Hydrogen desorption energies of Aluminum hydride (Al nH 3 n) clusters

Abstract

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 Al n H 3 n ( 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 H 2 for n=20, showing that for large cluster sizes approximating bulk behavior, aluminum hydride tends to be unstable. But Al n H 3 n clusters of sizes n=8–16 have desorption energies in the range 0.6–0.4 eV per H 2, which is suitable for hydrogen storage application.