Insights into the Structure-Sensitive Catalytic Performance of Palladium-Copper Alloys in Electrochemical Urea Synthesis

Palladium-copper (Pd-Cu) alloys have attracted widespread research interest because of their excellent catalytic activity for electrochemical urea synthesis. However, the current understanding of the catalytic performance of the Pd-Cu alloys with different components and crystal surfaces still needs to be improved. Herein, by means of systematic density functional theory calculation, we investigated the thermodynamics and kinetics of electrochemical urea synthesis on different crystal planes of Pd1Cu1 alloy and on the (211) planes of Pd-Cu alloys of varying compositions. We utilized the generalized coordinate number (CN) over bar, the d-band center, and the adsorption energy of N-2 (Delta E*N2 ) as descriptors to reveal the activity origin of these alloy catalysts, and on this basis, we established the relationship between the activity of catalysts and their geometric and electronic structures. In particular, Pd3Cu-(211) and Cu@Pd(211) emerged as promising catalysts for electrochemical urea synthesis because of their low thermodynamic limiting potential, as well as the low kinetic barrier of C-N coupling. Our work provides guidance for screening and searching for high-performance alloy catalysts for electrochemical urea synthesis.