Nanoscale dots can absorb sunlight and release hydrogen from water, without damage from bleaching
13:59 11 February 2010 by Colin Barras
Sunlight + water = hydrogen gas, in a new technique that can convert 60 per cent of sunlight energy absorbed by an electrode into the inflammable fuel.
To generate the gas Thomas Nann and colleagues at the University of East Anglia in Norwich, UK, dip a gold electrode with a special coating into water and expose it to light. clusters of indium phosphide 5 nanometres wide on its surface absorb incoming photons and pass electrons bearing their energy on to clusters of a sulphurous iron compound.
This material combines those electrons with protons from the water to form gaseous hydrogen. A second electrode – plain platinum this time – is needed to complete the circuit electrochemically.
Organic molecules have been used before to perform the same feat. But they are quickly bleached by the sunlight they are collecting, rendering them inefficient after a few weeks.
The inorganic materials used in the University of East Anglia's system are more resilient. Their first generation proof of concept is "a major breakthrough" in the field, they say, thanks to its efficiency of over 60 per cent and ability to survive sunlight for two weeks without any degradation of performance.
"In fact the 60 per cent figure is probably a worst-case scenario," says Nann. "This is still a preliminary study." …
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