Promotional role of Mn doping on catalytic oxidation of VOCs over mesoporous TiO2 under vacuum ultraviolet (VUV) irradiation

- Mn/meso-TiO2 cooperated well with VUV irradiation.
- Mn doping on the meso-TiO2 showed superior benzene removal efficiency in VUV-PCO.
- O3 can be completely removed and utilized to enhance benzene oxidation.

Volatile organic compounds (VOCs) are the crucial precursors to the formation of fine particulate matter and photochemical smog. Photocatalytic oxidation (PCO) under vacuum ultraviolet (VUV) irradiation has attracted increasing interest for VOCs degradation owing to its strong oxidation capability and excellent stability. However, the generation of O3 from VUV irradiation causes secondary pollution and needs to be addressed. In this study, the Mn doped mesoporous TiO2 (Mn/meso-TiO2) was developed and first combined with VUV irradiation to remove O3 as well as enhance benzene degradation via O3-assited catalytic oxidation. Results indicate that the Mn doped TiO2 exhibited a much higher benzene removal efficiency (82%) than undoped one (70%) and commercial TiO2 P25 (48%). The O3 by-product can be completely eliminated by Mn/meso-TiO2 and contributed to benzene removal efficiency of about 34%. The excellent performance was attributed to the formation of highly reactive oxidizing species such as O(1D), O(3P), hydroxyl radicals (OH) via catalytic decomposition of O3 over oxygen vacancy sites of Mn oxides. Mn/meso-TiO2 cooperated well with VUV and such a VUV-PCO process is very promising for VOCs degradation.

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