Electron Transfer from the Porphyrin S2 State in a Zinc Porphyrin-Rhenium Bipyridyl Dyad having Carbon Dioxide Reduction Activity

2009 ◽  
Vol 113 (27) ◽  
pp. 11667-11673 ◽  
Author(s):  
Kuniomi Kiyosawa ◽  
Naoki Shiraishi ◽  
Tetsuya Shimada ◽  
Dai Masui ◽  
Hiroshi Tachibana ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Electron Transfer ◽  
Carbon Dioxide Reduction ◽  
Zinc Porphyrin ◽  
Reduction Activity ◽  
S2 State

scholarly journals Microwave-Assisted Solvothermal Synthesis of Chalcogenide Composite Photocatalyst and Its Photocatalytic CO2 Reduction Activity under Simulated Solar Light

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 789
Author(s):  
Gang-Juan Lee ◽  
Yu-Hong Hou ◽  
Hsin-Ting Huang ◽  
Wenmin Wang ◽  
Cong Lyu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Photocatalytic Activity ◽  
Co2 Reduction ◽  
Carbon Dioxide Reduction ◽  
Photoluminescence Intensity ◽  
Composite Photocatalyst ◽  
Microwave Assisted ◽  
Reduction Activity ◽  
Operation Conditions ◽  
Co Doped

A novel heterostructure consisting of Ru and Cu co-doped ZnS nanopowders (RCZS) into a MoS2-graphene hybrid (MSG) is successfully prepared by the microwave-assisted solvothermal approach. RCZS nanopowders are fabricated on the surface of MSG, which produces a nanoscale interfacial between RCZS and MSG. As the photo-excited electrons of RCZS can easily migrate to MoS2 through graphene by hindering the electron and hole (e– and h+) recombination, the photocatalytic activity could be improved by effective charge transfer. As RCZS are anchored onto the MSG, the photoluminescence intensity of the chalcogenide composite photocatalyst obviously decreases. In addition, a quaternary ruthenium and copper-based chalcogenide RCZS/MSG is able to improve the harvest and utilization of light. With the increase in the concentrations of Ru until 4 mol%, the band gap significantly decreases from 3.52 to 2.73 eV. At the same time, moderate modification by ruthenium can decrease the PL intensity compared to the pristine CZS/MSG sample, which indicates the enhancement of e– and h+ separation by Ru addition. The photocatalytic activity of as-synthesized chalcogenide composite photocatalysts is evaluated by the photocatalytic carbon dioxide reduction. Optimized operation conditions for carbon dioxide reduction have been performed, including the concentration of NaOH solution, the amount of RCZS/MSG photocatalyst, and the content of co-doped ruthenium. The doping of ruthenium would efficiently improve the performance of the photocatalytic activity for carbon dioxide reduction. The optimal conditions, such as the concentration of 2 M NaOH and the 0.5RCZS/MSG dosage of 0.05 g L–1, provide the maximum methane gas yield of 58.6 μmol h−1 g–1.

scholarly journals On the Mechanism of Carbon Dioxide Reduction on Sn-Based Electrodes: Insights into the Role of Oxide Surfaces

Catalysts ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 636 ◽  
Author(s):  
Giane B. Damas ◽  
Caetano R. Miranda ◽  
Ricardo Sgarbi ◽  
James M. Portela ◽  
Mariana R. Camilo ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Electron Transfer ◽  
Formic Acid ◽  
Oxide Layer ◽  
Co2 Reduction ◽  
Carbon Dioxide Reduction ◽  
Oxide Surfaces ◽  
In Situ Conditions

