Photoelectrochemical properties of copper oxide (CuO) influenced by work functions of conductive electrodes

Copper (II) oxide (CuO) is a promising p-type semiconductor for water splitting to produce hydrogen under visible-light irradiation. The CuO photoelectrode was successfully fabricated on several conductive supports by an assist of electrochemical deposition methods. The electronic structures of CuO electrodes were characterized by FE-SEM, XRD, UV-Vis, Raman, electrochemical impedance spectroscopy, as well as photoelectrochemical properties. Cathodic photocurrent was observed on the CuO electrodes in 0.5 M Na2SO4 aqueous solution under AM1.5G solar irradiation. It was also found that the photocurrent densities significantly increased as an increase in work functions of conductive supports: carbon < FTO < gold < nickel < platinum plates. It was clearly demonstrated that Ohmic junction between CuO and conductive supports with large work function plays a significant role in the effective charge separations of holes and electrons.