Hollow Engineering to Co@N-Doped Carbon Nanocages via Synergistic Protecting-Etching Strategy for Ultrahigh Microwave Absorption

Carbon nanocages with N-doped carbon inner shell and Co/N-doped carbon outer shell as electromagnetic wave absorption materials

Multi-shell hollow porous carbon nanoparticles with excellent microwave absorption properties

CoFe2O4/N-doped reduced graphene oxide aerogels for high-performance microwave absorption

Review on the electromagnetic interference shielding properties of carbon based materials and their novel composites: Recent progress, challenges and prospects

Lightweight and high-efficiency microwave attenuation are two major challenges in the exploration of carbon-based absorbers, which can be achieved simultaneously by manipulating their chemical composition, microstructure, or impedance matching. In this work, core-shell CoNi@graphitic carbon decorated on B,N-codoped hollow carbon polyhedrons has been constructed by a facile pyrolysis process using metal-organic frameworks as precursors. The B,N-codoped hollow carbon polyhedrons, originated from the calcination of Co-Ni-ZIF-67, are composed of carbon nanocages and BN domains, and CoNi alloy is encapsulated by graphitic carbon layers. With a filling loading of 30 wt %, the absorber exhibits a maximum RL of -62.8 dB at 7.2 GHz with 3 mm and the effective absorption bandwidth below -10 dB remarkably reaches as strong as 8 GHz when the thickness is only 2 mm. The outstanding microwave absorption performance stems from the hollow carbon polyhedrons and carbon nanocages with interior cavities, the synergistic coupling effect between the abundant B-C-N heteroatoms, the strong dipolar/interfacial polarizations, the multiple scatterings, and the improved impedance matching. This study demonstrates that the codoped strategy provides a new way for the rational design of carbon-based absorbers with lightweight and superior microwave attenuation.

Core-Shell CoNi@Graphitic Carbon Decorated on B,N-Codoped Hollow Carbon Polyhedrons toward Lightweight and High-Efficiency Microwave Attenuation.

Structure design and composition control are two crucial factors in determining the microwave absorption performance for absorbers, however, it still possess formidable challenges to balance the dual coordination between them. Herein, a coordination assembly strategy is used to synthesize Co2+-organic polymer coordination materials, then, Co/N-doped porous carbon (Co/NPC) composites, in which Co particles encapsulated in the interior framework of N-doped porous carbon, are obtained by a high-temperature treatment. The increase of the pyrolysis temperature promotes the enhancement of specific surface area while leads to lower N heteroatoms and the agglomeration of Co particles, resulting in adjusted microwave absorption intensity and bandwidth with frequency-selectivity. Balancing the promoted impedance matching, the synergetic effects between dielectric/magnetic components and multiple reflection/scattering, the Co/NPC-800 composites display the strongest microwave absorption intensity with a minimum reflection loss of −65.1 dB at 2.5 mm while an effective bandwidth (

Juhua Luo

Papers

Carbon nanocages with N-doped carbon inner shell and Co/N-doped carbon outer shell as electromagnetic wave absorption materials

Core-Shell CoNi@Graphitic Carbon Decorated on B,N-Codoped Hollow Carbon Polyhedrons toward Lightweight and High-Efficiency Microwave Attenuation.

Metal-organic polymer coordination materials derived Co/N-doped porous carbon composites for frequency-selective microwave absorption