Swedish researchers at Linköping University have successfully created the world’s thinnest gold foil, known as “goldene”, which has numerous applications in carbon dioxide conversion and hydrogen production. The team utilized a 100-year-old technique used by Japanese ironsmiths to separate layers of gold in order to achieve this breakthrough.
In the journal Nature Synthesis, the research team demonstrated the unique optical, electronic, and catalytic properties of two-dimensional materials like goldene. These materials have a high surface area relative to volume, making them behave differently from bulk solids. While there have been several examples of 2D materials discovered since graphene in 2004, creating a pure metal sheet just one molecule thick has proven to be more challenging.
The lead author, Shun Kashiwaya and his colleagues developed a multi-layer structure of titanium, silicon, and carbon, and coated the surface with gold. By carefully separating the surrounding solid mass using a 100-year-old chemical etching method, they were able to isolate the goldene layer intact. The team further refined their method by experimenting with different reaction conditions and etching solution densities. They discovered that adding the amino acid cysteine as a surfactant helps stabilize the separated layer and prevent gold atoms from forming nanoparticles. The resulting goldene layer is up to 100 nanometers long and significantly thinner than regular gold leaf.
Goldene holds promise for applications in converting carbon dioxide into fuels like ethanol and methane, as well as producing hydrogen from water due to its enhanced chemical reactivity. The researchers are continuing to optimize their synthesis method for further advancements in this groundbreaking material.