Boosting the Photocatalytic Performance for Oxidative Coupling of Amines to Imines by Fabricating the Zn0.1cd0.9s/In2o3 Heterojunction

Abstract

A series of Zn0.1Cd0.9S/In2O3 (ZCS/IO) composites were prepared by a facile hydrothermal method. The obtained ZCS/IO composites exhibited a remarkable improved activity for the photocatalytic oxidation of benzylamine (BA) to N-benzylidene benzylamine (N-BDBA) under visible light illumination and ambient air as compared to pure Zn0.1Cd0.9S and In2O3. Especially, the ZCS/IO composite with a In2O3 mass ratio of 10%, denoted as ZCS/IO-10, showed the best photocatalytic performance, offering 99.6% conversion of benzylamine with high selectivity (>99.0%) to N-BDBA within 1 h of irradiation. The significant improvement in photocatalytic activity was attributed to the construction of a direct Z-scheme heterojunction between Zn0.1Cd0.9S and In2O3, and the increase in oxygen vacancies (OVs) concentration. As a result, the light absorption of the ZCS/IO composite was enhanced and the separation and migration of the photogenerated electrons and holes were accelerated, meanwhile the high redox ability of the composite was maintained, and thus resulting in the boosting of it’s photocatalytic activity for amine oxidation. In addition, the high activity of ZCS/IO-10 composite was maintained during the four consecutive cycles, suggesting its outstanding stability and reusability. Besides, the substituted benzylamines and heterocyclic amines can also be transformed to their corresponding imines phtocatalyzed by the ZCS/IO-10 composite, manifesting the good versatility of the composite catalyst.

Keywords: Zn0.1Cd0.9S/In2O3 composite, photocatalytic oxidation, amine, imine