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CoolHand writes:

Scientific American has a story on recent developments made by scientists in solar fueled vehicles.

Experts have long been experimenting with techniques to create solar fuels, which allow all the advantages of conventional fossil fuels along with the environmental benefits of renewable energy. However, this requires a "photoanode" — a sort of catalyst that can set the ball rolling — and researchers have had a tough time identifying them in the past.

Now, scientists from the Department of Energy's Lawrence Berkeley National Laboratory and the California Institute of Technology think they've found a better way. If their experiments bear fruit, the results could revolutionize the renewable energy landscape. [...] Photoanodes are key to this procedure.

"The job of the photoanode is to absorb sunlight and then use that energy to oxidize water — essentially splitting apart the H2O molecule and rearranging the atoms to form a fuel. And because this photoanode material needs to have the right sunlight absorption and catalytic properties, they're very rare," explained Gregoire.

In fact, photoanodes are so rare that in the last 40 years, scientists have only been able to find 16 of them.

[...] Gregoire and his colleagues have come up with a new way to hunt for the catalysts, however, and it's much more effective. In two years, the scientists have already pinpointed 12 new photoanodes.

The technique used to identify the photoanodes uses a combination of theory and practice — the scientists worked with a supercomputer and a database of around 60,000 materials, and used quantum mechanics to predict the properties of each material. They then selected the ones that seemed most promising as photoanodes and used experiments to determine whether their calculations were right.

"What's special about what we have been doing is that it's a fully integrated approach," said Jeffrey Neaton, a physics professor with the University of California, Berkeley, and director of the Molecular Foundry. "We come up with candidates based on first-principle calculations, then measure the properties of the candidates to understand whether the criteria we used to select them are valid. The supercomputer comes in because the whole database we're starting with has about 60,000 compounds — we don't want to end up doing calculations on all 60,000."

This technology allows scientists a road map to find catalysts and eventually use them to create solar fuel. The final product, Gregoire said, would look something like a solar panel and involve three components: the photoanode, a photocathode, which forms the fuel, and a membrane that separates the two.

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