Accessible active sites activated by cobalt-doping into MoS2/NiS2 nanosheet array electrocatalyst for enhanced hydrogen evolution reaction

It is of great importance to develop highly efficient electrocatalysts with low-cost, superior activity and good stability toward hydrogen production. The conductivity property and catalytic activity of transition metal electrocatalyst can be desirable optimized by metal doping for hydrogen evolution reaction (HER). Herein, a Co-doped MoS2/NiS2 nanosheet array was in-situ covered on the carbon cloth substrate (Co-MoS2/NiS2/CC) via facile successive three-step hydrothermal processes, in which Co-MoS2 nanosheets were hierarchically integrated with NiS2 nanosheets. Benefitting from the introduction of Co atom and numerous heterostructures, the as-obtained Co-MoS2/NiS2/CC allows high conductivity and plenty of accessible active sites, showing favorable synergistic effect for electrocatalytic HER properties. Specifically, the optimal Co-MoS2/NiS2/CC electrocatalyst requires low overpotentials of 92 and 122 mV to deliver current densities of 10 and 50 mA cm−2 in 0.5 M H2SO4. It presents excellent electrocatalytic activity in 0.1 M KOH simultaneously. Moreover, such a Co-MoS2/NiS2/CC electrocatalyst shows a small Tafel slope of 47 mV dec−1 and remarkable long-term stability. This work provides a novel strategy to synthesize transition metal-doped heterogeneous electrocatalysts for efficient hydrogen evolution reaction.