P-n Heterojunction photoelectrodes composed of Cu₂O-loaded TiO₂ nanotube arrays with enhanced photoelectrochemical and photoelectrocatalytic activities

Cu₂O/TiO₂ p-n heterojunction photoelectrodes were prepared by depositing different amounts of p-type Cu₂O nanoparticles on n-type TiO₂ nanotube arrays (i.e., forming Cu₂O/ TiO₂ composite nanotubes) via an ultrasonication-assisted sequential chemical bath deposition. The success of deposition of Cu₂O nanoparticles was corroborated by structural and composition characterizations. The enhanced absorption in the visible light region was observed in Cu ₂O/TiO₂ composite nanotubes. The largely improved separation of photogenerated electrons and holes was revealed by photocurrent measurements. Consequently, Cu₂O/TiO₂ heterojunction photoelectrodes exhibited a more effective photoconversion capability than TiO₂ nanotubes alone in photoelectrochemical measurements. Furthermore, Cu₂O/TiO₂ composite photoelectrodes also possessed superior photoelectrocatalytic activity and stability in the degradation of Rhodamine B. Intriguingly, by selecting an appropriate bias potential, a synergistic effect between electricity and visible light irradiation can be achieved.