Ti3+ self-doped TiO2−x anatase nanoparticles via oxidation of TiH2 in H2O2

Abstract

Anatase phase Ti3+ self-doped TiO2−x nanoparticles (NPs) has been successfully synthesized by a simple interface ion diffusion-redox reaction using TiH2 and H2O2 as precursors. The structure, crystallinity, morphology and other properties of the samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The chemical states of Ti in the samples were confirmed by X-ray photoelectron spectra (XPS). Electron spin resonance (ESR) spectra confirm the presence of high concentration of Ti3+ in the bulk and surface of the as-prepared substoichiometric TiO2−x NPs. Composition of the samples was also analyzed by energy dispersive X-ray spectra (EDX) and the results indicate the exist of oxygen vacancies. UV–vis diffuse reflectance spectroscopy (UV–vis DRS) showed that Ti3+ self-doped TiO2−x NPs have a strong absorption between 400 and 800nm. The formation mechanism of the Ti3+ self-doped TiO2−x NPs was also discussed. Methylene blue (MB) solutions were used as model wastewater to evaluate the visible-light photocatalytic activity of the samples. Under visible light radiation, the samples exhibit excellent ability in the photocatalytic degradation of MB and splitting of water to produce H2. The most active Ti3+ self-doped TiO2−x NPs obtained at 500°C exhibits 68-fold enhancement for the visible light decomposition of MB in comparison to commercial P25 TiO2. The samples also show an excellent cyclic stability of the photocatalytic activity of degrading MB.