Rapid synthesis of graphene/cobalt hydroxide composite with enhanced electrochemical performance for supercapacitors

Abstract

A simple and rapid one-pot process is developed for the synthesis of reduced graphene oxide/cobalt hydroxide (rGO/Co(OH)2) composite. The morphology and microstructure of the composite are examined by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Both morphology and element analyses confirm that Co(OH)2 nanoparticles are homogeneously and tightly attached on the surfaces of rGO. The electrochemical performances of the rGO/Co(OH)2 composite as electrode materials for supercapacitors are systematically investigated. A synergistic effort built from the excellent properties of graphene and fine structure of the composite guarantees its superior capacitive performances than those of pure rGO and Co(OH)2. The specific capacitance of the rGO/Co(OH)2 composite reaches 474 F g−1 at a current density of 1 A g−1 and this value can even retain 300 F g−1 at a high current density of 10 A g−1, showing a relatively good rate capability. Moreover, the specific capacitance of this electrode still remains 90% after 1000 times of cycling, demonstrating a good cycle stability of this composite.