Improved water oxidation with metal oxide catalysts via a regenerable and redox-inactive ZnOxHy overlayer.

We report a regenerable and redox-inactive ZnOxHy layer that was in situ deposited onto metal oxides MOz (M = Co, Fe, and Ni) in alkaline media containing [Zn(OH)4]2- species during water oxidation. An interface dipole was developed at the MOz/Zn interface, resulting in a decrease of the OER overpotential. Exemplified by the CoOz/ZnOxHy bilayer structure, it presented a 155 mV lower overpotential to deliver 10 mA cm-2 and long-term stability relative to the unmodified CoOz film.