Scalable fabrication of C/CoNi composites for high-efficiency microwave absorption

The increasing demand for high-efficiency microwave absorbing materials, driven by the rapid advancement of communication technologies such as 5G and 6G, necessitates the development of scalable and cost-effective solutions. In this study, biomass-derived carbon has recently gained significant attention due to its sustainability and potential for large-scale production. However, achieving both lightweight properties and strong, broadband absorption performance remains a challenge. To address these challenges, we employed a simple hydrothermal synthesis method to deposit magnetic particles onto the surfaces of biomass-derived carbon, thereby producing C/CoNi composites with excellent electromagnetic wave absorption (EWA) characteristics. The uniform dispersion of magnetic particles on the biomass carbon surface enhances the interfacial polarization effect, while the introduction of CoNi significantly enhances the surface conductivity of the C/CoNi composites, thereby improving their microwave absorption performance. Consequently, these composites demonstrate outstanding EWA properties, characterized by thin-layer structures, lightweight design, wide frequency bandwidth, and high absorption efficiency. When combined with paraffin wax (30 wt% loading), the composite exhibits a minimum reflection loss (RL_min) of −54.59 dB and an effective absorption bandwidth (EAB) of 3.96 GHz. This work demonstrates the feasibility of using biomass-derived carbon for the mass production of microwave absorbers, offering a scalable and efficient solution for the development of functional materials for EWA.