Molybdenum sulfide/graphene-carbon nanotube nanocomposite material for electrocatalytic applications in hydrogen evolution reactions

We report a three-dimensional hierarchical ternary hybrid composite of molybdenum disulfide (MoS₂), reduced graphene oxide (GO), and carbon nanotubes (CNTs) prepared by a two-step process. Firstly, reduced GO–CNT composites with three-dimensional microstructuresare synthesized by hydrothermal treatment of an aqueous dispersion of GO and CNTs to form a composite structure via π–π interactions. Then, MoS₂ nanoparticles are hydrothermally grown on the surfaces of the GO–CNT composite. This ternary composite shows superior electrocatalytic activity and stability in the hydrogen evolution reaction, with a low onset potential of only 35 mV, a Tafel slope of ~38 mV·decade^-1, and an apparent exchange current density of 74.25 mA·cm^-2. The superior hydrogen evolution activity stemmed from the synergistic effect of MoS₂ with its electrocatalytically active edge-sites and excellent electrical coupling to the underlying graphene and CNT network.