System transforms CO2 into CO using renewable electricity

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Researchers at Rowland Institute at Harvard have developed a new system capable of electrochemically transforming carbon dioxide into carbon monoxide using renewable electricity for use in industries.

As much as 2 million pounds of carbon dioxide is pumped into the atmosphere from factories, emissions from cars and trucks and the burning of coal and natural gas to generate electricity on any given day. The issue of CO2 is becoming a huge one and while it is definitely a massive greenhouse gas pollutant, some scientists believe it is a perfect raw material for many products currently used in industries.

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In a new paper published in Chem, researchers have described a system that uses renewable electricity to electrochemically transform carbon dioxide into carbon monoxide – a key commodity used in any number of industrial processes. The energy conversion efficiency from sunlight to CO can be as high as 12.7 per cent, more than one order of magnitude higher than natural photosynthesis.

That reaction takes place in an unassuming-looking device, barely the size of a smartphone, that includes two electrolyte-filled chambers separated by an ion exchange membrane.

On one site, an electrode powered by renewable energy oxidizes water molecules into oxygen gas and frees protons. These protons move to the other chamber where – with the help of a carefully designed metal single atom catalyst – they bind to carbon dioxide molecules, creating water and carbon monoxide.

Unfortunately, the two best-known such catalysts are gold and silver – precious metals that are very costly to make the reaction cost effective on a large scale. In addition, they can all very easily be poisoned by carbon monoxide. So even if it is possible to use them to reduce CO2, the resulting CO bonds very strongly to the surface, preventing any further reactions from taking place.

To solve those problems, scientists set about working to “tune” the electronic properties of the metals. The team rationalized the nature of active sites by atomic scale modeling and discovered that dispersing nickel metals into isolated single atoms, which are trapped in graphene vacancies, produced a material that was eager to react with carbon dioxide and willing to release the resulting carbon monoxide.