The electrochemical reduction of carbon dioxide into carbon monoxide, hydrocarbons and formic acid has offered an interesting alternative for a sustainable energy scenario. In this context, Sn-based electrodes have attracted a great deal of attention because they present low price and toxicity, as well as high faradaic efficiency (FE) for formic acid (or formate) production at relatively low overpotentials. In this work, we investigate the role of tin oxide surfaces on Sn-based electrodes for carbon dioxide reduction into formate by means of experimental and theoretical methods. Cyclic voltammetry measurements of Sn-based electrodes, with different initial degree of oxidation, result in similar onset potentials for the CO2 reduction to formate, ca. −0.8 to −0.9 V vs. reversible hydrogen electrode (RHE), with faradaic efficiencies of about 90–92% at −1.25 V (vs. RHE). These results indicate that under in-situ conditions, the electrode surfaces might converge to very similar structures, with partially reduced or metastable Sn oxides, which serve as active sites for the CO2 reduction. The high faradaic efficiencies of the Sn electrodes brought by the etching/air exposition procedure is ascribed to the formation of a Sn oxide layer with optimized thickness, which is persistent under in situ conditions. Such oxide layer enables the CO2 “activation”, also favoring the electron transfer during the CO2 reduction reaction due to its better electric conductivity. In order to elucidate the reaction mechanism, we have performed density functional theory calculations on different slab models starting from the bulk SnO and Sn6O4(OH)4 compounds with focus on the formation of -OH groups at the water-oxide interface. We have found that the insertion of CO2 into the Sn-OH bond is thermodynamically favorable, leading to the stabilization of the tin-carbonate species, which is subsequently reduced to produce formic acid through a proton-coupled electron transfer process. The calculated potential for CO2 reduction (E = −1.09 V vs. RHE) displays good agreement with the experimental findings and, therefore, support the CO2 insertion onto Sn-oxide as a plausible mechanism for the CO2 reduction in the potential domain where metastable oxides are still present on the Sn surface. These results not only rationalize a number of literature divergent reports but also provide a guideline for the design of efficient CO2 reduction electrocatalysts.

A highly efficient diatomic nickel electrocatalyst for CO2 reduction

2020 ◽  
Vol 56 (62) ◽  
pp. 8798-8801 ◽  
Author(s):  
Meng-Jiao Sun ◽  
Zhi-Wei Gong ◽  
Jun-Dong Yi ◽  
Teng Zhang ◽  
Xiaodong Chen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Co2 Reduction ◽  
Carbon Dioxide Reduction ◽  
Carbon Composite ◽  
Nitrogen Doped ◽  
Highly Efficient ◽  
Reduction Activity ◽  
Nitrogen Doped Carbon

Diatomic Ni2 clusters embedded in a nitrogen-doped carbon composite show high electrocatalytic carbon dioxide reduction activity.

The award of medals by the President, Sir George Porter, at the Anniversary Meeting, 30 November 1987

1988 ◽  
Vol 417 (1852) ◽  
pp. 1-5
Keyword(s):  
Carbon Dioxide ◽  
Electron Transfer ◽  
Chemical Analysis ◽  
Water Oxidation ◽  
Carbon Dioxide Reduction ◽  
Electron Transfer Pathway ◽  
Starting Point ◽  
Main Pathway ◽  
Isolated Chloroplasts ◽  
Detailed Chemical

The Copley Medal is awarded to Dr R. Hill, F. R. S., in recognition of his pioneering contributions to the understanding of the nature and mechanism of the main pathway of electron transport in photosynthesis. Almost fifty years ago Hill made the first important discovery that allowed detailed chemical analysis of the pathways of photosynthesis, when he demon­strated the light-driven oxidation of water by isolated chloroplasts, and this made it possible to study water oxidation separately from carbon-dioxide reduction. This was the starting point in the elucidation of the electron-transfer pathway in photosynthesis, and in 1951 Hill, with R. Scarisbrick, uncovered the first com­ponent in the chain when they discovered cytochrome and established its key properties. Subsequently, with H. E. Davenport, Hill discovered the second com­ponent of the chain, shown later by others to be ferredoxin. With F. Bendall he formulated the ‘Z-scheme’ to describe the mechanism of electron transfer in photosynthesis in chloroplasts, which showed the relation between the photochemically driven elements and conventional electron-transfer chains found in other biological systems. This proposal brought great clarity to the field and set the scene for further detailed elucidation of the mechanisms.

scholarly journals Mechanism of Aqueous Carbon Dioxide Reduction by the Solvated Electron

