It seems that it will be possibleto fabricate reliable photosynthetic material one atomic layer at a time usingindustrial methods. The protocol beenworked on would drive hydrogen production which is intriguing. Such a system could well accept fairly lowyields if it is sufficiently cost effective. Imagine a siding product that produces hydrogen as a byproduct. It does not have to be great to earn itskeep.
I suspect that such an endproduct is still a fair ways away but it is certainly a decent objective andproducing hydrogen is a viable alternative to simple electric power for thelikely style of application.
A lot has been done in the pastfew years to produce an energy absorbing and energy converting buildingprotocol. It appears that we are yet along ways away from a practical system, but the advantages are drivinginterest. Thus the flow of incrementalimprovements such as this.
New technique improves artificial photosynthesis
by Staff Writers
This discovery will make it possible to improve photoelectrochemical cells. Inthe same way that plants use photosynthesis to transform sunlight into energy,these cells use sunlight to drive chemicalreactions thatultimately produce hydrogen fromwater.
The process involves using a light-sensitive semi-conducting materialsuch as cuprous oxide to provide the current needed to fuel the reaction.Although it is not expensive, the oxide is unstable if exposed to light inwater. Research by Adriana Paracchino and Elijah Thimsen, published in thejournal Nature Materials, demonstrates that this problem can be overcome bycovering the semiconductor with a thin film of atoms using the atomic layer deposition(ALD)technique.
Under the supervision of Professor Michael Gratzel in EPFL's Laboratoryof Photonics and Interfaces, the two scientists achieved this remarkable featby combining techniques used at the industrial scale, and then applying them tothe problem of producing hydrogen. With their process, cuprous oxide can besimply and effectively protected from contact with water, making it possible touse it as a semiconductor.
The advantages are numerous: cuprous oxide is abundantly available andinexpensive; the protective layer is completely impermeable, regardless of theroughness of the surface; and the process can easily be scaled up forindustrial fabrication.
A promising technique
The research team developed the technique by "growing" layers of zincoxide and titanium oxide,one atom-thick layer at a time, on the cuprous oxide surface. By using the ALDtechnique, they were able to control the thickness of the protective layer downto the precision of a single atom over the entire surface.
This level of precision guarantees the stability of the semiconductorwhile preserving all of its hydrogen-producing efficiency. The next step in theresearch will be to improve the electrical properties of the protective layer.
Using widely available materials and techniques that can be easilyscaled up brings the "green" photoelectrochemical production ofhydrogen closer to the industrial interest.
Source : Highly active oxide photocathode for photoelectrochemicalwater reduction, Adriana Paracchino, Vincent Laporte, Kevin Sivula, MichaelGratzel and Elijah Thimsen, Nature Materials, 8 mai 2011. DOI: 10.1038/NMAT3017
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