Hierarchical ZnS@C@MoS2 core-shell nanostructures as efficient hydrogen evolution electrocatalyst for alkaline water electrolysis

Abstract Low-cost and highly efficient electrocatalysts are critical to advance the hydrogen production industry via water electrolysis in alkaline media. Molybdenum disulfide (MoS2) nanosheets as earth-abundant electrocatalyst became a star material due to its unique graphene-like layered structure favoring electron transfer for hydrogen evolution catalysis. However, its electrocatalytic activities greatly hindered by the poor conductivity and the fewer exposure of catalytically active edged sites. Herein, hierarchical ZnS@C@MoS2 core-shell nanostructures were designed by using a bottom-up strategy combined with a simple selective etching. The coexistence of semiconductor ZnS and defective porous carbonaceous shell as the core not only enhanced the electrical conductivity, but also separated and loaded the exfoliated MoS2 nanosheets which effectively proliferated the exposed catalytically active edge sites (Mo and S sites). Upon optimal conditions, hierarchical ZnS@C@MoS2 core-shell nanostructures gave an overpotential of 118 mV at 10 mA/cm2 with a Tafel slope value of 55.4 mV/dec and better cycling stability after 500 cycles during the alkaline HER process, superior to pristine MoS2.