In-situ sulfidation to fabricate NiSx modified g-C3N4/NiO composite for efficient photocatalytic hydrogen production under visible-light

Graphitic carbon nitride is a very potential photocatalytic catalyst for H 2 production, but its practical application is seriously limited by the fast recombination of photogenerated carriers and insufficient utilization of surface charge. In order to solve these problems, herein, a series of g-C 3 N 4 -NiO-NiS x photocatalysts were synthesized by first calcining the precursor to load NiO on g-C 3 N 4 and subsequently partial sulfidation of NiO into NiS x in situ via a hydrothermal process. Under the irradiation of visible light, the photocatalytic H 2 production rate of g-C 3 N 4 -NiO-0.4T can be up to 1248.1 μmol·g −1 ·h −1 using triethanolamine as sacrificial agent. In addition, recycling test also confirmed g-C 3 N 4 -NiO-0.4T has excellent photostability. It is believed that the formation of p-n junction between NiO and g-C 3 N 4 and the presence of NiS x promote the spatially fast separation of photogenerated carriers, while the abundant interface of NiS 2 and NiS also leads to the good proton trapping ability. These two factors jointly determine the efficient H 2 production of the composite photocatalysts. Furthermore, the detailed energy band structure and plausible photocatalytic mechanism of g-C 3 N 4 -NiO-NiS x are also proposed. This work can offer a new route and useful reference for the design and research of high efficiency composite photocatalysts for H 2 production.