Electromagnetic wave absorption characteristics of single and double layer absorbers based on trimetallic FeCoNi@C metal−organic framework incorporated with MWCNTs

The present study focuses on the design of single and double layer microwave absorbers based on FeCoNi@C metal−organic framework incorporated with MWCNTs. FeCoNi@C metal−organic framework (MOF) and MWCNTs decorated with MOF (MW/MOF) were successfully synthesized via hydrothermal method and characterized with XRD, VSM and FESEM. The electromagnetic parameters of material (complex permittivity and permeability) of the as-prepared nanocomposites dispersing in paraffin (30 wt% powder, single layer) were evaluated by a vector network analyzer in X-band frequency range. The simulation of microwave absorption performance of single- and double-layer absorbers was performed via CST Studio software. The results indicate that the double layer absorber using M/MOF structure as matching layer and MOF structure as absorbing layer can increase the microwave absorption bandwidth up to 4 GHz and greatly decrease the reflection loss down to −36 dB for a total thickness of 2 mm. In contrast, the single layer microwave absorber consisting of 30 wt% M/MOF composite structure exhibited a minimum reflection loss of −18 dB at 9 GHz with 2 GHz bandwidth and 2.5 mm thickness. The better absorption performance of the double-layer absorber maybe attributed to the better impedance matching ability of M/MOF layer, coupling interactions between two distinctive layers (absorbing and matching layers) and excellent magnetic loss ability of MOF layer. •FeCoNi@C metal−organic framework (MOF) and MWCNTs decorated with MOF (MW/MOF) synthesized via hydrothermal method.•FESEM images show spheroidal morphology with 100-200 nm diameter and MWCNTs are uniformly dispersed and wrap MOF particles.•S-like hysteresis loops confirm soft magnetic and ferromagnetic behavior linked to the presence of nanoparticles (Fe, Co, Ni).•Measured permittivity and magnetic permeability are used to predict the return losses for various thickness and stacking order.•five combinations of thickness and stacking achieve FOM values higher than 500, meaning large absorption over wide frequency range.