Sustainable, Cost-effective ,Lightweight Biochar Based Nanocomposites for Absorption-Dominant Electromagnetic Interference Shielding Aplplication over X-Band Frequencies.

5G communication networks and high-frequency electronic systems are growing quickly, necessitating the use of electromagnetic interference (EMI) shielding materials that are sustainable, lightweight, and flexible. In order to obtain high-performance EMI shielding in the X-band (8–12 GHz) area, graphene nanosheets and multi-walled carbon nanotubes (MWCNTs) were integrated into a polymer matrix to create a hybrid composite film based on biochar derived from sugarcane bagasse. Porous biochar and conductive fillers (MWCNT and graphene) worked in concert to enhance conductive and dielectric loss processes by facilitating repeated reflection-absorption events. Because of its strong interfacial polarization and conductive network continuity, the optimized hybrid film, which had a thickness of less than 1 mm, demonstrated a total shielding effectiveness (SET) of more than 40 dB, with absorption predominating (SE_A > SE_R). Additionally, the film showed outstanding mechanical integrity, flexibility, and environmental sustainability, which qualified it for use in flexible device enclosures and next-generation wearable electronics. For advanced EMI protection applications, this work lays forth a scalable route to create carbon–polymer hybrid films made from biowaste that have a high shielding effectiveness and a configurable microstructure.