共查询到20条相似文献,搜索用时 15 毫秒
1.
Dr. Chi Chung Lee Martin Stang Prof. Dr. Markus W. Ribbe Prof. Dr. Yilin Hu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(21):e202400273
Nitrogenase reduces N2 to NH3 at its active-site cofactor. Previous studies of an N2-bound Mo-nitrogenase from Azotobacter vinelandii suggest binding of three N2 species via asymmetric belt-sulfur displacements in the two cofactors of its catalytic component (designated Av1*), leading to the proposal of stepwise N2 reduction involving all cofactor belt-sulfur sites; yet, the evidence for the existence of multiple N2 species on Av1* remains elusive. Here we report a study of ATP-independent, EuII/SO32−-driven turnover of Av1* using GC-MS and frequency-selective pulse NMR techniques. Our data demonstrate incorporation of D2-derived D by Av1* into the products of C2H2- and H+-reduction, and decreased formation of NH3 by Av1* concomitant with the release of N2 under H2; moreover, they reveal a strict dependence of these activities on SO32−. These observations point to the presence of distinct N2 species on Av1*, thereby providing strong support for our proposed mechanism of stepwise reduction of N2 via belt-sulfur mobilization. 相似文献
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《化学:亚洲杂志》2017,12(16):1985-1996
The reduction of CO2 into useful products, including hydrocarbon fuels, is an ongoing area of particular interest due to efforts to mitigate buildup of this greenhouse gas. While the industrial Fischer–Tropsch process can facilitate the hydrogenation of CO2 with H2 to form short‐chain hydrocarbon products under high temperatures and pressures, a desire to perform these reactions under ambient conditions has inspired the use of biological approaches. Particularly, enzymes offer insight into how to activate and reduce CO2, but only one enzyme, nitrogenase, can perform the multielectron, multiproton reduction of CO2 into hydrocarbons. The vanadium‐containing variant, V‐nitrogenase, displays especial reactivity towards the hydrogenation of CO and CO2. This Focus Review discusses recent progress towards the activation and reduction of CO2 with three primary V‐nitrogenase systems. These systems span both ATP‐dependent and ATP‐independent processes and utilize approaches with whole cells, isolated proteins, and extracted cofactors. 相似文献
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在玻碳电极上采用吸附法制备了四溴代酞菁钴(CoPcBr4)、酞菁钴(CoPc)和四-α-(2,2,4-三甲基-3-戊氧基)酞菁钴(CoPc(OC8H17)4)修饰电极。利用循环伏安法和线性扫描伏安法研究了修饰电极在酸性介质中对分子氧的电催化还原,比较了不同取代基的酞菁钴对电催化性质的影响。结果表明,它们对分子氧还原均具有良好的电催化活性,其中酞菁钴和四-α-(2,2,4-三甲基-3-戊氧基)酞菁钴对O2的催化是2电子还原生成H2O2,与裸电极相比,O2的还原峰电位分别向正方向移动了0.33和0.48 V。而四溴代酞菁钴修饰电极在-0.1和-0.7 V附近产生的2个还原峰,说明它催化O2到H2O2的还原以后还可以促进H2O2继续还原到H2O,最终实现O2的4电子还原。 相似文献
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Electrocatalytic Dioxygen Reduction by Carbon Electrodes Noncovalently Modified with Iron Porphyrin Complexes: Enhancements from a Single Proton Relay 下载免费PDF全文
Soumalya Sinha Michael S. Aaron Jovan Blagojevic Prof. Dr. Jeffrey J. Warren 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18072-18075
Oxygen reduction in acidic aqueous solution mediated by a series of asymmetric iron (III)‐tetra(aryl)porphyrins adsorbed to basal‐ and edge‐ plane graphite electrodes is investigated. The asymmetric iron porphyrin systems bear phenyl groups at three meso positions and either a 2‐pyridyl, a 2‐benzoic acid, or a 2‐hydroxyphenyl group at the remaining meso position. The presence of the three unmodified phenyl groups makes the compounds insoluble in water, enabling catalyst retention during electrochemical experiments. Resonance Raman data demonstrate that catalyst layers are maintained, but can undergo modification after prolonged catalysis in the presence of O2. The introduction of a single proton relay group at the fourth meso position makes the asymmetric iron porphyrins markedly more robust catalysts; these molecules support higher sustained current densities than the parent iron tetraphenylporphyrin. Iron porphyrins bearing a 2‐pyridyl group are the most active catalysts and operate at stable current densities ≥1 mA cm?2 for over 5 h. Comparative analysis of the catalysts with different proton relays also is reported. 相似文献
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Markus W. Ribbe Kamil Grecki Mario Grosch Joseph B. Solomon Robert Quechol Yiling A. Liu Chi Chung Lee Yilin Hu 《Molecules (Basel, Switzerland)》2022,27(19)
