MOF-derived yolk-shell Co@ZnO/Ni@NC nanocage: Structure control and electromagnetic wave absorption performance

Abstract

Reasonable control of the composition and structure of porous nanomaterials is conducive to improving its electromagnetic wave absorption performance. In this paper, the bimetallic core–shell structure ZIF67@ZIF8 is used as the template, Ni(NO3)2·6H2O is used as the etchant, and the heterogeneous trimetal Co@ZnO/Ni@NC nanocage is prepared by Ni doping and vacuum carbonization. The nanocage uses Co as the core and ZnO/Ni particles coated with a nitrogen-doped carbon layer as the shell layer. When the optimal etching time is 1 h, the RLmin of Co@ZnO/Ni@NC can reach −55 dB@8.2 GHz, and the amount of filler is 27%. In addition, when the thickness of the absorber varies between 1 and 5 mm, it has an effective absorption bandwidth of 12.6 GHz (5.4–18 GHz). The research results of the absorbing performance and absorbing mechanism of the system show the synergistic effect of the three metal components, reasonable arrangement and hollow structure optimizes impedance matching, enhances the interface polarization, and thus improves the absorbing performance. This research provides a new way to prepare porous magnetic metal/carbon composites with excellent absorbing properties from heterogeneous bimetal MOFs.