Conductive\nMetal–Organic Frameworks with Tunable\nDielectric Properties for Boosting Electromagnetic Wave Absorption

Abstract

Metal–organic\nframeworks (MOFs) manifest enormous potential\nin promoting electromagnetic wave (EMW) absorption thanks to the tailored\ncomponents, topological structure, and high porosity. Herein, rodlike\nconductive MOFs (cMOFs) composed of adjustable metal ions of Zn, Cu,\nCo, or Ni and ligands of hexahydroxytriphenylene (HHTP) are prepared\nto attain tunable dielectric properties for a tailored EMW absorption.\nSpecifically, the influences of the cMOFs’ composition, charge\ntransport characteristic, topological crystalline structure, and anisotropy\nmicrostructure on dielectric and EMW absorption performance are ascertained,\nadvancing the understanding of EMW attenuation mechanisms of MOFs.\nThe boosted conductive and polarization losses derived from the conjugation\neffects and terminal groups, as well as shape anisotropy, lead to\na prominent EMW absorption of the cMOFs. The Cu-HHTP confers a minimum\nreflection loss (RL_min) of −63.55 dB at the thickness\nof 2.9 mm and a maximum effective absorption bandwidth of 5.2 GHz.\nMoreover, Zn-HHTP showcases the absorption superiority in the S-band\n(2–4 GHz) with an RL_min of −62.8 dB at a\nthickness of 1.9 mm. This work not only hoists the mechanistic understanding\nof the structure–function relationships for the cMOFs but also\noffers guidelines for preparing functional MOF materials.