S-doping induced phase engineering of MoSe2 for hydrogen evolution reaction

MoSe2 is a promising electrocatalyst for hydrogen evolution reaction (HER). It is confirmed that 1T-MoSe2 shows better activity for HER compared with 2H-MoSe2 since of wider interlayer spacing, higher conductivity and better hydrophilicity of 1T-MoSe2. Realization of 1T-MoSe2 is still a thorny issue due to its high formation barrier and thermodynamic metastable. Herein, considering the microstrain induced by atomic size mismatch through the substitution of Se by S, the MoSe2-2xS2x is prepared via one-pot hydrothermal synthesis, resulting in 70.3% high-purity 1T phase. Additionally, the MoSe2-2xS2x shows a low overpotential of 167 mV at 10 mA cm−2, Tafel slope of 54 mV dec−1, high double layer capacitance (Cdl) of 13.43 mF cm−2 and superior cycle stability. The results are ascribed to larger interlayer spacing, high conductivity and good hydrophilicity of 1T phase MoSe2-2xS2x. This study provides a simple and feasible route to achieve high-purity TMDs for promoting HER application.