01 Aug 2016

NEW SOLAR CELL TURNS CO2 INTO BURNABLE FUEL

Recreating a plant's ability to use sunlight to turn carbon dioxide into fuel, something known as artificial photosynthesis, is one of the holy grails of green energy research. Scientists at Chicago's University of Illinois have been working with new kinds of chemicals with new kinds of properties to take these efforts to the next level. The key, they say, is to discover a new type of catalyst that can turn atmospheric CO2 into burnable fuels in an efficient and inexpensive way.

In pursuit of this, the team was working with a set of nanostructured compounds called transition metal dichalcogenides, or TMDCs. It happened upon one TMDC called nanoflake tungsten diselenide which, when paired with water and a particular ionic liquid as the electrolyte, worked 1,000 times faster than the expensive metals usually used in these CO2 reduction technologies. The fact that it is about 20 times cheaper didn't hurt either.

The solar cell itself is made up of two silicon triple-junction photovoltaic cells measuring 18 cm sq (2.8 in sq) to harvest the light, with the co-catalyst system on the cathode side and cobalt oxide in potassium phosphate electrolyte on the anode side.

When 100 W of light per meter squared hits the cell, it kicks off a chemical reaction where hydrogen and carbon monoxide gas are produced from the cathode. Free oxygen and hydrogen ions are generated at the anode. This reaction creates synthesis gas, or syngas, which can be burned as is or turned into diesel and other hydrocarbon fuels.

According to the team, the solar cell could be adapted to large-scale use such as solar farms, along with smaller applications. The new solar cell is not photovoltaic but is photosynthetic, instead of producing energy in an unsustainable one-way route from fossil fuels to greenhouse gas, it reverses the process and recycles atmospheric carbon into fuel by using sunlight.

 



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