Super-small particles of silicon react with water to produce hydrogen almost instantaneously, according to American research.
In a series of experiments, University at Buffalo researchers created spherical silicon particles about 10 nanometers in diameter. When combined with water, these particles reacted to form silicic acid (a nontoxic byproduct) and hydrogen . . . a potential source of energy for fuel cells.
The reaction didn’t require any light, heat or electricity, and also created hydrogen about 150 times faster than similar reactions using silicon particles 100 nanometers wide, and 1,000 times faster than bulk silicon, according to the experimentation thus far.
It was previously unknown that it was possible to generate hydrogen this rapidly from silicon, one of Earth’s most abundant elements
The Buffalo team has been able to verify that the hydrogen made was relatively pure by testing it successfully in a small fuel cell that powered a fan.
“When it comes to splitting water to produce hydrogen, nanosized silicon may be better than more obvious choices that people have studied for a while, such as aluminum,” said researcher Mark Swihart, UB professor of chemical and biological engineering and director of Buffalo’s “strategic strength in integrated nanostructured systems”.
“With further development, this technology could form the basis of a ‘just add water’ approach to generating hydrogen on demand,” said colleague researcher Paras Prasad, executive director of UB’s Institute for Lasers, Photonics and Biophotonics (ILPB).
“The most practical application would be for portable energy sources,” he added.
It turns out that the speed at which the 10-nanometer particles reacted with water surprised the researchers. In under a minute, these particles yielded more hydrogen than the 100-nanometer particles yielded in about 45 minutes. The maximum reaction rate for the 10-nanometer particles was about 150 times as fast.
The discrepancy is due to geometry. As they react, the larger particles form non-spherical structures whose surfaces react with water less readily and less uniformly than the surfaces of the smaller, spherical particles.
Though it takes significant energy and resources to produce the super-small silicon balls, the particles could help power portable devices in situations where water is available and portability is more important than low cost. Military operations and camping trips are two examples of such scenarios.
“Perhaps instead of taking a gasoline or diesel generator and fuel tanks or large battery packs with me to the campsite (civilian or military) where water is available, I take a hydrogen fuel cell (much smaller and lighter than the generator) and some plastic cartridges of silicon nanopowder mixed with an activator,” Swihart added.
“Then I can power my satellite radio and telephone, GPS, laptop, lighting, etc. If I time things right, I might even be able to use excess heat generated from the reaction to warm up some water and make tea.”