Anionic MOF derived Bimetallic NixCoy@Nano-porous carbon composites toward strong and efficient electromagnetic wave absorption

Abstract

Metal-organic frameworks (MOFs) derived metallic nanoparticles embedded nano-porous carbon (NPC) composites have shown to be promising microwave absorbing materials. Although MOF precursors with diverse compositions and morphologies have been extensively investigated, anionic MOFs are rarely explored for this utility. In addition to the metal sites and ligands on the MOF framework, the guest counter-cations in the void provide supplementary parameters to tune the capability of microwave absorption. Herein, we applied an anionic NixCoy-MOF featuring N-rich ligands and hierarchical porous structures as a precursor for microwave absorption. The obtained dielectric-magnetic NixCoy@NPC composites with rich N dopants and multiple hetero-interfaces promote the microwave attenuation capability through enhanced dipole/interfacial relaxation. The synergistic effects of magnetic loss and conduction loss induced by metallic nanoparticles (NPs) and porous graphitic layers further facilitate the microwave dissipation. More significantly, impedance matching can be effectively improved by tuning the Co/Ni amount in the precursors to realize the modulation of electromagnetic parameters. Consequently, Ni@NPC exhibits the optimal electromagnetic wave (EMW) absorption with minimum reflection loss of −66 dB at only 2 mm and broad effective absorption band covering 4.56 GHz at a thin thickness of 2.07 mm, making this material promising absorber for EMW elimination.

Keywords

• Anionic MOFs
• MOF-Derived carbon composites
• N-rich ligands
• Dielectric loss
• Magnetic loss
• Electromagnetic wave absorption