Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage

Abstract

In a recent letter ͓T. Yildirim and S. Ciraci, Phys. Rev. Lett. 94, 175501 ͑2005͔͒, 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 H 2 storage medium. We also performed transition state analysis on the possible dimerization of Ti atoms adsorbed on the graphene and single-wall carbon nanotube.

Improved hydrogen storage in Ca-decorated boron heterofullerenes: a theoretical study

“…[20][21][22][23][24] However, not all hydrogens are then bonded equally. Upon loading, the rst hydrogen molecules are strongly chemisorbed in atomic form, and the subsequent ones are physisorbed in molecular form.…”

On the structure and normal modes of hydrogenated Ti-fullerene compounds

“…The number of studies of new nanostructures (Zhao et al 2005;Iñiguez et al 2007;Yildirim et al 2005;Bauschlicher et al 2002;Zope et al 2009;Zhang et al 2000;Yoon et al 2008;Yang et al 2009;Lee et al 2008;Durgun et al 2008;Koh et al 2011, Kiran et al 2006 able to absorb H 2 in at least 9 wt% have increased in the last years, following the goal proposed by the US Department of Energy of developing a system with this net gravimetric capacity for hydrogen storage. Among the different materials under consideration, systems composed by C 60 compounds coated with transition metals are between the most promising ones.…”

DFT Study of Planar Boron Sheets: A New Template for Hydrogen Storage

“…7 Recent studies show that metal doping enhances the strength of binding between hydrogen molecules and physisorption materials. 8,9 An ideal metal dopant should strongly bind to the host material, and it should bind hydrogen molecules effectively. For instance, for storage of molecular hydrogen at 30 bar under ambient temperature, and delivery at 1.5 bar, the optimum adsorption enthalpy needs to be 0.15 eV/H 2 .…”