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

Abstract

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. Graphical abstract