Co@N-doped double-shell hollow carbon via self-templating-polymerization strategy for microwave absorption

Metal-organic frameworks (MOFs) derivatives have been widely explored as highly efficient electromagnetic absorbing materials. Due to their diverse coordination arrangements, morphologies, and unique structures, MOFs provide promising avenues for synthesizing materials with customized properties. However, strategies for tailoring properties of low-dimensional MOFs-derived absorbers with hollow structures remain a considerable challenge. Herein, a well-defined Co@N-doped porous carbon composite (Co/N PC) with double-shell hollow structures has been successfully developed through self-templating-polymerization and subsequent pyrolysis. The proposed strategy for the synthesis of hollow architecture involves three simple steps (i) coordination, (ii) dissociation, and (iii) dopamine (DA) polymerization. The synthetic approach is realized at room temperature without a need for solvent etching. By effectively optimizing parameters including void thickness, surface structures, and graphitization levels, the as-designed Co/N PC composites feature wide absorption bandwidth of 5.93 GHz at a thickness of 2.4 mm with a filler loading of 15 wt%. The exceptional performance of microwave absorption (MA) is primarily achieved through excellent dielectric loss, and enhanced impedance matching, due to increased conductive loss through porous hollow structures and dipolar/interfacial polarization. This work provides an eco-friendly and facile route to designing hollow MOFs derivatives, offering substantial parameter space for optimized future lightweight and efficient absorbing materials.