2020 ◽  
Author(s):  
Vladimir Rybkin
Keyword(s):  
Carbon Dioxide ◽  
Electron Transfer ◽  
Plasma Chemistry ◽  
Reorganization Energy ◽  
Carbon Dioxide Reduction ◽  
Solvated Electron ◽  
Intermediate Transformation ◽  
Proton Coupled Electron Transfer ◽  
Key Species ◽  
Proton Migration

Aqueous solvated electron, e<sub>aq</sub>, a key species in radiation and plasma chemistry, can effciently reduce CO<sub>2</sub> in a potential green chemistry application. Here, the mechanism of this reaction is unravelled by condensed-phase Born-Oppenheimer molecular dynamics based on the correlated wave function and accurate DFT approximation. We introduce and apply the holistic protocol for solvated electron's reactions encompassing all relevant reaction stages starting from diffusion. The carbon dioxide reduction proceeds via a cavity intermediate, which is separated from the product, CO2<sup>-</sup>, by an energy barrier due to the bending of CO<sub>2</sub> and the corresponding solvent reorganization energy. The formation of the intermediate is caused by solvated electron's diffusion, whereas the intermediate transformation to CO<sub>2</sub><sup>-</sup> is triggered by solvent fluctuations. This picture of activation-controlled e<sub>aq</sub> reaction is very different from both rapid barrierless electron transfer, and proton-coupled electron transfer, where key transformations are caused by proton migration.

scholarly journals Polyoxometalate-based electron transfer modulation for efficient electrocatalytic carbon dioxide reduction

2020 ◽  
Vol 11 (11) ◽  
pp. 3007-3015 ◽  
Author(s):  
Jing Du ◽  
Zhong-Ling Lang ◽  
Yuan-Yuan Ma ◽  
Hua-Qiao Tan ◽  
Bai-Ling Liu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Electron Transfer ◽  
Aqueous Electrolyte ◽  
Carbon Dioxide Reduction ◽  
Highly Efficient

Polyoxometalates as electron regulators to promote the carbonyl manganese (MnL) electrocatalyst for highly efficient CO2 reduction in aqueous electrolyte.

scholarly journals Mechanisms for Electron Uptake by Methanosarcina acetivorans During Direct Interspecies Electron Transfer

2021 ◽  
Author(s):  
Dawn Holmes ◽  
Jinjie Zhou ◽  
Toshiyuki Ueki ◽  
Trevor Woodard ◽  
Derek Lovley
Keyword(s):  
Carbon Dioxide ◽  
Electron Transfer ◽  
Outer Surface ◽  
Expression Patterns ◽  
Amino Acid Content ◽  
Carbon Dioxide Reduction ◽  
Methanosarcina Acetivorans ◽  
Electrically Conductive ◽  
Direct Interspecies Electron Transfer ◽  
Interspecies Electron Transfer

Direct interspecies electron transfer (DIET) between bacteria and methanogenic archaea appears to be an important syntrophy in both natural and engineered methanogenic environments. However, the electrical connections on the outer surface of methanogens and the subsequent processing of electrons for carbon dioxide reduction to methane are poorly understood. Here we report that the genetically tractable methanogen Methanosarcina acetivorans can grow via DIET in co-culture with Geobacter metallireducens serving as the electron-donating partner. Comparison of gene expression patterns in M. acetivorans grown in co-culture versus pure culture growth on acetate revealed that transcripts for the outer-surface, multi-heme, c-type cytochrome MmcA were higher during DIET-based growth. Deletion of mmcA inhibited DIET. The high aromatic amino acid content of M. acetivorans archaellins suggests that they might assemble into electrically conductive archaella. A mutant that could not express archaella was deficient in DIET. However, this mutant grew in DIET-based co-culture as well as the archaella-expressing parental strain in the presence of granular activated carbon, which was previously shown to serve as a substitute for electrically conductive pili as a conduit for long-range interspecies electron transfer in other DIET-based co-cultures. Transcriptomic data suggesting that the membrane-bound Rnf, Fpo, and HdrED complexes also play a role in DIET were incorporated into a charge-balanced model illustrating how electrons entering the cell through MmcA can yield energy to support growth from carbon dioxide reduction. The results are the first genetics-based functional demonstration of likely outer-surface electrical contacts for DIET in a methanogen.

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