Nitrogen-Doped Cobalt–Molybdenum Sulfide Hybrid Heterojunctions as Active Electrocatalysts for Producing Hydrogen in Alkaline Media

The rational design and construction of efficient and low-cost hydrogen evolution reaction (HER) electrocatalysts are important current research tasks. Molybdenum disulfide (MoS2) is a typical platinum-like compound with limitless application potential in the HER. However, the application of MoS2 is greatly limited by its high overpotential and poor performance in alkaline media. We report here a three-dimensional (3D) porous nitrogen-doped CoMoS3.13/CoS/MoS2 (CoMoSx) hybrid heterojunction electrocatalyst with good alkaline HER performance. Nitrogen-doped CoMoSx was prepared by a simple electrodeposition method followed by annealing treatment. Optimized nitrogen-doped CoMoSx (CoMoSx-10) prepared by 10 min of electrodeposition showed good HER performance with an overpotential of 49 mV at 10 mA cm–2 and 133 mV at 100 mA cm–2 in 1.0 M KOH, better than most recently reported self-supported cobalt- or molybdenum-based electrocatalysts. It also showed good durability, operating at current densities of 10 and 100 mA cm–2 for 80 h without significant changes in its hydrogen production efficiency. The intrinsic HER kinetic characteristics suggest that the high catalytic activity of CoMoSx-10 is due to not only the large active surface area generated by its 3D porous fleece morphology but also its intrinsic catalytic properties, which are greatly enhanced by the formation of heterogeneous junctions.