Ce-Doped NiCo2O4/Polyvinyl Alcohol/Reduced Graphene Oxide Composites: Synthesis, Characterization, and Electromagnetic Interference Shielding Effectiveness

The structural, morphological, and magnetic properties of Ce-doped NiCo2O4 (Ce-NiCo2O4) spinel nanopowders synthesized via sol-gel autocombustion followed by annealing at 700 °C were systematically characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometry, and scanning electron microscopy. XRD analysis revealed the formation of a single-phase cubic spinel structure with the Fd3m space group. The introduction of Ce into the NiCo2O4 lattice increased the lattice parameter from 8.090 Å to 8.312 Å and reduced the crystallite size from 36 nm to 14 nm. Two prominent FTIR absorption bands were observed around 600 and 550 cm–1, corresponding to octahedral and tetrahedral sites, respectively. A linear relationship between magnetization and applied field was observed, confirming the paramagnetic nature of all samples at room temperature. Ce-NiCo2O4 nanopowders were blended with polyvinyl alcohol (PVA) and reduced graphene oxide (rGO) to fabricate thick composite films for electromagnetic interference (EMI) shielding in the X-band frequency range (8–12 GHz). The synergistic combination of magnetic Ce-NiCo2O4 nanopowders, conductive rGO, and the flexible PVA matrix resulted in an enhanced EMI shielding performance. Our results suggest that Ce-NiCo2O4/PVA/rGO thick films are promising lightweight, flexible, and efficient EMI shielding materials for electronic and telecommunication applications.