CeO2 nanosheets with anion-induced oxygen vacancies for promoting photocatalytic toluene mineralization: Toluene adsorption and reactive oxygen species

The deep oxidation of toluene is recognized as a major challenge for photocatalytic oxidation of toluene. Herein, we introduced oxygen vacancies into CeO 2 nanosheets through novel anion-removal of Ce-LDH, with the calcining temperatures of 750, 850, 950 °C. The photocatalytic toluene performance was ordered by CeMO-850 > CeMO-750 > CeMO-950, and CeMO-850 had better activity than P25, common CeO 2 , and CeO 2 -H 2 . Different reaction pathways were founded on CeMO photocatalysts, i.e., on CeMO-950 and CeMO-750, the cresol and hydroquinone intermediates were observed, which hindered toluene adsorption/activation and were hard to deep-mineralization. Whereas, more benzoic acid, open-loop oxygen-containing intermediates were observed on CeMO-850, which were resulted from its oxygen vacancies (Ov), i.e., surface Ov and Ce 3+ were beneficial for toluene adsorption, B acid sites and active radicals’ generation, respectively, and bulk Ov were helpful for oxygen mobility and efficient deep-mineralization. The mechanism of Ov generation and toluene degradation were proposed. • An anion-induced method is used to engineer CeO 2 nanosheet with different Ov. • CeMO-850 with rich Ov shows excellent photocatalytic toluene mineralization. • Ov promotes toluene adsorption, B acid sites, active radicals, and deep-oxidation. • Sulfate ions on CeMO-750 suppress toluene adsorption/activation and poorer activity. • Different reaction pathways are observed on CeMO-850, CeMO-750 and CeMO-950.