Elucidating the Structure of Ethanol-Producing Active Sites at Oxide-Derived Cu Electrocatalysts

The discovery of oxide-derived copper (OD-Cu) catalysts for CO₂ electroreduction is a remarkable advancement in the field of electrocatalysis. Their low overpotentials and improved selectivity toward C₂ products make them unique. However, the structure of the active sites responsible for these improvements remains unclear. Herein, by means of a computational model including thermodynamic, kinetic, solvent, and cation effects, we outline the atomic structure of the active sites responsible for ethanol evolution in OD-Cu catalysts. We also point out the specific features that determine selectivity and pinpoint the design criteria that should be fulfilled to enhance the selectivity of the catalysts toward ethanol. Specifically, we propose that square, four-atom Cu islands are the active sites of OD-Cu for CO electroreduction to ethanol as they display favorable *CO dimerization energetics and ethanol selectivity by virtue of their square, undercoordinated structure.