Direct growth of cobalt-doped molybdenum disulfide on graphene nanohybrids through microwave irradiation with enhanced electrocatalytic properties for hydrogen evolution reaction

Molybdenum disulfide (MoS2) nanosheets are promising candidates as electrode materials for the efficient hydrogen production through water splitting. However, their activities are only governed by the edge sites, and their charge transfer efficiencies are still unsatisfactory. Defect generation and hybridization are two very effective ways to tune the nanostructures of MoS2 and enhance their electrocatalytic properties. Herein, cobalt-doped molybdenum disulfide (Co-MoS2) nanosheets have been synthesized on graphene network (Co-MoS2/G) by an ultrafast, facile, and reliable microwave irradiation technique. The structural, morphological, and compositional properties were characterized for these Co-MoS2/G composites. The compositionally optimized catalyst of as-produced Co-MoS2/G delivers excellent hydrogen evolution reaction (HER) performance in acidic medium with the best combination of three major parameters, resulting in a low overpotential of 78.1 mV, a small Tafel slope of 40.0 mV per decade, and a high exchange current density of 0.0917 mA cm(-2), which also exhibits excellent electrochemical stability for 5000 cycles with negligible loss of the cathodic current and long-term durability for 94 h. Co-doping greatly enhanced the intrinsic activity of MoS2 nanosheet catalyst by creating abundant defects, and in addition, the integration of graphene notably promoted the electrical conductivity and mechanical properties of Co-MoS2/G composites. This study would supply an ultrafast, simple, and efficient strategy for developing excellent metal-doped electrocatalysts for HER.