Nanocatalyst Splits Water Molecules at a Fraction the Cost of Platinum

Nanotechnology-based solutions for improving fuel cells have fallen a bit short of expectations. So  recent research has focused instead on using nanotech to produce hydrogen gas for existing fuel cells more cheaply and efficiently.

Some of these solutions—like those from University of California, San Diego, or those of Angela Belcher of MIT—have been aimed at breaking down a water molecule into its constituent parts of hydrogen and oxygen by replicating photosynthesis. This is really cutting edge stuff and pretty far removed from the process currently used to create hydrogen gas, which involves applying electricity to water in the presence of a catalyst.

One of the main problems with this current method has been the cost of platinum, which is the best material to serve as a catalyst for the process. With platinum going for about $50,000 per kilogram, it’s pretty clear why this gets to be a very expensive process.

To address this issue researchers at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have developed a new nanomaterial that can duplicate the capabilities of platinum at a fraction of the cost.

“We wanted to design an optimal catalyst with high activity and low costs that could generate hydrogen as a high-density, clean energy source,” said Brookhaven Lab chemist Kotaro Sasaki in a press release covering the research. “We discovered this exciting compound that actually outperformed our expectations.”

The researchers—whose results were initially published online yesterday in the journal Angewandte Chemie International Edition—determined early on that nickel can take the reactive place of platinum, but didn’t have the same electron density. While the introduction of metallic molybdenum to the nickel improved its reactivity, it still wasn’t up to platinum standards.

Sasaki and his colleagues believed that they could push the nickel-molybdenum material up to platinum levels by applying nitrogen, based on the understanding that this had been done with bulk materials. They weren’t quite sure what to expect when you applied the nitrogen to nanoscale nickel-molybdenum but they suspected that it would change the structure of the material into discrete, sphere-like nanostructures. That’s not what they got.

To the surprise of the researchers, the infusing of nitrogen with nickel-molybdenum material produced two-dimensional nanosheets.

“Despite the fact that metal nitrides have been extensively used, this is the first example of one forming a nanosheet,” said research associate Wei-Fu Chen, the paper’s lead author in the Lab’s press release. “Nitrogen made a huge difference – it expanded the lattice of nickel-molybdenum, increased its electron density, made an electronic structure approaching that of noble metals, and prevented corrosion.”

While the researchers are realistic in their understanding that this new catalyst doesn’t answer all the issues facing the production of hydrogen gas, it does have the advantage over other solutions in that it can be directly substituted into current processes that use platinum as a catalyst to cut the costs dramatically. Whether this will usher in the age of the hydrogen economy is impossible to say, but it's a step in the right direction.

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Nanoclast

IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

 
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Dexter Johnson
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