Crystal orientation effects on the electrochemical conversion of CO2 to syngas over Cu-M (M = Ag, Ni, Zn, Cd, and Pd) bimetal catalysts

CO2 electrochemical reduction to syngas (CO2RR-to-syngas) is an environment friendly and promising CO2 utilization technology. However, there are still few efficient catalysts for CO2RR-to-syngas electrolysis. The crystal orientation regulation is one of the important methods to enhance the activity of catalyst and there is still a lack of systematic research in this field. In this work, a comparative study of the Cu-M bimetal catalysts (BMCs) for CO2RR-to-syngas is carried out using density functional theory (DFT) calculations to examine the crystal orientation effects. The results indicate that the reaction barrier is significantly changed on different crystal orientations. Gibbs free energy change of the potential limiting step (Delta G(PLS)) on the Cu (110) surface is lower than those on the Cu (1 1 1) and Cu (100) surfaces. The Cu-Pd catalyst exhibits better catalytic activity for HER than Cu-Ag, Cu-Ni, Cu-Zn, and Cu-Cd catalysts. CO2RR activity of the Cu-Pd catalyst is better than that of most of the catalysts reported so far. The Cu-Ni catalyst exposing the Cu(100) surface is the only catalyst which is more favorite to CO2RR than HER. This work provides guidance for the design of highly efficient catalysts for CO2RR-to-syngas.