Constructing ordered macropores in hollow Co/C polyhedral nanocages shell toward superior microwave absorbing performance

Rational design of porous carbon architecture is essential for superior microwave absorbing performance. Herein, we report a new type of hollow porous Co/C polyhedral nanocages with ordered macropores of -60 nm (HP-Co/C) as microwave absorber, which were readily manufactured by epitaxial growth of ZIF-67/SiO2 nanolayers on the surfaces of polyhedral ZIF-8 nanoparticle, and followed by simple calcination in Ar atmosphere and subsequent removal of SiO2 with HF. The ordered macropores can effectively tune the electromagnetic parameters of HP-Co/C, affording the obtained HP-Co/C composites strong attenuation capability and excellent impedance matching characteristics for electromagnetic wave (EMW) absorption. As a result, the reflection loss (RL) and effective absorption bandwidth (EAB) of HPCo/C prepared under pyrolysis temperature of 600 degrees C can reach up to -66.5 dB and 8.96 GHz, respectively, at filler fraction of only 15 wt%. Together, this study offers a new design philosophy to make lightweight and broadband microwave absorbent and can be extended to other types of microwave absorbers, significantly enriching the categories of the efficient microwave absorbing materials.(c) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study presents a new type of hollow porous Co/C polyhedral nanocages as microwave absorbers with ordered macropores. The ordered macropores effectively tune the electromagnetic parameters of the absorbers, resulting in strong attenuation capability and excellent impedance matching characteristics for electromagnetic wave absorption.