Mechanochemical synthesis of hydrogen storage materials

New synthesis methods are of utmost importance for most materials science research fields. The present review focuses on mechanochemical synthesis methods for solid hydrogen storage. We anticipate that the general methods and techniques are valuable with a range of other research fields, e.g. the rapidly expanding fields of ‘energy materials science’ and ‘green chemistry’ including solvent free synthesis. This review starts with a short historical reminder on mechanochemistry, followed by a general description of the experimental methods. The use of milling tools for tuning the microstructure of metals to modify their hydrogenation properties is discussed. A section is devoted to the direct synthesis of hydrogen storage materials by solid/gas reactions, i.e. by reactive ball milling of metallic constituents in hydrogen, diborane or ammonia atmosphere. Then, solid/solid mechano-chemical synthesis of hydrogen storage materials with a particular attention to alanates and borohydrides is surveyed. Finally, more specialised techniques such as solid/liquid based methods are mentioned along with the common characteristics of mechanochemistry as a way of synthesizing hydrogen storage materials.