Graphene aerogels with three-dimensional network structure exhibit excellent electromagnetic (EM) wave attenuation capacity and are often designed as EM-absorbing materials. However, the fabrication processes of these materials are generally sophisticated and time-consuming. Herein, a series of graphene aerogels are synthesized successfully through a simple modified hydrothermal method using ethanol and water as the solvent. The effects of the volume ratio of ethanol-to-water (EtOH/H2O) on the chemical compositions, microstructures, and EM absorption properties of the aerogels are investigated. Results demonstrate that the microstructure and EM-absorbing ability are strongly dependent on the volume ratio of EtOH/H2O, and the best performance is obtained with EtOH/H2O of 1:1. Owing to the optimized ratio, the aerogel with 4.1 mg/ml exhibits a remarkable minimum reflection loss of - 52.6 dB and a broad efficient absorption bandwidth of 7.65 GHz under an ultralow filler content (3 wt), showing obvious advantages compared with most graphene-based absorbers. This work reveals that the graphene aerogel prepared through this ethanol-assisted hydrothermal protocol is a promising candidate for lightweight and economical EM absorption material.
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