Electrochemical Properties of Porous Graphene/Polyimide-Nickel Oxide Hybrid Composite Electrode Material

Polyimide-graphene nanosheet composite electrodes are rigid and dense and, therefore, exhibit moderate electrochemical properties. The electrochemical properties of polyimide-graphene nanosheet electrodes were remarkably improved by creating voids in the composite followed by the insertion of nickel oxide into the composites. Nickel oxide particles were electrodeposited onto the porous graphene/poly(amic acid) composite, containing poly (acrylic resin). The hybrid composite was then subjected to thermal treatment at ≥ 300 °C to simultaneously complete imidization and degrade the poly (acrylic resin). Cyclic Voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to study the eletrochemical properties of the composite electrode material. It is shown that remarkable improvement in the electrochemical behavior of the hybrid composite occurred due to the removal of poly(acrylic acid) and the insertion of NiO particles into the polyimide matrix. Fourier Transform Infrared Spectroscopy (FTIR) spectra of the hybrid composites show distinct characteristic peaks for polyimide and NiO in the hybrid composite electrode. Scanning Electron Microscopy, SEM images of the composites, show the presence of NiO aggregates in the composite material. Compared to neat graphene/polyimide composite electrode (GR/PI) composites, the specific capacitance of the hybrid composite electrode increased remarkably by over 250% due to the high interfacial surface area provided by NiO and the concomitant improvement in the electrode–electrolyte interaction.