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David Bradley ISSUE #69
October 2007
Martin Demuth
An Economical Hydrogen Economy

If the hyperbole is to be believed, hydrogen gas will be one of the most important fuels of the future. However, in order to make a so-called hydrogen economy viable, energy technologists will have to develop efficient methods to produce the gas using renewable energy sources, such as solar power. After all, there is little benefit in using fossil fuels to produce hydrogen for alternatively powered vehicles, for instance, aside from the benefits of reduced local pollution.

With this in mind, researchers at the Max Planck Institute in Germany working with colleagues in Norway and the US, have now developed a catalyst that may be able to convert sunlight and water directly into hydrogen, in a process analogous to the photosynthesis of carbohydrates by plants using sunlight, carbon dioxide, and water as the raw materials.

The novel semiconductor catalyst, produced by Martin Demuth (of the Max Planck Institute for Bioinorganic Chemistry in Mulheim an der Ruhr) and his colleagues, not only splits water, but acts as a storage medium for the hydrogen produced, which means it can be easily separated from the other product of the reaction, oxygen.

"The generation of hydrogen and oxygen from water by means of semiconductors is an important contribution to the use of solar energy," explains Demuth. "Semiconductors suitable for use as photocatalysts have been difficult to obtain, have unfavorable light-absorption characteristics, or decompose during the reaction."

To overcome the various problems associated with previous materials, Demuth and his team turned to titanium disilicide (TiSi2). This material has some very unusual optoelectronic properties that are ideal for use in solar technology, the researchers say. Moreover, this material absorbs light over a wide range of the solar spectrum, is readily available, and is inexpensive.