Encapsulated prussian blue analogs derived nanocubes with tunable yolk-shell structure enabling highly efficient microwave absorption

Abstract

Pyrolytic Prussian blue analogs (PBAs) have attracted much attention in the field of microwave absorption (MA) because of their outstanding magnetic-carbon synergism effect. However, pure PBAs are prone to collapse and aggregate during pyrolysis, resulting in impedance mismatch that weaken the MA performance. Herein, the amorphous carbon layer with adjustable dielectric constant as the encapsulated layer, together with pyrolytic PBAs enables remarkable optimized performance via forming the classic yolk-shell structure. Specifically, the amorphous carbon obtained by quantitatively carbonizing phenolic resin, can not only avoid the collapse of pyrolytic PBAs but also optimize electromagnetic parameters to achieve optimum impedance matching by varying thickness. The NiFe alloys/graphite carbon core derived from pyrolytic NiFe–PBAs also enhance synergistic attenuation in the YS-NiFe/GC@C absorbers. According to experimental results, all YS-NiFe/GC@C absorbers exhibit impressive MA properties. When the thickness of the amorphous carbon shell is 50 nm, the minimum reflection loss value is as low as −56.3 dB and the maximum effective absorption bandwidth reaches 5.64 GHz, indicating that optimizing impedance matching via hierarchical and quantitative design can maximize the MA capability. The result is then verified by simulation calculations. Therefore, this promising work provides guidance for the sophisticated construction of tunable PBA-based MA materials.