Oxygen doped MoS₂ quantum dots for efficient electrocatalytic hydrogen generation

In this study, we report an oxygen-doped MoS₂ quantum dot (O-MoS₂ QD) hybrid electrocatalyst for the hydrogen evolution reaction (HER). The O-MoS₂ QDs were prepared with a one-pot microwave method by hydrazine-mediated oxygen-doping. The synthetic method is straightforward, time-saving, and can be applied in large scale preparation. Ultra-small O-MoS₂ QDs with the average size of 5.83 nm and 1-4 layers can be uniformly distributed on the surface of reduced graphene oxide (RGO). Benefited from the unique structure and the doping effect of oxygen in the MoS₂ QDs and the great number of active sites, the O-MoS₂ QD hybrid displayed outstanding electrocatalytic performance toward HER. A low overpotential of 76 mV at 10 mA/cm² and a Tafel slope of 58 mV/dec were obtained in an acidic solution toward HER. Additionally, the resultant O-MoS₂ QD hybrid also exhibited excellent stability and durability toward HER, displaying negligible current density loss after 1000 cycles of cyclic voltammetry. The design and synthesis of the electrocatalyst in this work open up a prospective route to prepare active and stable electrocatalysts toward substituting precious metals for hydrogen generation.