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A team of researchers at the at the University of Leeds, UK, has created gold nanosheets with a thickness of only 0.47 nm (two atomic layers thick) — the thinnest unsupported gold ever created. This 2D material could have wide-scale applications in the medical device and electronics industries, and also as a powerful catalyst.
This electron microscope (colorized) image shows the arrangement of electrons on the gold particle. Image credit: Ye et al, doi: 10.1002/advs.201900911.
“Our work amounts to a landmark achievement. Not only does it open up the possibility that gold can be used more efficiently in existing technologies, it is providing a route which would allow material scientists to develop other 2D metals,” said Dr. Sunjie Ye, first author of a paper published in the journal Advanced Science.
Synthesizing the gold nanosheet takes place in an aqueous solution and starts with chloroauric acid, an inorganic substance that contains gold.
It is reduced to its metallic form in the presence of a confinement agent, a chemical that encourages the gold to form as a sheet, just two atoms thick.
“The considerable gains that could be achieved from using these ultra-thin gold sheets are down to their high surface-area to volume ratio,” said Professor Stephen Evans, senior author of the study.
“Gold is a highly effective catalyst. Because the nanosheets are so thin, just about every gold atom plays a part in the catalysis. It means the process is highly efficient.”
Standard benchmark tests revealed that gold nanoscale sheets were ten times more efficient than the gold nanoparticles conventionally used in industry.
“Our data suggests that industry could get the same effect from using a smaller amount of gold, and this has economic advantages when you are talking about a precious metal,” Professor Evans said.
Similar benchmark tests revealed that the gold sheets could act as highly effective artificial enzymes.
The flakes are also flexible, meaning they could form the basis of electronic components for bendable screens, electronic inks and transparent conducting displays.
“There will inevitably be comparisons made between the 2D gold and the very first 2D material ever created, graphene,” Professor Evans noted.
“The translation of any new material into working products can take a long time and you can’t force it to do everything you might like to. With graphene, people have thought that it could be good for electronics or for transparent coatings — or as carbon nanotubes that could make an elevator to take us into space because of its super strength.”
“I think with 2D gold we have got some very definite ideas about where it could be used, particularly in catalytic reactions and enzymatic reactions. We know it will be more effective than existing technologies, so we have something that we believe people will be interested in developing with us.”
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Sunjie Ye et al. Sub-Nanometer Thick Gold Nanosheets as Highly Efficient Catalysts. Advanced Science, published online August 6, 2019; doi: 10.1002/advs.201900911
