Multi-electron transfer mechanism and band structures of CNTs in MOF-derived CNTs/Co hybrids for enhanced electromagnetic wave absorption property

Abstract

Metal-organic framework (MOF)-derived magnetic metal/carbon nanocomposites have received widespread attention for electromagnetic wave (EMW) absorption. The present study introduces a novel approach to MOF composite material design by constructing composites modified with carbon nanotubes (CNTs) and magnetic Co nanoparticles. The carbon confinement effect in CNT/Co not only regulates the electronic structure of Co-C bonds, but also maintains the redox cycle of Co0/2→Co3+→Co0/2+, improving electronic activity and exhibiting synergistic integration characteristics of efficient electromagnetic wave absorption. Particularly, the maximum reflection loss (RLmin) of CNTs/Co-900 reached −52.7 dB at 4.67 GHz in the case of an absorber thickness of 1.6 mm. The excellent microwave absorption performance may be attributed to the interwoven structure formed by novel ZIF-67, CNTs, and Co metal nanoparticles and the double loss of magnetic Co and dielectric CNTs. In addition, the band gap of CNTs was calculated to be Eg = 0.27 eV by the semi-empirical tight-binding method with DFTB+. It is confirmed that CNTs have high electron migration ability, which is beneficial to conductive loss. It is confirmed that CNTs have high electron migration ability, which is beneficial to conductive loss. This study provides a novel strategy for the development of metal-organic framework-based magnetic particles/carbon nanocomposites for electromagnetic wave absorption.