CoZnO/C@BCN nanocomposites derived from bimetallic hybrid ZIFs for enhanced electromagnetic wave absorption

Abstract

Rational design of dielectric–magnetic integrated nanomaterials for meeting impedance matching has been a significant challenge in the field of electromagnetic wave (EMW) absorption. Here, novel zeolitic imidazolate framework (ZIF) derivative-based carbon materials with a rational structure derived from ZIF-L(Zn)/ZIF-L(Co) are prepared to enhance the EMW absorption performance by simple mixing and pyrolysis. Tuning the molar ratio of ZIF-L(Zn) and ZIF-L(Co) can effectively alter the magnetic loss of the CoZnO/C@BCN composite. The metal particles embedded in the boron nitride nanotubes (BCNs) after ZIF-L(Zn) and ZIF-L(Co) pyrolysis reduce the dielectric coefficient, promote effective dispersion of metal particles, and regulate impedance matching. As a result, the CoZnO/C@BCN composite displays excellent EMW absorption with a minimum reflection loss (RL) of −54.9 dB at 6.5 GHz, as well as an effective absorption bandwidth (EAB) of 5.2 GHz (from 12.72 GHz to 17.92 GHz) with an equal absorber thickness of 1.9 mm. The CoZnO/C@BCNs achieve an excellent EMW absorption capacity, which is attributed to the multiple loss mechanisms and outstanding impedance matching. The results provide new insight into MOF-based carbon absorbers with light weight and high performance, which demonstrate significant potential in the treatment of EMW absorption.