Metal-organic framework-derived Co/CoO nanoparticles with tunable particle size for strong low-frequency microwave
Jing Li1, Qian Wu1, Xiangyu Wang1
1Key Laboratory of Aerospace Materials and Performance (Ministry of Education) School of Materials Science and Engineering, Beihang University, No. 37 Xueyuan Road, Beijing 100191, PR China.
Abstract:
Nowadays, constructing strong absorption materials addressing the low-frequency electromagnetic radiation (S and C bands) from electronic devices remains a significant challenge. In this work, size-tunable Co/CoO nanoparticles (NPs) are fabricated by decomposing zeolitic imidazolate framework (ZIF-67) precursors and subsequent hydrogen reduction. All samples show obvious low-frequency attenuation in the S and C bands. At a thin thickness of 2.3 mm, the minimum reflection loss (RL) value for the Co/CoO NPs of 30 nm reaches up to -90.3 dB at 4.4 GHz, and the corresponding effective absorption bandwidth (EAB) of RL ≤ -10 dB ranges from 3.8 to 5.4 GHz. Notably, 90 % of the electromagnetic waves can be absorbed in the frequency range of 2.3-13.2 GHz, covering almost the entire S, C, and X bands at a thickness of 1.0-4.0 mm. The strong low-frequency absorption performance is attributed to the nano-porous structure, high conduction loss, tunable dielectric/magnetic loss, as well as optimized impedance matching. These Co/CoO NPs are promising candidates for high-efficient microwave absorbers in the low-frequency application.
