Semi-artificial organic photocathode in operation. Celine Yeung
Researchers have developed a breakthrough method that could lead to ‘de-fossilised’ chemical industry. Researchers led by the University of Cambridge have demonstrated a new and sustainable way to make the chemicals, which help make thousands of products – from plastics to cosmetics.
Hundreds of thousands of chemicals are manufactured by the chemical industry, which transforms raw materials – usually fossil fuels – into useful end products. Due to its size and its use of fossil fuel feedstocks, the chemical industry is responsible for roughly 6% of global carbon emissions.
Researchers from University of Cambridge highlighted that their method could one day lead to the ‘de-fossilisation’ of this important sector.
The research team revealed that they developed a hybrid device that combines light-harvesting organic polymers with bacterial enzymes to convert sunlight, water and carbon dioxide into formate, a fuel that can drive further chemical transformations.
Their ‘semi-artificial leaf’ mimics photosynthesis: the process plants use to convert sunlight into energy, and does not require any external power source. Unlike earlier prototypes, which often relied on toxic or unstable light absorbers, the new biohybrid design avoids toxic semiconductors, lasts longer, and can run without additional chemicals that previously hindered efficiency, according to a press release.
“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 from 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.”
The research team also pointed out that they used sunlight to convert carbon dioxide into formate and then used it directly in a ‘domino’ chemical reaction to produce an important type of compound used in pharmaceuticals, with high yield and purity.
Published in the journal Joule, the results reveal that it’s the first time that organic semiconductors have been used as the light-harvesting component in this type of biohybrid device, opening the door to a new family of sustainable artificial leaves.
The chemical industry is central to the world economy, producing products from pharmaceuticals and fertilisers, to plastics, paints, electronics, cleaning products, and toiletries.
The team pointed out that the new device integrates organic semiconductors with enzymes from sulphate-reducing bacteria, splitting water into hydrogen and oxygen or converting carbon dioxide into formate.
“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.”
Researchers also pointed out that their tests showed the artificial leaf produced high currents and achieved near-perfect efficiency in directing electrons into fuel-making reactions. The device successfully ran for over 24 hours: more than twice as long as previous designs.
The researchers are hoping to further develop their designs to extend the lifespan of the device and adapt it so it can produce different types of chemical products, as per the release.
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