Absorber design based on In/C@Co/C composites for efficient microwave absorption

Due to increasing electromagnetic pollution, excellent microwave absorption materials (MAMs) are extremely desired in our daily life. In this work, MOF-derived prism-like core-shell structured In/C@Co/C-x (x = 700, 800 and 900) composites were prepared by using a simple pyrolysis approach. The unique hierarchical structure with evenly-distributed Co-nanoparticle magnetic shell covering porous In/C core renders the composites remarkable microwave absorption performance. The In/C@Co/C-800 shows a minimum reflection loss (RL_min) of − 55.14 dB with a broad effective absorption bandwidth (EAB) of 5.12 GHz at 2.19 mm. Moreover, a series of periodic stepped microwave absorption structures based on In/C@Co/C-800 are designed using HFSS to perform the broadband microwave absorption. The EAB of a four-layer periodic stepped structure reaches 15.28 GHz, covering 0.955 of the frequency range. This work demonstrates that a nanoparticle magnetic shell composite of In/C@Co/C achieves efficient microwave absorptions, and proposes a structural design strategy for broadband absorption.