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

Linnea Lundberg,Paul Scheier,Diethard K Bohme,Paul Martini,Marcelo Goulart,Michael Gatchell

doi:10.1140/epjd/e2020-10080-1

Linnea Lundberg, Paul Scheier + Show 4 more

Open Access

https://doi.org/10.1140/epjd/e2020-10080-1

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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

Highlights

The use of metal nanoparticles for high density H2 storage is becoming increasingly relevant in modern fuel technology
Three series are shown for each gold cluster size from n = 1–8: purely hydrogenated AunH+x clusters for x from 1 up to
We demonstrated experimentally that H2 molecules readily attach to cationic gold clusters with up to at least 8 gold atoms that are formed from neutral parents grown in a He environment near zero K

Summary

Introduction

The use of metal nanoparticles for high density H2 storage is becoming increasingly relevant in modern fuel technology. A disadvantage of purely metallic matrices for hydrogen storage is the weight and cost of the (often precious) metals used [1], but this can be, at least partially, overcome by doping other materials with metal nanoparticles. Examples of this include the doping of carbon matrices with metal particles, as small as one or a few atoms, that act as nucleation sites for binding H2 [4,5,6]. Nanosize effects have become an important research focus as has nanoparticle protection against oxidation by O2 and H2O, for example by using semipermeable pro-

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