MoS2−x/GCD-MoS2−x nanostructures for tuning the overpotential of Volmer-Heyrovsky reaction of electrocatalytic hydrogen evolution

MoS2 nanostructures are famous electrocatalysts in hydrogen evolution reaction (HER). The presence of graphene was already reported to boost the electrocatalytic activity of MoS2. This work reports the influence of Sulphur deficiency and economically synthesizable green carbon dot (GCD) incorporation into hydrothermally synthesized MoS2 nanostructures on the electrocatalytic activity of HER. All as-synthesized nanocatalysts are Sulphur deficient (MoS2−x and GCD-MoS2−x) and exhibited superior HER activity as compared to commercial MoS2. MoS2−x 220 exhibited a Tafel slope of 43 mV/Dec indicates the reaction mechanism as Volmer-Heyrovsky with Heyrovsky as rate determining step. Best electrocatalytic parameters are observed for the same catalyst with overpotential: 247 mV at 10 mA/cm2, Turnover frequency: 0.42 s−1, double layer capacitance: 23.8 mF/cm2 and electrochemically active surface area: 595/cm2. The obtained preferable HER parameters suggest that Sulphur deficiency and incorporation of GCD in MoS2 are playing a vital role in HER electrocatalysis.