Cobalt phthalocyanine-derived Co–C@C porous composites for tunable electromagnetic absorption

The metal-carbon nanocomposites are widely applied to electromagnetic wave (EMW) absorption due to their good impedance matching characteristics and multiple attenuation mechanisms. Here, the cobalt@carbon (Co–C@C) composites with the porous tubular structure were prepared by calcining the polydopamine (PDA) coated porphyrin derivative cobalt phthalocyanine (CoPc). The heating temperature has a significant effect on the morphology, porosity, magnetization intensity, and EMW absorption performance. These results show that Co–C@C composites after heat treatment temperature at 800 °C have the best EMW absorption performance because of their large specific surface area, abundant mesopores and macropores, and high magnetization. Meanwhile, the Co–N bond could generate at the surface of cobalt nanoparticles, resulting in an interfacial effect and enhancing polarization loss. The minimum reflection loss (RL_min) is −47.36 dB at 12.76 GHz and the effective absorption bandwidth (EAB) is 5 GHz. In addition, Co–C@C composites can be used as tunable EMW absorbers with superior performance.