One-step synthesis of the reduced graphene oxide@NiO composites for supercapacitor electrodes by electrode-assisted plasma electrolysis

Abstract

An electrode-assisted plasma electrolysis is developed to synthesize the reduced graphene oxide@NiO (rGO@NiO) composites as supercapacitor electrode materials. The method is fast and efficient, realizing one-step synthesis for the rGO@NiO composites. The composition, morphologies, electrochemical properties, and deposition dynamics of rGO@NiO composites are systematically investigated in current work. The results of X-ray diffraction (XRD) and Raman spectra show that NiO is synthesized on the rGO. The weight ratio of NiO in the rGO@NiO composites is about 50.2% by thermo gravimetric analysis (TGA). Transmission electron microscope (TEM) exhibits that lots of nanoparticles distribute uniformly relatively on the rGO, and the diameter of nanoparticles is mostly in 30–80 nm. The as-prepared rGO@NiO composite displays a specific capacitance of 1093 F·g−1 at 1 A·g−1 current density. In addition, it exhibits an excellent cycle stability, and still keeps ~87% of the original capacitance and 90.6% coulombic efficiency after 5000 cycles. Based on the electrochemical theory, the electrode-assisted plasma electrolysis process is dominated by the electrochemical polarization, shortening the deposition process and realizing a fast synthesis for the rGO@NiO composites. The synthesis method, electrode-assisted plasma electrolysis, presents a promising route for the efficient and rapid preparation of rGO-metal oxide composites as energy storage materials.

Keywords

• Electrode-assisted plasma electrolysis
• One-step synthesis
• rGO@NiO composites
• Electrochemical properties
• Supercapacitors