A unique hollow porous bowl-like nitrogen-doped cobalt/carbon nanocomposite (HBN-Co/C) composed of Co nanoparticles anchored in N-doped porous carbon was designed for enhancing electromagnetic microwave absorption (EMA). The inner cavities of the HBN-Co/C could be regulated to match the impedance and permittivity between the absorber and air, leading to a precise adjustment of the EMA performance. More importantly, the existence of inner cavities decreases the extra multi-interface promoted interfacial polarization and overall density. The synergetic effects of the multicomponents, multiple reflections, and scatterings promoted strong interfacial polarization and facilitated impedance matching. As a result, the HBN-Co/C nanocomposites displayed excellent EMA performance, for which the minimum reflection loss was −42.3 dB at 13.3 GHz with a thickness of only 1.9 mm. The effective absorption bandwidth below −10 dB was up to 5.1 GHz (12.9−18.0 GHz) when the thickness was 1.7 mm. This work provides a facile design and synthesis strategy of novel lightweight electromagnetic wave absorbers with broadband and strong absorption.

NiFe layer double metal hydroxide nanosheets (NiFe LDHs) have been extensively investigated to be one of the best promising candidates to construct the best performing bifunctional catalysts. In this research,...

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