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

Abstract

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 (<-10 dB) of 9.4 GHz can be achieved for Co/NPC-700 composites with a thickness of 3.2 mm. The synthesized Co/NPC composites with large specific surface area, lower filler loading and excellent microwave absorption possess a potential application in lightweight absorbers and this strategy provides a new paradigm for the design of microwave absorption materials derived from metal-organic polymer coordination composites.