Phimega Group Post #58

Modified virus splits water
posted by soliton at Wed, 28 Apr 2010 - 10:31:55

A team of MIT researchers has found a novel way to mimic the process
by which plants use the power of sunlight to split water and make
chemical fuel to power their growth. In this case, the team used a
modified virus as a kind of biological scaffold that can assemble the
nanoscale components needed to split a water molecule into hydrogen
and oxygen atoms.

Splitting water is one way to solve the basic problem of solar energy:
It=92s only available when the sun shines. By using sunlight to make
hydrogen from water, the hydrogen can then be stored and used at any
time to generate electricity using a fuel cell, or to make liquid
fuels (or be used directly) for cars and trucks.

Other researchers have made systems that use electricity, which can be
provided by solar panels, to split water molecules, but the new
biologically based system skips the intermediate steps and uses
sunlight to power the reaction directly. The advance is described in a
paper published on April 11 in Nature Nanotechnology.

The team, led by Angela Belcher, the Germeshausen Professor of
Materials Science and Engineering and Biological Engineering,
engineered a common, harmless bacterial virus called M13 so that it
would attract and bind with molecules of a catalyst (the team used
iridium oxide) and a biological pigment (zinc porphyrins). The viruses
became wire-like devices that could very efficiently split the oxygen
from water molecules.

Over time, however, the virus-wires would clump together and lose
their effectiveness, so the researchers added an extra step:
encapsulating them in a microgel matrix, so they maintained their
uniform arrangement and kept their stability and efficiency.

While hydrogen obtained from water is the gas that would be used as a
fuel, the splitting of oxygen from water is the more technically
challenging =93half-reaction=94 in the process, Belcher explains, so her
team focused on this part. Plants and cyanobacteria (also called
blue-green algae), she says, =93have evolved highly organized
photosynthetic systems for the efficient oxidation of water.=94 Other
researchers have tried to use the photosynthetic parts of plants
directly for harnessing sunlight, but these materials can have
structural stability issues.

Using the virus to make the system assemble itself is claimed to
improve the efficiency of the oxygen production fourfold. The
researchers hope to find a similar biologically based system to
perform the other half of the process, the production of hydrogen.
Currently, the hydrogen atoms from the water get split into their
component protons and electrons; a second part of the system, now
being developed, would combine these back into hydrogen atoms and
molecules. The team is also working to find a more commonplace,
less-expensive material for the catalyst, to replace the relatively
rare and costly iridium used in this proof-of-concept study.


Source: =93Biologically templated photocatalytic nanostructures for
sustained light-driven water oxidation=94 Yoon Sung Nam, Andrew P.
Magyar, Daeyeon Lee, Jin-Woong Kim, Dong Soo Yun, Heechul Park, Thomas
S. Pollom Jr, David A. Weitz and Angela M. Belcher. Nature
Nanotechnology, April 11, 2010.

More Info:
http://web.mit.edu/press/2010/virus-water.html


--=20
soliton
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