Defect engineering in N-doped OMC for lightweight and high-efficiency electromagnetic wave absorption

Developing low density and efficient dielectric loss materials has become a research hotspot, which can greatly meet the demands of modern radars and settle the problem of electromagnetic wave pollution. Herein, a series of N-doped ordered mesoporous carbon (OMC) materials with different nitrogen content were prepared via a modified self-assembly method and defect engineering in subsequent calcination treatment. It was discovered that the content and type of nitrogen doping can be effectively modulated by the amount of precursor dicyandiamide, resulting in the changes in porous structure, carbon defects, electromagnetic properties, microwave absorption (MA) performance and radar cross section (RCS) reduction values. Remarkably, as-fabricated OMC/N2.5 displays ideal MA performance, whose minimum reflection loss (R_L(min)) value reaches −35.3 dB at 7.76 GHz (3.0 mm) and its effective absorption bandwidth reaches 3.52 GHz (10.64–14.16 GHz, 2.0 mm). Furthermore, the optimal RCS reduction values can be obtained as 12.01 dB·m² when the detection theta is 30°, which validly reduces the chances of being detected by radar. Thus, this work opens up a novel way for the development of lightweight and high-efficiency MA materials.