Scientists in Switzerland have found a new way to split carbon dioxide using a low-cost copper catalyst in a system driven by solar power. The process is carbon neutral, efficient, and may be a first step towards creating a carbon-based fuel made with CO2 captured from the atmosphere.
The system, described in an article published by Nature Energy, was able to split carbon dioxide into oxygen and carbon monoxide — which can be used to create liquid fuel — at a rate of 13.4 percent.
“It’s the highest value that has been reported,” said Marcel Schreier, a chemical engineer and lead author on the study out of Ecole Polytechnique Fédérale de Lausanne (EPFL). “Everyone in this field is interested in seeing how far we can go with what we have.”
While current technology has succeeded in splitting carbon dioxide, it includes a number of major limitations. It often relies on the use of precious metals, such as gold, silver, and palladium, used as catalysts for the reaction. In general, the process is expensive, energy-intensive, and tends to be rather unselective — even if you want carbon monoxide, the reaction of carbon dioxide with water can lead to a number of unwanted byproducts.
“Without modification, there could be up to 15 products that result from a CO2 reduction and there is no selectivity,” said Luo Jingshan, an electrochemist at EPFL and co-author on the paper. “Afterward, it requires a lot of energy or cost to separate them.”
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The system developed in Switzerland relies on low-cost, “earth abundant” materials and appears to have addressed the selectivity problem. Schreier and his team created a device that would split carbon dioxide using a solar-derived current running through copper oxide wires.
What’s more, they discovered that by applying atomic layers of tin oxide to the wires they could effectively limit the generation of unwanted byproducts and maximize the production of carbon monoxide, which is the desired result. The same catalyst they developed to split carbon dioxide also appeared to work for the oxidation of water, which is necessary to complete the reduction.
The resulting device marks the most efficient example of a solar-derived carbon dioxide splitter using a low-cost catalyst. But the technology is not without limitations. In order for the process to be scaled to an industrial level, researchers will have to increase the activity of the materials used, which is still relatively low compared to that achieved with precious metals.
But even considering the challenges, Schreier and his team are optimistic that their device could contribute to global efforts to convert carbon in the atmosphere into a viable fuel used for transportation. Currently, major research has gone into hydrogen-fueled cars, but the challenge of storing and transporting gas remains a major hurdle to commercial-scale use.
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Researchers in Switzerland hope that liquid fuels derived from carbon monoxide could offer a viable solution to this problem.
“Today, we can transform carbon-based fuel into electricity, but we cannot transform it back,” he said. “There are efforts underway all over the world to try to achieve this back conversion of electricity into a carbon-based fuels.”
The research was funded by Siemens AG, a Marie Skłodowska-Curie Fellowship from the European Union’s Seventh Framework Program, and a contribution from Abengoa Research in Spain.
While Shreier and his team are hesitant to overstate their results, they are optimistic that their low-cost catalysts and solar-driven system could offer a tool that would help to “close the anthropogenic carbon cycle.”
“We don’t yet know where our technology will finally find an application,” Schreier said. “It can make carbon monoxide, but we still have a long way to go.”
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