Periodic Three-Dimensional Nitrogen-Doped Mesoporous Carbon Spheres Embedded with Co/Co 3 O 4 Nanoparticles toward Microwave Absorption

Although various bio-inspired materials with outstanding mechanical, acoustic, and optic properties have been developed, bio-inspired materials for microwave absorption applications are rarely reported. Herein, under the inspiration of the opal structure, for the first time, a kind of Co@Co 3 O 4 /nitrogen-doped (N-doped) mesoporous carbon sphere (Co@Co 3 O 4 /NMCS) with a periodic three-dimensional structure toward microwave absorption application was designed and synthesized. The microwave absorption performance was optimized with respect to the content of Co@Co 3 O 4 nanoparticles. Co@Co 3 O 4 /NMCS with ∼20 wt % Co@Co 3 O 4 achieves a reflection loss of −53.8 dB at 5.7 GHz. The simulated radar cross section demonstrated that the Co@Co 3 O 4 /NMCS can efficiently suppress the strong electromagnetic scattering from a metal groove structure, which further reveals its excellent absorbing performance. These periodic porous structures of N-doped mesoporous carbon spheres combined with the magnetic Co@Co 3 O 4 nanoparticles contribute to the excellent microwave-absorbing performance.