Commonly Neglected Ester Groups Enhanced Microwave Absorption

Abstract Oxygen‐containing functional groups have high potential to excite polarization loss. The nature and mechanism of the polarization loss brought on by oxygen‐containing functional groups, however, remain unclear. In this study, metal‐organic framework precursors are in situ pyrolyzed to produce ultrathin carbon nanosheets (UCS) that are abundant in oxygen functional groups. By altering the pyrolysis temperature, the type and concentration of functional groups are altered to produce good microwave absorption capabilities. It is demonstrated that the main processes of electromagnetic loss are polarization caused by “field effects and induced effects” brought on by strongly polar ester functional groups. Moreover, links between various oxygen functional groups and structural flaws are established, and their respective contributions to polarization are sharply separated. The sample with the highest ester group content ultimately achieves an effective absorption bandwidth of 6.47 GHz at a pyrolysis temperature of 800°C. This research fills a theoretical hole in the frequently overlooked polarization mechanism in the microwave band by defining the key polarization parameters in chaotic multiple dipole systems and, in particular, redefining the significance of ester groups.