Nanoparticulas

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Sorption of hydrogen onto titanate nanotubes decorated with a nanostructured Cd3[Fe(CN)6]2 Prussian Blue analogue
A.A. Al-Hajjaj a, B. Zamora b, D.V. Bavykin a,*, A.A. Shah a, F.C. Walsh a, E. Reguerab
a b

Energy Technology Research Group, School of Engineering Sciences, University of Southampton, Highfield, Southampton, SO17 1BJ, UK Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada del IPN, Unidad Legaria, Legaria 694, Col. Irrigacion, Mexico

article info
Article history: Received 17 June 2011 Received in revised form 30 August 2011 Accepted 19 September 2011Available online 19 October 2011 Keywords: Ferricyanide Titanate nanotubes Cadmium hexacyanoferrate Hydrogen storage High pressure

abstract
Nanostructured films of cadmium hexacyanoferrate (III), Cd3[Fe(CN)6]2 have been deposited on the surface of titanate nanotubes (TiNT) by ion exchange with CdSO4, followed by reaction with K3[Fe(CN)6] in an aqueous suspension. The composite demonstrates asignificantly higher hydrogen storage uptake than pure Cd3[Fe(CN)6]2 and TiNT. At a temperature of 77 K and a pressure 100 bar, the hydrogen uptake for the composite is approximately 12.5 wt %, whereas only 4.5 wt % and 4 wt % are achieved for the TiNT and Cd3[Fe(CN)6]2 respectively. Electron microscopy and infrared spectroscopy show that Cd3[Fe(CN)6]2 is uniformly distributed on the surface of the nanotubesforming a discontinuous nanostructured film with a well developed interface, which allows efficient interaction with the support. The possible reasons for the high uptake of hydrogen in the composite are discussed. Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

1.

Introduction

The limited availability and volatile prices of fossilfuels, together with concerns over their impact on the environment, has motivated the development of a host of sustainable, clean energy technologies. Due to its high-energy density, abundance and environmentally-friendly by-products of combustion, hydrogen has long been considered a potential energy carrier [1]. The development of practical and safe methods of hydrogen storage is, however, vital tothe advancement of hydrogen-based energy technologies, particularly the proton exchange membrane fuel cell; hydrogen storage is anticipated to be a major concern for meeting the US Department of Energy (DOE) targets in terms of both volumetric and gravimetric energy/power densities for vehicular applications. For practical applications, the DOE has established a target for hydrogen storage of 6e9wt % over the next 5 years [2].

Currently, only a small number of hydrogen storage technologies are considered commercially feasible; namely, storage as a compressed gas up to 700 bar [3], storage as liquid hydrogen at cryogenic temperatures [4], physical adsorption on the surface of porous materials at low temperatures [5,6] or storage as chemically bound hydrogen in the form of variousmetal hydrides [7e11]. Alternative methods of hydrogen encapsulation are constantly emerging, based on new types of adsorbents, such as nanostructured materials [12e14] and metal organic frameworks (MOFs) [15,16], or new strategies for hydrogen capture, including ambient temperature reversible hydrogenation [17,18] and the formation of clathrate hydrate structures [19]. Microporous solid materialsbased on metal-cyanide frameworks (MCFs), particularly Prussian Blue (PB) analogues of the type Mx[T(CN)6]y, where M (T) is the external (internal) metal, have recently attracted a great deal of attention as

* Corresponding author. Tel.: þ44 2380598358; fax: þ44 2380597051. E-mail address: D.Bavykin@soton.ac.uk (D.V. Bavykin). 0360-3199/$ e see front matter Copyright ª 2011, Hydrogen Energy...