The Fe protein of nitrogenase plays multiple roles in substrate reduction and metallocluster assembly. Best known for its function to transfer electrons to its catalytic partner during nitrogenase catalysis, the Fe protein is also a key player in the biosynthesis of the complex metalloclusters of nitrogenase. In addition, it can function as a reductase on its own and affect the ambient reduction of CO2 or CO to hydrocarbons. This review will provide an overview of the properties and functions of the Fe protein, highlighting the relevance of this unique FeS enzyme to areas related to the catalysis, biosynthesis, and applications of the fascinating nitrogenase system. 相似文献
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Stefan Dieckhöfer Dr. Denis Öhl João R. C. Junqueira Thomas Quast Prof. Dr. Thomas Turek Prof. Dr. Wolfgang Schuhmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(19):5906-5912
Discerning the influence of electrochemical reactions on the electrode microenvironment is an unavoidable topic for electrochemical reactions that involve the production of OH− and the consumption of water. That is particularly true for the carbon dioxide reduction reaction (CO2RR), which together with the competing hydrogen evolution reaction (HER) exert changes in the local OH− and H2O activity that in turn can possibly affect activity, stability, and selectivity of the CO2RR. We determine the local OH− and H2O activity in close proximity to a CO2-converting Ag-based gas diffusion electrode (GDE) with product analysis using gas chromatography. A Pt nanosensor is positioned in the vicinity of the working GDE using shear-force-based scanning electrochemical microscopy (SECM) approach curves, which allows monitoring changes invoked by reactions proceeding within an otherwise inaccessible porous GDE by potentiodynamic measurements at the Pt-tip nanosensor. We show that high turnover HER/CO2RR at a GDE lead to modulations of the alkalinity of the local electrolyte, that resemble a 16 m KOH solution, variations that are in turn linked to the reaction selectivity. 相似文献
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Dr. Nivedita Sikdar João R. C. Junqueira Dr. Denis Öhl Stefan Dieckhöfer Thomas Quast Michael Braun Dr. Harshitha B. Aiyappa Dr. Sabine Seisel Prof. Corina Andronescu Prof. Wolfgang Schuhmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(12):e202104249
Bimetallic tandem catalysts have emerged as a promising strategy to locally increase the CO flux during electrochemical CO2 reduction, so as to maximize the rate of conversion to C−C-coupled products. Considering this, a novel Cu/C−Ag nanostructured catalyst has been prepared by a redox replacement process, in which the ratio of the two metals can be tuned by the replacement time. An optimum Cu/Ag composition with similarly sized particles showed the highest CO2 conversion to C2+ products compared to non-Ag-modified gas-diffusion electrodes. Gas chromatography and in-situ Raman measurements in a CO2 gas diffusion cell suggest the formation of top-bound linear adsorbed *CO followed by consumption of CO in the successive cascade steps, as evidenced by the increasingνC−H bands. These findings suggest that two mechanisms operate simultaneously towards the production of HCO2H and C−C-coupled products on the Cu/Ag bimetallic surface. 相似文献
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We present herein a Cp*Co(III)‐half‐sandwich catalyst system for electrocatalytic CO2 reduction in aqueous acetonitrile solution. In addition to an electron‐donating Cp* ligand (Cp*=pentamethylcyclopentadienyl), the catalyst featured a proton‐responsive pyridyl‐benzimidazole‐based N,N‐bidentate ligand. Owing to the presence of a relatively electron‐rich Co center, the reduced Co(I)‐state was made prone to activate the electrophilic carbon center of CO2. At the same time, the proton‐responsive benzimidazole scaffold was susceptible to facilitate proton‐transfer during the subsequent reduction of CO2. The above factors rendered the present catalyst active toward producing CO as the major product over the other potential 2e/2H+ reduced product HCOOH, in contrast to the only known similar half‐sandwich CpCo(III)‐based CO2‐reduction catalysts which produced HCOOH selectively. The system exhibited a Faradaic efficiency (FE) of about 70% while the overpotential for CO production was found to be 0.78 V, as determined by controlled‐potential electrolysis. 相似文献
