Effect of nano-structuring on hydrogen sorption properties of materials

Storage of large quantities of hydrogen at safe pressures is a key factor in establishing a hydrogen-based economy [1]. Of the three ways of storing hydrogen, viz. by compressed gas, in liquid form, or as hydride, the latter is rather promising both for its relevant storage capacity and safety [2]. There are several materials which show reversible hydrogen absorption desorption properties. However, to be suitable for the on-board hydrogen storage for vehicular applications, the storage material should have the following properties: (a) high storage capacity; (b) moderate absorption/desorption temperatures; (c) fast hydrogenation/dehydrogenation kinetics; (d) high resistance to degradation and contamination on thermal and charge/discharge cycling. Recently, many research efforts have been devoted to modify the sorption properties of different materials in order to approach the above mentioned properties. Nanostructuring of the powders is one of the obliged ways in tailoring novel materials, inasmuch as this procedure increases the surface/volume ratio and has beneficial effects on the absorption/desorption kinetics. Citing few examples from literature, this presentation describes how nanostructuring can be utilized for improving the sorption kinetics of different potential hydrogen storage materials. To study the nanostructured materials for hydrogen storage applications, recently, we have set up a laboratory at Istituto Tecnologie Avanzate, Trapani. The presentation will also give a general outline of the Laboratory facilities, and show some preliminary results obtained from the ball milled and/or Ce doped LaNi5 samples. [1] R. Coontz and B. Hanson, Towards a Hydrogen Economy, Science 305, 957 (2004). [2] L. Schlapbach and A. Zuttel, Hydrogen-storage materials for mobile applications, Nature 414, 353 (2001).