The over-reliance on fossil fuels leads to deteriorating ecological environment and motivates us to develop sustainable and clean energy alternatives in order for our long-term survival on the earth. Hydrogen energy is one of the most promising energy carriers in the 21^st century since the only by-product is H₂O. In comparison to steam reforming of natural gas and coal, hydrogen evolution reaction (HER) via H₂O electrolysis is a more attracting pathway for H₂ production because of the low cost, high efficiency and abundant raw materials, which would contribute to a lower carbon footprint. HER requires stable and active enough catalyst materials to overcome the reaction barriers. It is well known that Pt group materials are state-of-the-art HER catalysts, but unfortunately, the low abundance and high cost complicate its large-scale applications. The transition metal disulfides (TMDs) possess a two-dimensional layered structure and a larger specific surface area, which is conducive to expose more active sites. In particular, MoS₂, a representative of TMDs, has attracted tremendous research interests in HER domain and is supposed to be a cost-affordable alternative to Pt-based catalysts. In this work, the research status of MoS₂ modified by single atoms (SA-MoS₂) of noble metal, non-noble metal, and nonmetal, to catalyze HER reactions is reviewed. Based on the overpotential and Tafel slope, the structure-function relationship between HER performance and SA-MoS₂ structures is summarized. Finally, future research directions are proposed and hopefully, this paper will guide rational design of SA-MoS₂ for a more efficient HER electrocatalyst.

Contents

1 Introduction

2 Metal single-atom doped MoS₂

2.1 Noble metal elements platinum (Pt), palladium (Pd), ruthenium (Ru), tungsten (W)

2.2 Transition metal elements nickel (Ni), cobalt (Co), copper (Cu)

3 Non-metal single-atom doped MoS₂

4 Conclusion and outlook