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T. A. Bazhenova N. V. Bardina G. N. Petrova M. A. Borovinskaya 《Russian Chemical Bulletin》2004,53(8):1646-1654
The effect of potential value and chemical properties of an external electron donor on C2H2 reduction catalyzed by nitrogenase active center (cluster [(6-N)Fe7MoS9·homocitrate] FeMoco isolated from the enzyme) has been investigated in the presence of proton donors of different acidity. The temperature—reaction rate dependences of these reactions have been studied. It has been shown that the rate-limiting steps of the reactions differ depending on the proton donor used. When thiophenol or water are used as proton donors, and electrochemical step — the electron transfer from cathode to adsorbed catalytic cluster — has been found to be a rate-limiting one. The effective activation energy of ethane formation as a product of four-electron C2H2 reduction is found to be 1.5 times lower than that of ethylene, namely, 13 kcal mol–1. When stronger acid, pentafluorothiophenol, is used as a proton donor, the chemical step of intramolecular rearrangement of the catalyst—substrate complex taking place in solution becomes a rate-limiting one. The effective activation energies of both ethylene and ethane become equal to 32 kcal mol–1.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1583–1591, August, 2004. 相似文献
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Dr. Chi Chung Lee Dr. Jarett Wilcoxen Caleb J. Hiller Prof. Dr. R. David Britt Prof. Dr. Yilin Hu 《Angewandte Chemie (International ed. in English)》2018,57(13):3411-3414
Binding and activation of CO by nitrogenase is a topic of interest because CO is isoelectronic to N2, the physiological substrate of this enzyme. The catalytic relevance of one‐ and multi‐CO‐bound states (the lo‐CO and hi‐CO states) of V‐nitrogenase to C−C coupling and N2 reduction was examined. Enzymatic and spectroscopic studies demonstrate that the multiple CO moieties in the hi‐CO state cannot be coupled as they are, suggesting that C−C coupling requires further activation and/or reduction of the bound CO entity. Moreover, these studies reveal an interesting correlation between decreased activity of N2 reduction and increased population of the lo‐CO state, pointing to the catalytic relevance of the belt Fe atoms that are bridged by the single CO moiety in the lo‐CO state. Together, these results provide a useful framework for gaining insights into the nitrogenase‐catalyzed reaction via further exploration of the utility of the lo‐CO conformation of V‐nitrogenase. 相似文献
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Masahide Shimokawabe Nozomu Takahata Takehiro Chaki Nobutsune Takezawa 《Reaction Kinetics and Catalysis Letters》2000,71(2):313-318
Pronounced activities on the reduction of N2O with CH4 were observed over Fe-ZSM-5, Pd-ZSM-5, and Pt-ZSM-5 catalysts, respectively. No significant deactivation has been detected over Fe-ZSM-5 in the presence of oxygen. 相似文献
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The electrochemical reduction of CO2 to fuels or commodity chemicals is a reaction of high interest for closing the anthropogenic carbon cycle. The role of the electrolyte is of particular interest, as the interplay between the electrocatalytic surface and the electrolyte plays an important role in determining the outcome of the CO2 reduction reaction. Therefore, insights on electrolyte effects on the electrochemical reduction of CO2 are pivotal in designing electrochemical devices that are able to efficiently and selectively convert CO2 into valuable products. Here, we provide an overview of recently obtained insights on electrolyte effects and we discuss how these insights can be used as design parameters for the construction of new electrocatalytic systems. 相似文献
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Mengwei Yuan Matthew J. Kummer Prof. Dr. Shelley D. Minteer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(63):14258-14266
Atmospheric CO2 is a cheap and abundant source of carbon for synthetic applications. However, the stability of CO2 makes its conversion to other carbon compounds difficult and has prompted the extensive development of CO2 reduction catalysts. Bioelectrocatalysts are generally more selective, highly efficient, can operate under mild conditions, and use electricity as the sole reducing agent. Improving the communication between an electrode and a bioelectrocatalyst remains a significant area of development. Through the examples of CO2 reduction catalyzed by electroactive enzymes and whole cells, recent advancements in this area are compared and contrasted. 相似文献
