Engineering compositions and hierarchical yolk-shell structures of NiCo/GC/NPC nanocomposites with excellent electromagnetic wave absorption properties

Designable microstructure was crucial for fabricating electromagnetic wave (EMW) absorbing materials. Herein, NiCo nanoparticles/graphitic carbon/nanoporous carbon (NiCo/GC/NPC) core–shell nanocomposites with novel hierarchical double yolk-shell structure were synthesized from metal-organic frameworks by a facile process. The yolk-shell nanoporous core–shell structure of the NiCo/GC/NPC nanocomposites was expertly tuned by regulating the composition of the Ni and Co elements, leading to the engineering relaxation polarization, conductive loss, magnetic resonance and multiple scatterings and reflections. The Ni1Co2/GC/NPC nanocomposite exhibited a minimum reflection loss (RLmin) value of −52.2 dB and a broad effective absorbing bandwidth (EAB) of 7.2 GHz (from 10.8 to 18 GHz) for RL < −10 dB with a thin thickness of 2.1 mm. The outstanding absorbing performance was ascribed to the optimized nanostructure which integrated the yolk-shell configuration, nanoporous structure and core–shell architecture, which brought in higher tunable dielectric and magnetic loss with the good impedance matching. This work provides a facile paradigm for the design and fabrication of the yolk-shell nanoporous core–shell structure for light weight and high-efficiency EMW absorbers.