Jena Puru, Distinguished Professor

Physics Department, Virginia Commonwealth University, Richmond, VA 23284-2000

Many Faces of Carbon

Abstract

Carbon is one of the most, if not the most, fascinating and important element in the Periodic Table. It is the basis of all life forms on the Earth and its importance to technology and society is also enormous. The unique properties of carbon emerge from its ability to form diversified spn (1 < n < 3) bonds. Until 1960’s two-dimensional (2D) graphite with sp2 and three-dimensional (3D) diamond with sp3 hybridization were the most common forms of known carbon. The discovery of one-dimensional chain-like polymer called “carbyne” in 1960 by Russian scientists ushered in a new era in carbon science which is further enriched by the discovery of zero-dimensional (0D) carbon fullerenes, 1D carbon nanotube, and 2D graphene, all with novel properties characteristic of their reduced dimensionality and size. Many new forms of nano-carbon are known today that exhibit a mixture sp2 and sp3 bonding pattern. In this talk I will focus on the new forms of carbon allotropes that have been studied in our group. These include functionalized C60 fullerenes for hydrogen storage1, semi-hydrogenated graphene for metal-free ferromagnetism2, all-carbon magnetic nanostructures composed of 2D triangular graphene nanoflakes linked by carbon chains3, 3D metallic carbon made of hybridized sp2 and sp3 bonded atoms4, and a quasi-2D pentagraphene made of only carbon pentagons5 reminiscent ofCairo-tilling. All calculations have been carried out using gradient corrected density functional theory. Metastability of the above carbon allotropes are confirmed from total energy calculations as well as quantum molecular dynamics. Possible routes for the synthesis of these novel carbon phases will also be outlined.

 
1.      Sun, Q., Jena, P., Wang, Q., and Marquez, M.: First-principles study of hydrogen storage on Li12C60, J. Am. Chem. Soc. 128, 9741 (2006).
 
2.      Zhou, J., Wang, Q., Sun, Q., Chen, X. S., Kawazoe, Y., and Jena, P.: “Ferromagnetism in semihydrogenated graphene”, Nano Letters 9, 3867 (2009).
 
3.      Zhou, J., Wang, Q., Sun, Q., and Jena, P: “Intrinsic ferromagnetism in two-dimensional carbon structures: Triangular graphene nanoflakes linked by carbon chains”, Phys. Rev. B. Rapid Commun. 84, 081402(R) (2011).
 
4.      Zhang, S., Wang, Q., Chen, X., and Jena, P.: “Stable Metallic 3D Metallic Phase of Carbon with Interlocking Hexagons”, Proc. Nat. Acad. Sci. 110, 18809 (2013)
 
5.      Zhang, S., Zhou, J., Wang, Q., Chen, X., Kawazoe, Y., and Jena, P.: “Penta-graphene: A New Carbon Allotrope “, Proc. Nat. Acad. Sci. (in press)

pjena@vcu.edu



Date: 19/3/2015
Time:12:00 (coffee & cookies will be served at 11:45)
Place:FORTH Seminar Room 1