MOF-derived hollow Co/C with order macropores prepared at low pyrolysis temperature as high-performance microwave absorber

Abstract

Herein, a new kind of metal organic framework (MOF)-based magnetic metal nanoparticle/carbon composite, hollow porous Co/C composite (HP-Co/C) with ordered macroporous (∼60 nm) embedded in shell has been fabricated by low-temperature carbonization (500 °C) of ZIF-8@ZIF-67/SiO2 core@shell precursor and subsequent HF etching process. Compared with its control sample of hollow Co/C (H-Co/C), HP-Co/C composite displays significantly improved microwave absorbing properties in matter of both reflection loss (RL) and effective microwave absorbing bandwidth (EAB, RL < −10 dB). Especially, the corresponding EAB is up to7.64 GHz with filler loading of only 15 wt%. This superior microwave absorbing performance is ascribed to the stronger attenuation capability and better impedance matching characteristics induced by the ordered macropores in the hollow Co/C shell. It is believed that this structural design strategy can be extended to prepare other MOFs-derived lightweight and broadband microwave absorbents at relatively low pyrolysis temperature.