Stable Loading of TiO2 Catalysts on the Surface of Metal Substrate for Enhanced Photocatalytic Toluene Oxidation

To promote the practical application of TiO₂ in photocatalytic toluene oxidation, the honeycomb aluminum plates were selected as the metal substrate for the loading of TiO₂ powder. Surface-etching treatment was performed and titanium tetrachloride was selected as the binder to strengthen the loading stability. The loading stability and photocatalytic activity of the monolithic catalyst were further investigated, and the optimal surface treatment scheme (acid etching with 15.0 wt.% HNO₃ solution for 15 min impregnation) was proposed. Therein, the optimal monolithic catalyst could achieve the loading efficiency of 42.4% and toluene degradation efficiencies of 76.2%. The mechanism for the stable loading of TiO₂ was revealed by experiment and DFT calculation. The high surface roughness of metal substrate and the strong chemisorption between TiO₂ and TiCl₄ accounted for the high loading efficiency and photocatalytic activity. This work provides the pioneering exploration for the practical application of TiO₂ catalysts loaded on the surface of metal substrate for VOCs removal, which is of significance for the large-scaled application of photocatalytic technology.