Hierarchical nitrogen/cobalt co-doped carbonaceous materials with electromagnetic waves absorption promoting nanostructures

In order to solve the pollution of electromagnetic interference (EMI), hierarchical Co/N-co-doped carbonaceous compounds with absorption promoting nanostructures were prepared as absorbing materials via a seaweed-based hydrogel strategy. XRD , Raman, SEM, TEM, VSM and XPS were used to characterize the resultant samples. All the tests indicated that the absorber carbonized at 700 °C (SA/N-Co x O y -700, among, SA represents sodium alginate and 700 means that the carbonization temperature was 700 °C) has an excellent performance, which minimal RL can reach to −47.31 dB at 16.16 GHz and the effective absorption bandwidth (RL  <  -10 dB) is 4.56 GHz from 13.44 to 18 GHz. The relative superior performance is mainly attributed to the cooperative effect of nitrogen-doped carbon skeleton, expanded surface, multiple defects, various phase interface and hierarchal pore structures , thus leading to the improvement in multiple reflections and scattering, nature resonance, eddy-current effect, the consumption of thermal energy, dipoles and interfacial polarization.