An “artificial leaf” mimics photosynthesis in plants.
Researchers are increasingly seeing the value in carbon monoxide as a source of alternative fuel rather than as merely a type of pollution. Now researchers at the University of Illinois at Chicago (UIC) have worked with solar energy to do something similar, engineering a solar cell that converts atmospheric carbon dioxide directly into usable hydrocarbon fuel.
The new device — an “artificial leaf” of sorts engineered by Amin Salehi-Khojin, assistant professor of mechanical and industrial engineering at UIC and his team — mimics photosynthesis in plants, making it “photosynthetic” rather than photovoltaic, which is what typical solar cells are.
“Instead of producing energy in an unsustainable one-way route from fossil fuels to greenhouse gas, we can now reverse the process and recycle atmospheric carbon into fuel using sunlight,” Salehi-Khojin said.
The artificial leaf is different from plants in that instead of delivering fuel in the form of sugar, it delivers syngas, or synthesis gas, which is a mixture of hydrogen gas and carbon monoxide. Syngas has several uses as a biofuel; it can be burned directly or converted into diesel or other hydrocarbon fuels, he said.
Key to the research is its reduction reaction — or chemical reaction that converts carbon dioxide into burnable forms of carbon. Researchers have been working with different catalysts to induce these reactions, with inefficient and expensive results so far, Salehi-Khojin said.
The UIC team was more successful because it focused on a family of nano-structured compounds called transition metal dichalcogenides, or TMDCs, as catalysts, researchers said. In experiments, they paired these with an unconventional ionic liquid as the electrolyte inside a two-compartment, three-electrode electrochemical cell, finding that the best catalyst was a nanoflake tungsten diselenide, which had the strongest ability to break carbon dioxide’s chemical bonds, according to the team. Indeed, the catalyst proved 1,000 times faster than typical noble-metal catalysts, and about 20 times cheaper, researchers said.
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