Regulation of TiO2/ZSM-5 catalyst for enhanced photocatalytic toluene oxidation: Intensified light absorption, charge separation and toluene adsorption

TiO 2 has been widely studied in photocatalytic VOCs oxidation but its photocatalytic activity is still unsatisfied due to poor visible light absorption, serious charge recombination and weak toluene adsorption . Herein, a composite catalyst (TiO 2 /ZSM-5) was constructed between TiO 2 and hierarchical ZSM-5 by ball milling for photocatalytic toluene oxidation. The optimal composite catalyst exhibited the toluene degradation efficiency of 91.08 %, which was 2.7 and 1.3 times than those of TiO 2 and TiO 2 /commercial ZSM-5. It showed that the strong interaction between TiO 2 and hierarchical ZSM-5 was established via the formation of Ti-O-Si bond, which decreased the band gap from 3.08 to 0.55 eV when compared with TiO 2 and was helpful for the enhanced charge separation. In addition, the mesoporous volume of hierarchical ZSM-5 was regulated by a dual-template method, making the mesoporous volume increased from 0.23 to 0.38 cm −3 g −1 when compared with TiO 2 /commercial ZSM-5, which improved the toluene adsorption capacity from 0.12 to 0.16 cm −3 g −1 . DFT calculation further indicated that the energy barrier of toluene oxidation and ring-opening reaction was reduced in the presence of hierarchical ZSM-5. This work provided a new catalyst design method to improve the photocatalytic activity by the synergy action of TiO 2 and ZSM-5.