Boosted electrochemical performance of magnetic caterpillar-like Mg(0.5)Ni(0.5)Fe(2)O(4) nanospinels as a novel pseudocapacitive electrode material.

Ni-incorporated MgFe(2)O(4) (Mg(0.5)Ni(0.5)Fe(2)O(4)) porous nanofibers were synthesized using the sol-gel electrospinning method. The optical bandgap, magnetic parameters, and electrochemical capacitive behaviors of the prepared sample were compared with pristine electrospun MgFe(2)O(4) and NiFe(2)O(4) based on structural and morphological properties. XRD analysis affirmed the cubic spinel structure of samples and their crystallite size is evaluated to be less than 25 nm using the Williamson-Hall equation. FESEM images demonstrated interesting nanobelts, nanotubes, and caterpillar-like fibers for electrospun MgFe(2)O(4), NiFe(2)O(4), and Mg(0.5)Ni(0.5)Fe(2)O(4), respectively. Diffuse reflectance spectroscopy revealed that Mg(0.5)Ni(0.5)Fe(2)O(4) porous nanofibers possess the band gap (1.85 eV) between the calculated value for MgFe(2)O(4) nanobelts and NiFe(2)O(4) nanotubes due to alloying effects. The VSM analysis revealed that the saturation magnetization and coercivity of MgFe(2)O(4) nanobelts were enhanced by Ni(2+) incorporation. The electrochemical properties of samples coated on nickel foam (NF) were tested by CV, GCD, and EIS analysis in a 3 M KOH electrolyte. The Mg(0.5)Ni(0.5)Fe(2)O(4)@Ni electrode disclosed the highest specific capacitance of 647 F g(-1) at 1 A g(-1) owing to the synergistic effects of multiple valence states, exceptional porous morphology, and lowest charge transfer resistance. The Mg(0.5)Ni(0.5)Fe(2)O(4) porous fibers showed superior capacitance retention of 91% after 3000 cycles at 10 A g(-1) and notable Coulombic efficiency of 97%. Moreover, the Mg(0.5)Ni(0.5)Fe(2)O(4)//Activated carbon asymmetric supercapacitor divulged a good energy density of 83 W h Kg(-1) at a power density of 700 W Kg(-1).