?1. This work raises attention on NMDs toward HER and provides insights for the rational construction of novel heterointerfaces.
- Fang, Baizeng,Gu, Lin,Guo, Shaojun,Lin, Yan,Lin, Zhiping,Meng, Fanqi,Wang, Zongpeng,Xiao, Beibei,Xu, Yaping,Zhang, Qinghua,Zhong, Wenwu
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supporting information
p. 23388 - 23393
(2021/09/20)
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- Electrochemical and Photophysical Study of Homoleptic and Heteroleptic Methylated Ru(II) Bis-terpyridine Complexes
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In this study, we investigate the impact of N-methylation on the electronic and photophysical properties of both homoleptic and heteroleptic Ru(II) bis-terpyridine complexes based on the recently reported ligand 4’-(4-bromophenyl)-4,4’’’ : 4’’,4’’’’-dipyr
- Rupp, Mira T.,Auvray, Thomas,Hanan, Garry S.,Kurth, Dirk G.
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supporting information
p. 2822 - 2829
(2021/07/16)
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- Semi-continuous regime for continuous hydrogen production from sodium borohydride methanolytic dehydrogenation
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With the objective of continuous H2 production from sodium borohydride (NaBH4), methanolytic dehydrogenation has been studied and semi-continuous regimes were evaluated for making H2 production continuous. Batch catalytic hydrogen generation profiles, with kinetic evaluation at different temperatures, were examined. The batch production experiments showed that H2 production at 40 °C reached almost 100% conversion of NaBH4 after 6.5 and 6.1 min for Co-O and Co-O-B catalyzed reactions, respectively. In addition to this, a figure of merit (FOM) was performed for a comparative analysis of the catalysts’ performance. The semi-continuous regime was achieved by the sequential feeding of NaBH4 into the reactor, with continuous and stable hydrogen production. It resulted in continuous H2 production of 0.94 Lh?1 for almost 2.6 h from Co-O-B catalyzed methanolytic dehydrogenation of NaBH4.
- Kantürk Figen, Aysel
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- Synthesis of highly stable cobalt nanorods anchored on a Ti4N3Tx MXene composite for the hydrolysis of sodium borohydride
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Cobalt-based catalysts are widely used for borohydride hydrolysis, but they are limited by their poor activity and stability. In this study, highly stable cobalt nanorods were facilely anchored on T4N3Tx MXene via hydrothermal synthesis. T4N3Tx effectively prevented the aggregation of the cobalt nanoparticles. The Co/T4N3Tx composite demonstrated superior activity and stability for the hydrolysis of sodium borohydride, which displayed a high hydrogen generation rate of 526 mL g?1 min?1 at 30 °C. The catalyst retained 75% of its initial activity after 15 cycles, which is much higher than previously reported results. Density functional theory (DFT) calculations showed that the Gibbs free energy of hydrogen adsorption on Co/T4N3Tx is close to 0 eV, further confirming the excellent activity of Co/T4N3Tx. These results indicate that the prepared Co/T4N3Tx catalyst is promising for use in hydrogen production via the hydrolysis of borohydride.
- Li, Tianshuo,Sun, Lixian,Xiang, Cuili,Xu, Fen,Zou, Yongjin
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- Synergistically Photo-Thermo-Catalytic Effect of Metal-Oxide Semiconductors with d 10 Electronic Configuration for Hydrogen Generation in NaBH4 Hydrolyzation
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Abstract: The hydrogen generation rate (HGR) of NaBH4 hydrolyzation is sensitive to the pH value of its aqueous solution. The highly dispersed conduction band of metal-oxide semiconductors with d10 electronic configuration allows excellent mobility of photoexcited electrons, ensuring effective separation of photoexcited electron–hole pairs. In this study, ZnGa2O4, a conventional photocatalytic material with d10 electronic configuration was investigated for the synergistically photo-thermo-catalytic effect in NaBH4 hydrolyzation. The hydrogen generation tests revealed that photoexcited holes as OH?-trapping agent promoted hydrogen generated from NaBH4 hydrolyzation. Meanwhile, the consumption of photoexcited holes accelerated hydrogen generated from photoexcited electron reduction. Coupled with these two factors, ZnGa2O4 exhibited synergistically photo-thermo-catalytic effect in NaBH4 hydrolyzation. The HGR in photo-thermo driven condition offered several times higher than that in single-energy driven condition (irradiation or thermal radiation). The obtained catalysts, bare-ZnGa2O4 and ZnGa1.90Fe0.10O4 achieved optimum HGR at 313.15?K under ultraviolet-light (7.81?mmol?h?1?g?1) and visible light (4.39?mmol?h?1?g?1), respectively. In addition, the circular tests demonstrated ZnGa2O4 catalysts with high thermodynamic and chemical stability. Graphic Abstract: [Figure not available: see fulltext.].
