High Electrochemical Performance of Bi₂WO₆/Carbon Nano-Onion Composites as Electrode Materials for Pseudocapacitors

Bi₂WO₆/CNO (CNO, carbon nano-onion) composites are synthesized via a facile low-cost hydrothermal method and are used pseudocapacitor electrode material. X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption-desorption techniques, and X-ray photoelectron spectroscopy (XPS) measurements are used to characterize the synthesized composite powders. The electrochemical performances of the composite electrodes are studied by cycle voltammetry, charge-discharge, and electrochemical impedance spectroscopy. The results indicate that the specific capacitance of the Bi₂WO₆/CNO composite materials reaches up to 640.2 F/g at a current density of 3 mA/cm² and higher than that of pristine Bi₂WO₆, 359.1 F/g. The capability of the prepared pseudocapacitor remains 90.15% after 1,000 cycles of charge-discharge cycling measurement. The cell performance and stability can be enhanced by further optimization and modification of the composition and microstructure of the electrode of the cell.