Cadmium sulfide/titanate hybrid green light photocatalysis for selective aerobic oxidative homocoupling of amines

Abstract

Semiconductor photocatalysis can carry out selective chemical transformations under ambient conditions, mitigating the associated environmental consequences. However, a single semiconductor photocatalyst usually cannot perform the transformations satisfactorily from the aspects of light-absorption, efficiency, and selectivity, etc. To address these challenges, cadmium sulfide (CdS)/titanate hybrid was fabricated by simultaneously growing titanate and CdS and had been comprehensively characterized. The optimized CdS/titanate hybrid can power the highly selective oxidative homocoupling of amines under the irradiation of green light-emitting diodes (LEDs). Specifically, CdS with a narrow bandgap captures green light; the conduction band of titanate activates molecular oxygen (O2). The valence band of CdS could ensure the selective oxidative homocoupling of amines in methanol (CH3OH). The hybridization between CdS and titanate accounts for the expeditious oxidative homocoupling of amines into imines and the improved stability. Reactive oxygen species (ROS) quenching experiments and in situ electron paramagnetic resonance (EPR) tests suggest that superoxide anion (O2−) and benzylamine radical are intermediates en route to imines. This work highlights the viability of hybridization of dual semiconductor nanostructures in implementing visible light-powered selective conversions.