Researchers Pentti Frondelius, Hannu Hkkinen and Karoliina Honkala have studied monolayer-thick gold clusters with 10-20 atoms, supported by thin magnesium oxide films that were grown on silver metal. These systems can be prepared experimentally, and last year the Jyvskyl group published a joint study with Professor Hans-Joachim Freund from the Fritz-Haber Institute in Berlin to characterize atomic and electronic structures of gold clusters in such systems (see http://prl.aps.org/abstract/PRL/v102/i20/e206801).
Intensive experimental work since the early 1980s has indicated that gold nanoparticles exhibit unexpected catalytic activity towards many industrially important chemical reactions that involve activation of atomic bonds inside oxygen or hydrocarbon molecules. Room-temperature formation of carbon dioxide (CO2) from carbon monoxide (CO) and oxygen molecule (O2) is one of the most extensively studied processes. A number of different factors have been suggested to contribute to the ability of gold particles to activate the O-O bond, which is considered to be the key reaction step.
"The study now published provides us with a new approach to the problem. The formation of gold oxide, that is, the oxidation of gold, is in contradiction with the known properties of macroscopic gold metal. On the nanometer scale, however, everything seems to be possible," Professor Hkkinen says.
|Contact: Hannu Hkkinen|
Academy of Finland