High efficiency electromagnetic wave absorber derived from transition metal layered double hydroxides

Transition metals and carbon materials are known as electromagnetic wave (EMW) nemesis, which can effectively attenuate EMW in the 2-18 GHz frequency band. Herein, three typical transition metal (Fe, Co, Ni) are freely combined into three layered double hydroxides (LDHs) through hydrothermal method and successfully grown in situ on the surface of short carbon fibers (SCFs). The SEM images show that although the three LDHs (CoNi-LDHs, FeNi-LDHs and FeCo-LDHs) are all sheet-like structures, their respective morphologies are completely different and each has its own merits. After calcination treatment at 500 °C, their distinct morphologies are basically retained, while the EMW absorption properties are greatly improved dramatically. Their effective absorption bandwidth (f_e) (RL ≤ -10 dB) reached 3.68 GHz, 1.68 GHz and 4.48 GHz at thicknesses of 2.2 mm, 2.2 mm and 2.0 mm, respectively. As an important transition metal-based material, the exploration of LDHs in EMW absorption has just begun.