Researchers at the University of Buffalo have created spherical silicon nanoparticles they claim could lead to hydrogen generation on demand becoming a “just add water” affair. When the particles are combined with water, they rapidly form hydrogen and silicic acid, a nontoxic byproduct, in a reaction that requires no light, heat or electricity. In experiments, the hydrogen produced was shown to be relatively pure by successfully being used to power a small fan via a small fuel cell.

According to the team’s study, the 10-nanometer diameter particles created hydrogen 1,000 times faster than similar reactions using bulk silicon and up to 150 times faster than silicon particles 100 nanometers wide, yielding more hydrogen in under a minute than the 100-nanometer particles yielded in around 45 minutes. This gives the smaller particles the potential to generate hydrogen on-demand for use in fuel cells to power portable devices.

“It was previously unknown that we could generate hydrogen this rapidly from silicon, one of Earth’s most abundant elements,” said Folarin Erogbogbo, first author of the study. “Safe storage of hydrogen has been a difficult problem even though hydrogen is an excellent candidate for alternative energy, and one of the practical applications of our work would be supplying hydrogen for fuel cell power.

According to Mark T. Swihart, UB professor of chemical and biological engineering and director of the university’s Strategic Strength in Integrated Nanostructured Systems, the speed of the reaction is due to the spherical shape of the 10-nanometer particles. This is because larger particles form nonspherical structures that react less uniformly and readily with the water than the surfaces of the smaller, spherical particles.

“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 UB’s Institute for Lasers, Photonics and Biophotonics (ILPB). “The most practical application would be for portable energy sources.”

The downside is the significant amount of energy and resources required to produce the smaller silicon particles. This would make the particles expensive and likely rule them out for widespread use in powering consumer electronic devices – at least initially. However, the researchers say the technology could find applications in situations where water is available and portability is more important than cost, such as camping and military operations.

“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.”

The team’s study is published in the journal Nano Letters.

Source: University of Buffalo