NiSFeS/N, S co‐doped carbon hybrid: Synergistic effect between NiS and FeS facilitating electrochemical oxygen evolution reaction

A series of NiSFeS/N, S co-doped carbon (NixFeyS/NSC) for electrochemical oxygen evolution reaction (OER) were synthesized by a co-precipitation method and followed by pyrolysis in N2 atmosphere. NiSFeS hybrid was uniformly integrated with N, S co-doped carbon in NixFeyS/NSC. NixFeyS/NSC showed high OER catalytic activity, and the optimized Ni60Fe40S/NSC afforded an OER overpotential of ~239 mV to deliver a current density of 10 mA cm−2 and showed a corresponding Tafel slope of ~30.9 mV dec−1 in 1 M KOH. Such OER catalytic activity was not only higher than that of IrO2, but also comparable with that of the most recently reported NiFe-based sulfides for OER. Further study indicated that hybridizing NiS with FeS resulted in a synergistic effect for OER. The hybridization increased total amount of sulfides as active species, therefore enhancing the OER catalytic activity. In addition, the hybridization benefited the formation of petal-like morphologies that contributing much to higher electrochemically active surface area (ECSA), and also boosted the content of graphitic and N, S co-doped carbon that improving charge transfer efficiency.