Visible-Light-Driven In Situ Generation of Organic Peroxides over Pd-Loaded WO₃ Photocatalysts

抄録

The development of on-demand sterilization systems for highly resistant bacterial spores remains a critical challenge in the fields of food safety and healthcare. In this study, we developed a visible-light-driven photocatalytic system for the in situ generation of organic peroxides from aqueous ethanol solutions using palladium-loaded tungsten trioxide (Pd/WO₃). The loading of Pd nanoparticles (0.1 wt%) significantly enhanced the photocatalytic activity compared to that of bare WO₃, promoting the simultaneous production of hydrogen peroxide (H₂O₂) and organic acids (acetic and formic acids). This enhancement could be attributed to the improved charge carrier separation and the role of Pd in facilitating the reduction of oxygen to H₂O₂. The generated H₂O₂ and organic acids further reacted on the WO₃ surface to form organic peroxides, such as peracetic acid, via a two-step sequential process. Under optimized conditions (80 % v/v EtOH/H₂O), the Pd/WO₃ system achieved a 6-log reduction in Bacillus subtilis spores within 12 h of visible-light irradiation, whereas bare WO₃ required 16 h for the same effect. Our findings demonstrate that the Pd/WO₃ photocatalytic system provides a safe and efficient approach for the localized production of high-level disinfectants, offering a promising alternative to conventional corrosive chemical agents for inactivating resilient pathogens.