Defect-Rich Heterogeneous MoS₂/rGO/NiS Nanocomposite for Efficient pH-Universal Hydrogen Evolution

Molybdenum disulfide (MoS₂) has been universally demonstrated to be an effective electrocatalytic catalyst for hydrogen evolution reaction (HER). However, the low conductivity, few active sites and poor stability of MoS₂-based electrocatalysts hinder its hydrogen evolution performance in a wide pH range. The introduction of other metal phases and carbon materials can create rich interfaces and defects to enhance the activity and stability of the catalyst. Herein, a new defect-rich heterogeneous ternary nanocomposite consisted of MoS₂, NiS and reduced graphene oxide (rGO) are synthesized using ultrathin αNi(OH)₂ nanowires as the nickel source. The MoS₂/rGO/NiS-5 of optimal formulation in 0.5 M H₂SO₄, 1.0 M KOH and 1.0 M PBS only requires 152, 169 and 209 mV of overpotential to achieve a current density of 10 mA cm^-2 (denoted as η₁₀), respectively. The excellent HER performance of the MoS₂/rGO/NiS-5 electrocatalyst can be ascribed to the synergistic effect of abundant heterogeneous interfaces in MoS₂/rGO/NiS, expanded interlayer spacings, and the addition of high conductivity graphene oxide. The method reported here can provide a new idea for catalyst with Ni-Mo heterojunction, pH-universal and inexpensive hydrogen evolution reaction electrocatalyst.