Boosting the solvent-free photocatalytic oxidation of benzylamine to N-benzylenebutylamine over BiOX/TiO2 heterojunction nanoflowers

• BiOCl/TiO 2 II-type heterojunction with flower-like morphology was prepared. • BiOCl/TiO 2 can achieve high efficiency for solvent-free photocatalytic oxidation of benzylamine to N-benzylenebutylamine. • The formation rate of N-benzylenebutylamine can reach 6316 µmol∙g −1 ∙h −1 . • The mechanism of the present photocatalytic system was proposed. Imines as valuable chemical intermediates can be synthesized by aerobic photocatalytic oxidation of amines, which is recognized as a promising and green route for imines synthesis. It is attractive to develop solvent-free photocatalytic oxidation of amines with high efficiency, especially with high activity and selectivity, but it is challenging. In the present work, flower-like BiOX/TiO 2 (X = Cl, Br, I) heterojunction was designed for solvent-free photocatalytic oxidation of benzylamine to N-benzylidenebenzylamine. Type II heterojunction of BiOCl/TiO 2 with 67.3 wt% of BiOCl achieved the high formation rate of 6316 µmol∙g −1 ∙h −1 and selectivity of 99 % on BiOCl/TiO 2 . To the best of our knowledge, the activity and selectivity are the highest for solvent-free photocatalytic system. The reason for the varied photocatalytic performances were investigated. The solvent-free photocatalytic mechanism was revealed and proposed. Moreover, the BiOCl/TiO 2 photocatalyst can be used for photocatalytic oxidation of varied benzylamines to imines.