Single-source-precursor derived SiOC ceramics with in-situ formed CNTs and core–shell structured CoSi@C nanoparticles towards excellent electromagnetic wave absorption properties

In this work, novel carbon nanotube (CNT)/CoSi/SiOC nanocomposite ceramics with in-situ formed multi-walled CNTs and core–shell structured CoSi@C nanoparticles were successfully prepared via a single-source-precursor derived ceramic approach. Ppolymeric precursor characterization as well as phase evolution, microstructure, and electromagnetic wave (EMW) absorption properties of the ceramics were investigated in detail. The results show that the in-situ formed CNTs and magnetic CoSi@C nanoparticles provide a synergistic effect on both dielectric loss (tanδ_ε) and magnetic loss, leading to outstanding EMW absorption properties of the ceramics annealed at only 1100 ℃. (i) For the Co feeding of 6.25 wt%, the minimum reflection loss (RL_min) is −53.1 dB, and the effective absorption bandwidth (EAB) is 4.96 GHz (7.12–12.08 GHz) with a ceramic–paraffin hybrid sample thickness of 3.10 mm, achieving full X-band coverage; (ii) for the Co feeding of 9.09 wt%, the RL_min value of −66.4 dB and the EAB value of 3.04 GHz (8.40–11.44 GHz) were achieved with a thickness of only 2.27 mm. Therefore, the present CNT/CoSi/SiOC nanocomposite ceramics have potential applications for thin, lightweight, and efficient EMW absorption in harsh environments.