Nanoflower-like 1T/2H mixed-phase MoSe2 as an efficient electrocatalyst for hydrogen evolution

Abstract Semiconducting 2H-phase MoSe2 usually has poor conductivity and does not exhibit satisfactory properties in the hydrogen evolution reaction (HER). The metallic 1 T phase can effectively boost the electrocatalytic activity of MoSe2 by adjusting its electronic structure to improve conductivity and intrinsic activity. Here, we report a unique structural 1 T/2H MoSe2 with defects, which is successfully prepared by controlling the reaction temperature, achieving synergistic modulation between active sites and conductivity. Defects can afford more electrocatalytic active sites, and the 1 T phase can effectively enhance the conductivity and intrinsic activity. Profiting from the coexistence of the 1 T phase and defects, 1 T/2H mixed-phase MoSe2 shows superior HER electrocatalytic performance, a low Tafel slope (48 mV dec-1) and a small overpotential at 10 mA cm-2 (-192 mV). This work offers additional insight into enhancing the electrochemical activity of MoSe2 and generally layered dichalcogenide-based catalysts by a simple and direct method.