Catfish Effect Induced by Anion Sequential Doping for Microwave Absorption

• Published in: Advanced functional materials Vol. 33; no. 8
• Main Authors: Tao, Jiaqi, Xu, Linling, Pei, Changbao, Gu, Yansong, He, Yanru, Zhang, Xianfei, Tao, Xuewei, Zhou, Jintang, Yao, Zhengjun, Tao, Shifei, Wu, Hongjing
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.02.2023
• Subjects: Absorbers; anion competitions; Anions; Carbon; Catfish; catfish effects; Chemical properties; Competition; Conduction losses; Crystal defects; Doping; Electrical properties; heteroatom doping; Induced polarization; Lattice vacancies; Materials science; Metamaterials; Microwave absorption; porous carbon
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202211996

Heteroatom doping engineering is desirable in tuning crystal structures and electrical properties, which is considered an opportunity to further develop microwave absorption materials. However, the competition mechanism and priority among doped atoms have not been revealed, which are insufficient to guide the most reasonable dielectric coupling model and design high‐performance absorbers. In this work, based on in situ N and O, ex situ S is introduced through external thermal driving, leading to fierce competition among anions. Specifically, S atoms replace pyrrole N, drive out lattice O, and create O vacancies, bringing more extensive local charge redistribution and stronger electron interaction, thus activating the defect‐induced polarization (3–6 times higher than conduction loss) in the middle/high‐frequency region. Therefore, the effective absorption bandwidth (EAB) of 9.03 GHz and the minimum reflection loss (RLmin) of −64.05 dB at a filling rate of 10 wt.% are obtained, which improves the record of carbon absorbers as reported. Through macro‐designs, i.e., multi‐layer gradient metamaterial, or utilizing other advantages, e.g., cost‐effective, stable chemical properties and wide‐angle absorption, porous carbon may possess a great application prospect in the naval field. Under the external thermal driving, secondary ex situ doped S brings a significant “catfish effect”, which squeezes out in situ doped pyrrole N, drives away in situ doped O, and builds more vacancy defects in a more ordered carbon atom network, thus enhancing the defect‐induced polarization and breaking the record of biomass absorbers.