Multi-dimensional Ni@C-CoNi composites with strong magnetic interaction toward superior microwave absorption

Abstract

• Multi-dimensional Ni@C-CoNi with 0D CoNi alloy and 1D Ni@C were synthesized. • The multi-layer heterogeneous interfaces trigger strong interfacial polarization. • Inner 1D Ni interacts with outer 0D CoNi alloy to induce magnetic coupling. • An optimal R L value of -51.4 dB and bandwidth of 4.6 GHz were achieved. Dielectric-magnetic integrated absorbers have attracted arousing attention in microwave absorption, however, it still remains a great challenge to simultaneously achieve superior dielectric polarization and strong magnetic loss. Herein, we propose a multi-scale structure optimization strategy to anchor CoNi-MOFs derived 0D CoNi alloy onto 1D core-shell Ni@C surface. By decorating with the poly-dopamine layer, the connection between 1D NiO and CoNi-MOFs precursors was greatly improved via the electrostatic interaction. Benefiting from the overlapping conductive networks, enhanced interfacial polarization among the multi-dimensional heterogeneous interfaces and strong magnetic interaction, the fabricated multi-dimensional Ni@C-CoNi composites exhibit outstanding microwave absorption. Typically, the optimal reflection loss is as high as –51.4 dB at 1.9 mm, and the effective absorption bandwidth achieves 4.6 GHz with a thickness of only 1.3 mm. This multi-scale structure optimization strategy inspires us with an efficient method to fabricate ideal microwave absorbers and the obtained multi-dimensional composites can be used as promising candidates in electromagnetic radiation protection.