AsianScientist (Oct. 21, 2014) – Researchers in Japan have developed a novel technique to construct graphene into porous three-dimensional (3D) structures, for applications in devices such as batteries and supercapacitors. Their study has been published in Nature Communications.
Graphene is essentially an ultra-thin sheet of carbon which has high mechanical stability and electrical conductivity.
However, the thin structure of graphene also acts as a major obstacle for practical uses. When piecing together the tiny sheets into larger structures, the sheets easily stack with one another, resulting in a significant loss of unique material properties. While several strategies have been proposed to deal with this sticky issue, they are often costly, time consuming and difficult to scale up.
To overcome this challenge, researchers from the Institute for Integrated Cell-Material Sciences at Kyoto University, Japan, developed a method to assemble graphene into porous 3D architectures, while preventing stacking between the sheets: by placing graphene oxide (an oxidized form of graphene) in contact with an oppositely charged polymer, the two components can form a stable composite layer in a process known as “interfacial complexation.”
“Interestingly, the polymer could continuously diffuse through the interface and induce additional reactions, which allowed the graphene-based composite to develop into thick multi-layered structures. Hence, we named this process ‘diffusion driven layer-by-layer assembly’,” explained Dr. Zou Jianli, a co-investigator in the study.
The resulting products display a foam-like porous structure, ideal for maximizing the benefits of graphene, with the porosity tunable from ultra-light to highly dense through simple changes in experimental conditions.
Additionally, the process is easily scaleable for the creation of large-area films that will be useful as electrodes and membranes for energy generation or storage.
“While we have only demonstrated the construction of graphene-based structures in this study, we strongly believe that the new technique will be able to serve as a general method for the assembly of a much wider range of nanomaterials,” concluded Dr. Franklin Kim, the principal investigator of the study.
The full article can be found at: Zou and Kim. (2014) Diffusion driven layer-by-layer assembly of graphene oxide nanosheets into porous three-dimensional macrostructures.
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Source: Institute for Integrated Cell-Material Sciences, Kyoto University; Photo: CORE-Materials/Flickr/CC.
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