CeO₂ nanoparticles incorporated into a polyaniline matrix, prepared using an environmentally friendly method to enhance dielectric performance

Cerium oxide (CeO₂) nanoparticles were fabricated through a green route using Syzygium cumini (SC) leaf extract as a reducing and capping agent. The as-synthesized CeO₂ nanoparticles were incorporated into a polyaniline (PANI) matrix to form CeO₂/PANI nanocomposites via in situ chemical oxidative polymerization. A series of CeO₂/PANI nanocomposites with varying nanoparticle loadings (1–7 wt%) was fabricated to study the influence of CeO₂ contents on the optical, morphological, structural, thermal, and dielectric properties. The CeO₂ nanoparticles had an average crystallite size of 13 nm. SEM images confirmed the formation of compact and uniform composite structures compared to pristine PANI. TGA analysis demonstrated that CeO₂ incorporation enhanced the thermal stability of PANI, although excessive nanoparticle loading (≥ 5 wt%) led to thermally activated degradation and a subsequent reduction in stability. The dielectric constant and the dielectric loss peaked at 3 wt.%, attributed to enhanced interfacial polarization and interfacial relaxation, respectively. The developed CeO₂/PANI nanocomposites can be explored further to evaluate their potential for electronic, energy storage, and sensing applications.