Engineering news
Currently, the chemical industry is responsible for around 6% of global carbon emissions due to its size and the use of fossil fuel feedstocks, which are transformed through a variety of processes into hundreds of thousands of types of chemicals.
But Cambridge researchers have 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 be used to drive chemical transformations. This process mimics photosynthesis, the natural way plants convert sunlight into energy, and requires no external power.
In tests, the researchers used their device to convert sunlight and carbon dioxide into formate, which was then used in a ‘domino’ chemical reaction to make an important chemical compound often used in the pharmaceutical industry. This is the first time organic semiconductors have been used as the light-harvesting component of such a device, a departure from previous attempts at artificial leaves, which often relied on toxic or unstable light absorbers.
“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.”
“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 Celine Yeung, co-first author, 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 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.”
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.
“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.”
Want the best engineering stories delivered straight to your inbox? The Professional Engineering newsletter gives you vital updates on the most cutting-edge engineering and exciting new job opportunities. To sign up, click here.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.