Construction of 0D/1D CdS/g-C3N4 Z-scheme heterojunction for highly selective photocatalytic benzylamine oxidative coupling

The efficient solar-to-chemical energy conversion system is a green and cost-effective approach for producing high-value-added chemicals in chemical industry, which is highly demanded to develop. Photocatalytic C–N coupling of benzylamine into economic N-benzylidenebenzylamine is a great potential method for alternative conventional organic synthesis. In this work, a zero-dimensional/one-dimensional CdS/g-C3N4 Z-scheme heterojunction was constructed via in situ growing CdS quantum dot onto g-C3N4 nanorod surface for enhancing the spatial separation of charge carriers and maintaining the strong redox ability of the photogenerated charges and applied simultaneously in photocatalytic C–N coupling of benzylamine. This enables 20 wt% CdS/g-C3N4 to exhibit a remarkable photocatalytic performance enhancement for the production of C–N coupled product of benzylamine with the optimal yield of 199.79 μmol which is approximately 4.3 folds than those of pristine g-C3N4 under 2 h visible irradiation. Moreover, benzylamine conversion of approximately 90% within 100 h can be obtained in a gram scale-up reaction. By means of controlled photoelectric chemistry and in situ electron spin resonance spectroscopy experiments, possible spatial photogenerated charges separation and benzylamine conversion mechanisms on the Z-scheme junction were investigated in detail. This work paves a promising strategy for constructing zero-dimensional/one-dimensional Z-scheme heterojunction for the photocatalytic synthesis of high-value-added products.