Researchers in Japan have developed a technique called diffusion driven layer-by-layer assembly to construct graphene into porous 3D structures for applications in devices such as batteries and supercapacitors.
The study, conducted at Kyoto University, was recently published in the journal Nature Communications.
Graphene is an ultra-thin sheet of carbon that possesses properties that include high mechanical stability and excellent electrical conductivity.
However, the thin structure of graphene also acts as a major obstacle for practical uses. When piecing together these 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 problem, they are often costly, time consuming, and difficult to scale up.
To overcome this challenge, the researchers from the Institute for Integrated Cell-Material Sciences (iCeMS) at Kyoto University borrowed a principle from polymer chemistry and developed it into a technique to assemble graphene into porous 3D architectures while preventing stacking between the sheets.
By putting graphene oxide into contact with an oppositely charged polymer, the two components could form a stable composite layer, a process also known as interfacial complexation.
In a statement Jianli Zou, a co-investigator in the project said: ‘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.’
The resulting products are said to display a foam-like porous structure – which is conducive to maximising the benefits of graphene – with the porosity tuneable from ultra-light to highly dense through simple changes in experimental conditions.
Furthermore, the process is scalable for creating large-area films which will be highly 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,’ said Franklin Kim, the principal investigator of the study.