A proof-of-concept device that can split water and produce recoverable hydrogen has been developed by researchers at Penn State University.

Thomas E Mallouk, the DuPont professor of materials chemistry and physics, W Justin Youngblood, postdoctoral fellow in chemistry, and a number of collaborators from Arizona State University have developed a catalyst system that, when combined with a dye, can mimic the electron transfer and water oxidation processes that occur in plants during photosynthesis.

At the root of this breakthrough is a small complex of molecules with a centre catalyst of iridium oxide molecules surrounded by orange-red dye molecules.

When visible light comes into contact with the dye, electrons in the dye are excited and act, with the help of the catalyst, to split water molecules and create free oxygen.

"Each surface iridium atom can cycle through the water oxidation reaction about 50 times per second," commented Professor Mallouk.

"That is about three orders of magnitude faster than the next best synthetic catalysts, and comparable to the turnover rate of Photosystem II in green plant photosynthesis."

Professor Mallouk believes that if the proof of concept device is realised, water photosynthesis could be used to provide a clean source of hydrogen fuel from water and sunlight.

Scientists have also used ruthenium and platinum to mimic photosynthesis in recent months.

Sources:

Solar cell directly splits water for hydrogen
http://www.eurekalert.org/pub_releases/2008-02/ps-scd021108.php

Ruthenium catalysts driving 'artificial photosynthesis' 29th March 2007
http://www.platinum.matthey.com/media_room/1175158805.html

Platinum electrode used to mimic photosynthesis - 29th November 2007
http://www.platinum.matthey.com/media_room/1196330407.html

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