In-situ phase conversion of composited 1T@2H–MoSe2 nanosheets with enhanced HER performance

Transition metal dichalcogenides (TMDCs) are considered as the potential electrocatalysts for hydrogen evolution reaction (HER) owing to the two-dimensional (2D) geometry and tunable band gap. However, both the inefficient electron transferring and high Gibbs free energies for hydrogen adsorption (ΔG H *) in MoSe 2 limit its further improvement in catalytic performance. Herein, the few-layered 1T@2H–MoSe 2 composite nanosheets are synthesized by one-pot hydrothermal reaction . It is found that the morphology and composites of nanosheets could be influenced by hydrothermal reaction parameters. As compared to pure 2H–MoSe 2 , 1T@2H–MoSe 2 electrode exhibits remarkable activity for HER with a low overpotential (118 mV), small Tafel slope (65.8 mV·dec −1 ) as well as large electrochemical active area (C dl  = 37.5 mF cm −2 ) in acid electrolytes. Density functional theory (DFT) calculations demonstrate that ΔG H * of 1T@2H–MoSe 2 (0.232 eV) is much lower than these of pure 1T-MoSe 2 and 2H–MoSe 2 . It could be ascribed to both the optimized charge transfer and increased density of active sites in 1T@2H–MoSe 2 nanosheets.