Helium nanodroplets doped with copper and water★,
Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck,
2 Physics Department, University of New Hampshire, Durham NH 03824, USA
Received in final form: 10 May 2018
Published online: 12 July 2018
Copper nanoparticles are promising, low-cost candidates for the catalytic splitting of water and production of hydrogen gas. The present gas-phase study, based on the synthesis of copper-water complexes in ultracold helium nanodroplets followed by electron ionization, attempts to find evidence for dissociative water adsorption and H2 formation. Mass spectra show that H2O–Cu complexes containing dozens of copper and water molecules can be formed in the helium droplets. However, ions that would signal the production and escape of H2, such as (H2O)n−2(OH)2Cum+ or the isobaric (H2O)n−1OCum+, could not be detected. We do observe an interesting anomaly though: While the abundance of stoichiometric (H2O)nCum+ ions generally exceeds that of protonated or dehydrogenated ions, the trend is reversed for (H2O)OHCu2+ and (H2O)2OHCu2+; these ions are more abundant than (H2O)2Cu2+ and (H2O)3Cu2+, respectively. Moreover, (H2O)2OHCu2+ is much more abundant than other ions in the (H2O)n−1OHCu2+ series. A byproduct of our experiment is the observation of enhanced stability of He6Cu+, He12Cu+, He24Cu+, and He2Cu2+.
Contribution to the Topical Issue “Atomic Cluster Collisions”, edited by Alexey Verkhovtsev, Andrey V. Solov’yov, Germán Rojas-Lorenzo, and Jesús Rubayo Soneira.
© The Author(s) 2018. This article is published with open access at Springerlink.com
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