PKS-Derived Porous Carbon/Epoxy Composites for EMI Shielding

Nowadays, many individuals utilize the 5G network, which can give detrimental effects due to electromagnetic interference (EMI). EMI may harm not only high-tech electronic devices but also human health. In this study, the porous carbon was synthesized from palm kernel shell (PKS) via hydrothermal treatment at varying temperatures (160 °C, 180 °C, and 200 °C) followed by carbonization, and comprehensively characterized to understand its structural, chemical, and electromagnetic properties. X-ray diffraction (XRD) revealed broad (002) and (100) peaks across all samples, indicating amorphous graphitic carbon with limited crystallinity. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of O–H, C–H, and C=C functional group. As the synthesis temperature increased, aromatic and graphitic characteristics became more pronounced, with 180 °C exhibiting a significant rise in C–H peak intensity. This suggests that 180 °C is an optimal carbonization temperature, promoting the formation or preservation of stable aliphatic structures without excessive degradation. Surface area analysis using the BET method showed that the sample treated at 180 °C exhibited the highest surface area (547.4 m²/g), suggesting optimal porosity formation. Scanning electron microscopy (SEM) supported this finding, showing a fragmented and open morphology at 180 °C, in contrast to denser, spherical agglomerates observed at 200 °C. Due to its characteristics, the 180 °C sample was selected for electromagnetic characterization. S-parameter measurements at X-band frequency for epoxy composites filled with porous carbon revealed that increasing filler content led to reduced transmission coefficient, indicating enhanced electromagnetic wave attenuation. These improvements are attributed to increased dielectric losses and interfacial polarization facilitated by the highly porous carbon network. In conclusion, the study highlights the significance of hydrothermal synthesis temperature in tuning the structure and electromagnetic performance of biomass-derived porous carbon.