CuBi electrocatalysts modulated to grow on derived copper foam for efficient CO2-to-formate conversion

[Display omitted] •CuBi catalysts were grown on derived copper foam by electrodeposition for CO2 electroreduction.•Electrodeposition potential significantly affected bimetallic catalyst and CO2 electroreduction.•The highest formate Faradaic efficiency (FEformate) of 94.4 % was recorded at 38.5 mA/cm2 in a H-type cell.•A higher FEformate of 98.3 % was achieved at 56.6 mA/cm2 in a continuous-flow MEA reactor. Electrochemical reduction of CO2 to fuels and chemicals is an effective way to reduce greenhouse gas emissions and alleviate the energy crisis, but the highly active catalysts necessary for this reaction under mild conditions are still rare. In this work, we grew CuBi bimetallic catalysts on derived copper foam substrates by co-electrodeposition, and then investigated the correlation between co-electrodeposition potential and electrochemical performance in CO2-to-formate conversion. Results showed that the bimetallic catalyst formed at a low potential of − 0.6 V vs. AgCl/Ag electrode achieved the highest formate Faradaic efficiency (FEformate) of 94.4% and a current density of 38.5 mA/cm2 at a low potential of − 0.97 V vs. reversible hydrogen electrode (RHE). Moreover, a continuous-flow membrane electrode assembly reactor also enabled the catalyst to show better performance (a FEformate of 98.3% at 56.6 mA/cm2) than a traditional H-type reaction cell. This work highlights the vital impact of co-electrodeposition potential on catalyst performance and provides a basis for the modulated growth of bimetallic catalysts on substrates. It also shows the possibility of preparing Bi-based catalysts with no obvious decrease in catalytic activity that have been partially replaced with more economic copper.