Electrochemical conversion of CO2 to syngas over Cu-M (M = Cd, Zn, Ni, Ag, and Pd) bimetal catalysts

The electrochemical reduction of CO2 to syngas (H2 + CO) offers a resultful solution for the ongoing carbon emission and energy crisis issues. However, there are still few efficient catalysts for CO2RR-to-syngas electrolysis. Herein, a density functional theory (DFT) study of the Cu-M (M = Cd, Zn, Ni, Ag, and Pd) bimetal catalysts (BMCs) for CO2RR and HER is reported. The results indicate that the reaction barrier is significantly changed in the electrochemical conversion of CO2 into CO and HER by changing the Cu/M ratio. d band center (εd) has a good linear relationship with ΔGH*, ΔGCOOH* and ΔGCO*, so εd is a good descriptor for hydrogen reduction reaction (HER) and carbon dioxide reduction reaction (CO2RR) activity. The Cu-Pd catalyst displays outstanding catalytic activity for HER and CO2RR. HER activity of the Cu-Pd catalyst is even comparable to that of the current most effective Pt catalysts. Compared with other catalysts with different Cu/M ratios (Cu/M = 0.5 and Cu/M = 2), the Cu-Cd catalyst at low Cu/Cd ratio (0.5) is the only catalyst which is more favorite to CO2RR than HER. This theoretical study may provide guidance to design the effective electrocatalysts for the CO2RR and HER, and shed light on the application of Cu-based bimetal materials in syngas production.