Illustration of the multidisciplinary approach for producing hydrogen through silicon oxidation. The approach involves synthesizing silicon nanoparticles, the silicon-water reaction which generates hydrogen on demand, and using the hydrogen in a fuel cell for portable power. Credit: Folarin Erogbogbo, et al. ©2013 American Chemical Society

Nanosilicon rapidly splits water without light, heat, or electricity

January 24, 2013 by Lisa Zyga

(Phys.org)—Although scientists know that when silicon mixes with water, hydrogen is produced through oxidation, no one expected how quickly silicon nanoparticles might perform this task. As a new study has revealed, 10-nm silicon nanoparticles can generate hydrogen 150 times faster than 100-nm silicon nanoparticles, and 1,000 times faster than bulk silicon. The discovery could pave the way toward rapid “just add water” hydrogen generation technologies for portable devices without the need for light, heat, or electricity.

The researchers, Folarin Erogbogbo at the University of Buffalo and coauthors, have published their paper on using nanosilicon to generate hydrogen in a recent issue of Nano Letters.

If hydrogen is ever to be used to deliver energy for wide commercial applications, one of the requirements is finding a fast, inexpensive way to produce hydrogen. One of the most common hydrogen production techniques is splitting water into hydrogen and oxygen. There are several ways to split water, such as with an electric current (electrolysis), heat, sunlight, or a substance that chemically reacts with water. Such substances include aluminum, zinc, and silicon.

As the scientists explained, silicon-water oxidation reactions have so far been slow and uncompetitive with other water splitting techniques. However, silicon does have some theoretical benefits, such as being abundant, being easy to transport, and having a high energy density. Further, upon oxidation with water, silicon can theoretically release two moles of hydrogen per mole of silicon, or 14% of its own mass in hydrogen.

For these reasons, the scientists decided to take a closer look at silicon, specifically silicon nanoparticles, which have not previously been studied for hydrogen generation. Because silicon nanoparticles have a larger surface area than larger particles or bulk silicon, it would be expected that the nanoparticles can generate hydrogen more rapidly than the larger pieces of silicon.

Read more: Nanosilicon rapidly splits water without light, heat, or electricity — phys.org.

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