Restructuring and Activation of Cu(111) under Electrocatalytic Reduction Conditions

The dynamic restructuring of Cu surfaces in electroreduction conditions is of fundamental interest in electrocatalysis. We decode the structural dynamics of a Cu(111) electrode under reduction conditions by joint first-principles calculations and operando electrochemical scanning tunneling microscopy (ECSTM) experiments. Combining global optimization and grand canonical density functional theory, we unravel the potential- and pH-dependent restructuring of Cu(111) in acidic electrolyte. At reductive potential, Cu(111) is covered by a high density of H atoms and, below a threshold potential, Cu adatoms are formed on the surface in a (4x4) superstructure, a restructuring unfavorable in vacuum. The strong H adsorption is the driving force for the restructuring, itself induced by the electrode potential. On the restructured surface, barriers for hydrogen evolution reaction steps are low. Restructuring in electroreduction conditions creates highly active Cu adatom sites not present on Cu(111).

Automated summary

The dynamic restructuring of Cu surfaces in electroreduction conditions was investigated using first-principles calculations and operando electrochemical scanning tunneling microscopy experiments. The restructuring of Cu(111) in acidic electrolyte was found to be potential- and pH-dependent. The strong adsorption of H atoms on the surface induced the formation of Cu adatoms, creating highly active sites for the hydrogen evolution reaction.