Efficient Photo-Assisted Thermal Selective Oxidation of Toluene Using N-Doped TiO2.

Selective oxidation of toluene is a key reaction to produce high value-added products but remains a big challenge. In this study, we introduce a nitrogen-doped TiO2 (N-TiO2) catalyst to create more Ti3+ and oxygen vacancy (OV), which act as active sites for selective oxidation of toluene via activating O2 to superoxide radical (•O2-). Interestingly, the resulting N-TiO2-2 exhibited an outstanding photo-assisted thermal performance with a product yield of 209.6 mmol·gcat-1 and a toluene conversion of 10960.0 μmol·gcat-1·h-1, which are 1.6 and 1.8 times greater than those obtained under thermal catalysis. We showed that the enhanced performance under photo-assisted thermal catalysis was attributed to more active species generation by making full use of photogenerated carriers. Our work suggests a viewpoint to apply a noble-metal-free TiO2 system in the selective oxidation of toluene under solvent-free conditions.