Laser irradiation induced CoNi@carbon composites as high-performance microwave absorbers

Abstract

Metal-organic-frameworks (MOFs) derivatives, known for their lightweight and high-performance properties, are highly sought after as microwave absorbers. However, most reported MOFs derived absorbers are pyrolyzed in tube furnaces, which is time-consuming and difficult to finely tune the microstructure due to the low heating-quenching process. In this study, laser irradiation was used as a heat source to pyrolyze CoNi ZIF. By controlling the irradiation power (30mW, 50mW), Co/C composites were obtained in just a few seconds, with Co nanocrystals ranging from 10∼50 nm. The presence of Ni could modulate the microstructure and electric-magnetic parameters of Co/C composites. The effects of Ni content and irradiation power on the electromagnetic absorption properties of Co/C were analyzed. Considering the enhanced dipolar/interfacial polarization, matched impedance, and strong magnetic coupling network, a minimum reflection loss of -45 dB with the effective absorption bandwidth of 6 GHz can be achieved by Co/C at the thickness of 2 mm. Additionally, the laser irradiation was performed in air atmosphere, providing an effective way for industrial production of high-efficiency and broadband wave-absorbing materials.