In-situ evaporation of nano Zn to prepare alginate-derived lightweight porous carbon for electromagnetic wave absorption

Alginate-derived lightweight porous carbons (ZnAc-C) were successfully prepared from Zn 2+ -alginate hydrogels by freeze-drying and carbonization. During carbonization of the aerogels, the Zn 2+ was in-situ transformed into nano Zn, with the evaporation of the Zn generating abundant micropores in the ZnAc-C products. By adjusting the amount of zinc acetate used to prepare the aerogels and the carbonization temperature, ZnAc-C materials with different porosities were obtained. Benefitting from the well-developed porous structure and the moderate graphitization degree, ZnAc-C carbonized at 750 °C and 800 °C delivered excellent electromagnetic wave (EMW) absorption performance. At a low filling ratio (3 wt%), their maximum reflection loss reaches −53.8 dB and −46.8 dB, and their effective absorption bandwidth reaches 5.0 GHz and 4.5 GHz, respectively. This research identifies a simple low-cost preparation route towards lightweight porous carbon with outstanding electromagnetic wave absorption performance. Download: Download high-res image (468KB) Download: Download full-size image