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Dr. Kazuki Tanifuji Dr. Chi Chung Lee Prof. Dr. Yasuhiro Ohki Prof. Dr. Kazuyuki Tatsumi Prof. Dr. Yilin Hu Prof. Dr. Markus W. Ribbe 《Angewandte Chemie (International ed. in English)》2015,54(47):14022-14025
Nitrogenase catalyzes substrate reduction at its cofactor center ([(Cit)MoFe7S9C]n?; designated M‐cluster). Here, we report the formation of an artificial, nitrogenase‐mimicking enzyme upon insertion of a synthetic model complex ([Fe6S9(SEt)2]4?; designated Fe6RHH) into the catalytic component of nitrogenase (designated NifDKapo). Two Fe6RHH clusters were inserted into NifDKapo, rendering the conformation of the resultant protein (designated NifDKFe) similar to the one upon insertion of native M‐clusters. NifDKFe can work together with the reductase component of nitrogenase to reduce C2H2 in an ATP‐dependent reaction. It can also act as an enzyme on its own in the presence of EuIIDTPA, displaying a strong activity in C2H2 reduction while demonstrating an ability to reduce CN? to C1–C3 hydrocarbons in an ATP‐independent manner. The successful outcome of this work provides the proof of concept and underlying principles for continued search of novel enzymatic activities based on this approach. 相似文献
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Karla Calfumán Paulina Dreyse Camilo García Maria J. Aguirre Tomás Beltrán Eva Guillamón Iván Sorribes Cristian Vicent Rosa Llusar Mauricio Isaacs 《Macromolecular Symposia》2011,304(1):93-100
Summary: This paper describes the electrochemical reduction of nitrite ion in 0.1 M NaClO4, on glassy carbon or ITO electrodes modified with mixtures PVC- tetraruthenated metalloporphyrins. This electrode is able to keep the extraordinary electrocatalytic properties of the macrocycle allowing multielectronic transfers and a great stability as a consequence of the inclusion of the macrocycles into a polymeric support such as PVC. On the other hand, the electrochemical reduction of nitrite ion on these modified electrodes studied by cyclic voltammetry shows an enhancement in the current values and lower overpotential compared with the activity of the bare glassy carbon electrode. Controlled potential electrolysis experiments verify the production of ammonia, hydrazine and hydroxylamine, showing the electrocatalytic character and the stability of this modified electrode. 相似文献
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Lee A. Rettberg Dr. Martin T. Stiebritz Dr. Wonchull Kang Dr. Chi Chung Lee Prof. Dr. Markus W. Ribbe Prof. Dr. Yilin Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(57):13078-13082
The Fe protein of nitrogenase catalyzes the ambient reduction of CO2 when its cluster is present in the all-ferrous, [Fe4S4]0 oxidation state. Here, we report a combined structural and theoretical study that probes the unique reactivity of the all-ferrous Fe protein toward CO2. Structural comparisons of the Azotobacter vinelandii Fe protein in the [Fe4S4]0 and [Fe4S4]+ states point to a possible asymmetric functionality of a highly conserved Arg pair in CO2 binding and reduction. Density functional theory (DFT) calculations provide further support for the asymmetric coordination of O by the “proximal” Arg and binding of C to a unique Fe atom of the all-ferrous cluster, followed by donation of protons by the proximate guanidinium group of Arg that eventually results in the scission of a C−O bond. These results provide important mechanistic and structural insights into CO2 activation by a surface-exposed, scaffold-held [Fe4S4] cluster. 相似文献
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Guangtao Wang Xiang Li Xiaohan Yang Dr. Li-Xia Liu Yanming Cai Yajun Wu Shengyan Wang Huan Li Prof. Yuanzhen Zhou Prof. Yuanyuan Wang Prof. Yang Zhou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(64):e202201834
General strategies for metal aerogel synthesis, including single-metal, transition-metal doped, multi-metal-doped, and nano-metal-doped carbon aerogel are described. In addition, the latest applications of several of the above-mentioned metal aerogels in electrocatalytic CO2 reduction are discussed. Finally, considering the possibility of future applications of electrocatalytic CO2 reduction technology, a vision for industrialization and directions that can be optimized are proposed. 相似文献