Electrochemical Growth of Polyaniline Nanowire Arrays on Graphene Sheets in Partially Exfoliated Graphite Foil for High-Performance Supercapacitive Materials

Direct electrochemical growth of polyaniline nanowire arrays (PANI NWAs) on surfaces of graphene sheets in partially exfoliated graphite foil (Ex-GF) was achieved through electropolymerization of aniline to fabricate hierarchical nanostructured pseudocapacitive electrodes. The PANI NWAs were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Due to the combined merits of PANI NWA and graphene sheets, the hierarchical nanostructured electrodes demonstrated high pseudocapacitive performances. More importantly, fast capacitance fading of pseudocapacitive materials upon mass loading increase can be suppressed by the novel structure, making it a good candidate for supercapacitor electrode with high areal capacitance. The PANI NWA with a high mass loading of 5.89 mg cm−2 showed an exceptionally high areal capacitance of 3.57 F cm−2 and a quite high specific capacitance 607 F g−1. 72.4% of the capacitance can be retained when the discharge current increase 10 times, demonstrating its high rate capability.