Directional deep oxidation of toluene via phenolized pathway—A review concerning dominant factors involved in photocatalysis

Highlights

	● Phenolized pathway of toluene degradation was summarized for the first time.
	● The role of oxygen vacancies realizing phenolized pathway was elucidated.
	● Strategies for creating oxygen vacancies were summarized.

Abstract

Photocatalytic oxidation through semiconductor photocatalysis is an efficient and green technology for pollutant removal, which has been widely applied to degrade volatile organic chemicals under ambient conditions. However, most of reports focus on the reduction of VOCs concentration while ignore the generation of toxic intermediates, as well as the corresponding secondary pollution. Therefore, it is necessary to further explore how to timely achieve efficient and deep oxidation of VOCs. In this review, we undertake a detailed analysis of photocatalytic degradation of toluene, a representative compound of aromatic hydrocarbon VOCs, and identify the most capable phenolized pathway governed by hydroxyl radicals (•OH). With this pathway, no toxic intermediate like benzene is produced during the photocatalysis. The driving factor, oxygen vacancy (OV), for fueling the generation of •OH is highlighted and the specific approaches including doping engineering and co-catalyst loading that can create rich OVs in semiconductor photocatalysts are described. Furthermore, the challenges and opportunities faced by the phenolized pathway in the future development are prospected.

Graphical abstract

Keywords

Toluene degradation / Oxygen vacancy / Photocatalysis / Phenolized pathway

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Acknowledgements

This work was supported by the National Natural Science Foundation of China (Nos. 52070092 and 52260016) and the Key Laboratory of Jiangxi Province for Persistent Pollutants Prevention Control and Resource Reuse (No. 2023SSY02061). We are grateful for the financial support of the projects and research platform support provided by the laboratory.

Conflict of Interests

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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