NiCo2S4 nanotubes in situ anchored double-layered hollow carbon nanospheres towards enhanced overall water splitting

Abstract

An efficient approach is developed to fabricate hybrid nanomaterials by anchoring in situ NiCo2S4 components on hollow double-layered carbon nanospheres (DCs). NiCo(CO3)(OH)2 is deposited on DCs and then reacted with S ions to create NiCo2S4 phase. Because of the homogeneous distribution of nanoparticles and well-developed interface, samples reveal excellent electrochemical activity. The compositions of NiCo2S4/hollow DCs (denoted as DCs-x-y, x and y are the molar ratios of Ni and Co in precursors) are adjusted to test the growth kinetics and morphology evolution. Under optimized conditions, the capabilities of composite sample DCs-0.20–0.30 outperform DCs and NiCo2S4 alone, which is ascribed to the high specific surface area and the existence of monodispersed hollow carbon spheres improving the distribution of NiCo2S4 and the overall conductivity to increase active sites. Especially, the optimized sample DCs-0.20–0.30 exhibits high performances and stability for enhanced hydrogen evolution reaction (HER) in both acidic and alkaline conditions and oxidation evolution reaction (OER) in alkaline electrolyte. Furthermore, using DCs-0.20–0.30 sample as both the cathode and anode in the alkaline electrolyzer, the current density of 10 and 100 mA cm−2 at 1.736 and 2.171 V are obtained. The sample also displays excellent durability for 20 h at 10 mA cm−2.