The synthesis of Co-doped 1T-rich MoSe2 effectively enhances electrochemical hydrogen evolution reaction

Molybdenum diselenide (MoSe 2 ) has been extensively researched as a promising electrocatalyst for hydrogen evolution reaction (HER). However, its intrinsic properties are still constrained by insufficient exposure of the active site and poor electrical conductivity. Therefore, it is essential to synthesize metallic phase MoSe 2 (1T-MoSe 2 ) with abundant active sites in order to further enhance its HER performance. To achieve this goal, Co-doped MoSe 2 nanosheets with a high 1T phase concentration were synthesized using a simple one-step hydrothermal method. Experiments and theories have demonstrated that Co doping induces the phase transition of MoSe 2 from the 2H to the 1T phase. In a 1 M KOH solution, the overpotential of Co-doped 1T-MoSe 2 at 10 mA cm −2 is only 218 mV, which is significantly superior to that of pure MoSe 2 (287 mV), and the Tafel slope is lower at 115.7 mVdec −1 . Furthermore, the nanosheets exhibited high stability, retaining their catalytic properties even after 200 h of continuous use. Density functional theory (DFT) calculations indicate that Co doping enhances the electrical conductivity and the achieves a minimal value of ΔG H∗ (only about 0.094 eV). This work proposes a strategy to design highly efficient electrocatalysts based on 1T-MoSe 2 .