Template free sol-gel synthesis of mesoporous TiO₂ particles as an efficient photocatalyst for gaseous toluene removal

Mesoporous anatase TiO₂ particles, named as 200-TiO₂ (pore size: 4–8 nm, particle size: 200–400 nm) with high surface area (196.2 m²/g) was prepared via a template-free sol-gel method and subsequent drying at 200 °C. Three different TiO₂ particles (450-, 550-, and 650-TiO₂) were prepared by annealing the 200-TiO₂ at 450, 550, and 650 °C, respectively. The 200-TiO₂ exhibited the highest and most stable photocatalytic activity towards toluene degradation under the UV light irradiations among the four samples which mainly attributed to its mesoporosity and high surface area. The ex-situ FT-IR and operando DRIFT studies revealed that the benzoic acid formed on the surface of 200-TiO₂ samples during the toluene oxidation can be decomposed into CO₂ under UV light irradiations, so that the 200-TiO₂ can be resistant to the accumulation of recalcitrant reaction intermediates.