Inexpensive and robust earth-abundant electrocatalysts with excellent electrocatalytic reaction kinetics must be developed to realize electrochemical water-splitting. In this study, nickel sulfide@cobalt iron -molybdenum oxide (NiS@CoFeMoO4) nanosheet heterostructures supported on nickel foam were fabri-cated. The as-built NiS@CoFeMoO4/NF with a sheet-on-sheet morphology delivered a current density of 10 mA cm-2 with a low overpotential of 72 and 200 mV for the hydrogen evolution and oxygen evolution reactions, respectively. The formation of a synergistic heterostructure between NiS and CoFeMoO4/NF via interfacial engineering facilitated the generation of a micro-mesoporous surface and modulation of the charge density at interfaces. Consequently, this configuration outperformed many non-precious-metal -based catalysts as an electrocatalyst for water oxidation.(c) 2022 Elsevier B.V. All rights reserved.