Enhanced Electromagnetic Wave Absorption Performance of Co0.5Zn0.5 ZIF-Derived Binary Co/ZnO and RGO Composites

Composites of porous Co0.5Zn0.5 zeolitic imidazolate framework (CZ-ZIF)-derived binary Co/ZnO with reduced graphene oxide (RGO) have been prepared by a wet chemical method and carbonization process. CZ-ZIF-derived Co/ZnO microframes with diameter of about 250 nm were dispersed onto the surface of RGO nanosheets. The impedance matching of the composite could be adjusted by controlling the weight ratio of RGO to Co/ZnO microframes. Due to its porous structure, excellent impedance matching, and dielectric loss characteristics, the Co/ZnO/RGO composite exhibited maximum reflection loss (RL) of - 52.2 dB at 10.96 GHz. Coatings with thickness of 2.0 mm to 4.0 mm showed bandwidth of 5.6 GHz (from 8.72 GHz to 14.32 GHz) for RL of - 10 dB (90% absorption). Additionally, the amount of composite added into paraffin matrix was only 8 wt.%, less than for most electromagnetic (EM) wave absorbers in previous reports. Therefore, such Co/ZnO/RGO composites may be promising candidate EM wave absorbing materials.