1T@2H-MoSe2 nanosheets directly arrayed on Ti plate: An efficient electrocatalytic electrode for hydrogen evolution reaction

Few-layered MoSe 2 nanosheets with mixed 1T/2H phase were successfully arrayed on a Ti substrate (forming 1T@2H-MoSe 2 /Ti) through a facile one-step solvothermal process. After testing different synthesis conditions, it was found that the optimal process involves a temperature of 200 °C and a reaction time of 12 h. Structural characterizations reveal that the morphology of 1T@2H-MoSe 2 consists of edge-terminated nanosheets with one to five layers, composed of a mixed 1T/2H phase dominated by the 1T one. The 1T@2H-MoSe 2 /Ti electrode shows excellent HER catalytic activity, with a small onset potential (−120 mV vs. reversible hydrogen electrode, RHE) and an electrode potential of only −133 mV (vs. RHE) to achieve a current density of 20 mA·cm −2 . This excellent electrocatalytic activity is due to the synergistic effects of 1T metallic phase, few-layered nanosheet morphology, and direct growth of 1T@2H-MoSe 2 on the Ti substrate. In addition, the 1T@2H-MoSe 2 /Ti electrode shows excellent stability towards long-term electrolysis. This is due to the long-term stability of the valence states of Mo and Se, as shown by post-electrolysis X-ray photoelectron spectroscopy analysis.