Ultralight reduced graphene oxide/SiO2–C nanofibers composite aerogel decorated with Li0.35Zn0.3Fe2.35O4 nanoparticles with a three-dimensional bridging network for efficient electromagnetic wave absorption

Abstract

Developing flexible, lightweight, and highly efficient electromagnetic wave (EMW) absorption materials was an effective strategy for mitigating the adverse health effects of microwaves. However, synthesizing flexible wave-absorbing aerogels via a novel method is challenging. In this study, a 3D porous reduced graphene oxide (RGO)/SiO2–C nanofibers (NFs)/Li0.35Zn0.3Fe2.35O4 (LZFO) flexible composite aerogel with a crosslinked structure was synthesized via electrospinning, freeze-drying, and in situ curing. To achieve this, electrospun SiO2 and polyacrylonitrile NFs, graphene oxide (GO), and LZFO nanoparticles were uniformly dispersed in an aqueous solution containing (Al(H3PO4)3) as a crosslinking agent and a crosslinked aerogel was formed by freeze-drying, pre-oxidation and carbonization. The obtained aerogels exhibited a good 3D porous structure. By introducing (Al(H3PO4)3) the cell binding force between the 0D, 1D and 2D materials was improved. Further, the introduction of SiO2 NFs reduced the brittleness of the C NFs and improved the flexibility of the aerogel. Under 60% strain, the stress reached 132 kPa, and a complete closed loop was formed. The RGO and C NFs conductive network coupled with the LZFO nanoparticles magnetic network form an ideal impedance matching. The minimum reflection loss (RLmin) of the RGO/SiO2–C NFs/LZFO-2 aerogel reached −55.2 dB (2.5 mm), and effective absorption bandwidth (EAB) was 5.5 GHz (2 mm) to cover the entire X-band. Moreover, by adjusting the matching thickness (2–4 mm), the RLmin was below −20 dB, and more than 99% of the EMW was absorbed. This study provides a new way to develop flexible absorbent materials for human protection.