Manipulating the Dual Role of Water via Ti–O Vacancy Coupling for the Humidity-Resistant Photocatalytic Oxidation of VOCs

Aromatic volatile organic compounds remain difficult to remove via photocatalytic oxidation because this process is highly sensitive to humidity fluctuations and prone to catalyst deactivation. To address this issue, a dual-vacancy TiO 2 photocatalyst enriched with both titanium and oxygen vacancies was constructed by regulating the local coordination environment of the titanium precursor. The coupled vacancies induce local charge redistribution and a built-in electric field, promoting photogenerated charge separation and interfacial electron transfer. Meanwhile, their synergistic effect facilitates surface water dissociation, increases the surface hydroxyl coverage, and strengthens the OH···π interaction, thus endowing H 2 O with a dual role in accelerating toluene adsorption/activation and reactive oxygen species generation for deep oxidation. The optimized catalyst achieves ∼80% toluene removal and nearly 90% mineralization with excellent stability and humidity tolerance over 10–75% RH. This study provides a novel strategy for designing efficient, stable, and humidity-resistant TiO 2 -based photocatalysts for volatile organic compounds abatement.