Inherent N‑Doped Honeycomb-like Carbon/Fe<sub>3</sub>O<sub>4</sub> Composites with Versatility for Efficient Microwave Absorption and Wastewater Treatment

To our knowledge, the utilization of chitosan-derived materials in microwave absorbing is currently scarce. Herein, for the first time, by fully exploiting its potential properties via facile means, chitosan was employed as the exclusive joint source of carbon and nitrogen, and the inherent N-doped honeycomb-like carbon/​Fe<sub>3</sub>O<sub>4</sub> composites with favorable versatility that can efficiently treat microwave interference and even wastewater pollution were controllably prepared. The optimal microwave absorbency is attractive, of which the minimum reflecting loss reaches to −59.5 dB, and the maximum effective absorbing bandwidth is 5.36 GHz when filler content is only 10%. Beyond the major trying, another function for wastewater treatment was also demonstrated by excellent toxic Cr­(VI) adsorption and peroxymonosulfate activation for organic pollutants (azo-dye Orange II) degradation. More significantly, the embedding magnetic component makes it convenient to be magnetically separated from the testing solution. Totally, these N-doped honeycomb-like carbon/​Fe<sub>3</sub>O<sub>4</sub> composites with versatility prepared by simple methods not only open a new road for the diversified utilization of chitosan but also would possibly make a referrable guidance to the design or even synthesis for superior microwave absorption and environmental remediating materials.