Enhanced Photocatalytic Hydrogen‐Production Performance of Graphene–ZnxCd1−xS Composites by Using an Organic S Source

Abstract

In response to the increasing concerns over energy and environmental sustainability, photocatalytic water‐splitting technology has attracted broad attention for its application in directly converting solar energy to valuable hydrogen (H 2) energy. In this study, high‐efficiency visible‐light‐driven photocatalytic H 2 production without the assistance of precious‐metal cocatalysts was achieved on graphene–ZnxCd 1−xS composites with controlled compositions. The graphene‐ZnxCd 1−xS composites were for the first time fabricated by a one‐step hydrothermal method with thiourea as an organic S source. It was found that thiourea facilitates heterogeneous nucleation of ZnxCd 1−xS and in situ growth of ZnxCd 1−xS nanoparticles on graphene nanosheets. Such a scenario results in abundant and intimate interfacial contact between graphene and ZnxCd 1−xS nanoparticles, efficient transfer of the photogenerated charge carriers, and enhanced photocatalytic activity for H 2 production. The highest H 2‐production rate of 1.06 mmol h−1 g−1 was achieved on a graphene–Zn 0.5 Cd 0.5 S composite photocatalyst with a graphene content of 0.5 wt %, and the apparent quantum efficiency was 19.8 % at 420 nm. In comparison, the graphene–ZnxCd 1−xS composite photocatalyst prepared by using an inorganic S source such as Na 2 S exhibited much lower activity for photocatalytic H 2 production. In this case, homogeneous nucleation of ZnxCd 1−xS becomes predominant and results in insufficient and loose contact with the graphene backbone through weak van der Waals forces and a large particle size. This study highlights the significance of the choice of S source in the design and fabrication of advanced graphene‐based sulfide photocatalytic materials with enhanced activity for photocatalytic H 2 production.