Ball milling-engineered nanostructured MoSe 2 /graphite electrocatalyst: Achieving superior hydrogen evolution with a high density of active sites

Nanostructured MoSe 2 and its composites with graphite nanoparticles were prepared by a simple, inexpensive, and productive ball-milling method, demonstrating their superior effectiveness as electrocatalysts for the hydrogen evolution reaction (HER). The study revealed that the ball-milling duration significantly influences the prepared nanomaterials' morphology and electrocatalytic properties. The materials prepared in this way are characterized by significant delamination of both components and high defectiveness of molybdenum diselenide. The introduction of graphite nanoparticles into the molybdenum diselenide composition significantly enhances the material's electrocatalytic properties. It has been established that the electrocatalyst based on gMoSe 2 /Gr(2h) is characterized by a Tafel slope of 40 mV/dec and a potential of −75 mV at a current density of 10 mA/cm 2. The electrode modified with gMoSe 2 /Gr(2h) demonstrates exceptional stability for over 20 hours while maintaining a high current density of approximately 450 mA/cm 2 at −300 mV. The study establishes that the high electrocatalytic activity of materials obtained in this manner is directly related to the presence of a high concentration of selenium vacancies in their structure, which can act as catalytically active centers in HER.