Highly efficient In-Sn alloy catalysts for electrochemical reduction of CO2 to formate

•GDE-In0.90Sn0.10 is superior as a catalyst compared with the other In-Sn alloys studied and the single metal electrodes.•With GDE-In0.90Sn0.10 as the catalyst, the Faradaic efficiency towards formate production reaches 92%.•The activity of GDE-In0.90Sn0.10 remains stable for 20 h.•The excellent catalytic performance of GDE-In0.90Sn0.10 is attributed to its composition, crystal structure and nanostructure.

Gas diffusion electrodes (GDEs), including GDE-In0.90Sn0.10, GDE-In0.47Sn0.53 and GDE-In0.22Sn0.78, were prepared by electrodeposition of In-Sn alloys on carbon fiber paper, and then used to explore the electroreduction of CO2 to formate in aqueous solution. Compared with commercial indium or Sn foil catalysts, the GDE-In0.90Sn0.10 electrode in particular is shown to have excellent catalytic performance towards electroreduction of CO2 to formate, with a high Faradaic efficiency (~ 92%). More importantly, the catalytic activity of GDE-In0.90Sn0.10 remained reasonably stable over a 22-hour period of electrolysis, and a relatively high electrolytic current density (15 mA cm− 2) was obtained in an aqueous medium, demonstrating its potential for electrochemical reduction of CO2 to formate.

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