ZIF-67 derived Mo-CoS2 nanoparticles embedded in hierarchically porous carbon hollow sphere for efficient overall water splitting

Abstract

Regulation of active sites and intrinsic activity is essential for achieving highly efficient electrocatalysts. Herein, a dual-template route is adopted to prepare Mo-CoS2 nanoparticles embedded in hierarchically porous carbon hollow sphere (Mo-CoS2/NC (H)). The in-situ growth of phosphomolybdic acid/zeolitic imidazolate framework-67 (ZIF-67) nanoparticles on the surface of polystyrene sphere (PS) are pyrolyzed to obtain hollow sphere. Mo-CoS2/NC (H) can be obtained by subsequent vulcanization treatment. The results indicate that Mo-CoS2/NC (H) with favorable features including abundant active sites, better conductivity and optimized electronic structure contribute to superior overall water splitting performance. The intrinsic catalytic activity and electronic structure are analyzed by combining the results of characterizations and density functional theory (DFT) calculations. Consequently, Mo-CoS2/NC (H) delivers the overpotentials of 158 mV for hydrogen evolution reaction (HER) and 296 mV for oxygen evolution reaction (OER) at 10 mA cm−2 in 1.0 M KOH electrolyte. Moreover, the electrolyzer assembled by Mo-CoS2/NC (H) as two-electrode delivers a low potential of 1.59 V at 10 mA cm−2 for overall water splitting. This work gives an insight about cooperative contributions of hierarchically porous structure and electron structure towards the electrocatalytic performance.