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

Abstract

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·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.