1333-74-0Relevant articles and documents
New assay method based on Raman spectroscopy for enzymes reacting with gaseous substrates
Kawahara-Nakagawa, Yuka,Nishikawa, Koji,Nakashima, Satoru,Inoue, Shota,Ohta, Takehiro,Ogura, Takashi,Shigeta, Yasuteru,Fukutani, Katsuyuki,Yagi, Tatsuhiko,Higuchi, Yoshiki
, p. 663 - 670 (2019)
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.
Formal Kinetic Description of Photocatalytic Hydrogen Evolution from Ethanol Aqueous Solutions in the Presence of Sodium Hydroxide
Markovskaya,Kozlova
, (2018)
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
Tribarium tetrahedro-tetragermanide acetylenide, Ba3[Ge4][C2]: Synthesis, structure, and properties
Curda, Jan,Carrillo-Cabrera, Wilder,Schmeding, André,Peters, Karl,Somer, Mehmet,Von Schnering, Hans Georg
, p. 929 - 936 (1997)
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.
Photochemical In Situ Exfoliation of Metal–Organic Frameworks for Enhanced Visible-Light-Driven CO2 Reduction
Chen, Er-Xia,He, Liang,Huang, Shan-Lin,Lin, Qipu,Luo, Ming-Bu,Wei, Qin,Zheng, Hui-Li
, p. 23588 - 23592 (2021)
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.
Synthetic Metallodithiolato Ligands as Pendant Bases in [FeIFeI], [FeI[Fe(NO)]II], and [(μ-H)FeIIFeII] Complexes
Bhuvanesh, Nattamai,Darensbourg, Donald J.,Darensbourg, Marcetta Y.,Elrod, Lindy Chase,Ghosh, Pokhraj,Hsieh, Chung-H.,Kariyawasam Pathirana, Kavindu Dilshan
, (2020)
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.
Large Current Density CO2 Reduction under High Pressure Using Gas Diffusion Electrodes
Hara, Kohjiro,Sakata, Tadayoshi
, p. 571 - 576 (1997)
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.
Electroreduction of a CoII coordination complex producing a metal-organic film with high performance toward electrocatalytic hydrogen evolution
Bezerra, Leticia S.,Rosa, Persiely P.,Fortunato, Guilherme V.,Pizzuti, Lucas,Casagrande, Gleison A.,Maia, Gilberto
, p. 19590 - 19603 (2018)
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.
Unsymmetrical dirhodium single molecule photocatalysts for H2production with low energy light
Millet, Agustin,Xue, Congcong,Turro, Claudia,Dunbar, Kim R.
, p. 2061 - 2064 (2021)
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.
Photocatalytic H2 evolution from NADH with carbon quantum dots/Pt and 2-phenyl-4-(1-naphthyl)quinolinium ion
Wu, Wenting,Zhan, Liying,Ohkubo, Kei,Yamada, Yusuke,Wu, Mingbo,Fukuzumi, Shunichi
, p. 63 - 70 (2015)
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.
The mechanism of methane reforming with carbon dioxide: Comparison of supported Pt and Ni (Co) catalysts
Bychkov,Tyulenin,Korchak
, p. 353 - 359 (2003)
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.
Enhanced hydrogen production by carbon-doped TiO2 decorated with reduced graphene oxide (rGO) under visible light irradiation
Kuang, Liyuan,Zhang, Wen
, p. 2479 - 2488 (2016)
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
Improved hydrogen release from ammonia borane confined in microporous carbon with narrow pore size distribution
Yang, Zhuxian,Zhou, Dan,Chen, Binling,Liu, Zongjian,Xia, Qinghua,Zhu, Yanqiu,Xia, Yongde
, p. 15395 - 15400 (2017)
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.
Conformational Effects of [Ni2(μ-ArS)2] Cores on Their Electrocatalytic Activity
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
, p. 3301 - 3312 (2019)
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.
