Atomic nickel cluster decorated defect-rich copper for enhanced C₂ product selectivity in electrocatalytic CO₂ reduction

This work describes a coordination enabled galvanic replacement method to decorate atomic Ni clusters on defect-rich Cu surface to provide the first Ni/Cu bimetallic system that significantly enhances the production of C₂ products from electrocatalytic CO₂ reduction. Specifically, with a surface Ni/Cu ratio of 0.82 %, a 7-fold increase in the selectivity for C₂ products was found in comparison with pristine Cu. Density functional theory calculations reveal that the rate determining step for *CO formation changes from the formation of *COOH on copper to the chemisorption of CO₂ on Ni decorated surfaces. An alteration of binding sites from Ni-Ni bridge for *CO₂ and *COOH to Ni-Cu bridge for *CO is discovered and is proposed to favor the key C–C coupling step. The catalytic mechanism demonstrated in the Cu-Ni system points to the new directions for the development of advanced bimetallic electrocatalysts for producing multi-carbon materials from CO₂ reduction.