Harvard scientists have unveiled an improved version of a "bionic leaf" that converts solar energy into liquid fuel through an artificial version of photosynthesis that's more efficient than the natural version.

"Bionic Leaf 2.0" uses solar electricity generated by solar panels to divide water molecules into oxygen and hydrogen, their component elements. The hydrogen is then transferred to a chamber where a bacteria called Ralstonia eutropha feed on it and converts CO2 in the air into alcohol fuels. The process uses a special cobalt and phosphorus catalyst to generate liquid fuel.

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The new catalyst improved version 2.0's efficiency at producing alcohol fuels like isopropanol and isobutanol to about 10 percent. That also means for every kilowatt hour of electricity used, the microbes can remove 130 grams of CO2 out of 230,000 liters of air to make 60 grams of isopropanol fuel.

That's better than the efficiency of natural photosynthesis at converting water sunlight and air into stored energy.

The new artificial leaf has been able to operate for up to 16 days at a go, said chemist Daniel Nocera of Harvard. His team worked with synthetic biologist Pamela Silver of Harvard Medical School on the new version. Nocera described Bionic Leaf 2.0 as a melding of biology and technology.

"This is a true artificial photosynthesis system," said Nocera. "Before, people were using artificial photosynthesis for water-splitting, but this is a true A-to-Z system, and we've gone well over the efficiency of photosynthesis in nature."

The team's first artificial photosynthesis device appeared in 2015 but the team went back to the drawing board to seek out a better catalyst. Nocera said the new catalyst can never die while it's functioning.

He also noted the new cobalt catalyst also splits water into hydrogen and oxygen without generating reactive oxygen molecules that can damage DNA or other processes essential to continuing life. 

Tagsbionic leaf, Bionic Leaf 2.0, Photosynthesis, Ralstonia eutropha, Harvard, Daniel Nocera, Pamela Silver