Effect of reduced graphene oxide (rGO)- like derived from coconut shells in Fe 3 O 4 /rGO composite for radar absorption: Synthesis and characterization

A radar absorbing material based on magnetite (Fe3O4) and reduced graphene oxide (rGO)-like derived from coconut shells, has been successfully synthesized through co-precipitation and thermal treatment followed by liquid-assisted exfoliation methods, respectively. The rGO-like phase is confirmed by X-ray diffraction (XRD), which shows two broad typical peaks around 23° and 43°, as well as FTIR spectra indicating C=C, C=O, and C–H vibrations. XPS further verifies an rGO-like structure with a C/O ratio of ∼3.5. The success of Fe3O4/rGO composites formation is verified through XRD, FTIR, and SEM-EDX, which show the combined properties of the two materials (Fe3O4 and rGO). The Fe3O4/rGO composite fraction is varied by ratios of 2:1, 1:1, and 1:2, showing a significant effect on the radar absorber performance. The Fe3O4 provides the highest reflection loss (RL), while the addition of rGO tends to decrease the RL. It is associated with impedance mismatch, where a large difference between the intrinsic impedance of the composite and that of free space limits electromagnetic wave penetration and reduces absorption efficiency. This study supplies an insight into the potential use of biomass-based rGO as an environmentally friendly additive for the development of lightweight and sustainable electromagnetic wave-absorbing materials.