Conductive Metal-Organic Frameworks with Tunable Dielectric Properties for Boosting Electromagnetic Wave Absorption

Metal-organicframeworks (MOFs) manifest enormous potentialin promoting electromagnetic wave (EMW) absorption thanks to the tailoredcomponents, topological structure, and high porosity. Herein, rodlikeconductive MOFs (cMOFs) composed of adjustable metal ions of Zn, Cu,Co, or Ni and ligands of hexahydroxytriphenylene (HHTP) are preparedto attain tunable dielectric properties for a tailored EMW absorption.Specifically, the influences of the cMOFs' composition, chargetransport characteristic, topological crystalline structure, and anisotropymicrostructure on dielectric and EMW absorption performance are ascertained,advancing the understanding of EMW attenuation mechanisms of MOFs.The boosted conductive and polarization losses derived from the conjugationeffects and terminal groups, as well as shape anisotropy, lead toa prominent EMW absorption of the cMOFs. The Cu-HHTP confers a minimumreflection loss (RLmin) of -63.55 dB at the thicknessof 2.9 mm and a maximum effective absorption bandwidth of 5.2 GHz.Moreover, Zn-HHTP showcases the absorption superiority in the S-band(2-4 GHz) with an RLmin of -62.8 dB at athickness of 1.9 mm. This work not only hoists the mechanistic understandingof the structure-function relationships for the cMOFs but alsooffers guidelines for preparing functional MOF materials.