Towards efficient carbon nanodot-based electromagnetic microwave absorption via nitrogen doping

Abstract The development of electromagnetic (EM) microwave absorption materials is essential for the whole electrical and electronic systems. Although carbon-based materials have been widely studied as EM absorber, the problems such as high cost, complicated processing technology and insufficient shielding performance still remain unsettled. Here, carbon nanodots (CDs) prepared through a one-step microwave-assisted heating method are demonstrated as EM absorption materials for the first time. With regulation of the doped nitrogen contents and degree of graphitization, the minimum EM reflection loss of the CDs at 10.7 GHz is −26.5 dB, and the effective absorption bandwidth of 1.5-mm thickness is 4.85 GHz. By adjusting the thickness, the effective absorption band ranges from 3.3 to 18 GHz, which is better than most non-composite carbon materials. The superior performance can be attributed to the excellent impedance matching and high dielectric loss in CDs. These results may extend the application fields of CDs and offer new insight into the exploitation of effective carbon-based EM shielding materials.