Two-Step Hydrothermal Synthesis of CoSe/MoSe2 as Hydrogen Evolution Electrocatalysts in Acid and Alkaline Electrolytes

Recently, composite electrocatalytic hydrogen evolution materials have received a lot of attention, especially the composite material of transition metal dichalcogenides. In this article, CoSe/MoSe2 was successfully synthesized by a simple two-step hydrothermal method, then the nanostructure and chemical composition of the composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). Compared to pure MoSe2 and CoSe, CoSe/MoSe2 exhibits excellent catalytic. The current density of 10 mA cm(-2) could be reached at low overpotentials of 192 and 115 mV in acidic and alkaline electrolytes, respectively. In addition, such composite has a small Tafel slope and low electron transport resistance, which indicates that CoSe/MoSe2 has a high hydrogen dissociation rate. Furthermore, it shows high cycling stability.