Co3O4/Ni(OH)2 composite mesoporous nanosheet networks as a promising electrode for supercapacitor applications

Abstract

Co3O4/Ni(OH)2 composite mesoporous nanosheet networks (NNs) grown on conductive substrates were synthesized by heat treatment of Co(OH)2/Ni(OH)2 NNs that were synthesized on Ti substrates by a facile electrochemical deposition route. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and micro-Raman spectroscopy. The above products were directly functionalized as supercapacitor electrodes without using any ancillary materials such as carbon black or binder. Co3O4/Ni(OH)2 composite mesoporous NNs achieved a high specific capacitance (Csp) of 1144 F g−1 at 5 mV s−1 and long-term cyclability. The electrochemical measurements showed Co3O4/Ni(OH)2 composite mesoporous NNs exhibited much better electrochemical performances than single Co3O4 or Ni(OH)2. The binary redox couples of Ni2+/Ni3+ and Co2+/Co3+, nanosheet networks with porous structures, the mesoporous structure within nanosheets, the interconnections among nanosheets, together with the excellent electrical contact with the current collector (substrate) are responsible for the improved electrochemical performances of Co3O4/Ni(OH)2 composite mesoporous NNs. With the ease of large scale fabrication and superior electrochemical characteristics, Co3O4/Ni(OH)2 composite mesoporous NNs grown on Ti substrates will be good candidates for supercapacitor applications.