Gas Reactions of Carbon
Walker Jr.,Rusinko Jr., Frank,Austin
, p. 133 - 221 (1959)
-
Trans-(Cl)-[Ru(5,5′-diamide-2,2′-bipyridine)(CO)2Cl2]: Synthesis, Structure, and Photocatalytic CO2 Reduction Activity
Kuramochi, Yusuke,Fukaya, Kyohei,Yoshida, Makoto,Ishida, Hitoshi
, p. 10049 - 10060 (2015)
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
Capacity enhancement of aqueous borohydride fuels for hydrogen storage in liquids
Schubert, David,Neiner, Doinita,Bowden, Mark,Whittemore, Sean,Holladay, Jamie,Huang, Zhenguo,Autrey, Tom
, p. S196 - S199 (2015)
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.
Immobilizing cobalt phthalocyanine into a porous carbonized wood membrane as a self-supported heterogenous electrode for selective and stable CO2electroreduction in water
Min, Shixiong,Wang, Fang,Zhang, Haidong,Zhang, Zhengguo
, p. 15607 - 15611 (2020)
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
Carbon quantum dot sensitized integrated Fe2O3@g-C3N4 core-shell nanoarray photoanode towards highly efficient water oxidation
Yi, Sha-Sha,Yan, Jun-Min,Jiang, Qing
, p. 9839 - 9845 (2018)
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.
Remedying Defects in Carbon Nitride to Improve both Photooxidation and H2 Generation Efficiencies
Wu, Wenting,Zhang, Jinqiang,Fan, Weiyu,Li, Zhongtao,Wang, Lizhuo,Li, Xiaoming,Wang, Yang,Wang, Ruiqin,Zheng, Jingtang,Wu, Mingbo,Zeng, Haibo
, p. 3365 - 3371 (2016)
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
HYDROGEN AND OXYGEN EVOLUTION ON GRAPHITE FIBER-EPOXY MATRIX COMPOSITE ELECTRODES.
Lipka, S. M.,Cahen, G. L. Jr.,Stoner, G. E.,Scribner, L. L. Jr.,Gileadi, E.
, p. 753 - 760 (1988)
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.
Photocatalytic Carbon Dioxide Reduction at p-Type Copper(I) Iodide
Baran, Tomasz,Wojty?a, Szymon,Dibenedetto, Angela,Aresta, Michele,Macyk, Wojciech
, p. 2933 - 2938 (2016)
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.
Pietsch, E.,Seuferling, F.
, p. 573 (1931)
Manganese complexes as models for manganese-containing pseudocatalase enzymes: Synthesis, structural and catalytic activity studies
Singh, Udai P.,Tyagi, Pooja,Upreti, Shailesh
, p. 3625 - 3632 (2007)
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.
A readily accessible ruthenium catalyst for the solvolytic dehydrogenation of amine-borane adducts
Munoz-Olasagasti, Martin,Telleria, Ainara,Perez-Miqueo, Jorge,Garralda, Maria A.,Freixa, Zoraida
, p. 11404 - 11409 (2014)
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.
Direct Coupling of Thermo- and Photocatalysis for Conversion of CO2–H2O into Fuels
Zhang, Li,Kong, Guoguo,Meng, Yaping,Tian, Jinshu,Zhang, Lijie,Wan, Shaolong,Lin, Jingdong,Wang, Yong
, p. 4709 - 4714 (2017)
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.
Oxygen-vacancy generation in MgFe2O4 by high temperature calcination and its improved photocatalytic activity for CO2 reduction
Chen, Haowen,Fu, Liming,Wang, Kang,Wang, Xitao
, (2021/09/28)
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.
Copper phthalocyanine@graphene oxide as a cocatalyst of TiO2 in hydrogen generation
Keshipour, Sajjad,Mohammad-Alizadeh, Shima,Razeghi, Mohammad Hossein
, (2021/10/21)
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.
Ethanol Steam Reforming by Ni Catalysts for H2 Production: Evaluation of Gd Effect in CeO2 Support
Assaf, Elisabete M.,Ferreira, Gabriella R.,Lucrédio, Alessandra F.,Nogueira, Francisco G. E.
, (2022/01/19)
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.]