Dynamic Structural Evolution of Single-Atom Catalysts at the Catalyst–Electrolyte Interface: Insights from Electrochemical Coupled Field

Dynamic catalytic structures at the catalyst–electrolyte interface pose significant challenges in accurately identifying active sites and establishing precise structure–activity relationships essential for catalyst design and performance optimization. Herein, we unveil the dynamic structural evolution of Cu–N–C single-atom catalysts (SACs) under electrochemical conditions, elucidating the critical role of the electrochemical coupled field. Using hybrid-solvation constant potential simulations, we identify that the unique dx2–y2 orbital occupancy at the Fermi level, stemming from copper’s d9 electronic configuration, renders Cu–N bonds highly sensitive to external voltage. Proton transfer (PT) triggers electronic reordering that converts discrete energy levels into continuous states near the Fermi level, enhancing charge accumulation in the Cu–N antibonding state. Consequently, the Cu–N bonds are weakened, ultimately leading to copper atom leaching. Our work provides a fundamental understanding of SACs’ dynamics under realistic electrochemical environments, offering new insights for the rational design of robust electrocatalysts.