- Chen, Jianmei,Li, Qiaoqi,Li, Yuxin,Wang, Chuang,Wang, Fei,Xuan, Tingfeng,Yang, Dingfeng,Zhang, Lili,Zhou, Xin
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- Synthesis of cobalt A2B triaryl corroles bearing aldehyde and amide pyridyl groups and their performance in electrocatalytic hydrogen evolution
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Four A2B type cobalt triaryl corrole complexes (1-4) bearing aldehyde and pyridyl substituents at the 10-meso-phenyl group with different spatial configurations have been synthesized and thoroughly characterized using high-resolution mass spectrometry, nuclear magnetic resonance spectroscopy (NMR), X-ray photoelectron spectroscopy, and single-crystal X-ray diffractometry. These complexes all exhibited good activity in the electrocatalytic hydrogen evolution reaction (HER) when acetic acid, trifluoroacetic acid (TFA) orp-toluenesulfonic acid (TsOH) was used as the proton source. The Tafel catalytic plot revealed the intrinsic characteristics of the catalytic activity. The HER followed the EECEC pathway when acetic acid was used as a proton source, while it proceeded through the EECC or EECEC pathway when using TFA or TsOH as the proton source, depending on the acid concentration. The presence of CoIII-H was detected by1H NMR, which provided evidence for the catalytic mechanism. The amide pyridyl may function as the proton relay group since themeta-substituted cobalt corroles3and4exhibited significantly higher turnover frequency (TOF)maxvalues than corroles1and2in an organic medium.
- Fang, Jun-Jia,Lan, Jian,Yang, Gang,Yuan, Gao-Qing,Liu, Hai-Yang,Si, Li-Ping
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supporting information
p. 5127 - 5136
(2021/03/26)
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- Planar or Bent? Redox Modulation of Hydrogenase Bimetallic Models by the [Ni2(μ-SAr)2] Core Conformation
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Five neutral nickel(II) bimetallic models of the active site of [NiFe]-hydrogenase supported by tridentate sulfur-rich RNS2 ligands, were synthesized and tested as electrocatalysts for proton (H+) reduction. Complexes were classified according to the ?NR substituent (1: 1-methylpyrene; 2: 2-methylthiophene; 3: phenyl) and as type a for those without bulky substituents and type b for the analogues with voluminous groups. Solid state structures were determined for three dimers, revealing [Ni2(μ-SAr)2] frameworks, in which the two coordination planes around the Ni centres define a dihedral angle (θ) that is influenced by the substituents on the ligands (2 a: θ=180.0°, Ni ??? Ni=3.356 ?; 2 b: θ=98.55°, Ni ??? Ni=2.760 ?; 3 a: θ=107.32°, Ni ??? Ni=2.825 ?). Using CF3COOH as H+ source, 1 b and 2 b exhibit catalytic activity at ?1.72 V (icat/ip≈2.40) and ?1.80 V (icat/ip≈2.89) vs the ferrocenium/ferrocene couple (Fc+/Fc), respectively. In contrast, type a complexes were not viable catalysts. This behaviour suggests a relationship between the dimer conformation and its activity, due to a Ni ??? Ni cooperative effect, which is favoured in angular molecules and appears to assist during electrocatalytic H+ reduction.
- Murueta-Cruz, Brenda A.,Berlanga-Vázquez, Armando,Martínez-Otero, Diego,Benitez, Luis Norberto,Castillo, Ivan,Mondragón-Díaz, Alexander
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p. 2089 - 2098
(2021/05/27)
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- Redox behavior of iridium octaethylporphycene and electrocatalytic hydrogen evolution
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The electrochemical properties of β-octaethylporphycene iridium complex (Ir-OEPo) were determined. Based on the electro-spectro measurement results, the reduction of Ir-OEPo did not occur at the central metal but at the ligand, while the reduction of β-octaethylporphyrin iridium complex (Ir-OEPor) occurred at the central iridium. A catalytic current was observed during the cyclic voltammetry (CV) measurements with trifluoroacetic acid (TFA) under a reductive condition, indicating the catalytic reactivity of Ir-OEPo for the hydrogen evolution reaction (HER). By constant potential electrolysis, hydrogen gas was detected by gas chromatography (GC) and the catalytic reactivity of Ir-OEPo was confirmed. The HER mechanism via ligand reduction of macrocyclic aromatic complexes could be one of the concepts for the development of new catalysts.
- Hisaeda, Yoshio,Koide, Taro,Shimakoshi, Hisashi,Zhang, Zhi,Zhou, Zihan
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- Synthesis of first antimony porphycene and electrocatalytic hydrogen evolution driven by ligand-centered reduction
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For post-transition metal electrocatalytic H2 evolution reaction (HER), the new porphycene antimony complexes, Sb(III) octaethyl porphycene (OEPo) and Sb(V)OEPo-Br2, were prepared and evaluated. Electrochemical and electro-spectro measurements revealed that the two-step one-electron reduction processes of Sb(III)OEPo were indicated to be both ligand-centered and the irreversible reduction process observed for Sb(V)OEPo-Br2 was assigned to be the reduction from Sb(V)OEPo-Br2 to Sb(III)OEPo. Electrocatalytic HER happened at -1.0 V (vs. Ag/AgCl) under acidic conditions via the ligand-centered reductions. The electron accepting nature of the porphycene ligand enabled the utilization of a main-group element as a central element for the ligand-centered HER at anodically shifted potentials.
