Mechanistic Insights into Acetate Selectivity on Intermetallic CuPd(110) in CO Reduction

Experimental studies demonstrate that CuPd(110) uniquely favors acetate formation during CO reduction (CORR), contrasting with the preference for ethylene on Cu surfaces. To elucidate this selectivity, we employed explicit solvation density functional theory (DFT) calculations to investigate the reaction mechanism from both thermodynamic and kinetic angles. Our findings reveal that on CuPd(110), the acetate-pathway intermediate H₂CCO is thermodynamically favored at experimental conditions, while CHCHO─a precursor to ethylene─is preferred on Cu(111). Beyond thermodynamics, we find that H₂CCO is kinetically accessible under the experimental conditions on CuPd(110), aiding acetate formation. Electron density difference analyses further corroborate distinct protonation preferences supporting this mechanism. We propose a thermodynamic screening parameter based on the Gibbs free energy, G_H2CCO < G_CHCHO, as a guide for designing Cu-based catalysts with enhanced acetate selectivity. These results offer critical mechanistic insights into the CORR product distribution and a rational framework for future catalyst design.