Enhancing the microwave absorption capability of metal–organic frameworks through the incorporation of polypyrrole nanoparticles

Metal-organic frameworks (MOFs) have emerged as promising microwave absorbers owing to their tunable composition, structural diversity, and high porosity. However, their low intrinsic permittivity leads to impedance mismatch and inadequate attenuation capacity. To address this limitation, we developed a series of polypyrrole (PPy)/MOFs composites through ultrasonic integration of high-permittivity PPy nanoparticles with hydrothermally synthesized [(CH₃)₂NH₂]Mn(HCOO)₃(Mn-MOF). The optimal composite with a PPy-Mn mass ratio of 4:1 (50 wt% filler in paraffin) achieved a minimum reflection loss (<i>RL</i>) of -63.4 dB at 17.67 GHz with an ultrathin thickness of 1.7 mm. Its maximum effective absorption bandwidth (<i>EAB, RL</i>⩽ -10 dB) reached 5.44 GHz (10.60-16.04 GHz) at a thickness of 2.2 mm. Unlike typical PPy-based absorbers limited to medium frequencies and greater thicknesses, this work achieves the integration of strong absorption, high-frequency, and an ultrathin profile (~2 mm). Enhanced performance stemmed from synergistic interfacial polarization, dipole relaxation, and optimized impedance matching. This study presented an effective strategy to design MOF-based as the promising microwave absorber.