Experimentally, it remains a formidable challenge to build up the elegant covalent graphene networks inside the confined space posed between graphene nanosheets. Dr. Wenyi Huang, Professor L. James Lee and their colleagues at the Ohio State University discover a facile process to achieve carbide-bonded graphene networks on both metallic and non-metallic substrates (Adv. Mater. 2013, DOI: 10.1002/adma.201301899).
Specifically, graphene nanosheets were exfoliated from a functional graphene nanopaper under vacuum at elevated temperatures. Notice that these nanosheets would float inside a quartz tube instead of being dispersed in solvents, and carbon radicals were formed on the surface of graphene. Simultaneously, a silicone rubber was decomposed into silicon or silicon oxide radicals, and the surface of substrate was also activated to generate reactive radicals. As the vacuum was released, the graphene nanosheets were deposited sequentially on the substrate surface, between the graphene layer and the substrate, while the carbide bonds were formed at the same time among the graphene nanosheets. These carbide bonds provide covalent links between graphene nanosheets with an interlayer distance of 3~6 angstroms including the interface between graphenes and substrates. These graphene coatings (with a thickness ranging from several to hundreds nanometers) exhibit a unique combination of desired properties. Some of these include: strong bonding; Young’s modulus and hardness better than silicon and steel; electrical and thermal conductivities better than natural graphite; low surface friction; excellent chemical corrosion resistance and anti-abrasion; good cytocompatibility; easy micro-patterning by microfabrication techniques; and attractive semiconductive and optoelectronic characteristics with an adjustable bandgap and high Hall mobilities.
This may lead to a new generation of materials for various coating applications. Examples include: low friction; electrically conductive; acid/base resistant and thermally manageable mold; tool and ball bearing surfaces; easy de-icing glass windows; non-stick; fast-heating and thermally stable cookware; electrically conductive glass and optical fibers; new implant and tissue engineering materials. It can also lead to new semiconductors; transistors; sensors; solar panels; light-emitting diode devices; and nano-electromechanical systems. This intriguing finding would open up a broad avenue toward engineering applications of graphenes.
Wenyi Huang and L. James Lee
This story is reprinted from material from Wenyi Huang, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.