Nickel-decorated g-C3N4 hollow spheres as an efficient photocatalyst for hydrogen evolution and oxidation of amines to imines

Abstract

Photocatalysts composed of earth-abundant elements are highly desired for photocatalytic hydrogen evolution as well as oxidation of amines to imines without the requirement of precious metals. Herein, non-precious Ni metal decorated g-C₃N₄ hollow spheres (Ni–CNHS) with different Ni contents were prepared by a simple calcination strategy followed by photoreduction loading of the Ni metal. Under visible light illumination, Ni–CNHS exhibited efficient photocatalytic performance for the oxidation of amines to imines and hydrogen production from water splitting using triethanolamine as a sacrificial agent. The optimal amount of Ni was 0.41 wt% with a H₂-production rate of 596 μmol g⁻¹ h⁻¹ and the conversion rate of benzylamine of 61.3%. The probable photocatalytic mechanism of Ni–CNHS was investigated. This work provides the possibility to construct non-noble metal photocatalysts with great performance for hydrogen production and organic synthesis.