Chemical bath deposition synthesis of TiO2/Cu2O core/shell nanowire arrays with enhanced photoelectrochemical water splitting for H2 evolution and photostability

Abstract

In this study, we have developed a facile chemical bath deposition (CBD) method to grow p-type Cu2O nanoparticles on n-type TiO2 nanowire arrays (TiO2 NWAs) to fabricate TiO2/Cu2O core/shell heterojunction nanowire arrays (TiO2/Cu2O core/shell NWAs). When used as photoelectrode, the fabricated TiO2/Cu2O core/shell NWAs show improved photoelectrochemical (PEC) water splitting activity to pure TiO2 NWAs. The effects of the CBD cycle times on the PEC activities have been studied. The TiO2/Cu2O core/shell heterojunction nanowire array photoelectrode prepared by cycling 5 times in the CBD process achieves the highest photocurrent of 2.5 mA cm−2, which is 2.5 times higher than that of pure TiO2 NWAs. In addition, the H2 generation rate of this photoelectrode reaches to 32 μmol h−1 cm−2, 1.7 times higher than that of pure TiO2 NWAs. Furthermore, the TiO2/Cu2O core/shell heterojunction nanowire array photoelectrode shows excellent photostability and achieves a stable photocurrent of over 2.3 mA cm−2 during long light illumination time of 5 h. The enhanced photocatalytic activity of TiO2/Cu2O core/shell heterojunction nanowire array photoelectrode is attributed to the synergistic actions of TiO2 and Cu2O for improving visible light harvesting, and efficient transfer and separation of photogenerated electrons and holes.