ABSTRACT
Metal hydrides have been in focus for a long time as one of several alternatives to store hydrogen in a hydrogen-based economy. In metal hydrides, one uses the fact that hydrogen uptake in certain metals is exothermic and furthermore allows saturation uptakes that are close to, or may even exceed, that of liquid hydrogen. Sodium, lithium, and beryllium are the only elements lighter than magnesium that can also form solid-state compounds with hydrogen. The binary hydride, a reaction product, can be of different types: metal hydrides; ionic hydrides; and covalent molecular hydrides. The group of metallic hydrides is increased in number if, in addition to binary systems, one also includes hydrides based on intermetallic compounds of transition metals. There is a renewed interest in hydrogen storage materials, both conventional metal hydrides and new materials such as carbon nanostructures and novel compounds. Additionally there are also other forms of carbon structures such as fullerenes, nanotubes, and graphene.
