Some metals like palladium (Pd), platinum (Pt), etc.have a capacity to adsorb large volume of hydrogen on their surface forming hydrides. In fact. Hydrogen dissociates on the surface of metal as H atoms which are adsorbed. In order to accommodate these atoms, the metal lattice expands and becomes rather unstable upon heating. The hydride releases hydrogen and changes back to the metallic state. The hydrogen evolved in this manner can be used as a fuel. The metals listed above (belonging to transition metals) can be used to store as well as transport hydrogen which is to be used as a fuel. Thus, metal hyderides have a ver useful role in hydrogen economy.
