Metal–Organic Framework-Derived Carbon/Carbon Nanotubes Mediate Impedance Matching for Strong Microwave Absorption at Fairly Low Temperatures

The use of magnetic particles and carbon materials, particularly those with compatible dielectric and magnetic loss, is crucial in managing microwave pollution. However, the mismatched impedance of currently available absorbers constrains their practical applications. Herein, we demonstrate the potential of a metal-organic framework (MOF)-derived composite whose impedance matching is optimized through spraying and immersion of MOF precursors in carbon nanotube socks followed by carbonization. The composite presents extremely strong microwave absorption with a reflection loss of -30 dB, a thin thickness of 1.5 mm, and a wide frequency bandwidth of 7.8 GHz. The excellent absorption can still be maintained even at a fairly low temperature of -40 °C. Such results are primarily attributed to the synergistic effect between the hierarchical architecture and multiple components that greatly optimizes the impedance matching. We believe that the composite is a promising microwave absorber that can help to solve the critical electromagnetic wave pollution.