Hierarchical engineering of CoNi@Air@C/SiO2@Polypyrrole multicomponent nanocubes to improve the dielectric loss capability and magnetic-dielectric synergy

Impedance matching characteristics and loss capabilities including magnetic loss, polarization loss and conduction loss are critical factors to improve microwave absorption performances (MAPs). To elevate these aspects, herein, yolk-shell structured CoNi@Air@C/SiO2@Polypyrrole (PPy) magnetic multicomponent nanocubes (MCNCs) were designed and successfully fabricated in high efficiency through a continuous co-precipitation route, classical Stöber method, thermal treatment and polymerization reaction. The obtained results indicated that the formation of SiO2 effectively stabilized the cubic geometrical morphology and yolk-shell structure during the high-temperature pyrolysis process. The introduction of PPy greatly boosted their polarization loss and conductive loss capabilities. Therefore, the as-prepared yolk-shell structured CoNi@Air@C/SiO2@PPy MCNCs presented superior MAPs compared to CoNi@Air@C/SiO2 MCNCs. Furthermore, by regulating the content of PPy, the obtained CoNi@Air@C/SiO2@PPy MCNCs displayed tunable and excellent comprehensive MAPs in terms of strong absorption capabilities, broad frequency bandwidths and thin matching thicknesses, which could be ascribed to the unique structure and excellent magnetic-dielectric synergistic effect. Therefore, our findings provided an alternative pathway to effectively utilize the magnetic-dielectric synergy and loss capabilities for the developing yolk-shell structured magnetic MCNCs as the strong wideband microwave absorbers.