Photocatalytic potential of a titanium dioxide–supported platinum catalyst against VOCs with complicated composition under varying humidity conditions

It is more important to assess the performance of photocatalysts against volatile organic compounds (VOCs) as a mixture rather than as single-component systems to understand the factors and processes governing photocatalytic (PC) destruction of VOCs under real-world operation condition. It is often critical because VOCs in ambient air generally exist in the form of complicated mixtures. In this context, the PC destruction of 14 VOCs as a mixture was studied using a reduced titanium dioxide (TiO2)-supported platinum (1 wt%) catalyst under varying humidity conditions (room temperature (RT) and ultraviolet irradiation (λmax: 254 nm)). The removal efficiencies for aromatic hydrocarbons (e.g., benzene, toluene, m-xylene, and styrene), when examined in the relative humidity (RH) range of 0 to 100%, were in four distinctive ranges of 8.93% and 13.3%, 29.1% and 39.4%, 61.9% and 75.6%, and 92.9% and 96.6%, respectively. In contrast, the removal of ketones increased with RH between 0% and 20%, such as 30.7%–73.8% for methyl ethyl ketone and 68.7%–95.9% for methyl isobutyl ketone. Aldehydes were removed efficiently in the dark through a synergy between thermal oxidation and adsorption at RT. Overall, RH had positive and/or negative effects on photocatalysis depending on the VOC type. The overall results of this study are expected to offer a theoretical framework and practical insights into the PC processes occurring toward complex VOC systems.