Fabrication of NiO-Coated Single-Walled Carbon Nanotube Films on Nickel Foam as Supercapacitor Electrodes

NiO-coated single-walled carbon nanotube (SWNT) films, referred to NiO/SWNT composite films, are fabricated on nickel foam by electrophoretic deposition from Ni2+-decorated SWNTs suspension using a three-electrode device. Uniform NiO/SWNT composite films are obtained on both sides of the nickel foam. X-ray photoelectron spectroscopy and X-ray diffraction analyses demonstrate that nickel ions are reduced to metal Ni on SWNT surfaces and subsequently oxidized to NiO. Scanning electron microscopy and transmission electron microscopy observation reveals that the composite films possess a network-like architecture formed by the open space between the entangled nanotubes. The SWNTs decorated by NiO particles act as a charging layer of the electric double layer capacitor and the electronic collection substrate of NiO pseudocapacitor. We find that the rate property of the as-prepared electrode is improved as there is an electrochemical redox reaction even at a scan rate as high as 50 mV s(-1). The electrode constructed with 2x NiO-coated SWNT films on nickel foam exhibits the best capacitive behavior, with a capacitance of 1075 Fg(-1) at a current density of 5 Ag-1.