VATIS UPDATE Article

Researchers at the University of Illinois (U of I), the United States, have engineered a potentially game-changing solar cell that cheaply and efficiently converts atmospheric CO2 directly into usable hydrocarbon fuel, using only sunlight for energy. Unlike conventional solar cells, that convert sunlight into electricity which must be stored in heavy batteries, the new device essentially does the work of plants, converting atmospheric CO2 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.

“The new solar cell is not photovoltaic – it’s photosynthetic. 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,” said Amin Salehi-Khojin, at U of I. 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 new catalyst is 1,000 times faster than noble-metal catalysts and about 20 times cheaper. The artificial leaf consists of two silicon triple-junction photovoltaic cells of 18 square centimeters to harvest light; the tungsten diselenide and ionic liquid co-catalyst system on the cathode side; and cobalt oxide in potassium phosphate electrolyte on the anode side. When light of 100 watts per square meter – about the average intensity reaching the Earth’s surface – energizes the cell, hydrogen and carbon monoxide gas bubble up from the cathode, while free oxygen and hydrogen ions are produced at the anode.