Recent advance and prospectives of electrocatalysts based on transition metal selenides for efficient water splitting

Electrochemical water splitting comprising the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) plays critical role in energy conversion technology that transfers renewable electricity to hydrogen fuel and the proper catalysts are crucial to efficient electrochemical water splitting. Transition metal selenides (TMSes) are potential electrocatalysts for both HER and OER due to the special layered structure, relatively narrow bandgap, unique morphology, and low cost. However, their electrocatalytic HER and OER properties are still far from satisfactory from the standpoint of commercial implementation, especially the catalytic activity and durability for large charge densities in alkaline media. These drawbacks arise from the sluggish water dissociation kinetics, surface oxidization, and structure degradation. In this review, recent advance of TMSes is reviewed comprehensively from the perspectives of HER, OER, and overall water splitting. The electrochemical characteristics of TMSes are discussed and organized according to the metal cation species in single-metal TMSes and multi-metal TMSes. The composition and structural engineering of TMSes are summarized. Finally, the challenges and opportunities confronting TMSes-based electrocatalysts in advanced HER, OER and other electrocatalytic applications are discussed.