13.9.2019 Theoretical physicist predicted structure of gold cluster that chops carbon dioxide (Kaappa)
Gold and silver nanoclusters can accelerate various chemical reactions. M.Sc. Sami Kaappa, a theoretical physicist, investigated nanometer-sized gold and silver clusters in his doctoral dissertation. Such species have diameter of about one hundred thousandth of a thickness of hair.
“Speaking of nanoclusters, we usually mean relatively large molecules with a nucleus consisting of dozens of metal atoms, protected by monolayer of organic molecules so that the structure is stable in solution. Typically, the protecting layer consists of sulfur or phosphine ligands,” Sami Kaappa describes.
In his research, Kaappa used computer simulations to study properties of nanosized particles. The calculations were run on Sisu supercomputer in Kajaani, Finland, and Mare Nostrum supercomputer which is located in Barcelona.
“Using simulations, we can predict possible chemical structures even if there is only a little experimental data available,” Kaappa tells of the methodology.
CO2-splitting cluster was observed
One of the most remarkable findings of the dissertation research was the structure of a cluster with 11 gold atoms. The work was done in collaboration with experimental groups in Canada and Japan.
“The experimentalists were able to synthesize and realize the gold-11 cluster, but the atom-precise structure could not be determined at that point. Using computational methods, I could determine some possible structures, of which a single one seemed to be more favourable than others. Later, the experimental work verified this prediction,” Kaappa says.
In the same study, they found that the decomposition of carbon dioxide is accelerated in the presence of the cluster.
“In the cluster, one of the phosphine ligands is exchanged to carbene, which is a new type of ligand in clusters. The kinds of observation of the catalytic activity may contribute to development of new technologies, such as catalytic converters or innovations in recycling harmful compounds. This is also fascinating for a theoretician since the reaction of carbon dioxide to carbon monoxide is still not known in detail,” Sami Kaappa says.
The dissertation is published in the JYU Dissertations, number 120, Jyväskylä, 2019. ISBN 978-951-39-7833-4 (PDF) URN: ISBN:978-951-39-7833-4 ISSN 2489-9003.
A link to publication:
M.Sc. Sami Kaappa defends his doctoral dissertation in Physics "Analysis and Applications of Electronic Structure in Gold and Silver Nanoclusters" on Friday 13th of September at 12 o'clock at the Department of Physics in lecture hall FYS1 (Ylistönrinne, Survontie 9). The opponent is Associate Professor Nicola Gaston from University of Auckland, New Zealand, and Custos is Academy Professor Hannu Häkkinen from Ģֱ. The doctoral dissertation is held in English.
For further information:
Sami Kaappa, sami.j.kaappa@student.jyu.fi, phone +358 50 5286722
Communications officer Tanja Heikkinen, tanja.s.heikkinen@jyu.fi, puh. +358 50 581 8351
The Faculty of Mathematics and Science
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