Cage-like eggshell membrane-derived Co-CoxSy-Ni/N,S-codoped carbon composites for electromagnetic wave absorption

Eggshell membrane-derived Co-CoxSy-Ni/N,S-codoped carbon composites (EM-Co-CoxSy-Ni/N,S-C) were synthesized by heating a Co2+-Ni2+-2-methylimidazole/eggshell membrane precursor in a N2 atmosphere. The dual atom (nitrogen (N) and sulfur (S)) doping of C was realized easily by using eggshell membrane as the joint source of carbon, N and S. The EM-Co-CoxSy-Ni/N,S-C composites showed remarkable electromagnetic wave absorption (EMWA) performance. The minimum reflection loss (RLmin) reached −48.5 dB (10.1 GHz, 3.5 mm) and the Effective absorption bandwidth (EAB) achieved 7.4 GHz (10.3–17.7 GHz, 3 mm). By adjusting the concentration of 2-methylimidazole, impressive RLmin (-41.5 dB, 13.9 GHz) and EAB (6.5 GHz, 11.5–18 GHz) could be achieved at an absorber thickness of 2.5 mm. Eggshell membrane exhibits considerable potential in designing heteroatom doped carbon based EMW absorbents with high-performance and low cost.