Molecular dynamics simulations of rapid hydrogen production from water using aluminum clusters as catalyzers.

Hydrogen production by metal particles in water could provide a renewable energy cycle, if its reaction kinetics is accelerated. Here, ab initio molecular dynamics simulation reveals rapid hydrogen production from water by a cluster (or superatom) consisting of a magic number of aluminum atoms, Al{n} (for instance, n=12 or 17). We find a low activation-barrier mechanism, in which a pair of Lewis-acid and base sites on the Al{n} surface preferentially catalyzes hydrogen production. This reaction is immensely assisted by rapid proton transport in water via a chain of hydrogen-bond switching events similar to the Grotthuss mechanism, which converts hydroxide ions to water molecules at the Lewis-acid sites and supplies hydrogen atoms at the Lewis-base sites.