Facile fabrication of Ag-doped NiO nanostructures as a potential electrode material for enhanced supercapacitor applications

Nickel oxide-based nanoparticles have emerged as promising pseudocapacitive
electrode compounds for energy storage applications due to their affordability,
distinct redox activity, and flexibility in tuning their microstructures through con
trolled synthesis techniques and doping mechanisms. In this present work, silver
(Ag) doped NiO nanomaterials were successfully synthesized using the sol–gel
technique and applied as electrode material for the supercapacitors, achieving
high pseudocapacitive performance. The properties of the as-prepared electrode
materials were investigated using various characteristic techniques. The X-ray
diffraction (XRD) analysis reinforced the sample’s purity and phase, with no sec
ondary phase detected. In addition, as NiO concentration increased, the average
crystallite size of the nanocomposites decreased from 13.79 to 5.34 nm as the con
centration of Ag increased.The surface morphological investigations confirmed
the spherical nanostructured compounds and the elemental distribution of the
prepared sample, respectively. Electrochemical assessments were carried out in
a three-electrode configuration via cyclic voltammetry (CV), galvanostatic charg
ing–discharging (GCD), and electrochemical impedance spectroscopy (EIS) in a
2 M KOH electrolyte solution. The specific capacitance (Csp) of the as-fabricated
electrode samples with varied dopant (Ag) concentrations was examined at dif
ferent scan rates of 5 to 200 mV/s. The specific capacitance (Csp) of the Ag-doped
NiO1-x electrode with x = 10% was significantly higher (662 F/g) at a current den
sity of 1 A/g, compared to other electrodes. Additionally, the Ag-doped NiO
electrode demonstrated an energy density of 33.1 Wh/kg and a power density
of 969 kW/kg. These results indicate that the fabricated nanostructures, particu
larly with Ag doping, are promising candidates for enhancing energy storage
applications