Facile regulation of crystalline phases and exposed facets on Ti3+ self-doped TiO2 for efficient photocatalytic hydrogen evolution

The control of the photocatalytic activity of TiO2 by tailoring their crystalline structure and electronic structure is a current topic of great interest. In the present study, the phase composition and exposed facets on Ti3+ self-doped TiO2 were regulated by simply changing the fluorinion concentration during the hydrothermal synthesis process of TiO2. It was found that the phase composition can be tuned facilely, and the phase transformation process was analyzed by XRD and UV Raman spectroscopy. The introducing fluorinion during the hydrothermal preparation of TiO2 resulted in F-doping and phase transformation. And the F-doping also affects the amount of Ti3+ ions in the TiO2. SEM analysis indicated that the morphology and exposed facets changed with the change in fluorinion concentration, and the ratios of exposed facets are adjustable. Through systematically optimizing these parameters, the TiO2 prepared under fluorinion concentration of 17.5 mM showed the excellent photocatalytic performance under full spectrum illumination. The good photocatalytic performance was mainly attributed to the more phase junctions and surface heterojunctions for enhancing charge separation.