Atomistic Origin of Non-equilibrium Surface Restructuring on Copper under Pulsed Potentials.

Pulsed electrochemical conditions are known to modify copper (Cu) surface structures and alter catalytic behavior. However, the atomistic pathway underlying such dynamic evolution remains unclear. Here, we develop a parallel-evolution grand canonical Monte Carlo/molecular dynamics (PE-GCMC/MD) framework combined with a constant-potential machine learning force field to capture the redox-driven evolution of Cu surfaces at an explicit Cu-water interface. Specifically, anodic polarization induces oxygen incorporation and lattice expansion, whereas subsequent reduction drives continuous deoxygenation, accompanied by concurrent lattice reorganization that generates a transient, vacancy-rich Cu framework. This coupled evolution of oxygen removal and lattice contraction progressively generates low-coordination, pit-like surface features. These dynamically generated undercoordinated surface motifs exhibit favorable kinetics for C-C coupling. Furthermore, by tuning the pulse waveform, the population of these non-equilibrium active states can be quantitatively regulated. These results establish a mechanistic link between pulsed electrochemical history and the resulting catalytically active surface states, providing fundamental insight into non-equilibrium interfacial restructuring.