Dye-Sensitized NiS_<i>x</i> Catalyst Decorated on Graphene for Highly Efficient Reduction of Water to Hydrogen under Visible Light Irradiation

Abstract

In this work, a highly active H2 evolution NiSx catalyst decorated on graphene (NiSx/G) nanohybrid was prepared by an in situ chemical deposition method, in which nickel ion was first adsorbed onto graphene and subsequently reacted with sulfide ion to yield the NiSx/G nanohybrid. The NiSx/G catalyst exhibited activity for hydrogen generation 2-fold higher than that of pristine NiSx under visible light irradiation. The highest quantum efficiency of 32.5% was reached at 430 nm when Eosin Y was used as a photosensitizer. In this system, graphene not only provided a large area and two-dimensional substrate for the confined growth of NiSx but also greatly enhanced the transfer of photoelectrons from excited Eosin Y to the NiSx cocatalyst because of its promotion of charge separation, leading to the great enhancement of photocatalytic hydrogen evolution.