Solar Cells converts Co2 into hydrocarbon fuel.

A new finding reported in the July issue of Science and was funded by the National Science Foundation and the U.S. Department of Energy. A provisional patent application has been filed. Researchers at the University of Illinois at Chicago have engineered a potentially solar cell that cheaply and efficiently converts atmospheric carbon dioxide directly into usable hydrocarbon fuel, using only sunlight for energy. The conventional solar cells, convert sunlight into electricity that must be stored in heavy batteries, but this new device essentially does the work of plants, converting atmospheric carbon dioxide into fuel, solving two crucial problems at once. A solar farm of such “artificial leaves” could remove significant amounts of carbon from the atmosphere and produce energy-dense fuel efficiently. Amin Salehi-Khojin, assistant professor of mechanical and industrial engineering at UIC and senior author on the study explained that the new solar cell is not photovoltaic but rather it’s photosynthetic. He remarked that 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. While plants produce fuel in the form of sugar, the artificial leaf delivers syngas, or synthesis gas, a mixture of hydrogen gas and carbon monoxide. Syngas can be burned directly, or converted into diesel or other hydrocarbon fuels. The ability to turn CO2 into fuel at a cost comparable to a gallon of gasoline would render fossil fuels obsolete. Chemical reactions that convert CO2 into burnable forms of carbon are called reduction reactions, the opposite of oxidation or combustion. Salehi-Khojin explained that engineers have been exploring different catalysts to drive CO2 reduction, but so far such reactions have been inefficient and rely on expensive precious metals such as silver. Salehi-Khojin and his coworkers focused on a family of nano-structured compounds called transition metal dichalcogenides — or TMDCs — as catalysts, pairing them with an unconventional ionic liquid as the electrolyte inside a two-compartment, three-electrode electrochemical cell. The best of several catalysts they studied turned out to be nanoflake tungsten diselenide.“The new catalyst is more active; more able to break carbon dioxide’s chemical bonds,” said UIC postdoctoral researcher Mohammad Asadi, first author on the Science paper. continue