Self-assembled three-dimensional graphene/Fe3O4 hydrogel for efficient pollutant adsorption and electromagnetic wave absorption

3D composite hydrogels composed of graphene sheets and Fe 3 O 4 nanoparticles (G/Fe 3 O 4 ) were prepared via a simple hydrothermal method. The composite has an interconnected 3D porous network, and the Fe 3 O 4 nanoparticles with the size of ∼13   nm are uniformly dispersed onto the graphene sheets. Due to the synergistic effects of the assembled graphene sheets and Fe 3 O 4 nanoparticles, the resultant G/Fe 3 O 4 exhibited efficient adsorption for organic pollutant using Rhodamine B as the adsorbate and electromagnetic wave absorption. The maximum removal ratio of Rhodamine B was 99.6%, and the G/Fe 3 O 4 hydrogel demonstrated wide and strong wave absorption achieved in the frequency range of 2–20   GHz. Present work shows a way to design and prepare lightweight and high performance materials for both electromagnetic wave absorption and wastewater treatment based on 3D graphene and Fe 3 O 4 nanomaterials.