Photoelectrochemical characteristics of ZnO/ TiO2 nanoheterojunctions

Abstract

In this paper, TiO₂ nanotubes are fabricated on Ti foils by anodic oxidation, a layer of ZnO nanorod arrays is further deposited on the TiO₂ nanotube without seed layer by a hydrothermal method at different Zn²⁺ concentration. The result shows that the ZnO nanorods mainly present needle-like structure and the density of the nanorods increases with the Zn²⁺ concentration. The PL of the ZnO nanorods show that there are defect levels formed in the ZnO nanorods. When the ZnO/TiO₂ heterostructure is irradiated by the light, the photocurrent is significantly increased by about 2-3 times of that from pure TiO₂ nanotubes. The band diagram of the ZnO/TiO₂/Ti was proposed to interpret the photocurrent characteristics. Our result indicates that the ZnO/TiO₂ can be excellent candidate semiconductor material for the photoelectrochemical energy transfer.