Sepiolite-templated PANI@ZIF-67 derivative skeleton/skin heterostructures for impedance-matched microwave absorption

Microwave absorbers with strong attenuation, broad bandwidth and thin matching thickness are highly desired for electromagnetic (EM) protection and stealth applications. Herein, sepiolite-supported PANI@ZIF-67 derivative ternary composites with a reinforcing skeleton/skin heterostructure were fabricated through room-temperature precipitation, thermal conversion and in-situ chemical oxidative polymerization. Sepiolite acted as a one-dimensional internal skeleton and heterogeneous nucleation platform, suppressing the agglomeration of ZIF-67 derivative nanoparticles and promoting multiple scattering of incident EM waves. The conductive PANI skin introduced continuous conductive pathways and abundant interfaces, enhancing conductive loss and interfacial polarization. By regulating the sepiolite content, the EM parameters were optimized, enabling a favorable balance between impedance matching and attenuation capability. The optimized composite delivered a minimum reflection loss of −57.67 dB at 12.16 GHz with a thickness of 2.09 mm and an effective absorption bandwidth of 4.87 GHz at only 1.72 mm. This work offers a feasible strategy for high-performance sepiolite-based microwave absorbers.