Efficient Electrocatalytic Water Oxidation by a Copper Oxide Thin Film in Borate Buffer

A robust water oxidation catalyst based on copper oxide was prepared by facile electrodeposition of Cu2+ from borate buffer solution under near neutral conditions. The Cu-B-i thin film exhibits high activity and long-term stability in Cu2+-free pH 9 borate buffer. A steady current density of 1.2 mA/cm(2) was sustained for at least 10 h at 1.3 V versus NHE without iR compensation, which sets a new benchmark for copper-based OEC.