High-Efficiency Electromagnetic Wave Absorption of Cobalt-Decorated NH₂-UIO-66-Derived Porous ZrO₂/C

Broadband absorbers derived from metal-organic frameworks are highly desirable in the electromagnetic (EM) wave absorption field. Herein, a strategy for cobalt-decorated porous ZrO₂/C hybrid octahedrons by pyrolysis of Co(NO₃)₂-impregnated NH₂-UIO-66 was developed. The hybridization of Co nanoparticles with ZrO₂/C results in remarkable EM wave absorption performance with a minimum reflection loss (RL) of -57.2 dB at 15.8 GHz, corresponding to a matching thickness of 3.3 mm. The maximum effective absorption bandwidth (RL ≤ -10 dB) reaches 11.9 GHz (6.1-18 GHz), covering 74.4% of the whole measured bandwidth. The textural properties of nanocomposites have been thoroughly characterized by powder X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption-desorption isotherms. The corresponding results show that the face-centered cubic-phased ∼50 nm Co nanoparticles are evenly distributed on the surface of porous ZrO₂/C hybrid octahedrons. The excellent performance of Co/ZrO₂/C can be ascribed to the strong interface polarization and the suitable impedance matching, originating from the synergistic effect among the components.