CFs@Co3O4/Co(OH)2 absorbent derived from cottonwood fibers pyrolysis for electromagnetic wave absorption

In light of electromagnetic pollution caused by the excessive or unregulated use of electromagnetic waves (EMWs), there is an urgent requirement to identify economical EMWs absorption materials. However, the facing challenge lies in the precise design of microstructure and the controlled tuning of electromagnetic parameters. Herein, natural cottonwood fiber was converted into carbon fiber (CF) through optimized pyrolysis, followed by the synthesis of CFs@Co 3 O 4 /Co(OH) 2 composites via in situ hydrothermal method. Ingenious structural design, multi-faceted synergy and heterogeneous interfaces endowed the CFs@Co 3 O 4 /Co(OH) 2 composites with exceptional impedance matching and electromagnetic loss, showing outstanding EMWs absorption ability. The CFs@Co 3 O 4 /Co(OH) 2 sample (CF S @Co-25) with 2.5 mm thickness displayed a maximum reflection loss ( RL max ) of −78.7 dB and an effective absorption bandwidth ( EAB ) of 9.9 GHz. At 3.0 mm matching thickness, the impedance matching value ( Z ) reached 0.99, with an RL max of −105.3 dB. This work offers a scalable and economical approach to developing high-performance carbon-based EMWs absorbers.