NOVELTY - Reactant(s) comprising lithium, germanium and/or magnesium, is disposed on a substrate comprising aluminum, and heat treated to form a diffusion multiple having two or more phases. The diffusion multiple is contacted with hydrogen, and absorption and/or desorption of hydrogen is detected. Thus, a combinatorial library is prepared and screened.    USE - For preparing and screening combinatorial library used for determining aluminides and germanides used as hydrogen storage material for generating energy in fuel cell of automobiles, homes, apartments and manufacturing industries.    ADVANTAGE - The method enables simultaneous large-scale testing of materials, and creation of controlled large compositional variation and compounds in bulk samples for fast and systematic survey of hydrogen storage property of aluminides and germanides having high hydrogen affinity.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) recovery of hydrogen, which involves contacting compound(s) (P) with hydrogen, and heating the obtained hydrogenated compound, to recover hydrogen. The compound is aluminum lithium complex (AlLi, Al2Li3, Al4Li9), aluminum magnesium complex (Al3Mg2. Al12Mg17), aluminum boride (AlB12), germanium potassium complex (Ge4K, GeK, GeK3), germanium lithium complex (GeLi3, Ge5Li22), magnesium germanium complex (Mg2Ge), germanium sodium complex (Ge4Na, GeNa, GeNa3), aluminum doped germanium potassium, aluminum doped germanium lithium, aluminum doped magnesium germanium and/or aluminum doped germanium sodium;    (2) energy generating device, which generates energy by hydrogen recovery method;    (3) diffusion multiple, which contains compounds having formula: (LiaNabMgcKdCaeGef)x(Al)y and (LiaNabMgcKdCaeAlf)x(Ge)y, where Li is lithium, Na is sodium, Mg is magnesium, K is potassium, Ca is calcium, Ge is germanium, Al is aluminum, a-f is 0-1, x and y is 1-22, and sum of a-f is 1. At least one phase of diffusion multiple absorbs hydrogen;    (4) composition, which comprises hydride of compound(s) (P); and    (5) hydrogen storage and recovery system, which has hydrogen generation reactor (A) in fluid communication with hydride recycle reactor. Reactor (A) uses light metal aluminides and germanides to recover hydrogen.    DESCRIPTION OF DRAWING(S) - The figure shows the schematic diagram illustrating the arrangement of diffusion multiples in the aluminum substrate.