Upcycling waste plastic and spent batteries into hierarchical Co/carbon nanocomposites for high-performance electromagnetic wave absorption

Abstract

Here we upcycle waste polyethylene terephthalate (PET) plastics and spent LiCoO₂ batteries to synthesize hierarchical Co/C nanocomposites. Recovered terephthalic acid (R-TPA) and cobalt ions are used to fabricate a Co-based metal organic framework (Co-MOF) precursor, which is subsequently co-pyrolyzed with R-TPA to yield a well-designed structure featuring carbon nanotubes grown on carbon nanosheets. This unique architecture enhances impedance matching and enables synergistic dielectric–magnetic loss mechanisms. The optimized composite exhibits a minimum reflection loss of −43.2 dB at 3.0 mm and an effective absorption bandwidth of 4.32 GHz at a thin thickness of 1.6 mm.