KASHIWAYA, S. et al. Nature Synthesis. 2024Two representations of the structure of goldene (top) and the solution containing the gold (photograph)KASHIWAYA, S. et al. Nature Synthesis. 2024
In 2019, scientists at the University of Leeds, UK, announced a new form of gold that is just two atoms thick. It was the thinnest unsupported gold ever created, at just 0.47 nanometers (nm) thick. Now, a group from Linköping University, Sweden, has presented a gold foil just one atom thick called goldene, the latest metallic cousin of graphene. Each gold atom is bonded to six others, rather than 12 in a three-dimensional crystal, forming a sheet with a thickness of about 50 micrometers (μm; 1 μm corresponds to one thousand nm). Materials physicist Lars Hultman and his team used an electrically conductive ceramic called titanium silicon carbide, which they intended to coat with gold. Under high temperatures, the gold replaced the silicon and formed titanium gold carbide. They then used a potassium-based solution to release the goldene. The problem was that the gold layer curled up on itself like a scroll. Luckily, the team was able to flatten the sheet by adding a surfactant (a substance that reduces the surface tension of the liquid) to the solution in which the sheets were floating. A kind of sieve was then used to collect the gold dispersed in the solution. Because of its structure, the new material could be used in carbon dioxide conversion, hydrogen production, water purification, and electronic devices (Advanced Science, August 6, 2019; Nature Synthesis, April 16, 2024).
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