High Permittivity and Supercapacitor Applications of Manganese Substitution in Biosynthesized-NPs Copper Spinel Ferrites

Researchers have paid particular attention to transition metal oxides in recent years due to their higher specific capacitance and conductivity, making them ideal candidates for improved electrode materials. The present study successfully synthesized the spinel ferrites CuFe_2-<i>y</i> Mn _<i>y</i> O₄ (where <i>y</i> = 0.0 and 0.5) using the hydrothermal biosynthesis route at low sintered temperature. Several techniques are used to analyze the synthesized samples: XRD, XPS, S/TEM, and BET surface area analyzer. Complex impedance analysis was employed to examine the electrical and dielectric properties of the CuFe_2-<i>y</i> Mn _<i>y</i> O₄. The substitution of Fe by Mn significantly improved the electrical conductivity by about one hundred factors over a wide range of temperatures. Additionally, the studied compound exhibits a high dielectric constant around ε_r' ≈10⁴, with an observed low dielectric loss. Via the obtained electrochemical results, it is found that the substituted sample (CuFe_1.5Mn_0.5O₄) can be considered an effective material for the working electrode in an electrochemical supercapacitor. Thus, the CuFe_1.5Mn_0.5O₄ nanoparticles demonstrate motivating electrochemical performance, such as a high specific capacitance of 396 F/g at 0.1 A/g, energy density of 49.5 Wh/kg, and strong cycling stability, retaining 78% capacity after 1000 cycles at 0.1 A/g.