Floating artificial leaves make fuel from sunlight, water and CO2

Floating artificial leaves make fuel from sunlight, water and CO2

Technology News |
By Peter Clarke

Researchers at Cambridge University have produced a lightweight artificial leaf that can float on water photosynthesizing ‘syn-gas’ from sunlight, water and carbon-dioxide.

The work was done in the research group of Professor Erwin Reisner at Cambridge University and is a lightweight version of its previously developed artificial leaf (see Improved artificial leaf a step closer to climate-saving deployment).

Syn-gas is a fuel gas mixture of hydrogen and carbon monoxide and the researchers are proposing that large areas of water could be covered with such syn-gas generators as a source of sustainable solar-generated fuel.

The researchers have shown that perovskite-BiVO4 photocathodes deposited into indium tin oxide polyethylene terephthalate generated hydrogen using a platinum catalyst and reduced CO2 and split water.


The devices showed unassisted solar-to-fuel efficiencies of 0.58 percent (H2) and 0.053 percent (CO), respectively. Their potential for scalability is demonstrated by stand-alone artificial leaves with an active area of 10cm by 10 cm.

Bubbles formed under operation further enabled the devices that weighed 30 to 100 mg per square centimeter to float. Lightweight reactors facilitated gas collection during outdoor testing on the River Cam.

The activity per gram is comparable to photocatalytic suspensions in liquid and to plant leaves. The researchers argue that such floating systems may enable open-water applications, thus avoiding competition with land use.

“Artificial leaves could substantially lower the cost of sustainable fuel production, but since they’re both heavy and fragile, they’re difficult to produce at scale and transport,” said Virgil Andrei, the paper’s co-lead author, in a statement.

Water not land

“We wanted to see how far we can trim down the materials these devices use, while not affecting their performance,” said Professor Reisner. “If we can trim the materials down far enough that they’re light enough to float, then it opens up whole new ways that these artificial leaves could be used.”

The devices were covered with thin, water-repellent carbon-based layers that prevented moisture degradation. The research team produced a device that not only works like a leaf but also looks like one.

“These could supply coastal settlements, remote islands, cover industrial ponds, or avoid water evaporation from irrigation canals,” said Andrei.

Additional work needs to be done to demonstrate the long-term stability and life time of such systems.

Related links and articles:

Virgil Andrei et al. ‘Floating perovskite-BiVO4 devices for scalable solar fuel production.’ Nature (2022). DOI: 10.1038/s41586-022-04978-6

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