Tuning the selectivity of benzylamine photo-oxidation with different rhodium modes anchored on BiOIO3

Abstract

Selective benzylamine (BA) oxidation to high value-added imines is of great significance in the chemical industry, but it still remains challenging. In this study, we demonstrate rhodium single atom and nanoparticle modes (Rh₁ and Rh_NP) anchored on BiOIO₃ nanosheets as two efficient photocatalysts (Rh₁/BOIO and Rh_NP/BOIO) to achieve the selective BA oxidation reaction. Notably, these two photocatalysts displayed completely opposite selectivity during BA photo-oxidation. Benzonitrile (BN) was the main product over Rh₁/BOIO, while Rh_NP/BOIO preferentially produced N-benzylidenebenzylamine (N-BBA) under the same reaction conditions. To reveal the reason for such differences, we combined density functional theory (DFT) simulation and experiments to investigate the BA oxidation reaction mechanism over these two photocatalysts. As a consequence, it was found that the different active intermediates ˙OH and ˙O₂⁻ generated on Rh₁ and Rh_NP would lead to the opposite selectivity of BA photo-oxidation over Rh₁/BOIO and Rh_NP/BOIO, respectively. This study offers a valuable strategy to tune the selectivity of photo-oxidation reactions as required.