t 3.8 to about 4.2), R is an organic group and y is 0 to about 0.5, and wherein the metal hydride (i) has a surface area of about 2 m2/g or greater and/or (ii) is capable of absorbing hydrogen (H2) in an amount of at least 2.0% (e.g., from about 2.0% to about 8.0%, from about 8.0% to about 12.0%, or higher) (based upon 100% total weight of the metal hydride without hydrogen stored in it).In certai