Abstract
Modified bimetallic chalcogenides with numerous active sites of appropriate structures for extensive water splitting in alkaline hydrogen evolution reaction (HER) are quite challenging. In this study, we have designed a graphene nano-sheet anchored NiS2/MoS2 heterostructure through a facile two-step method and have employed them towards HER. To evaluate the performance of the NiS2/MoS2@GNS, The crystalline phase, morphology and material purity are evaluated by XRD, SEM, high resolution transmission microscopy HR-TEM and EDS. In addition, the electrochemical performance of the as-synthesized NiS2/MoS2@GNS composites and other electrocatalysts are tested towards the HER in 1 M KOH electrolyte. It is noted that the graphene nano-sheet (GNS) anchored NiS2/MoS2 composite shows an excellent electrocatalytic activity with a less overpotential of 130 mV at current density (|j|) of 10 mA cm−2 and a low Tafel slope of 40 mV dec−1 compared with pristine NiS2/MoS2 material (141 mV at 10 mA cm−2 and Tafel slope of 48 mV dec−1). Furthermore, it possessed good stability for 1000 cycles and performed time-dependant current density for 10 h at a limited overpotential of 130 mV. The high synergistic effect between NiS2/MoS2 and GNS in promotion of hydrogen (H2) generation efficiency is ascribed to more active sites, low charge transfer resistance and great electrochemical kinetics which justified the use of NiS2/MoS2@GNS hybrid material as a best alternative to replace noble metal for efficient HER.
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•A cost effective graphene supported NiS2/MoS2 heterostructure were prepared by hydrothermal and wet-chemical method.•The NiS2/MoS2@GNS showed good catalytic behavior for HER in 1.0 M KOH.•The catalyst achieved low overpotential of 130 mV at 10 mA cm−2 in 1.0 M KOH.•The NiS2/MoS2@GNS exhibited long-term stability for 10 h.•The NiS2/MoS2@GNS composite has been used good alternative for hydrogen evolution reaction.