CO Intermediate-Assisted Dynamic Cu Sintering During Electrocatalytic CO₂ Reduction on Cu-N-C Catalysts

The electrochemical CO₂ reduction reaction (eCO₂RR) to multicarbon products has been widely recognized for Cu-based catalysts. However, the structural changes in Cu-based catalysts during the eCO₂RR pose challenges to achieving an in-depth understanding of the structure-activity relationship, thereby limiting catalyst development. Herein, we employ constant-potential density functional theory calculations to investigate the sintering process of Cu single atoms of Cu-N-C single-atom catalysts into clusters under eCO₂RR conditions. Systematic constant-potential ab initio molecular dynamics simulations revealed that the leaching of Cu-(CO)_x moieties and subsequent agglomeration into clusters can be facilitated by synergistic adsorption of H and eCO₂RR intermediates (e.g., CO). Increasing the Cu²⁺ concentration or the applied potential can efficiently suppress Cu sintering. Both microkinetic simulations and experimental results further confirm that sintered Cu clusters play a crucial role in generating C₂ products. These findings provide significant insights into the dynamic evolution of Cu-based catalysts and the origin of their activity toward C₂ products during the eCO₂RR.