Silicon Generates Hydrogen when Oxidized
Silicon Generates Hydrogen when Oxidized

The science of nanotechnology, specifically nanomaterials, has grown by leaps and bounds in the last decade, and scientists are discovering more material characteristics than they ever could have before, just examining macromaterials.

For example, when silicon [Si] oxidizes with water [H2O], it gives off hydrogen gas [H2], leaving a layer of silicon dioxide [SiO2]. While macrosize Si reacts with H2O intially, the SiO2 layer effectively blocks further oxidation at temperatures up to 1,652°F.

Oxidized in this way, Si needs to be heated additionally to 2,552°F before it reacts any further. Obviously, macrosize Si isn’t a very good hydrogen generator, since hydrogen is spontaneously combustible at just 932°F.

Scientists working with nanosize silicon made an important discovery recently, that smaller Si particles oxidate and release hydrogen very efficiently. As a matter of fact, Si particles around 10nm in diameter were about 150x more efficient in generating H2 on oxidation than Si particles at 100nm, and about 1,000x more efficient than bulk Si. Another benefit of working with nanosize Si is that no heat is required to start the reaction, just water.

“With further development, this technology could form the basis of a ‘just add water’ approach to generating hydrogen on demand,” said researcher Paras Prasad, executive director of University of Buffalo’s Institute for Lasers, Photonics and Biophotonics, “The most practical application would be for portable energy sources.”

Another benefit of using nanosize silicon and water to fuel such a reaction is that it is the second-most-abundant element on the planet, after oxygen. Hydrogen fuel can be generated on demand without the need for electricity or high heat.

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