Porous carbon/Fe composites from waste fabric for high-efficiency electromagnetic wave absorption

Nowadays, a large amount of waste fabrics has brought huge environmental and resource problems, while the traditional recycling routes are downcycling with low efficiency and complex separation processes. Herein, we demonstrate a green and facile route to up-recycle waste fabrics (cotton-polyester blending or cotton fabrics) into a high-performance microwave absorber. In this design, an assistant coating was deposited onto the fiber surface of the waste fabric through the assembly of tannic acid-Fe2+ (TA-Fe2+), which effectively catalyzed the polymer fiber into highly graphitized porous carbon fiber at high temperatures. Meanwhile, the Fe nanoparticles from the reduction of Fe2+ ions were evenly embedded on the surface of porous carbon fibers. Consequently, the resultant porous carbon/Fe composites with hierarchical microstructures displayed excellent microwave absorption performances. Typically, the microwave absorber from waste polyester-cotton blended fabric could reach a minimum reflection loss (RL) of -50.5 dB at a thin coating thickness of 1.7 mm, and the minimum RL from waste cotton fabric absorber reached -47.1 dB at a thickness of 2.5 mm. This work provides a new idea to convert waste fabrics into high value-added microwave absorbing materials in a simple and environmentally friendly way, which will help reuse resources and protect the environment.