Solvothermal preparation of Ti3+ self-doped TiO2-x nanotube arrays for enhanced photoelectrochemical performance.

Ti3+ self-doped TiO2-x nanotube arrays (TiO2-x NTs) were prepared by solvothermal treatment in KBH4 ethanol solution followed by calcination, and were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis diffusion reflection spectroscopy (DRS). The photoelectrochemical properties of TiO2-x NTs prepared in different KBH4 concentrations were investigated. The TiO2-x NTs exhibited high visible light response, visible light photocurrent and photoelectrocatalytic activities. The active species and photocatalytic mechanism for the dye degradation were proposed, and the improved photoelectrochemical performance was attributed to the synergistic effect of the narrowed energy gap and enhanced electron transportation. The ability to improve the photoelectrochemical properties of TiO2-x electrode materials should open up new opportunities for high-performance solar cells and photocatalysts.