Cerium(IV) Decorated Coconut Shell-Reduced Graphene Oxide in Epoxy Resin Matrix as X-Band Radar Absorber Composite

The development of lightweight and efficient radar-absorbing materials (RAM) remains a critical challenge for electromagnetic (EM) attenuation in modern stealth applications. In this study, a cerium(IV) oxide (CeO2)-decorated, coconut shell-derived reduced graphene oxide composite embedded in an epoxy matrix (cs-rGO/CeO2/epoxy) was successfully synthesized using a modified Hummers method followed by hydrothermal reduction. The use of biomass-derived carbon offers a sustainable and low-cost alternative to conventional precursors. Structural and morphological analyses by SEM-EDX, Raman, XRD, and FT-IR instrument confirmed the successful reduction of graphene oxide, the formation of CeO2 nanoparticles, and their uniform dispersion within the matrix, with an average particle size of 15.38 nm. Electromagnetic measurements revealed a maximum reflection loss (RL) of −7.72 dB at 9.77 GHz in the X-band at a thickness of 1 mm. This performance is attributed to the combined effects of dielectric loss, interfacial polarization, and multiple scattering within the heterogeneous structure. Although the absorption performance remains moderate, the ability of the composite to achieve effective attenuation at low thickness demonstrates its strong potential as a lightweight RAM. The favourable combination of reduced thickness, lightweight characteristics, and microwave attenuation capability makes this composite a promising candidate for advanced electromagnetic wave absorption applications and merits further comprehensive investigation. Keywords: reduced graphene oxide, coconut shell, cerium(IV) oxide, epoxy resin, radar absorbing material