This news release is available in German.
This was determined using Small-Angle X-ray Scattering (SAXS) at BESSY II. A thorough examination with an electron microscope (TEM) confirmed their result. "The research on this phenomenon is now proceeding because we are convinced that such nanoclusters lend themselves as catalysts, whether in fuel cells, in photocatalytic water splitting, or for other important reactions in chemical engineering", explains Dr. Armin Hoell of HZB. The results have just appeared in two peer reviewed international academic journals.
"What is special about the new process is that it is extremely simple and works with an environmentally friendly and inexpensive solvent", explains Professor Klaus Rademann from HU Berlin. The solvent actually consists of two powders that one would sooner expect to find in agriculture that in a research laboratory: a supplement in chicken feed (choline chloride, aka vitamin B), and urea. British colleagues discovered a few years ago that mixing the two powders forms a transparent liquid able to dissolve metal oxides and heavy metals, called deep eutectic solvent (DES). The researchers in Berlin then positioned above the solvent gold foil that they could bombard with ions of noble gas in order to detach individual atoms of gold. This is how nanoparticles initially formed that distributed themselves in the solvent.
Two surprising results: Nanoparticles stay small and form clusters
The longer the bombardment (sputtering) of the gold foil lasted, the larger the nanoparticles could become, the scientists reasoned. However, this was not the case: the particles ceased growing at five nanometres. Instead, an increasing number of nanoparticles formed over longer sputtering times. The second surpris
|Contact: Armin Hoell|
Helmholtz-Zentrum Berlin fr Materialien und Energie