Unveiling the sp<sup>2</sup>─sp<sup>3</sup> C─C Polar Bond Induced Electromagnetic Responding Behaviors by a 2D N‐doped Carbon Nanosheet Absorber
Can Zhang, Jian‐Tang Jiang, Zhen-Jie Guan, Yuanyuan Zhang, Yining Li, Bo Song, Wen‐Zhu Shao, Liang Zhen
Abstract
Abstract The infertile electromagnetic (EM) attenuating behavior of carbon material makes the improvement of its performance remain a significant challenge. Herein, a facile and low‐cost strategy radically distinct from the prevalent approaches by constructing polar covalent bonds between sp 2 ‐hybridized and sp 3 ‐hybridized carbon atoms to introduce strong dipolar polarization is proposed. Through customizing and selectively engineering the N moieties conjugated with carbon rings, the microstructure of the as‐synthesized 2D nanosheet is gradually converted with the partial transition from sp 3 carbons to sp 2 carbons, where the electric dipoles between them are also tuned. Supported by the DFT calculations, a progressively enhanced sp 2 ─sp 3 C─C dipolar polarization is caused by this controllable structure evolution, which is demonstrated to contribute dominantly to the total dielectric loss. By virtue of this unduplicated loss behavior, a remarkable effective absorption bandwidth (EAB) beyond ‐10 dB of 8.28 GHz (2.33 mm) and an ultrawide EAB beyond ‐5 dB of 13.72 GHz (4.93 mm) are delivered, which upgrade the EM performance of carbon material to a higher level. This study not only demonstrates the huge perspective of sp 2 ─sp 3 ‐hybridized carbon in EM elimination but also gives pioneering insights into the carbon–carbon polarization mechanism for guiding the development of advanced EM absorption materials.