It sounds like science fiction: a leaf that is part machine, part biological organism, quietly turning sunlight, water and carbon dioxide into useful fuel and chemicals. Yet that is exactly what scientists at the University of Cambridge and their collaborators have created — a “semi-artificial” leaf that could point the way to cleaner industry and more sustainable living across the colder, sun-hungry regions of the world.
The team has managed to combine the elegance of biology with the precision of materials science. Their solar device uses organic semiconductors — carbon-based materials that conduct electricity when illuminated — together with natural enzymes, the protein catalysts that make life’s chemistry possible. By linking the two, they have built a system that mimics photosynthesis but does something plants never evolved to do: it produces formate, a liquid fuel and chemical building block, directly from sunlight and carbon dioxide.
Traditional artificial-photosynthesis systems rely on heavy metals or “sacrificial” chemicals to shuttle electrons around. These are effective but toxic or short-lived, and they can’t be scaled sustainably. The Cambridge design sidesteps those pitfalls. The researchers embedded the enzymes inside a delicate titanium-oxide scaffold, where they can tap into the steady stream of electrons generated by the light-harvesting layer above. Working together, one enzyme splits water to release hydrogen, while another captures carbon dioxide and turns it into formate — all in ordinary bicarbonate solution, without the need for any harmful additives.
In laboratory tests, the leaf ran for many hours, powered only by light, achieving high efficiency and stability. Crucially, the formate it produced could be used straight away, without purification, to drive a synthetic chemical reaction — the same kind used in making medicines, plastics and fragrances. Using a well-known ruthenium catalyst, the researchers transformed acetophenone into a chiral alcohol, a key intermediate for pharmaceuticals, with remarkable precision. In effect, sunlight became a direct energy source for fine-chemical synthesis.
The implications go beyond the laboratory bench. In northern Europe and Canada, where low temperatures and diffuse sunlight make biological growth slow, such hybrid systems could enable “chemical greenhouses”: compact units that use sunlight to produce clean fuels and industrial ingredients on-site, even in winter. Because the materials are based on abundant elements and biodegradable components, they could eventually be mass-produced with little environmental cost.
The project’s leader, Erwin Reisner, describes it as a step toward biohybrid chemical refineries — factories that use nature’s catalysts but no fossil fuels. Instead of burning carbon, they would capture it, recycling the gas into new products with the help of light. The beauty of this approach lies in its adaptability: by swapping in different enzymes, the same platform could one day produce a range of fuels and chemicals, from hydrogen to methanol.
If the 20th century belonged to oil refineries, the next may belong to leaves like these — silent, sunlight-powered workshops for the sustainable world we urgently need.
Source
Semi-artificial leaf interfacing organic semiconductors and enzymes for solar chemical synthesis, Joule 9, 2025-11-19
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