Silicon Nano-Particles Found to Turn Water Into Hydrogen Rapidly

University at Buffalo researchers have discovered that super-small particles of silicon react with water to produce hydrogen almost instantaneously. They 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, which could be handy for example to feed fuel cells.

The reaction doesn't require any exogenic energy, like the electricity needed for hydrolysis, for example, light or heat. The process is also about 150 times faster than similar reactions using silicon particles 100 nanometers wide, and 1,000 times faster than bulk silicon.

Of course this isn't a free lunch, since it takes significant energy and resources to produce the nano-sized silicon balls, but the effort could be worth it to power portable devices and even vehicles in situations where water is available and portability is more important than low cost, the researchers said.

"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 T. Swihart, UB professor of chemical and biological engineering and director of the university's Strategic Strength in Integrated Nanostructured Systems.

Swihart said the discrepancy is due to geometry: As they react, the larger particles form nonspherical structures whose surfaces react with water less readily and less uniformly than the surfaces of the smaller, spherical particles.

The particles could eventually be part of portable high-energy systems that are both safer and lighter than current combustion motor and generator based solutions.

"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 said, envisioning future applications.

Swihart and Prasad led the study, which was completed by UB scientists, some of whom have affiliations with Nanjing University in China or Korea University in South Korea. Folarin Erogbogbo, a research assistant professor in UB's ILPB and a UB PhD graduate, was first author.