CAMBRIDGE, UK: Cambridge University researchers have developed floating ‘artificial leaves’ that can generate clean fuels from sunlight and water as efficiently as plant leaves.

Published in the journal Nature, the study shows it is possible to develop alternative sustainable energy sources to fossil fuel based on the principles of photosynthesis.

This is the first time that clean fuel has been generated on water. The ultra-thin, flexible devices can be used on polluted waterways, in ports or even at sea to help reduce the global shipping industry’s reliance on fossil fuels.

In 2019, a research group led by professor Erwin Reisner from St John’s College Cambridge, developed an artificial leaf that makes syngas – a key intermediate in the production of many chemicals and pharmaceuticals – from sunlight, carbon dioxide and water.

Tests of the new artificial leaves showed that they could split water into hydrogen and oxygen, or reduce CO2 to syngas.

However while the leaves had the potential to substantially lower the cost of sustainable fuel production they were both heavy and fragile, thus making it difficult to produce at scale according to co-lead author Virgil Andrei from Cambridge’s Yusuf Hamied Department of Chemistry.

To overcome these challenges, the research team used thin-film metal oxides and materials known as perovskites, which can be coated onto flexible plastic and metal foils. The devices were then covered with micrometre thin, water-repellent carbon-based layers that prevented moisture degradation.

The result was a device that not only worked but also looked like a real leaf.

“This study demonstrates that artificial leaves are compatible with modern fabrication techniques, representing an early step towards the automation and up-scaling of solar fuel production,” explained Andrei. “These leaves combine the advantages of most solar fuel technologies, as they achieve the low weight of powder suspensions and the high performance of wired systems.”

Noting many renewable energy technologies can take up large amounts of space on land, Reisner said moving production to open water would mean that clean energy and land use aren’t competing with one another. “In theory, you could roll up these devices and put them almost anywhere, in almost any country, which would also help with energy security.”