Korean Journal of Materials Research ISSN:1225-0562(Print) 2287-7258(Online) 한국재료학회지

Recent industrialization has led to a high demand for the use of fossil fuels. Therefore, the need for producing hydrogen and its utilization is essential for a sustainable society. For an eco-friendly future technology, photoelectrochemical water splitting using solar energy has proven promising amongst many other candidates. With this technique, semiconductors can be used as photocatalysts to generate electrons by light absorption, resulting in the reduction of hydrogen ions. The photocatalysts must be chemically stable, economically inexpensive and be able to utilize a wide range of light. From this perspective, cuprous oxide(Cu₂O) is a promising p-type semiconductor because of its appropriate band gap. However, a major hindrance to the use of Cu₂O is its instability at the potential in which hydrogen ion is reduced. In this study, gold is used as a bottom electrode during electrodeposition to obtain a preferential growth along the (111) plane of Cu₂O while imperfections of the Cu₂O thin films are removed. This study investigates the photoelectrochemical properties of Cu₂O. However, severe photo-induced corrosion impedes the use of Cu₂O as a photoelectrode. Two candidates, TiO₂ and SnO₂, are selected for the passivation layer on Cu₂O by by considering the Pourbaix-diagram. TiO₂ and SnO₂ passivation layers are deposited by atomic layer deposition(ALD) and a sputtering process, respectively. The investigation of the photoelectrochemical properties confirmed that SnO₂ is a good passivation layer for Cu₂O.