Alternating current assisted preparation of three-dimensional graphene aerogels and the application in electromagnetic interference shielding

Three-dimensional (3D) graphene aerogels (GA) have obtained significant attention across various fields due to their lightweight and porous properties. Nevertheless, the development of a scalable and environmentally friendly method for synthesizing self-supported 3D GA remains a challenge. In this study, we introduced an innovative method for the preparation of 3D GA using alternating current (AC) strategy, which fully used the characteristic of AC's constantly changing current direction to attract graphene oxide (GO) particles to the electrode surface and subsequently reduced them to reduced GO (rGO). Ultimately, GA is self-assembled on the electrode surface under repeated cycles. An applied AC signal with optimal parameters produced a porous GA with an oxygen content of 10.76 at%, which is 66.67% less than that of the original GO. When applying GA to electromagnetic interference (EMI) shielding, it provides a maximum specific shielding effectiveness of 9100 dB cm2 g-1 at X-band due to the repeated reflection and absorption of electromagnetic waves (EMWs) by the abundant pore wall. Furthermore, the shielding effectiveness can be significantly improved to 68.60 dB at the Xband for a multilayer GA. Notably, it is worth emphasizing that this AC-assisted synthesis method has proven its adaptability to various metal electrodes, such as cost-effective iron and copper. Importantly, this method avoids the high-temperature treatments and the use of environmentally hazardous chemicals. It is envisaged that this environmentally friendly and low-cost approach will greatly facilitate the cost-effective production of 3D GA with diverse applications.