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An abstract computer illustration of a web of connected golden points of light. — Researchers have synthesized sheets of gold that are one atom thick.Credit: imaginima/Getty

Goldene is a cousin of graphene, the single-atom-thick sheet of carbon first discovered in 2004 — but made of gold. Goldene is roughly 400 times as thin as the thinnest commercial gold leaf, and might find use as a catalyst, or in light-sensing devices.

Nature | 4 min read

Reference: Nature Synthesis paper

GOLD MINING. Graphic shows the method researchers used to create goldene – a single layer of interconnected gold atoms. — Source: Adapted from Ref. 1.

Researchers in Canada are thrilled by “the largest investment in graduate students and postdocs in over 21 years”, says Kaitlin Kharas, a PhD student and executive director of the campaign group Support Our Science.

The 2024 Canadian federal budget gave:

• whopping increases to stipends for masters and PhD students and postgraduate researchers

• an extra Can$1.8 billion over five years in core funding for the three federal research councils

• more than Can$2 billion for the AI sector in Canada

Nature | 4 min read

The queens of some species of bumblebee can survive after being underwater for one week, which could help them withstand floods when they hibernate underground. An experimental accident revealed the possibility, and tests on 126 common eastern bumblebee (Bombus impatiens) queens confirmed that most can survive immersion for up to 7 days. The findings hint that other bee species could also have built-in flood resilience. “This seems to be one small aspect of climate change that we need not worry about,” says bee researcher Dave Goulson.

The Guardian | 4 min read

Reference: Biology Letters paper

Hundreds of artefacts sheltered by a lava-tube cave in what is now Saudi Arabia show that herders and their livestock used the cave on and off for the past 10,000 years. The region near the Umm Jirsan cave was once lush and green. Now, wind and scorching heat mean that, across the surface of Saudi Arabia, “the fossil record is just horrendous”, says zooarchaeologist and study co-author Mathew Stewart. But an 88,000-year-old finger bone described in 2018 — one of the oldest human fossils found outside Africa — hints at the region’s hidden history.

Nature | 4 min read

Reference: PLoS One paper

Four people standing in a tunnel with an arch-shaped roof made of basalt. — Inside the Umm Jirsan lava-tube cave, researchers have found evidence of human occupation dating back 10,000 years.Credit: Green Arabia Project

Features & opinion

During the pandemic, sewage provided a critical source of data for monitoring the spread of SARS-CoV-2. In Hong Kong, routine wastewater tests traced the virus to a single apartment block where no COVID had been reported — ultimately uncovering nine active cases. Now “every day, we come up with new things that we can interrogate wastewater for”, says public-health researcher Ted Smith — including signs of drug misuse, antimicrobial resistance and exposure to air pollution. Wastewater research coordinator Bernd Manfred Gawlik calls wastewater the “dirty blood of the city”, and compares sewage sampling to blood testing. “We are now only starting to understand” how to diagnose this “blood” at the collective level, he says.

Nature | 12 min read

Corporate lobbyists with vested interests in fossil fuels should be kept at arm’s length from negotiations for a global plastics treaty, writes ecotoxicologist Martin Wagner. The number of lobbyists from chemical and oil companies outnumbered scientists four to one in the previous round of talks. Their presence threatens to weaken the treaty by casting doubt on plastics research or demanding cumbersome risk assessments for individual component chemicals, says Wagner. Scientists also need better access to the talks for them to be meaningful, argues a Nature editorial.

Nature World View | 5 min read | & Nature Editorial | 5 min read

Countries are introducing some of the toughest restrictions ever on tobacco use and vaping — especially among young people. New laws in the United Kingdom, Australia and France could save thousands of lives and billions of dollars, say scientists. Many nations are banning disposable vapes that don’t contain tobacco but still deliver nicotine, which can raise blood pressure and disrupt brain development. “This policy push should see the upswing in youth vaping contained and reversed,” says epidemiologist Tony Blakely.

