Tuning the activity and selectivity of CuPt/C catalysts for the electrochemical CO2 reduction

Copper-based bimetallic catalysts have garnered significant attention for CO2 electrochemical CO2 conversion due to their ability to catalytically reduce CO2 to hydrocarbons and alcohols. Herein, a set of CuPt/C catalysts with different Cu:Pt atomic ratios are successfully synthesised through galvanostatic displacement. The progressive incorporation of platinum on Cu/C nanoparticles significantly impacts the CO2 electro-reduction performance in a 0.1 M KHCO3 solution. The results revealed that Cu:Pt atomic ratios of 99:1 and 95:5 enhance formate production at mild potentials (-0.6 V vs. RHE) due to an improved water activation compared to monometallic Cu/C and, thus a higher availability of protons (or adsorbed hydrogen, *H) near the active sites. In contrast, lower Cu:Pt ratios or higher overpotentials result in diminished formate production. This behaviour is likely due to the affinity of Pt for the carbon-bound *COOH intermediate, which favors CO formation over formate. These findings demonstrate that Pt incorporation in Cu/C nanoparticles can alter the CO2 reduction mechanism, providing insights into the design of selective formate-producing catalysts.