Engineering of Co₃O₄ electrode via Ni and Cu-doping for supercapacitor application

Although cobalt oxides show great promise as supercapacitor electrode materials, their slow kinetics and low conductivity make them unsuitable for widespread application. We developed Ni and Cu-doped Co₃O₄ nanoparticles (NPs) via a simple chemical co-precipitation method without the aid of a surfactant. The samples were analyzed for their composition, function group, band gap, structure/morphology, thermal property, surface area and electrochemical property using X-ray diffraction (XRD), ICP-OES, Fourier transform infrared (FTIR) spectroscopy, Ultraviolet-visible (UV-Vis), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and/or Differential thermal analysis (DTA), Brunauer-Emmett-Teller (BET), and Impedance Spectroscopy (EIS), Cyclic voltammetry (CV), respectively. Notably, for the prepared sample, the addition of Cu to Co₃O₄ NPs results in a 11.5-fold increase in specific surface area (573.78 m² g^-1) and a decrease in charge transfer resistance. As a result, the Ni doped Co₃O₄ electrode exhibits a high specific capacitance of 749 F g^-1, 1.75 times greater than the pristine Co₃O₄ electrode's 426 F g^-1. The electrode's enhanced surface area and electronic conductivity are credited with the significant improvement in electrochemical performance. The produced Ni doped Co₃O₄ electrode has the potential to be employed in supercapacitor systems, as the obtained findings amply demonstrated.