Ti3+ self-doped TiOx@anatase core–shell structure with enhanced visible light photocatalytic activity

Abstract

Ti³⁺ self-doped TiO_x@anatase core–shell structures were prepared via hydrolysis of Ti₂(SO₄)₃ around TiO particles, followed by post-calcination at temperatures from 723 to 823 K. The as-prepared TiO_x@anatase was examined by means of transmission electronic microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. It was demonstrated that the samples displayed core–shell structures with the shell in the anatase form and the core in the anatase and rutile phases, and a large number of Ti³⁺ ions were present. Electron paramagnetic resonance analysis indicated that the Ti³⁺ ions were located throughout the whole sample, including the shell, the core and the interface between the core and the shell. The as-prepared TiO_x@anatase core–shell catalysts can absorb visible light and showed good activity for catalyzing the degradation of Rhodamine B under visible light irradiation. In particular, the TiO_x@anatase obtained at 773 K showed the best performance, due to the high concentration of well-dispersed Ti³⁺ ions in the sample.