Scientists Create Sheet of Gold Just Two Atoms Thick, Thinnest in the World

Scientists have created the thinnest layer of gold ever produced, a potentially game-changing development for one of the most expensive and essential industrial materials on Earth.

Gold has been one of the most sought after metals on Earth for both its beauty and luster as well as its significance as a store of value. It is also an essential material for electronics and industrial processes, driving up the costs on everything from electronic devices to machinery and scientific equipment. Now, a major development from the University of Leeds in the United Kingdom has produced the thinnest unsupported sheet of gold ever created, just two atoms thick, opening the door to a major cost-saving technique for industrial, scientific, and commercial applications.

Researchers Produce Gold Nanosheets Just Two Atoms Thick

Gold Nanosheet
A gold nanosheet under an electron microscope           Source: Sunjie Ye, et al. | University of Leeds/Advanced Science

Researchers at the University of Leeds announced this month in the journal Advanced Science that they have developed a technique for producing sheets of gold lattices just two atoms thick, a potentially game-changing development for the incredibly expensive but essential industrial and scientific material.

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The nanosheets were measured by the researchers at less than half a nanometer, 0.47 nanometers to be exact, and every atom in the gold nanosheet is a surface atom, meaning no bulk, non-reactive atoms are present in the material. In terms of efficiency, you cannot produce a more effective material as every atom in the sheet can be utilized in industrial and scientific processes as well as various electronic devices that rely heavily on components that require the precious metal to operate.

Even more notable, the process used to create the gold nanosheet isn't limited to just gold, it can be used to produce nanosheets of many different elements or materials, according to paper lead-author Dr. Sunjie Ye, from Leeds' Molecular and Nanoscale Physics Group and the Leeds' Institute of Medical Research.

"This 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. This method could innovate nanomaterial manufacturing."

Any time you are making something at the nanoscale, it is an impressive feat of engineering, but producing a two-dimensional sheet of gold atoms is even more incredible. To create the sheet, the Leeds researchers started with chloroauric acid, a compound containing gold, suspended in an aqueous solution. They then introduced a 'confinement agent', or a substance that induces the gold in the acid to reduce to its metallic form, which in this case produces a layered sheet two atoms thick. That's it.

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The relative simplicity of the technique is important since it is likely to scale much more quickly than more complicated methods of material fabrication. Given the potential cost savings offered by the new material, industrial firms and scientific institutes have every reason to invest in developing this process further.

How Gold Nanosheets Can Drastically Lower Costs for Industrial Applications and Scientific Research

Gold Nanosheet Process
The process used to produce a gold nanosheet            Source: Sunjie Ye, et al. | University of Leeds/Advanced Science

The emphasis on gold is important given its integral role in industry, science, and technology. Besides being widely used in the connectors of every kind of electronic component under the sun, gold nanoparticles play an essential role as a catalyst for various chemical reactions required in industrial processes. Gold nanoparticles are widely used, and given the cost of the substance, this unavoidable reliance on gold can drive up costs for research and industrial applications.

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This is especially true since so much of the gold nanoparticles used today are largely bulk particles hidden away below the surface layer atoms. These hidden atoms don't act as a catalyst for chemical reactions since they never come into contact with other substances.

The new gold nanosheets, however, are two dimensional. Every atom in the gold nanosheet is a surface atom, so no excess gold is wasted in the process. This could help dramatically lower costs for the industrial and scientific use of the precious metal. Because of this, the Leeds researchers have determined that the gold nanosheets offer ten times the efficiency as a catalytic substrate compared to the widely-used, but much larger, gold nanoparticles.

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Professor Stephen Evans, head of the Leeds' Molecular and Nanoscale Physics Group and supervisor for the research team believes that this innovation has the potential to be transformative in current industrial processes and hi-tech devices.

"Gold is a highly effective catalyst," Evans' said. "Because the nanosheets are so thin, just about every gold atom plays a part in the catalysis. It means the process is highly efficient," adding "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."

The development calls to mind the development of the original two-dimensional material, graphene, over a decade ago by researchers at the University of Manchester. Graphene still holds incredible promise as a material, but the widespread use of the material that many predicted at the time has yet to materialize.

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While graphene has incredible strength relative to other materials, it is also costly to produce, and there really isn't anything that graphene can effectively replace at a lower cost. As a result, graphene hasn't seen the widespread industrial or commercial use that many were hoping to see back in 2004.

The same cannot be said for gold, a material that is already widely used in industry at incredible expense. Replacing the existing gold material you are already using with an even more efficient form of that same material at a drastically reduced cost is a no-brainer.

"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," said Evans. "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.

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"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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