Functionalization of Carbon-based Nanostructures with Light Transition-metal Atoms

In a recent letter [T. Yildirim and S. Ciraci, Phys. Rev. Lett. 94, 175501 (2005)], the unusual hydrogen storage capacity of Ti decorated carbon nanotubes has been revealed. The present paper extends this study further to investigate the hydrogen uptake by light transition-metal atoms decorating various carbon-based nanostructures in different types of geometry and dimensionality, such as carbon linear chain, graphene, and nanotubes. Using first-principles plane-wave method we show that not only outer but also inner surface of a large carbon nanotube can be utilized to bind more transition-metal atoms and hence to increase the storage capacity. We also found that scandium and vanadium atoms adsorbed on a carbon nanotube can bind up to five hydrogen molecules. Similarly, light transition-metal atoms can be adsorbed on both sides of graphene and each adsorbate can hold up to four hydrogen molecules yielding again a high-storage capacity. Interestingly, our results suggest that graphene can be considered as a potential high-capacity H2 storage medium. We also performed transition state analysis on the possible dimerization of Ti atoms adsorbed on the graphene and single-wall carbon nanotube. Disciplines Engineering | Materials Science and Engineering Comments Suggested Citation: E. Durgun, S. Ciraci and T. Yildirim. (2008). "Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage. " Physical Review B. 77, 085405. © 2008 The American Physical Society http://dx.doi. org/10.1103/PHysRevB.77. 085405 This journal article is available at ScholarlyCommons: http://repository.upenn. edu/mse_papers/200 Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage E. Durgun,1,2 S. Ciraci,1,2,* and T. Yildirim3,4 1Department of Physics, Bilkent University, Ankara 06800, Turkey 2National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey 3NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA 4Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA Received 5 October 2006; revised manuscript received 30 September 2007; published 4 February 2008 In a recent letter T. Yildirim and S. Ciraci, Phys. Rev. Lett. 94, 175501 2005 , the unusual hydrogen storage capacity of Ti decorated carbon nanotubes has been revealed. The present paper extends this study further to investigate the hydrogen uptake by light transition-metal atoms decorating various carbon-based nanostructures in different types of geometry and dimensionality, such as carbon linear chain, graphene, and nanotubes. Using first-principles plane-wave method we show that not only outer but also inner surface of a large carbon nanotube can be utilized to bind more transition-metal atoms and hence to increase the storage capacity. We also found that scandium and vanadium atoms adsorbed on a carbon nanotube can bind up to five hydrogen molecules. Similarly, light transition-metal atoms can be adsorbed on both sides of graphene and each adsorbate can hold up to four hydrogen molecules yielding again a high-storage capacity. Interestingly, our results suggest that graphene can be considered as a potential high-capacity H2 storage medium. We also performed transition state analysis on the possible dimerization of Ti atoms adsorbed on the graphene and single-wall carbon nanotube. DOI: 10.1103/PhysRevB.77. 085405 PACS number s : 73.63. Nm, 72.25. b, 75.75. a