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A new nanostructure based on Ni 3 S 2 nanowires@N-doped graphene-like carbon layers supported by nickel foam (Ni 3 S 2 @NGCLs/NF) was synthesized by a conventional CVD technique for overall electrocatalytic water splitting. • N-doped graphene-like carbon layers (NGCLs) coated Ni 3 S 2 nanowires is first reported. • A conventional CVD technique is developed for the construction of Ni 3 S 2 @NGCLs/NF. • Ni 3 S 2 @NGCLs/NF shows lower overpotential and outstanding electrochemical stability. • NGCLs changes Ni 3 S 2 lattice and electron structure, leading to high catalytic activity. A new core/shell 1-D nanostructure based on Ni 3 S 2 nanowires and N-doped graphene-like carbon layers on nickel foam (i.e. Ni 3 S 2 @NGCLs/NF) has been fabricated and applied as composite electrocatalyst for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and overall water splitting. The Ni 3 S 2 @NGCLs exhibit a unique architecture with a well-defined core–shell cable-like one-dimensional nanostructure in which NGCLs act as conductive shell and Ni 3 S 2 nanowire as active core. The composite has a nitrogen content of 6.39% in atomic ratio. The Ni 3 S 2 @NGCLs/NF shows low overpotentials of 271 mV and 134 mV at 10 mA cm−2 in 1.0 M KOH for OER and HER, respectively. Highly durable OER and HER performances were demonstrated by 40 h chronopotentiometry and 10,000 CV cycle tests. Excellent overall water splitting electrocatalytic activity was found in a Ni 3 S 2 @NGCLs/NF‖Ni 3 S 2 @NGCLs/NF two-electrode system. Particularly, an active-phase NiOOH, a highly active substance for OER, can be controllably formed in the reaction process due to the shell structure of multi-layer carbon that slows down the dissolution of Ni 3 S 2. Theoretical calculations suggest that Ni 3 S 2 @NGCLs/NF has a lower ΔG (H*) value of 0.51 eV for HER and lower overpotential value of 0.39 V for OER. These results suggest that the composite structure is a promising bifunctional electrocatalyst. [ABSTRACT FROM AUTHOR]