Coconut shell waste-based ZnFe₂O₄/PANI/rGO nanohybrid composites as excellent radar-absorbing material

In this work, we developed ZnFe₂O₄/PANI/rGO nanocomposites based on coconut shell waste through in situ polymerization as excellent radar-absorbing material (RAM). This research mainly focused on adjusting the ZnFe₂O₄ content to obtain optimal absorption of radar waves, especially in the X-band. The results showed that the diffraction pattern of the ZnFe₂O₄/PANI/rGO nanocomposites showed multiple phases (crystalline and amorphous), which increased the ZnFe₂O₄ content and affected the increasing diffraction intensity. The functional group of the ZnFe₂O₄/PANI/rGO nanocomposites was identified with the presence of the M–O group originating from ZnFe₂O₄ at wavenumbers 517 and 419 cm⁻¹ of Zn–O and Fe–O groups, respectively. Meanwhile, quinoid and benzenoid rings from PANI and C[dbnd]O from rGO were identified at wavenumbers 1580, 1504, and 1710 cm⁻¹, respectively. The morphology of the ZnFe₂O₄/PANI/rGO nanocomposites showed PANI was distributed on the ZnFe₂O₄ nanoparticles, which were subsequently deposited on the rGO. The ZnFe₂O₄/PANI/rGO nanocomposites exhibited superparamagnetic properties, as confirmed by their coercivity values ranging from 9.2 to 124.4 Oe. Interestingly, the ZnFe₂O₄/PANI/rGO nanocomposites with the P3 sample showed optimal RAM performance with a minimum reflection loss value of −39.8 dB at 7.6-GHz frequency with an effective absorption bandwidth of 1.1 GHz.