Sep 23, 2009
Scaling up graphene nanoribbons – a bioinspired solution
Graphene nanoribbons present intriguing electronic properties due to their characteristic size and edge shape, and have been suggested for a wide range of uses from electronics to electromechanical systems. However, there are hurdles to achieving larger-scale applications of graphene nano-ribbons. Specifically, the need for nanoscale precision, the material’s structural instability at elevated temperature, and its chemical activity along open edges. To be successful, a material approach must 1) be able to assemble graphene nanoribbons into macroscopic materials, while 2) preserving their physical significance and novel properties at larger scales.
To address this, researchers at MIT are proposing the use of hierarchical assemblies of graphene nanoribbons connected through hydrogen bonds, inspired by biological structures found in nature such as proteins and DNA macromolecules. The selective and directional binding of the hydrogen bond enables the design and synthesis of scalable graphene nanoribbon materials linking nano to macro.
The team used a bottom-up atomistic simulation approach based on first principles calculations. A series of simulations were performed to examine the functional properties of hierarchical structures of graphene nanoribbons with different geometries. Based on the simulations, larger-scale hydrogen bonded assemblies based on functionalized graphene nano-ribbons, with -C=O group functionalization and -N=H substitution at the edge have been proposed (see image, above).
The hydrogen bond network provides considerable structural stability with respect to both tensile and shear loads. It was shown that the weak nature of the hydrogen bond preserves the intrinsic electronic properties of graphene nanoribbons in the assemblies. Specifically, it was confirmed that the edge states are observed near the Fermi level and the electronic structures are controllable by the width of graphene nanoribbon. These results address for the first time the concerns 1) and 2) described above, and show how functional large-scale nanostructured materials made of hierarchically assembled graphene nanoribbons can be fabricated.
This work was funded by DARPA and the MIT Energy Initiative (MITEI).
The researchers presented their work in Nanotechnology.
About the authors
Professor Buehler is the Esther and Harold E. Edgerton Associate Professor in the Department of Civil and Environmental Engineering at the Massachusetts Institute of Technology, and heads the Laboratory for Atomistic and Molecular Mechanics. Dr Zhiping Xu is a Postdoctoral Associate in the Laboratory for Atomistic and Molecular Mechanics at the Massachusetts Institute of Technology. Their work is focused on computational bottom-up modelling of natural, biological and synthetic nanomaterials, focused on mechanical, thermal and electronic properties. The group focuses in particular on the properties of biological and bioinspired materials based on proteins. The long-term goal of their work is the development of a new paradigm that combines materials engineering with synthetic biological methods, to select, design, and produce a new class of materials designed from the molecular level upwards.