A Computational Perspective on Carbon-Carbon Bond Formation by Single Cu Atom on Pd(111) Surface for CO Electrochemical Reduction

This study focuses on the computational characterization of electrochemical C-C bond formation through the CO and CHO coupling process utilizing a dioxo-coordinated Cu single atom site ([CuO₂]*) supported on a Pd(111) surface. The stable intermediate, [CuO₂]*(CO)₂, was identified as a tetradentate-and-tetrahedral species formed upon exposure to CO gaseous molecules. Electrochemically, the hydrogenation of the carbonyl group to CHO was found to be 0.87 eV, conceivably lower than the corresponding step for conventional Cu surfaces. This study observed a considerable charge transfer effect from the top layer of Pd atoms to the adsorbate moiety, especially at the TS structure. This phenomenon resulted in an accessible C-C bond formation barrier at 0.67 eV. Furthermore, the reaction energy of C-C bond formation was found to be exothermic at −0.21 eV, indicating a favorable chemical equilibrium condition. Considering the temperature effect and pressure of the gaseous molecules (CO, CO₂, O₂), the [CuO₂]*(CO)₂ intermediate was substantially populated at room temperature and was found to be chemically resilient under dry ambient conditions, as suggested by the kinetic modeling results.