Promote hydroxyl radical and key intermediates formation for deep toluene mineralization via unique electron transfer channel

The degradation and mineralization of volatile organic compounds (VOCs) in gas–solid phase photocatalytic systems suffer great challenges due to the low electron transfer efficiency and slow benzene ring-opening kinetics. Hence, a heterojunction photocatalyst of Bi2SiO5/TiO2 has been synthesized by a facile method. Bi2SiO5/TiO2 shows the ability of mineralizing toluene to CO2 with a degradation rate of 85.5%, while TiO2 is 49.0% and presents a continuous deactivation. Experimental characterizations and theoretical calculations indicate that a unique electron transfer channel of Bi/Si-O-Ti can be established in the heterojunction sample due to the coupling of the interface. The channel facilitates electron transfer to the catalyst surface, generating •OH radicals with strong oxidation and ring-opening ability. Moreover, in-situ DRIFTS reveal that the selective generation of benzoic acid on Bi2SiO5/TiO2 heterojunction plays a critical role in the ring-opening of toluene. This work discloses a novel paradigm to obtain the deep and durable photocatalytic mineralization of toluene.