Single Zinc Atoms Anchored on MOF-Derived N-Doped Carbon Shell Cooperated with Magnetic Core as an Ultrawideband Microwave Absorber

Polarization behaviors of no-magnetic shell dominate the dielectric properties for core-shell magnetic-carbon composites, which faces a huge challenge. Herein, a single atom-doping strategy is established to adjust local electric potential in the metal-organic framework (MOF)-derived carbon shell. Benefiting from the confined transformation, single Zn atoms and N atoms are evenly distributed in the porous carbon shell using ZIF-8 as a template. Dielectric assembled carbon layers with functionalized Fe3O4 core construct unique magnetic-dielectric synergy system. The electromagnetic parameters of Fe3O4@Zn-N-Carbon composites can be modified by tuning the pod-like Zn-N-doping carbon shell via repeating ZIF-8 growth cycles. Surprisingly, the core-shell Fe3O4@Zn-N-Carbon exhibits superior microwave absorption (MA) performance both in the reflection loss ability and wide-frequency responding feature. The reflection loss value of Fe3O4@Zn-N-Carbon microspheres reach -61.9 dB and the effective absorption bandwidth up to 11.5 GHz at only 2.5 mm thickness. The excellent MA mechanism is ascribed to following reasons. High-density stacking Zn-N doping carbon layers boost the interfacial polarization and plentiful Zn single atoms maximize the dipole polarization because of maximum atom utilization efficiency. Enhanced magnetic loss ability results from the compulsory magnetic coupling responding among Fe3O4 cores. Magnetic-dielectric synergy of core-shell Fe3O4@Zn-N-Carbon microspheres can build ultrawide MA frequency.

Automated summary

By employing a single atom-doping strategy to adjust local electric potential in the metal-organic framework (MOF)-derived carbon shell, a unique magnetic-dielectric synergy system is constructed in the core-shell Fe3O4@Zn-N-Carbon microspheres, leading to enhanced microwave absorption performance.