Photoinduced Terminal Fluorine and Ti <sup>3+</sup> in TiOF <sub>2</sub> /TiO <sub>2</sub> Heterostructure for Enhanced Charge Transfer
Jie Hu, Yi Lu, Xiaolong Liu, Christoph Janiak, Wei Geng, Si-Ming Wu, Xiao-Fang Zhao, Liying Wang, Ge Tian, Yuexing Zhang, Bao‐Lian Su, Xiaoyu Yang
Abstract
As an effective way to enhance the photo/electro-catalytic performance of titanium dioxide (TiO<sub>2</sub>) is to explore the positive roles of doped fluorine sites in the fluorinated TiO<sub>2</sub> systems, which, currently still lacks the direct experimental evidence due to the complexity of the species involved. Herein, we have fabricated TiOF<sub>2</sub>/TiO<sub>2</sub> with interfacial bridging fluorine (Ti<sub>2</sub>–F) via a coherent phase transition through hydrothermal synthesis. Nuclear magnetic resonance and electron paramagnetic resonance characterization have provided strong evidence of the transformation of the doped fluorine from Ti<sub>2</sub>–F to Ti<sub>1</sub>–F and the subsequent generation of Ti<sup>3+</sup> at the interface of the TiOF<sub>2</sub> and TiO<sub>2</sub> under UV–visible (UV–vis) light irradiation. Density functional theory (DFT) calculations and photo/electrochemical measurements further confirmed the electron donor behavior of the Ti<sup>3+</sup>. The benefit is a significantly enhanced charge transfer efficiency in TiOF<sub>2</sub>/TiO<sub>2</sub>, which not only resulted in improved performances for the photodegradation of acetone being 5.5 times higher than the commercial TiO<sub>2</sub> but also supported high capacity for sodium-ion storage. Thus, the TiOF<sub>2</sub>/TiO<sub>2</sub> with Ti<sub>2</sub>–F provided a perfect structure to investigate the roles of fluorine sites in fluorinated TiO<sub>2</sub> systems and their interaction with material properties.