Development of 3D graphene structures and their prospective applications

Meganne CHRISTIAN, IMM CNR Bologna

3D graphene materials have attracted a lot of interest due to their ability to transfer many of the unique properties of 2D graphene to a macroscale, with high surface area, high electrical conductivity, and good structural integrity. Good quality graphene may be grown on templates of virtually any shape by Chemical Vapour Deposition (CVD), and in this way free-standing macrostructures called graphene foams (GF) were first produced from nickel foam templates in 2011. Since then there have been many investigations into their use either alone or in composites with other materials in applications such as electrodes for supercapacitors and batteries, gas sensors and adsorbents. We present our investigations into the synthesis of graphene foams and expand their potential even further by significantly reducing the pore size from the 200-400 μm range achievable using commercially available metal foam templates. To achieve this, we have developed a new technique to reach a pore size range of 1-10 μm using networks of nanoparticles as the templates for graphene growth, significantly increasing the graphene surface area available in a given volume. In addition, we present the promising preliminary results of two different applications that we are exploring for 3D graphene structures. In the first, we demonstrate their potential as electrodes in Li-ion batteries, and show that by using an electrochemical method to completely cover the surface of the graphene with flower-like iron (III) oxide nanocrystals, we can further enhance the properties. In the second application, graphene foams are successfully colonised with microorganisms and proposed as electrode materials for microbial fuel cells, which have the potential to directly harvest chemical energy from several classes of environmental and waste waters.

 
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