Oxygen Vacancies Enhance Water-Driven Activation of Surface Lattice Oxygen on TiO2 for Efficient Photocatalytic Oxidation of Toluene

Due to an insufficient active oxygen supply, aromatic volatile organic compounds (VOCs) often exhibit suboptimal activity and stability during photocatalytic degradation. To address this challenge, this study utilizes the water dissociation properties of oxygen vacancies (O-v) to weaken the Ti-O bond in TiO2 through hydrothermal treatment, thereby enhancing lattice oxygen activity and optimizing photocatalytic performance. Theoretical calculations and experimental results reveal that protons from water dissociation diffuse and reduce the orbital overlap between Ti and the O atoms, weakening the Ti-O bond and activating surface lattice oxygen. O-2-TPD and in situ diffuse reflectance infrared Fourier transform spectroscopy characterization confirm that the weakened Ti-O bond facilitates O-2 adsorption and lattice oxygen regeneration, significantly increasing lattice oxygen activity. TiO2 with weakened Ti-O bonds exhibited significantly enhanced toluene removal and mineralization rates, outperforming those of P25. While the toluene degradation pathway remained unchanged, the enhanced lattice oxygen functioned as an "oxygen pump," providing additional reactive oxygen species, markedly improving mineralization rates and enhancing catalyst stability. This study proposes a novel strategy based on the hydrolytic dissociation effect of O-v to weaken Ti-O bonds, systematically exploring the mechanism by which O-v enhances lattice oxygen activity and offering theoretical guidance for designing efficient photocatalytic materials for VOCs degradation.