Graphene aerogel based multifunctional composites

Abstract

Graphene oxide (GO) nanosheets can be assembled into multifunctional three-dimensional graphene aerogels (3D GAs) via hydrothermal assembly for sensing and energy storage applications. However, due to strong van der Waals forces, GO nanosheets often stack together, significantly compromising their performance. A well-designed and highly interconnected 3D GAs are still one of the biggest and most debated challenges in achieving multifunctional compressible materials. To address these issues, first, a novel two-step freezing method was demonstrated to synthesize a unique core-shell structured 3D graphene aerogel (3D GA). In this method, a dual temperature gradient was created to control the ice crystal growth, leading to the formation of a well-structured 3D GA with honeycomb-like densely packed core and sparsely packed shell. A high-performance multifunctional 3D GAs with carbon materials was prepared using a hydrothermal assisted two-step freezing method followed by natural drying to increase the structural stability and surface area of GAs by preventing the stack of graphene sheets during their assembly. The carbon materials significantly prevent the restacking of graphene sheets caused by van der walls forces and make available a space between graphene layers, facilitating a strong structure and superb electrical conductivity by facilitating an excellent pathway for electron transport. The GAs were applied in strain sensors to detect various human bio-signals. Furthermore, the GAs were used as free-standing electrodes to create flexible supercapacitors, demonstrating satisfactory electrochemical performances. Overall, we show that 3D graphene/nano carbon hybrid aerogels have excellent multifunctional properties for applications in flexible electronics and energy storage devices.