Designing novel nanoporous architectures of carbon nanotubes for hydrogen storage Emmanuel Tylianakis a,b , Georgios K. Dimitrakakis b , Francisco J. Martin-Martinez c , Santiago Melchor c , Jose A. Dobado c , Emmanuel Klontzas b , George E. Froudakis b, * a Materials Science and Technology Department, University of Crete, P.O. Box 2208, 71003 Heraklion, Crete, Greece b Department of Chemistry, University of Crete, P.O. Box 2208, 71003 Heraklion, Crete, Greece c Grupo de Modelizacion y Disen ˜o Molecular, Departamento de Quimica Organica, Universidad de Granada, 18071 Granada, Spain article info Article history: Received 3 October 2013 Accepted 2 March 2014 Available online xxx Keywords: Hydrogen storage Super diamond CNT network Grand canonical monte carlo simu- lations Porous carbon based material abstract A multi-technique theoretical approach was used to investigate hydrogen storage in a three-dimensional diamond-like architecture composed by interconnected carbon nano- tubes (CNT). This is achieved with nodes formed by four nanotubes joined together by the inclusion of heptagonal rings placed appropriately. This novel nanoporous material, named Super Diamond has, by design, tunable pore size and exhibit large free volume and surface area, which can reach the values of 95% and 2535 g/m 2 respectively. The interaction and the adsorption properties of this material with hydrogen were studied thoroughly via ab-initio and Grand Canonical Monte Carlo simulations. Our results show that a large pore Super Diamond can surpass the gravimetric capacity of 20% at 77 K and can reach the high value of 8% at room temperature. Copyright ª 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Introduction The lack of an efficient storage system is one of the major drawbacks for hydrogen as a real alternative in the fuel in- dustry. Nevertheless, since it is actually considered to be one of the best candidates, several investigations are being carried out nowadays to solve the problem concerning its storage. Within this framework, the design of new materials arises as a promising strategy. To guide the development of such mate- rials, United States’ Department of Energy (D.O.E.) has estab- lished the requirements to be met by 2015, regarding the reversible storage of hydrogen. According to these re- quirements, the gravimetric density should be 5.5% wt. and the volumetric capacity 40 g/L [1]. Consequently, once the requirements are set, the appropriate materials for hosting hydrogen have to be developed. Towards this direction, assembling nanostructures into ordered micro-networks is a formidable challenge in modern nanotechnology. Indeed, for hydrogen storage purposes, there are two main families of nanomaterials that attract most of the scientific interest: carbon based nanoporous materials and Metal Organic Frameworks (MOFs) [2e5]. They both are pre- sented as materials with large surfaces that can store * Corresponding author. Tel.: þ30 2810 545055; fax: þ30 2810 545001. E-mail address: frudakis@chemistry.uoc.gr (G.E. Froudakis). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2014) 1 e5 Please cite this article in press as: Tylianakis E, et al., Designing novel nanoporous architectures of carbon nanotubes for hydrogen storage, International Journal of Hydrogen Energy (2014), http://dx.doi.org/10.1016/j.ijhydene.2014.03.011 http://dx.doi.org/10.1016/j.ijhydene.2014.03.011 0360-3199/Copyright ª 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.