Identifying Cu reconstruction mechanism in CO2 and CO electroreduction via Cu+ detection and in situ atomic force microscopy
Elucidating the fundamental mechanisms underlying Cu reconstruction is paramount for the rational design of catalysts that meet the stringent activity, selectivity, and durability requirements for industrial-scale CO2/CO electroreduction (CO2RR/CORR). While both dissolution-redeposition and atomic migration pathways have been proposed, the operational conditions dictating their relative dominance remain poorly understood. Through quasi in situ Cu+ detection and in situ atomic force microscopy (AFM), we reveal a striking mechanistic dichotomy: Cu reconstruction during CO2RR occurs strictly in the presence of Cu+, whereas CORR-induced reconstruction proceeds independently of Cu+ species. These findings suggest that Cu reconstruction in CO2RR follows a dissolution-redeposition mechanism induced by oxidative radicals, while atomic migration emerges as the dominant pathway in CORR. Density functional theory calculations further demonstrate that adsorbed *CO intermediates reduce Cu–Cu bond strength, creating metastable surface configurations that promote Cu atomic migration. The investigation extends to broader metal catalysts (e.g., Ag, Au, Zn) and highlights the interplay between adsorbed species, interfacial environments, and applied potentials. Our findings establish a unified framework for understanding Cu restructuring dynamics, providing a paradigm for strategically engineering metal catalysts through controlled reconstruction, advancing the rational design of CO2RR/CORR systems.