International Journal of Hydrogen Energy 32 (2007) 4900 – 4906 www.elsevier.com/locate/ijhydene Enhanced hydrogen storage property of magnesium hydride by high surface area Raney nickel Vinay Bhat a , Aline Rougier a , ∗ , Luc Aymard a , Gholam-Abbas Nazri b , Jean-Marie Tarascon a a University of Picardie, Amiens, France b GMR&D, Chemical and Environmental Sciences Lab, Warren, MI, USA Received 27 March 2007; received in revised form 28 June 2007; accepted 28 June 2007 Available online 10 September 2007 Abstract This paper describes the improvement of hydrogen sorption capacity and kinetics of MgH 2 by addition of high surface area (≈ 100 m 2 /g) Raney nickel (RN). Herein, we demonstrate that enhanced hydrogen sorption by MgH 2 due to RN is not only linked to the catalytic nature of Ni, but also correlates well with the BET surface area for the MgH 2 –Ni composites. The Raney Ni also tends to form the less stable Mg 2 NiH 4 hydrides, which desorb hydrogen at much higher pressure as compared with that of the MgH 2 . We have observed a significant improvement in hydrogen sorption capacity and increase in pressure of hydrogen desorption for MgH 2 catalyzed by RN.  2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. Keywords: Magnesium hydride; Nickel; Surface area; Catalyst; Ball-milling 1. Introduction The success of fuel cell technology is dependent on the avail- ability of an economical, safe and practical storage of hydrogen. Metal hydrides, imides, alanates and metal organic frameworks (MOF) are high density hydrogen storage alternatives as com- pared to the high pressure and cryogenic liquid storage tanks [1,2]. MgH 2 is a low cost and non-toxic material with a high, 7.6wt% hydrogen storage capacity. However, the high thermo- dynamic stability of MgH 2 , (-75 kJ/mol H 2 ), limits the practi- cal application of MgH 2 for PEM-fuel cells that operate around 80–100 ◦ C [3]. Several ways have been reported to enhance the sorption kinetics of magnesium-based hydrides including particle size reduction by high energy ball milling [4] and carbon addi- tion [5]. A successful route remains the addition of transition metals [6–9], oxides [10], halides [11,12], carbides and ni- trides [13]. Among the transition metals, Ni acts as a good catalyst and enables MgH 2 to desorb 5 wt% of hydrogen in 6–7 min at 300 ◦ C under primary vacuum, 0.015 MPa pressure [7]. However, the authors demonstrated that Ti, Fe and V exhibit ∗ Corresponding author. Fax: +33 3 22 82 75 90. E-mail address: aline.rougier@u-picardie.fr (A. Rougier). 0360-3199/$ - see front matter  2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2007.06.030 higher catalytic activity than commonly used hydrogenation catalyst Ni. Interestingly, Shang et al. [8] deduced an opposite conclusion from first principle calculations together with ther- mogravimetric studies on various transition metals added to the MgH 2 . To understand the origin of such controversy, we stud- ied the influence of Ni addition and especially focused on the effect of high surface area and concentration of catalyst on the sorption kinetics of ball milled MgH 2 at different pressures and temperatures. Herein, the effect of high surface area Raney Ni (RN) and commercial Granular Ni (GN) on sorption properties of MgH 2 are compared. 2. Experimental RN, (from Aldrich), initially stored and activated in wa- ter medium, was transferred in a beaker and water was de- canted out. Before drying, the powder was repeatedly washed with acetone and later sealed under vacuum in a glass tube and handled in a glove box for further experimentation. Poorly crystallized RN shows 0.5 m width elongated particles and a high specific surface area of 100 m 2 /g. Highly crystallized GN (Alpha Aeser) with a particle size of 50 m and a low spe- cific surface area of 0.5m 2 /g was chosen as the second source of Ni.