Theoretical study on the reduction mechanism of CO2 to HCOOH on Pd3Au: an explicit solvent model is essential

Abstract

Due to the differences in atomic arrangement and electronic structures, solid catalysts with different crystal planes have different catalytic properties. Therefore, studying the reaction mechanism on different crystal planes of catalysts at the atomic level is helpful to better understand the structure–activity relationship and improve the activity of catalysts. In this work, the mechanism of reduction of CO₂ to formic acid on different surfaces of the Pd₃Au alloy is investigated by using density functional theory, and the potential relationship between the difference in the work function and d-band center of the catalyst and the overpotential is revealed. The electronic structure calculation results show that the surface roughness and the electronic structure of the catalyst together determine the catalytic activity of CO₂ reduction to formic acid. At the same time, a good linear relationship was found between the surface net charge of the catalyst and the HER activity. The Pd₃Au (110) surface with less net surface charge can effectively suppress the HER. The dynamic hydrogen bonding network of water solution is the key to determine the reaction mechanism, which reflects the indispensable role of water molecules in the catalytic reaction and indicates the importance of using an explicit solvent model to simulate solvation effects in the calculation of the reaction mechanism.