Enhanced microwave absorption properties of biomass-derived carbon decorated with transition metal alloy at improved graphitization degree

In this work, absorbers with lightweight, low loading, and strong absorption capacity have been made by biomass-derived carbon (BC) with magnetic alloy. Because of an innovative synthetic method, not only the NiFe and CoFe alloy are successfully synthesized on the surface of the BC, but also the graphitization degree of the BC has been improved greatly by transition metals. This way makes the BC acquire superior dielectric, magnetic loss, better impedance matching, and excellent attenuation ability of electromagnetic waves. NiFe exhibits a higher catalytic performance, but the imbalance electromagnetic parameters lead to imperfect impedance matching. Due to the superior balance between attenuation ability and impedance matching, the BC/CoFe composite material shows excellent electromagnetic absorbing capacity. BC/CoFe has a minimum reflection loss of −54.4 dB with a thickness of 2.2 mm, and the widest effective bandwidth can reach 2.6 GHz with a thickness of 2.4 mm. Results indicate that the BC/CoFe composite material is expected to be a superior electromagnetic wave absorber. These innovative findings and preparation methods provided a new guideline for developing biomass-derived carbon as a low-cost, lightweight, and high-performance microwave absorber.