Newly Designed One-Pot In-Situ Synthesis of VS2/rGO Nanocomposite to Explore Its Electrochemical Behavior towards Oxygen Electrode Reactions

A facile and effective one-step in-situ technique for the synthesis of layered two-dimensional metallic vanadium sulfide-reduced graphene oxide (VS2/rGO) nanocomposite (NComp) hasbeen described and their electrocatalytic properties towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have been studied. From transmission and scanning electron microscopy analyses, it was observed that the layered two-dimensional VS2 nanoparticles successfully grew over the layered graphene matrix. The as-synthesized NComp displayed excellent electrocatalytic activities towards ORR with a four-electron transfer pathway, and OER in alkaline medium. The synthesized nanocatalyst exhibits lower Delta E value (0.75 V) as compared to other literature values, high catalytic current density (-6.26 mA cm(-2) for ORR) with a lower Tafel slope (59 mV dec(-1)), as compared to Pt/C, and lower overpotential (eta=0.31 V at 10 mA cm(-2) for OER) with a smaller Tafel slope (68 mV dec(-1)) than those of RuO2. Moreover, it displays high electrochemically active surface area, long-term stability in alkaline medium and good resistance to the methanol crossover effect. The enhanced bifunctional electrocatalytic properties of the synthesized nanocatalyst may be owing to the synergistic effect of combining VS2 and rGO, which improves the surface area, adsorption of reaction intermediates, active sites density, and electrical conductivity. Along with the high stability of the hybrid NComp, these advantages provide immense promise for triggering breakthroughs in fuel-cell electrocatalysis.