Graphene, formed from hexagonal rings of carbon atoms, has been called a “miracle material” since its invention 17 years ago. His creation won the 2010 Nobel Prize in Physics and dozens, if not hundreds of applications are being studied.
For at least sixty years, scientists imagined a related format for carbon atoms which they called graphyne, and interest has grown since the production of graphene. However, attempts to manufacture graphyne have produced microscopic quantities not even large enough to display large-scale behaviors.
An announcement in Nature Synthesis of a reliable path to making graphyne changed that.
Carbon has an unparalleled ability to form the basis of complex molecules, bonding to itself and other elements. This is why we (and all other life forms we know) are built from molecules with scaffolds of carbon, even though we contain more oxygen and hydrogen atoms. Even pure carbon can organize very differently – represented in nature by graphite, soot and diamonds.
Alternative carbon structures – rare or non-existent in nature – include near-spherical or cylindrical fullerenes, the accidental production of which won the Nobel Prize in Chemistry in 1996 and which are being studied as potential stealth bombers for cancer cells. More recently, graphene’s strength and electrical conductivity have made it a candidate for body armor and better batteries among many other possibilities.
Graphene resembles graphene in more than name – both are sheets of carbon only one atom thick. However, where graphene has a simple honeycomb structure formed of infinitely repeating hexagonal rings, graphene is more complex. Rather than directly flanking each other, benzene rings are further spaced and connected by alkyne bonds, where two carbon atoms form a covalent triple bond (six electrons) to each other.
Graphene conducts electrons exceptionally quickly, but does so in all directions, whereas graphene’s conductivity should be able to be controlled to only go in the desired direction. Theoretical models also suggest that graphyne is capable of forming localized electric fields called Dirac cones. The electrical effects they produce could be modified in such a way as to make graphene even more efficient for transistors or solar cells than graphene should be.
Nothing is useful if you can’t do it, however, and on these rocks, graphyne’s hopes have so far failed. Dr. Yiming Hu, a recent graduate of the University of Colorado at Boulder, and his co-authors changed that by using alkyne metathesis, a reaction that redistributes alkyne bonds. The metathesis of alkynes is reversible, opening the way to much greater flexibility in the synthesis of materials.
“The whole audience, the whole field, is really excited that this long-standing problem, or this imaginary material, is finally coming to fruition,” Hu said in a statement.
“There is quite a big difference [between graphene and graphyne] but in a good way,” said Professor Wei Zhang of UC Boulder, although so far these differences have been largely based on theoretical modeling rather than experimentation.
The process is still complex and costly; the team aims to address both, and if they can’t, apps may be limited. In the meantime, however, the described process is good enough to produce the quantities needed for research so that the characteristics and potential uses of the graph can be explored.