The possibility to improve the electrochemical behaviour of AB5-alloy commercial electrodes was studied using different carbons as support, such as carbon blacks and a selection of commercial and in-lab synthesised carbon nanotubes. The carbons selected for this work present different morphologies (i.e., spherical and tubular). Furthermore, they also present a variation of the porous structure and subsequent surface area, which are also going to influence their further electrochemical behaviour. Carbon samples were texturally characterised by the adsorption–desorption of N2 and CO2 at 77 and 273 K, respectively. The carbon structure was analysed by XRD, Raman, TEM, and the chemistry of the samples was also characterised by elemental analysis. The charge and discharge techniques, cyclic voltammetry, rate capability and linear polarisation were used for the electrochemical characterisation of the electrodes studied. The electrochemical behaviour of all the samples was related to their morphological, textural and chemical properties. The results show that there is a clear influence of the nature of the carbon support on the hydriding/dehydriding reaction of the alloy, and in the case of active carbons the kinetics decreases with the increase of the surface area of the carbon support.

This work was supported by Consejo Nacional de Investigaciones Científicas y Técnicas of Argentina (CONICET), the Agencia Nacional de Promoción Científica, Tecnológica, the Comisión de Investigaciones Científicas (CIC), the Czech Academy of Sciences (Research Plan AV0Z40320502), Ministry of Education (project MSM 0021630516), and by the Cooperation programme between the Czech Academy of Sciences and CONICET.

8 pages, 13 figures.-- Available online Sep 9, 2008.-- Issue title: Electrochemistry for a healthy planet: environmental, analytical and engineering aspects: Selection of papers from the 6th ISE Spring Meeting, Foz do Iguaçu, Brazil, Mar 16-19, 2008.

Peer reviewed