Properties, applications, and challenges of copper- and zinc-based multinary metal sulfide photocatalysts for photocatalytic hydrogen evolution

The issues of fossil energy shortage and environmental pollution caused by the excessive consumption of conventional fossil fuels necessitates the exploration of renewable and clean energy sources such as hydrogen, which is viable alternative to traditional energy sources in view of its high energy density and nonpolluting nature. In this regard, photocatalytic technology powered by inexhaustible solar energy is an ideal hydrogen production method. The recently developed copper- and zinc-based multinary metal sulfide (MMS) semiconductor photocatalysts exhibit the advantages of suitable bandgap, wide light-harvesting range, and flexible elemental composition, thus possessing great potential for achieving considerable photocatalytic hydrogen evolution (PHE) performance. Despite great progress has been achieved, the current photocatalysts still cannot meet the commercial application demands, which highlights the mechanisms understanding and optimization strategies for efficient PHE. Herein, the basic mechanisms of PHE, and effective optimization strategies are firstly introduced. Afterwards, the research process and the performance of copper- and zinc-based MMS photocatalysts, are thoroughly reviewed. Finally, the unresolved issues, and challenges hindering the achievement of overall water splitting have been discussed. This review comprehensively summarizes the copper-based and zinc-based multinary metal sulfide photocatalysts for photocatalytic hydrogen evolution application. The corresponding challenges and issues need to be overcome, and the perspectives are discussed.