Researchers have developed floating “artificial leaves” that generate clean fuels from sunlight and water and could eventually operate on a large scale at sea.
Researchers have designed ultra-thin devices inspired by photosynthesis. In 2019, Professor Erwin Reisner’s research group in Cambridge developed an artificial leaf, which makes syngas — a key intermediate in the production of many chemicals and pharmaceuticals — from sunlight, CO2, and water. The earlier prototype generated fuel by combining two light absorbers with suitable catalysts. However, its thick glass substrates and moisture-protective coatings made the device bulky. For the new version of the artificial leaf, the researchers were inspired by the electronics industry, where miniaturization techniques have led to the creation of flexible displays. The challenge for the researchers was how to deposit light absorbers onto lightweight substrates and protect them against water infiltration. The team used thin-film metal oxides and materials known as perovskites, which can be coated onto flexible plastic and metal foils. The devices were covered with micrometer thin, water-repellent carbon-based layers that prevented moisture degradation. They ended up with a device that works and looks like a real leaf. Tests of the new artificial leaves showed that they can split water into hydrogen and oxygen, or reduce CO2 to syngas.
Since the artificial leaves are light enough to float, they could be used to generate a sustainable alternative to gas without taking up space on land.
This is the first time that clean fuel has been generated on water, and if scaled up, the artificial leaves could be used on polluted waterways, in ports or even at sea, and could help reduce the global shipping industry’s reliance on fossil fuels.