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 ◽  
...  

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.

Author(s):  
Zuoyu Yan ◽  
Xiuxiu Wang ◽  
Yang Tan ◽  
Aihua Liu ◽  
Fenqiang Luo ◽  
...  

Metals and their alloys based electrocatalysts continue to attract great attention for electrochemical carbon dioxide reduction reaction (CO2RR). Herein, cuprous oxide (Cu2O) supported on N-doped flexible roughed graphite paper (NGP)...


Author(s):  
Rajasekaran Elakkiya ◽  
Govindhan Maduraiveeran

Design of high-performance and Earth-abundant electrocatalysts for electrochemical carbon dioxide (CO2) reduction reaction (CO2RR) into fuels and value-added chemicals offers an emergent pathway for environment and energy sustainable concerns. Herein,...


Nanoscale ◽  
2021 ◽  
Author(s):  
Hongping Zhang ◽  
Run Zhang ◽  
Chenghua Sun ◽  
Yan Jiao ◽  
Yaping Zhang

Electrochemical carbon dioxide reduction (CRR) to fuels is one of the significant challenges in materials science and chemistry. Recently, single metal atom catalysts based on 2D materials provide a promising...


2020 ◽  
Vol 8 (31) ◽  
pp. 15936-15941 ◽  
Author(s):  
Pengda An ◽  
Lai Wei ◽  
Huangjingwei Li ◽  
Baopeng Yang ◽  
Kang Liu ◽  
...  

Enhanced carbon dioxide reduction reaction (CO2RR) with suppressed HER was achieved on polytetrafluoroethylene (PTFE) coated Cu nanoneedles (CuNNs).


Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 789
Author(s):  
Gang-Juan Lee ◽  
Yu-Hong Hou ◽  
Hsin-Ting Huang ◽  
Wenmin Wang ◽  
Cong Lyu ◽  
...  

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.


2020 ◽  
Vol 56 (62) ◽  
pp. 8798-8801 ◽  
Author(s):  
Meng-Jiao Sun ◽  
Zhi-Wei Gong ◽  
Jun-Dong Yi ◽  
Teng Zhang ◽  
Xiaodong Chen ◽  
...  

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


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