Metal-organic frameworks derived carbon nanotube and carbonyl iron composite materials for broadband microwave absorbers with a wide filling range

Abstract

• CI/CNT composite was obtained by epitaxial growth-pyrolysis scheme. • Embedding CNT between CI sheets, it exhibits great EMWA in a wide filling range. • By the meta-structure design, the composite achieved RL < −10 dB in 2–18 GHz. Magnetic carbon-based composites derived from metal organic frameworks (MOFs), with tunable morphology and highly dispersed magnetic particles, show great potential as electromagnetic wave absorbing (EMWA) materials. Here, a composite with carbon nanotube (CNT) embedded only between the gaps of carbonyl iron (CI) sheets were obtained, which was achieved by controlling the collapse state of the MOF skeleton during pyrolysis. The unique distribution can prevent the production of global conduction channels, resulting in the impedance matching between air and the composites in the broadened filling range. The composite thus can achieve a broadband absorption in the frequency range of 2–18 GHz by structure design. This work provides a new approach for EMWA materials to reduce the preparation difficulty of broadband absorbers.