Optimizing the Reaction Pathway by Active Site Regulation in the CdS/Fe 2 O 3 Z-Scheme Heterojunction System for Highly Selective Photocatalytic Benzylamine Oxidation Integrated with H 2 Production

Simultaneous photocatalytic H 2 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/Fe 2 O 3 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/Fe 2 O 3 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 H 2 production active sites to further accelerate charge separation and H 2 production kinetics but also facilitates the condensation of N-benzylideneamine with benzylamine for N-benzylidenebenzylamine production and NH 3 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/Fe 2 O 3 composite displays a high H 2 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%.