University of Illinois at Chicago (UIC) engineers have designed a new type of solar cell that can transform carbon dioxide in the atmosphere into usable hydrocarbon fuel. Amazingly, it uses only sunlight as energy.

The innovative system can convert carbon dioxide into fuel that is like producing gasoline, describes engineer Amin Salehi-Khojin. "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," noted Salehi-Khojin in a press statement. 

Researchers harnessed a photosynthetic cell----unlike a traditional photovoltaic cell that can turn sunlight into electric energy to be stored in batteries. Instead, the photosynthetic cell turns atmospheric carbon dioxide into fuel, which in effect does the work of plants. However, instead of converting fuel into sugar, the "artificial leaf" delivers synthetic gas, or "syngas," which is a mixture of hydrogen gas and carbon monoxide. This solar-produced gas can be burned directly, or converted into other forms of fuel, like diesel.

"The beauty of this work is it directly uses the energy of the sun. This doesn't need any electricity or external energy," said Mohammad Asadi, the study's lead author and a researcher in Salehi-Khojin's lab.

To make the process efficient, the researchers turned to a family of nano-structured compounds called transition metal dichalcogenides (TMDCs). These compounds served as active catalysts, breaking carbon dioxide's chemical bonds. Experiments showed that the new catalyst is 1,000 times faster than conventional catalysts, and about 20 times less expensive.

In coming times, a solar farm can use thousands of such "artificial leaves" in order to produce fuel and also clean the atmosphere of carbon dioxide. It can be made to work on smaller scales. It might even be useful to be employed on Mars, which is composed of mostly carbon dioxide.

The study was published in journal Science.