High‐Performance and Antimicrobial Chitosan‐Fe ₂ O ₃ @Ni ² ⁺ Nanocomposites for Supercapacitor Applications

The Fe 2 O 3 @Ni 2+ nanoparticles loaded in biocompatible chitosan‐based matrix are effectively synthesized using a sol–gel‐assisted polymerization method and carefully characterized for their structural, electrochemical, and antibacterial properties. X‐Ray diffraction confirms the formation of crystalline NiFe 2 O 4 with crystallite sizes of 17–25 nm, while scanning electron microscopy and transmission electron microscopy shows uniformly dispersed spherical nanoparticles (21–30 nm) within the polymer matrix. This hybrid nanocomposite significantly increases the material's energy storage capability, achieving a notable specific capacitance of 1150 F g −1 at 50 mV s −1 , along with a low charge transfer resistance ( R ct ) of 134.2 Ω. In addition to this high‐performance energy storage, the environmentally friendly nanocomposites exhibit broad‐spectrum antimicrobial activity against Gram‐positive Bacillus subtilis with an inhibition zone range of 27–45 mm. Also, these samples show an excellent antibacterial activity against both Gram‐negative bacteria strains, Shigella flexneri and Pseudomonas aeruginosa , with inhibition zone ranges of 22–42 mm & 29–44, respectively. The minimum inhibitory concentration values for these nanocomposites range from 2.5 to 7.5 mg mL −1 , while the minimum bactericidal concentration values span from 5 to 10 mg mL −1 . The obtained results demonstrate that the chitosan–Fe 2 O 3 @Ni 2+ nanocomposites are promising eco‐friendly materials for high‐performance supercapacitor electrodes and biosensing platforms, combining enhanced structural uniformity, electrochemical conductivity, and biocidal effectiveness.