Nature | 6 min read

QUOTE OF THE DAY

In Kenya, this traditional adage reflects a modern reality: herders are replacing cattle with milk-producing camels to adapt to climate change. (The Washington Post | 12 min read)

Today we’re reeling from the sight of what is probably an ancient hominid jaw bone encased in a stone tile. A Reddit user, who’s also a dentist, spotted the mandible in his parents’ new travertine floor. This type of limestone often contains fossils, notes paleoanthropologist John Hawks. “This naturally raises a broader question: How many other people have installed travertine with hominin fossils inside?”

Let me know about what telltale hearts you’ve got hidden under the floorboards — plus any other feedback on this newsletter — at [email protected].

Thanks for reading,

Flora Graham, senior editor, Nature Briefing

With contributions by Gemma Conroy, Sarah Tomlin and Katharine Sanderson

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It is the world’s thinnest gold leaf: a gossamer sheet of gold just one atom thick. Researchers have synthesized¹ the long-sought material, known as goldene, which is expected to capture light in ways that could be useful in applications such as sensing and catalysis.

Goldene is a gilded cousin of graphene, the iconic atom-thin material made of carbon that was discovered in 2004. Since then, scientists have identified hundreds more of these 2D materials. But it has been particularly difficult to produce 2D sheets of metals, because their atoms have always tended to cluster together to make nanoparticles instead.

Researchers have previously reported single-atom-thick layers of tin² and lead³ stuck to various substances, and they have produced gold sheets sandwiched between other materials. But “we submit that goldene is the first free-standing 2D metal, to the best of our knowledge”, says materials scientist Lars Hultman at Linköping University in Sweden, who is part of the team behind the new research. Crucially, the simple chemical method used to make goldene should be amenable to larger-scale production, the researchers reported in Nature Synthesis on 16 April¹.

“I’m very excited about it,” says Stephanie Reich, a solid-state physicist and materials scientist at the Free University of Berlin, who was not involved in the work. “People have been thinking for quite some time how to take traditional metals and make them into really well-ordered 2D monolayers.”

In 2022, researchers at New York University Abu Dhabi (NYUAD) said that they had produced goldene, but the Linköping team contends that the prior material probably contained multiple atomic layers, on the basis of the electron microscopy images and other data that were published in ACS Applied Materials and Interfaces⁴. Reich agrees that the 2022 study failed to prove that the material was singler-layer goldene. The principal authors of the NYUAD study did not respond to Nature’s questions about their work.

Golden age

To prepare goldene, the Linköping researchers started with a material containing atomic monolayers of silicon sandwiched between titanium carbide. When they added gold on top of this sandwich, it diffused into the structure and exchanged places with the silicon to create a trapped atom-thick layer of gold (see ‘Gold mining’). They then etched away the titanium carbide to release free-standing goldene sheets that were up to 100 nanometres wide, and roughly 400 times as thin as the thinnest commercial gold leaf, Hultman estimates.

That etching process used a solution of alkaline potassium ferricyanide known as Murukami’s reagent. “What’s so fascinating is that it’s a 100-year-old recipe used by Japanese smiths to decorate ironwork,” Hultman says. The researchers also added surfactant molecules — compounds that formed a protective barrier between goldene and the surrounding liquid — to stop the sheets from sticking together.

The Linköping team suggests that goldene might be useful in applications in which gold nanoparticles already show promise. Light can generate waves in the sea of electrons at a gold nanoparticle’s surface, which can channel and concentrate that energy. This strong response to light has been harnessed in gold photocatalysts to split water to produce hydrogen, for instance. Goldene could open up opportunities in areas such as this, Hultman says, but its properties need to be investigated in more detail first.

“I think the research is really interesting,” says Graham Hutchings, a chemist at the University of Cardiff, UK, who develops gold catalysts. But he worries that any residual traces of iron from Murukami’s reagent might hamper the development of goldene as a catalyst. “I would think that potential contamination with iron is going to cause a few problems in applications,” he says.

For now, the Linköping researchers are seeking better ways to sieve goldene from the solution used to make it, and to grow larger flakes of the material. They are also exploring whether their method can be used to make monolayers of other catalytic metals, including iridium, platinum and palladium.

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