Absence of Oxidized Phases in Cu under CO Reduction Conditions

The surface structure and oxide content near the surface of copper electrodes under CO and CO2 reduction conditions are debated. By live-monitoring Cu and Cu2O Bragg peaks from the surface of a polycrystalline Cu electrode while scanning from open-circuit potential to CO reduction potentials, we show that the near-surface region is fully converted to the metallic phase at approximately +0.3 V vs RHE.