Amorphous Molybdenum Sulfide on Graphene–Carbon Nanotube Hybrids as Highly Active Hydrogen Evolution Reaction Catalysts

In this study, we report on the deposition of amorphous molybdenum sulfide (MoSx, with x ≈ 3) on a high specific surface area conductive support of Graphene–Carbon Nanotube hybrids (GCNT) as the Hydrogen Evolution Reaction (HER) catalysts. We found that the high surface area GCNT electrode could support the deposition of MoSx at much higher loadings compared with simple porous carbon paper or flat graphite paper. The morphological study showed that MoSx was successfully deposited on and was in good contact with the GCNT support. Other physical characterization techniques suggested the amorphous nature of the deposited MoSx. With a typical catalyst loading of 3 mg cm–2, an overpotential of 141 mV was required to obtain a current density of 10 mA cm–2. A Tafel slope of 41 mV decade–1 was demonstrated. Both measures placed the MoSx-deposited GCNT electrode among the best performing molybdenum sulfide-based HER catalysts reported to date. The electrode showed a good stability with only a 25 mV increase in ove...