Surface-Engineered WO ₃ Enables Photocatalytic Mineralization of Toluene under Visible Light by Boosting Mobile OH Radicals

Visible light-driven photocatalysis is a sustainable approach for air purification, but full mineralization of aromatic volatile organic compounds (VOCs) such as toluene to carbon dioxide (CO2) remains elusive due to their chemical stability and weak surface affinity. Here, we report a platinum-loaded, surface-fluorinated tungsten trioxide (F-WO3/Pt) that achieves mineralization of toluene under visible-light irradiation, markedly outperforming conventional Pt/WO3, which cannot degrade toluene at all under the same condition. Mechanistic studies reveal that the surface fluorination of Pt/WO3 promotes the formation of mobile hydroxyl radicals (·OH). These radicals diffuse into the gas phase, extending the active reaction zone beyond the catalyst surface. This fluorination-driven ·OH mobility compensates for WO3’s inherently low photocatalytic oxidation (PCO) activity, low surface area, and weak toluene adsorption. Remote PCO experiments, scavenger tests, and ESR analyses collectively demonstrate the generation and active role of mobile radicals, whereas DFT calculations reveal an additional effect arising from the enhanced affinity of toluene with the fluorinated surface. The synergy between radical mobility and surface affinity establishes a new conceptual framework for the design of highly efficient photocatalysts for air pollutant degradation. These results present a scalable approach to modulating radical dynamics for enhanced visible-light-driven VOC removal and underscore the broad potential of this strategy for developing advanced materials for air purification.