Designing and developing earth-abundant, low-price and high-efficiency catalysts for hydrogen evolution reaction (HER) is remaining a great challenge from the standpoint of energy. Herein, we have synthesized, firstly, three-dimensional (3D) urchin-like NiCo2@Ni1/3Co2/3S2@C catalyst composed of one-dimensional (1D) peapod-like structure, in which the nanoparticles of the peapod are characterized with a special structure: NiCo2 alloy as the core and thin Ni1/3Co2/3S2 layer as the shell. Notably, the internal NiCo2 core offers efficient routes for electron transfer and the external Ni1/3Co2/3S2 shell provides a great number of active sites for HER. Owing to the synergistic effect between the inner core and the outer shell, NiCo2@Ni1/3Co2/3S2@C catalyst displays excellent catalytic performance, including a low overpotential of similar to 41.0 mV at 10 mA cm(-2), a corresponding small Tafel slope of similar to 39.2 mV dec(-1), and an excellent stability in acidic medium for 200 h, which is greater than many reported transition metal chalcogenides (TMCs). Simultaneously, the free energy of H* adsorption (Delta G(H*)) for NiCo2@Ni1/3Co2/3S2@C (about -0.10 eV) is extremely near to that for Pt (similar to 0.09 eV) by density functional theory (DFT) calculated results, which is significantly beneficial to HER performance. (C) 2018 Elsevier Inc. All rights reserved.