- Fujioka, Taro,Hisaeda, Yoshio,Koide, Taro,Ono, Toshikazu,Yano, Yoshio,Zhang, Zhi
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p. 2048 - 2053
(2021/09/16)
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- Phosphine-substituted diiron complexes Fe2(μ-Rodt)(CO)6?n(PPh3)n(R = Ph, Me, H andn= 1, 2) featuring desymmetrized oxadithiolate bridges: structures, protonation, and electrocatalysis
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Two new series of phosphine-substituted diiron complexes Fe2(μ-Rodt)(CO)6?n(PPh3)n(n= 1 for4-6andn= 2 for7-9) bearing desymmetrized oxadithiolate bridges (i.e., Rodt bridges), which can be considered as diiron subsite models of [FeFe]-hydrogenases, were prepared through the Me3NO-induced replacements of all-CO diiron precursors Fe2(μ-Rodt)(CO)6(Rodt = SCH(R)OCH2S; R = Ph (1), Me (2), and H (3)) with one equivalent or excess PPh3. All the as-obtained complexes have been fully characterized by elemental analysis, various spectroscopy methods, and especially for4,7-9by X-ray crystallography. Further protonation and electrochemistry of4-6and7-9with Rodt bridges are studied and compared without and with CF3CO2H (TFA) and CH3CO2H (HOAc) as strong and weak acidic proton sources byin situIR plus NMR spectroscopies and cyclic voltammetry. On the one hand, under excess TFA, the monosubstituted complexes4-6are partially protonated to produce a mixture of main precursors4-6and minor Fe-protonated species[4(μH)]+,[5(μH)]+, and[6(μH)]+, whereas the disubstituted counterparts7-9are completely protonated to form an isomeric mixture of their hydride species[7(μH)]+,[8(μH)]+, and[9(μH)]+intransoid-dibasal and apical-basal fashions. On the other hand, complexes7-9show better electrocatalytic proton reduction activities (i.e., higher turnover numbers/TONs) under TFA or HOAc relative to counterparts4-6, in which the TONs of4,5and7,8with Phodt or Meodt bridges are a little higher than those of6and9with odt bridges, respectively. These findings reveal that the redox and electrocatalytic behaviors of4-6and7-9with Rodt bridges are affected not only by phosphine coordination modes (PPh3, mono-vs.di-substitution) but also by desymmetrized dithiolate bridges (Rodt, R = Ph, Mevs.H).
- Gu, Xiao-Li,Guo, Yang,Jin, Bo,Jing, Xing-Bin,Li, Jian-Rong,Zhao, Pei-Hua
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supporting information
p. 17996 - 18007
(2021/10/12)
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- Mononuclear Mn complexes featuring N,S-/N,N-donor and 1,3,5-triaza-7-phosphaadamantane ligands: Synthesis and electrocatalytic properties
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Two phosphaadamantane-substituted, new mononuclear Mn(i) carbonyl complexes, fac-[Mn(CO)3(κ2-S2NC7H4)(PTA)] 1 and fac-[Mn(CO)3(κ2-SN2C7H5)(PTA)] 2, were synthesized by the aerobic reaction of dinuclear {MnMn} complexes [Mn2(CO)6(μ-S2NC7H4)2] A and [Mn2(CO)6(μ-SN2C7H5)2] B with 1,3,5-triaza-7-phosphaadamantane (PTA) ligand in dichloromethane at room temperature. The complexes were characterized using SC-XRD, FTIR, NMR, mass spectrometry and elemental analysis. The cage-like monodentate phosphaadamantane ancillary ligand was incorporated with the aim of increasing the solubility of the Mn carbonyl complexes in aqueous media. Complexes 1 and 2 effectively catalyzed electrochemical proton reduction in CH3CN and the CH3CN/water (1?:?1) mixture with trifluoroacetic acid and acetic acid as proton sources. Complexes 1 and 2 displayed a turnover frequency (TOF/s-1) (O.P., η/V) of 718 (1.11) and 254 (1.55), respectively, in CH3CN, and a TOF of 280 (1) and 61 (2) in CH3CN/water mixture for the catalytic process.
- Kaim, Vishakha,Kaur-Ghumaan, Sandeep
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p. 20272 - 20279
(2021/11/22)
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- Non-oxidative Decomposition of CH4 Over CeO2 and CeO2–SiO2 Supported Bimetallic Ni–Mo Catalysts
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The development of highly active and durable catalysts for H2 production through CH4 decomposition process is still a great challenge. In this study, CeO2 and CeO2–SiO2 supported bimetallic Ni–Mo cata
- Aboul-Enein, Ateyya A.,Aboul-Gheit, Noha A. K.,Ahmed, Hanan A.,Awadallah, Ahmed E.,Solyman, Sanaa M.
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