Regular Article

Hydrogenated gold clusters from helium nanodroplets: displacement of H₂ by H₂O^★

¹ Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
² Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
³ Department of Chemistry, York University, Toronto, ON M3J 1P3, Canada

^a e-mail: paul.scheier@uibk.ac.at

Received: 13 February 2020
Received in final form: 21 March 2020
Published online: 21 May 2020

Abstract

Cationic clusters of gold, containing up to 8 atoms, and decorated with molecular hydrogen and water, were investigated with mass spectrometry. The clusters were grown as neutrals in superfluid helium nanodroplets that were ionized by electron impact. The resulting gas phase cluster cations exhibit magic sizes corresponding to the number of H₂ molecules that form the first solvation layer, consistent with previous findings. The presence of water is found to efficiently displace hydrogen, one H₂ molecule for each H₂O. Our calculations show that the binding energy of water to the charged gold clusters is about twice as large as for hydrogen, though this depends on the charge of the clusters. This suggests that residual water could reduce the efficiency for metal particles to chemically store hydrogen gas, a promising technique for hydrogen fuel storage.