http://www.physorg.com/news97255464.html

Cheap source of energy: Cell splits water via sunlight to produce hydrogen
By Tony Fitzpatrick

Pratim Biswas and his group have developed a method to make a variety of
oxide semiconductors that, when put into water promote chemical reactions
that split water into hydrogen and oxygen. The method provides a new low
cost and efficient option for hydrogen production. Credit: David
Kilper/WUSTL Photo

Engineers at Washington University in St. Louis have developed a unique
photocatalytic cell that splits water to produce hydrogen and oxygen in
water using sunlight and the power of a nanostructured catalyst.
The group is developing novel methodologies for synthesis of nanostructured
films with superior opto-electronic properties. One of the methods, which
sandwiches three semiconductor films into a compact structure on the
nanoscale range, is smaller, more efficient and more stable than present
photocatalytic methods, which require multiple steps and can take from
several hours to a day to complete.

The discovery provides a new, low-cost and efficient option for hydrogen
production and can be used for a variety of distributed energy applications.

Pratim Biswas, Ph.D., the Stifel and Quinette Jens Professor and Chair of
the Department of Energy, Environmental and Chemical Engineering, and his
graduate student Elijah Thimsen, recently have developed the
well-controlled, gas phase process, and have demonstrated it for
synthesizing a variety of oxide semiconductors such as iron and titanium
dioxide films in a single step process. It is based on a simple, inexpensive
flame aerosol reactor (FLAR) and consists of four mass flow controllers to
regulate process gases, a standard bubbler to deliver a precursor, a metal
tube that acts as a burner and a water-cooled substrate holder.

"We put these films in water and they promote some reactions that split
water into hydrogen and oxygen," said Biswas. "We can use any oxide
materials such as titanium dioxide, tungsten oxide and iron oxide in
nanostructures sandwiched together that make very compact structures. The
process is direct and takes only a few minutes to fabricate. More important,
these processes can be scaled up to produce larger structures in a very cost
effective manner in atmospheric pressure processes."

Collaborations have now been established with Dewey Holten, Ph.D.,
Washington University professor of chemistry in Arts & Sciences, to better
understand the electron-hole pair kinetics, information that can then be
used to tune the synthesis process. Other collaborations with Robert
Blankenship, Ph.D., Washington University professor of biology and chemistry
in Arts & Sciences, are being explored to create hybrid bio-nanostructures
that will improve the light absorption efficiencies over a broader range of
wavelengths. Electrospray and other aerosol techniques are being used to
create these hybrid films.

The method was described in a recent issue of SPIE, a publication of the
International Society for Optical Engineering.

The research is among the first wave of news out of the new Washington
University Department of Energy, Environmental and Chemical Engineering,
which performs research on energy and environment, including alternative
fuels and energy sources, air quality research, nanoparticle technology and
particle emission control, among other topics.

Some of the department faculty - 14 members now, expected to double in five
to ten years - are active in the University's ambitious BioEnergy
Initiative, which is focused on the development of technologies for the
production of next generation biofuels. The adoption of a systems approach
will not only enable development processes for large volume production of
liquid fuels from plant-based sources, but also at a low cost, and most
importantly, in an environmentally benign manner - not only during the
production, but also during the actual usage.

Source: Washington University in St. Louis

-- 

Ken

"Buddhism elucidates why we are sentient."
"Buddhism follows thought throughout the Universe."
"Karma means that you don't get away with anything."