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Solar cell captures CO2 and sunlight

Bill Burton

Researchers at the University of Illinois at Chicago (UIC) have engineered a potentially game-changing solar cell that cheaply and efficiently converts atmospheric carbon dioxide directly into usable hydrocarbon fuel, using only sunlight for energy. Unlike conventional solar cells, which convert sunlight into electricity that must be stored in heavy batteries, the new device essentially does the work of plants, converting atmospheric carbon dioxide into fuel and thus solving two 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. “The new solar cell is not photovoltaic — it’s photosynthetic,” said Amin SalehiKhojin, assistant professor of mechanical and industrial engineering at UIC and with extraordinary properties,” he said.

senior author on the study. “Instead of producing energy in

The UIC artificial leaf consists of two

an unsustainable, one-way route from

silicon triple-junction photovoltaic cells

fossil fuels to greenhouse gas, we can

of 18 cm2 to harvest light: the tungsten

now reverse the process and recycle

diselenide and ionic liquid co-catalyst

atmospheric carbon into fuel using

system on the cathode side and cobalt oxide in potassium phosphate electrolyte

sunlight,” he said.

on the anode side.

While plants produce fuel in the form

Chemical reactions that convert CO2 into

of sugar, the artificial leaf delivers syngas,

burnable forms of carbon are called reduction

The technology should be adaptable

or synthesis gas — a mixture of hydrogen

reactions, the opposite of oxidation or

not only to large-scale use, like solar

gas and carbon monoxide. Syngas can be

combustion. Engineers have been exploring

farms, but also to small-scale applications,

burned directly or converted into diesel

different catalysts to drive CO2 reduction, but

Salehi-Khojin said. The finding is reported

or other hydrocarbon fuels.

so far such reactions have been inefficient

in the journal Science and was funded by

The ability to turn CO 2 into fuel at a

and rely on expensive precious metals

the National Science Foundation and the

cost comparable to petrol could render

such as silver, Salehi-Khojin said. “What

US Department of Energy. A provisional

fossil fuels obsolete.

we needed was a new family of chemicals

patent application has been filed.

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Sustainability Matters Oct/Nov 2016  

Sustainability Matters is a bi-monthly magazine showcasing the latest products, technology and sustainable solutions for industry, governmen...

Sustainability Matters Oct/Nov 2016  

Sustainability Matters is a bi-monthly magazine showcasing the latest products, technology and sustainable solutions for industry, governmen...