In this work, a facile and low cost route is used to synthesize defect-rich MoS2 nanocrystals in an aqueous solution through ultrasonication and hydrothermal treatment. It is an environmentally friendly process, as organic solvents are not used throughout the synthesis. The ability to exfoliate MoS2 nanosheets considerably increased with the SDS surfactant. The defect-engineered MoS2 nanocrystals showed excellent HER (H2 evolution reaction) activity compared to bulk and MoS2 nanosheets in a 0.5 M H2SO4 electrolyte. The as-synthesized MoS2 nanocrystal catalysts exhibited outstanding HER activity in an acidic medium with a low overpotential of ∼95 mV and a Tafel slope of 41 mV/decade, thus demonstrating the Volmer–Heyrovsky mechanism for the HER activity. The morphology of MoS2 nanocrystals and the increase in active sites result in excellent catalytic activity, supported by ECSA and EIS results. This process can be advanced to other systems to develop cost-effective catalysts with enhanced HER performance for large-scale applications.
Dr. Bhaskar Kaviraj