An artificial leaf that could one day produce a 'clean' fuel alternative to petrol has been developed by scientists.
The leaf, created by researchers at Cambridge University, creates synthetic gas by gathering energy using sunlight, carbon dioxide and water.
Currently, synthetic gas or syngas is produced from fossil fuels and is used to produce a range of commodities, such as fuels, pharmaceuticals, plastics and fertilisers.
"You may not have heard of syngas itself, but every day you consume products that were created using it," explained Professor Erwin Reisner, of Cambridge's Department of Chemistry and a senior author of the research.
"Being able to produce it sustainably would be a critical step in closing the global carbon cycle and establishing a sustainable chemical and fuel industry."
Syngas is currently made from a mixture of hydrogen and carbon monoxide, and is used to produce a range of commodities, such as fuels, pharmaceuticals, plastics and fertilisers.
Scientists say they have managed to make the artificial leaf sustainable unlike others in the past because of the combination of materials and catalysts they used.
The overall process is achieved using two light absorbers, similar to the molecules in plants that harvest sunlight, which are combined with a catalyst made from cobalt.
When in water, one light absorber uses the catalyst to produce oxygen, while the other carries out the chemical reaction that reduces carbon dioxide and water into carbon monoxide and hydrogen, forming the syngas mixture.
The artificial leaf is able to work just as well on cloudy and overcast days.
"This means you are not limited to using this technology just in warm countries, or only operating the process during the summer months," said Virgil Andrei, a PhD student and first author of the paper, published in the Nature Materials journal.
"You could use it from dawn until dusk, anywhere in the world."
He added: "We are aiming at sustainably creating products such as ethanol, which can readily be used as a fuel. It's challenging to produce it in one step from sunlight using the carbon dioxide reduction reaction.
"But we are confident that we are going in the right direction, and that we have the right catalysts, so we believe we will be able to produce a device that can demonstrate this process in the near future."
Professor Reisner continued: "What we'd like to do next, instead of first making syngas and then converting it into liquid fuel, is to make the liquid fuel in one step from carbon dioxide and water.
"There is a major demand for liquid fuels to power heavy transport, shipping and aviation sustainably."
The results are reported in the journal Nature Materials.