Key role of •O2− in promoting deep degradation of VOCs in VUV-based process

VUV photolysis presents a simple process for VOCs degradation, while the poor mineralization rate and extensive by-products greatly limit its application. In this study, the contribution and synergy between •OH and •O2− to toluene degradation in the VUV-based process were comprehensively investigated by controlling water and oxygen in the gas flow. It was found that •OH promoted the initial degradation of toluene and macromolecular intermediates, while •O2− dominated toluene mineralization by boosting the formation of small molecules and CO2. Compared with the •OH-dominated VUV photolysis, the presence of catalyst greatly changed the degradation pathway, promoted toluene mineralization into CO2 and reduced health toxicity via promoting •O2− formation. This study originally focuses on the key role of •O2− in VOCs deep oxidation and provides an effective strategy to boost its clean mineralization via the VUV-based process. [Display omitted] ••OH mainly promotes the initial degradation and ring-opening of toluene in VUV system.••O2− is essential to toluene mineralization into small molecules and CO2.••O2− and •OH well cooperate in deep toluene oxidation in the VUV system.•The increased •O2− produced by catalyst greatly promotes toluene mineralization and reduces health toxicity.