Ni/Mo Bimetallic-Oxide-Derived Heterointerface-Rich Sulfide Nanosheets with Co-Doping for Efficient Alkaline Hydrogen Evolution by Boosting Volmer Reaction.

Molybdenum disulfide (MoS2 ) is a promising alternative to Pt-based catalysts for electrocatalytic hydrogen evolution reaction (HER) in an acidic environment. However, alkaline HER activity for molybdenum disulfide is limited by its slow water dissociation kinetics. Interface engineering is an effective strategy for the design of alkaline HER catalysts. However, the restricted heterointerfaces of current catalysts have significantly limited their alkaline HER performance. Herein, a novel assembly of cobalt-doped interface- and defect-rich MoS2 /Ni3 S2 hetero-nanosheet anchoring on hierarchical carbon framework for alkaline HER is reported by directly vulcanizing NiMoO4 nanosheets. In the heterostructure nanosheet, Ni3 S2 acts as a water dissociation promoter and MoS2 acts as a hydrogen acceptor. Density functional theory calculations find that redistribution of charges at the heterointerface can reduce hydrogen adsorption Gibbs free energy (∆GH* ) and water decomposition energy barrier. The resulting hierarchical electrode with the synergistic effect of both hybrid components shows a low overpotential of 89 mV at -10 mA cm-2 in 1 m KOH, a Tafel slope as low as 62 mV dec-1 , and can run at -100 mA cm-2 for at least 50 h without obvious voltage change. This study provides a potentially feasible strategy for the design of heterostructure-based electrocatalysts with abundant active interfaces.