Nanocomposite-electrocatalysts from oxide and sulfide of molybdenum in alkaline medium for hydrogen evolution

Abstract

Hybrid materials combining oxides and sulfides have emerged as promising electrocatalysts for the hydrogen evolution reaction (HER). However, their efficacy in replacing the noble metal electrocatalysts is challenged due to insufficient charge transfer and corrosion losses in acidic media. Hybrid nanocomposite-electrocatalysts were synthesized using 200 nm wide MoO₃ nanorods, and MoS₂ nanosheets. This hybrid catalyst utilizes the synergistic interaction between the oxide and sulfide components. Among the synthesized nanocomposites, the MoS₂ enriched catalyst showed an excellent stability in the alkaline media. The uniform MoO₃ rods act as proton adsorption sites to hold water molecules, by providing the oxygen lattice. The MoS₂ nanosheets offer active edge sites and high HER kinetics for the efficient release of hydrogen. A low overpotential of 177 mV at a current density of 100 mA cm⁻² with a Tafel slope of 86 mV dec⁻¹ was obtained. The inclusion of MoS₂ has reduced the bandgap of the nanocomposite, facilitating an enhanced charge transfer and a high hydrogen evolution rate of 2.13 mmol h⁻¹ cm⁻² at −0.5 V versus RHE. The superior catalytic activity of the MoS₂ enriched catalyst can be attributed to its abundant active and proton-adsorbing sites, which have boosted its performance for HER in alkaline conditions.