Synergistic enhancement of photocatalytic hydrogen evolution by ultrathin oxygen-doped graphitic carbon nitride nanosheets loaded amorphous mesoporous nickel hydroxide

Graphitic carbon nitride (g-C3N4, CN) is widely utilized in the field of photocatalytic hydrogen production owing to its exceptional visible light absorption, addressing the challenge of energy scarcity. However, its development has been hindered by the issue of low charge separation efficiency. In this study, an ultrathin (∼1.65 nm) oxygen-doped graphitic carbon nitride nanosheets loaded amorphous mesoporous nickel hydroxide (a-Ni(OH)2/OCN) photocatalyst was developed through a straightforward calcination and stirring approach. Under visible light irradiation, a-Ni(OH)2/OCN exhibited a remarkably high photocatalytic hydrogen evolution rate of 4764.9 μmol·h−1 g−1, which is 4.7 times greater than that of the original CN. The synergistic effect between O-doping and heterojunction was proved by experimental data analysis combined with DFT calculations. Totally, the introduction of oxygen into CN led to a reduction in its band gap, while a-Ni(OH)2/OCN heterojunction achieved a broaden light absorption range and an effective charge separation due to a type-Ⅱ internal electric fields.