Optimizing the Reaction Pathway by Active Site Regulation in the CdS/Fe2O3 Z-Scheme Heterojunction System for Highly Selective Photocatalytic Benzylamine Oxidation Integrated with H2 Production

Abstract

Simultaneous photocatalytic H2 production and preparation of high-value chemicals by the selective oxidation of organic substances is of great significance for solar energy utilization and conversion. Herein, a Pt-modified 2D/2D CdS/Fe2O3 Z-scheme heterojunction was dexterously designed for photocatalytic dehydrogenation coupling of benzylamine with high performance and product selectivity. The Z-scheme charge transfer in CdS/Fe2O3 greatly boosts charge separation and maintains the strong redox capacity of photogenerated electrons and holes. Impressively, the loading of the Pt cocatalyst not only provides rich H2 production active sites to further accelerate charge separation and H2 production kinetics but also facilitates the condensation of N-benzylideneamine with benzylamine for N-benzylidenebenzylamine production and NH3 releasing. The selectivity for C═N coupling products is significantly enhanced and the C–C coupling side reaction is greatly suppressed. With sufficient benzylamine substrate and visible light irradiation, the optimal Pt/CdS/Fe2O3 composite displays a high H2 production rate of 39.4 mmol h–1 g–1 with a quantum efficiency of 32.81% at 420 nm, and the selectivity of benzylamine oxidation to N-benzylidenebenzylamine is above 90%.