Metallic 1T-VS2 nanosheets featuring V2+ self-doping and mesopores towards an efficient hydrogen evolution reaction

Defect engineering of layered two-dimensional metal-dichalcogenide nanosheets is important for their promising application as an efficient and low-cost electrocatalyst towards hydrogen generation. In this work, metallic 1T-VS2 nanosheets featuring V2+-doping and plenty of mesopores are synthesized and demonstrated as a superior hydrogen evolution reaction (HER) electrocatalyst. The V2+-doped and mesoporous VS2 nanosheets are evolved from a VS2 center dot NH3 precursor by removing the intercalated NH3 molecules in an acid solution. V2+-doping can significantly increase the vacancies and disorder of VS2 basal planes, while the mesopores can provide plenty of additional edge sites, thereby resulting in abundant defects as active catalytic sites. Owing to the synergistic effects of V2+-doping, the mesoporous structure and metallic conductivity, the as-prepared V2+-doped VS2 nanosheets work as a highly active catalyst for electrochemical water splitting. It delivers striking kinetic metrics of a very low onset potential of 19 mV and a small Tafel slope of 38 mV dec(-1), which are much better than those of the pristine VS2 nanosheets without doping and mesopores. Furthermore, the V2+-doped and mesoporous 1T-VS2 catalyst exhibits excellent long-term stability for 70 h. The present work paves a new way for synergistically increasing active catalytic sites of VS2 nanosheets towards an efficient HER.