Efficient and bifunctional catalyst for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is crucial for achieving of easily-operable water electrolysis. Herein, Ni,Fe sulfides embedded N,S co-doped carbon hybrids (NiFeS@NSCs) with tunable Ni:Fe ratios were devised through pyrolysis of methionine chelated Ni, Fe precursors. In this type of heterojunction hybrids, the spontaneous diffusion of electrons from embedded sulfides to NSC shell increases the reducibility of NSC and the oxidizability of sulfides, which are therefore capable of catalyzing OER and HER simultaneously. The typical Ni 2 FeS@NSC hybrid with Ni:Fe molar ratio of 2:1 offered high electrocatalytic ability for alkali OER (overpotential of 247 mV at 10 mA cm−2), which is significantly superior to that of individual sulfide. In addition, good HER efficiency was concurrently ensured by Ni 2 FeS@NSC. The symmetric water electrolyzer based on Ni 2 FeS@NSC required an input voltage of 1.77 V to arouse an electrolysis current density of 10 mA cm−2. This work offers a feasible approach to enhance the OER, HER bifunctional catalytic performances via interfacial electrons diffusion within heterojunction hybrid. [Display omitted] • A sulfide-carbon hybrid was prepared by pyrolysis of amino acid chelated salts. • Efficient charge redistribution was achieved in this heterostructured hybrid. • OER and HER bifunctional catalytic efficiencies for water splitting were yielded. [ABSTRACT FROM AUTHOR]