The current experimental investigation emphases on the synthetization and characterizations of pure and Fe3+&

Cu2+

co-doped [

Ni0.5Fe0.02Cu0.06Ox, Ni0.5Fe0.04Cu0.04Ox,

and Ni0.5Fe0.06Cu0.02Ox]

NiO nanoparticles (NPs) prepared through the

hydrothermal method for improved supercapacitor performance. The synthesized NiO NPs were subjected to annealing at

800 °C and subsequently examined using a range of characterization methods.The XRD analysis verified the existence of

a face-centered cubic (FCC) structure.The FESEM-EDAX confirmed successful dopant incorporation, revealing changes

in surface morphology and particle size. An enhancementin the optical bandgap from 3.15 to 3.45 eV was found by the

UV–Vis-DRS study, indicating the possibility of quantum confinement effects. The XPS provided insights into the surface

chemistry, confirming the presence and concentrations of Ni2+,

Fe3+

and Cu2+

ions in their respective chemical states. BET

analysis indicated a reduction in the specific surface areafrom 18.59 m2/

g (pure NiO) to 11.04 m2/

g (co-doped NiO), but

an increase in pore diameter facilitates ion diffusion. Electrochemical analysis showed that [

Ni0.5Fe0.06Cu0.02Ox] achieved

a highest specific capacitance of 546 F g−

1, at 10 mVs−

1exhibiting significantly superior performance than pure NiO NPs.

This study highlighted the potential of Fe3+

and Cu2+

co-doped NiO NPs in enhancing the electrochemical performance of

supercapacitors through improved charge storage capacity and conductivity.Furthermore, cyclic stability testing revealed that

the co-doped sample retained approximately 92.12% of its initial capacitance after 2000 charge–discharge cycles, demonstrating

excellent long-term electrochemical durability. These results underline the importance of doping in optimizing material

properties for next-generation energy storage devices, making these nanoparticles a promising candidate for sustainable and

high-performance supercapacitors.