2@Ni 1/3Co 2/3S 2@C catalyst with synergistically high-efficiency electrocatalytic properties toward hydrogen evolution reaction]]>

摘要

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: NiCo2alloy as the core and thin Ni1/3Co2/3S2layer as the shell. Notably, the internal NiCo2core offers efficient routes for electron transfer and the external Ni1/3Co2/3S2shell 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 ～41.0?mV at 10?mA?cm?2, a corresponding small Tafel slope of ～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 (ΔGH?) for NiCo2@Ni1/3Co2/3S2@C (about ?0.10?eV) is extremely near to that for Pt (～0.09?eV) by density functional theory (DFT) calculated results, which is significantly beneficial to HER performance.