Tailoring structural, conductivity, dielectric and electric modulus of mesoporous Cu–Co–Ni ferrite-reinforced polyaniline nanocomposites

Abstract

Cu–Co–Ni ferrite (CCNF) nanoparticles and their polyaniline (PANI)-based nanocomposite (PCCNF) were synthesized via cost-effective auto-combustion method followed by in-situ polymerization. X-ray diffraction confirmed the formation of single-phase spinel ferrite structure. FTIR spectra showed characteristic metal–oxygen vibrational modes, with additional peaks indicating PANI incorporation. SEM images showed a compact polygranular morphology in CCNF and fibrous structures in PCCNF. Transmission electron microscopy revealed uniform distribution of CCNF nanoparticles throughout PANI with an average particle size of 24–49 nm. The x-ray photoelectron spectroscopy analysis confirmed the successful incorporation and chemical state of constituent elements in PCCNF nanocomposites. BJH analysis revealed mesoporous structures with pore diameters of 40.252 nm for CCNF and 29.955 nm for PCCNF. Brunauer–Emmett–Teller analysis showed that CCNF had a surface area of 2.61 m2 g−1, whereas PCCNF had 13.2 m2 g−1, indicating a significant increase in specific surface area after PANI incorporation. The interfacial interactions and charge transport were demonstrated by electrical studies, which exhibited frequency-dependent AC conductivity, consistent with a hopping conduction mechanism and well described by Jonscher’s power law. The PCCNF composite demonstrated an AC conductivity of approximately 6.9 ×10−3 S cm−1 at room temperature, which increased to 8.32 ×10−3 S cm−1 at 393 K owing to the conductive polymer matrix, in comparison to CCNF with a conductivity of 2.013 ×10−6 S cm−1 at room temperature. The real and imaginary components of the dielectric and impedance functions exhibited strong frequency-dependent behaviour, revealing the influence of contributions from heterogeneous grains and grain boundaries. Nyquist plots were interpreted through equivalent circuit fitting, and the dielectric relaxation behaviour was confirmed using the modified Debye equation. Electrochemical analyses using cyclic voltammetry revealed distinct redox peaks, indicating pseudocapacitive behaviour. PCCNF exhibited a specific capacitance of approximately 92.3 F g−1 at 0.5 A g−1 and a power density of 215 W kg−1, as derived from galvanostatic charge discharge curves. EIS results showed lower charge-transfer resistance and improved ion diffusion in PCCNF, highlighting the positive impact of the conductive matrix. These results indicate that the synergistic interaction between CCNF and PANI significantly improves electrical conductivity, dielectric response, and electrochemical performance.