Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/ijhydene Hydrogen storage of the Mg–C composites A.D. Rud a,Ã , A.M. Lakhnik a , V.G. Ivanchenko a , V.N. Uvarov a , A.A. Shkola a , V.A. Dekhtyarenko a , L.I. Ivaschuk a , N.I. Kuskova b a G.V. Kurdyumov Institute for Metal Physics of NASU, 36, Academician Vernadsky Blvd, 03680 Kiev-142, Ukraine b Institute of Pulse Research and Engineering of NASU, 43a, Oktyabrskii Pr., 54018 Nikolaev, Ukraine article info Article history: Received 21 September 2007 Received in revised form 12 December 2007 Accepted 12 December 2007 Available online 1 February 2008 Keywords: Hydrogen adsorption/desorption Nanopowders Mechanical alloying Carbon nanomaterials Magnesium–carbon nanocomposites abstract The effect of different kinds of carbon on the hydrogen sorption kinetics by magnesium– carbon composites was analyzed. To prepare magnesium-based composites by ball milling, graphite and carbon nanomaterials (hereinafter CNM) obtained by the electroexplosion technique were used. Phase composition and structure state of the as-milled and hydrogenated magnesium–carbon and magnesium–nickel–carbon composites have been investigated. It was found the crystallite size in the Mg–CNM composite is smaller in comparison with the magnesium–graphite and magnesium–graphite–nickel mixtures. The CNM additives to magnesium essentially improve the hydrogen sorption kinetics. It results in a reduction of hydrogen sorption temperature. The noticeable hydrogen absorption took place already at a temperature of 363 K. The hydrogen capacity was about 5 wt% for magnesium ball milled with CNM additives. & 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. 1. Introduction Developing new inexpensive, safe and innocuous materials capable of storing and reversibly desorbing a large amount of hydrogen at low both temperature and pressure is an urgent question in hydrogen energetic. Magnesium hydride is one of the most studied hydrides due to its high hydrogen storage capacity (7.6 wt%), high abundance and low cost. The hydro- gen storage capacity of magnesium hydride essentially exceeds one for the rare-earth-based hydrides and titanium. However, it has not been widely adopted commercially because of its high operating temperature (553–573 K) and sluggish sorption kinetics. Various alloy additives [1–7] are used to destabilize magnesium hydride and noticeably improve the hydrogen sorption/desorption kinetics in the magnesium. However, the hydrogen storage capacity is less for this case. It has been found that better sorption kinetics could be achieved by the mechanical grinding of magnesium (or magnesium hydride) with 3d-transition elements [1–7], var- ious oxides [6,8–12], graphite [13–19], carbon multiwalled nanotubes [20], etc. The benefits of mechanical milling consist of the production of nanocrystalline materials with fresh and highly reactive surfaces and ability to form nanocomposites, etc. The high ductility of magnesium impedes its high-degree dispersion. This problem could be overcome by adding carbon as anti-sticking agent and for activation purpose [7,14]. Last time the new carbon materials (carbon nanotubes, graphite nanofibers, etc.) have become interest as hydrogen storage matter. These materials play an important role in enhancing the hydrogen sorption properties of the composite materials. Imamura et al. [22–25] examined the effect of magnesium ball milling in the organic liquids on its sorption properties. It has been shown such material has a good performance of hydriding/dehydriding with satisfying absorption rate. In our recent works [26–28] we have found a principal avail- ability to produce a different allotropic forms of nanocarbon ARTICLE IN PRESS 0360-3199/$ - see front matter & 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2007.12.032 Ã Corresponding author. Tel.: +380 44 4243210; fax: +380 44 4242561. E-mail address: rud@imp.kiev.ua (A.D. Rud). INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 33 (2008) 1310– 1316