A Novel double-shelled C@NiO hollow microsphere: Synthesis and application for electrochemical capacitor

Herein, double-shelled hollow architecture composed of carbon inner shell and flower-like NiO exterior shell has been prepared through a facile hydrothermal process, followed by a heat treatment. Taking SiO2@RF (resorcinol-formaldehyde resin, RF) sphere as template, the flower-like NiSilicate shell was grown on the surface of RF during the formation of hollow inner structure. The calcination process in the inert atmosphere gives rise to the carbonization and decomposition simultaneously, leading to the formation of carbon-based NiO hollow spheres (C@NiO HSs) with similar structure to that of the parent precursor, which possess large specific surface area (217 m(2)g(-1)) and favorable pore structure for supercapacitor application. It is found that C@NiO composite shows higher electrochemical performance than that of pure NiO hollow sphere without interior carbon shell. The C@NiO hollow spheres have high specific capacitance of 211 F/g at the current density of 1 A/g and good cycle stability (84.6%) after 1000 cycles at the current density of 5 A/g, which are superior to NiO HSs without carbon shell. The synthetic strategy can be expanded to fabricate other functional hybrid materials, which should be potential in diverse fields. (C) 2014 Elsevier Ltd. All rights reserved.