The team positioned the technology as a platform for sustainable manufacturing across products from plastics and paints to pharmaceuticals and toiletries. Earlier artificial-leaf designs often relied on inorganic semiconductors or synthetic catalysts that degraded quickly, used toxic elements such as lead, or wasted large parts of the solar spectrum, limiting practical use.
The new device integrates organic semiconductors with enzymes from sulphate-reducing bacteria to either split water into hydrogen and oxygen or convert carbon dioxide into formate. In operation, it produced high currents and achieved near-perfect efficiency in steering electrons into fuel-making reactions, running for more than 24 hours, over twice the duration of previous designs.
A key stability challenge was eliminated by embedding the helper enzyme carbonic anhydrase within a porous titania structure. This allowed the system to operate in a simple bicarbonate solution, similar to sparkling water, and removed the need for chemical buffers that break down quickly and hinder long-term performance.
In proof-of-concept tests, the researchers used sunlight to generate formate and then fed it directly into a domino reaction to yield a pharmaceutical-relevant compound with high purity and high yield. The result marks the first use of organic semiconductors as the light-harvesting element in this class of biohybrid artificial leaves.
"If we're going to build a circular, sustainable economy, the chemical industry is a big, complex problem that we must address," said Professor Erwin Reisner of Cambridge's Yusuf Hamied Department of Chemistry, who led the research. "We've got to come up with ways to de-fossilise this important sector, which produces so many important products we all need. It's a huge opportunity if we can get it right."
"If we can remove the toxic components and start using organic elements, we end up with a clean chemical reaction and a single end product, without any unwanted side reactions," said co-first author Dr Celine Yeung, who completed the research as part of her PhD work in Reisner's lab. "This device combines the best of both worlds - organic semiconductors are tuneable and non-toxic, while biocatalysts are highly selective and efficient."
"It's like a big puzzle," said co-first author Dr Yongpeng Liu, a postdoctoral researcher in Reisner's lab. "We have all these different components that we've been trying to bring together for a single purpose. It took us a long time to figure out how this specific enzyme is immobilised on an electrode, but we're now starting to see the fruits from these efforts."
"By really studying how the enzyme works, we were able to precisely design the materials that make up the different layers of our sandwich-like device," said Yeung. "This design made the parts work together more effectively, from the tiny nanoscale up to the full artificial leaf."
"We've shown it's possible to create solar-powered devices that are not only efficient and durable but also free from toxic or unsustainable components," said Reisner. "This could be a fundamental platform for producing green fuels and chemicals in future - it's a real opportunity to do some exciting and important chemistry."
Research Report:Semi-artificial leaf interfacing organic semiconductors and enzymes for solar chemical synthesis
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