Oxygen defect engineering at TMOx (TM = Mn, Co, Fe, Ni, Cu, Zn)/TiO2 interfaces: A strategy for high-efficiency catalytic toluene degradation

Volatile organic compounds (VOCs), as hazardous environmental pollutants emitted from chemical industries, cause significant threats to human health and ecological environment owing to their inherent toxicity and carcinogenicity. Catalytic oxidation has emerged as a promising technology for VOC elimination, enabling complete degradation of pollutants into CO 2 and H 2 O. This study investigates transition metal oxide (TMO x , TM = Mn, Co, Fe, Ni, Cu, Zn)/TiO 2 catalysts for toluene degradation. Since the catalytic efficacy of TiO 2 -based catalysts critically depends on the quantity of surface oxygen vacancy (O v ) in heterogeneous processes, we engineered O v -rich interfaces by breaking atomic periodicity arrangements and generating unsaturated coordination sites. These structural modifications enhanced oxygen migration rates and increased reactive oxygen species availability. Among the synthesized catalysts, CuO/TiO 2 exhibited the highest performance, achieving 90 % toluene conversion (T 90 ) at 286 °C under a weight hourly space velocity (WHSV) of 20,000 mL/(g·h) with an initial toluene concentration of 1000 ppm. The measurement of in-situ DRIFTS suggested that toluene oxidation process abided by the path of toluene → benzaldehyde → benzoic acid → anhydride →CO 2 and H 2 O. Furthermore, the by CuO/TiO 2 catalyst demonstrated great reusability, and long-term stability, highlighting its potential for industrial-scale VOC abatement applications.