ZnO/nitrogen-doped carbon nanocomplex with controlled morphology for highly efficient electromagnetic wave absorption

In this work, zeolitic imidazolate framework-8 (ZIF-8) with yolk-shell and hollow structures were prepared by a convenient chemical etching method. A subsequent pyrolysis of ZIF-8 enabled one to produce ZnO/nitrogen-doped carbon nanocomplexes with original ZIF-8 morphology, where hollow structure showed superior electromagnetic wave absorption capacity and was responsible for matching the impedance of free space. The minimum reflection coefficients of hollow ZnO/nitrogen-doped carbon nanocomplexes were -51.2 dB (700 °C) and -52.4 dB (800 °C), respectively, whereas the effective absorption band width was as large as 4 GHz and the content of pyrolyzed hollow ZIF-8 was 15 wt%, which was inferior to the level among similar electromagnetic wave (EMW) absorption materials. The convenient and facile strategy paves the way toward designing hierarchical structures for highly efficient and light-weight electromagnetic wave absorbers.