Hydrogen desorption energies of Aluminum hydride (AlnH3n) clusters

Hydrogen desorption energies are considered an important factor in the selection of hydrogen storage materials. Among metal hydrides, aluminum hydride seems to be a promising material for hydrogen storage. We report the theoretical calculations of the hydrogen desorption energies of AlnH3n (n=1, 2, 3…) clusters based on Density Functional Theory (DFT). Except for very small clusters, desorption energy is seen to steadily decrease with cluster size n and reach a value of 0.19 eV per H2 for n=20, showing that for large cluster sizes approximating bulk behavior, aluminum hydride tends to be unstable. But AlnH3n clusters of sizes n=8–16 have desorption energies in the range 0.6–0.4 eV per H2, which is suitable for hydrogen storage application.