Research uncovers mechanism behind water-splitting catalyst

February 6, 2018 by Emily Velasco, California Institute of Technology
Ball-and-stick model of the molecular structure of the solar-fuel catalyst developed at Caltech. Blue represents iron atoms; green is nickel; red is oxygen; white is hydrogen. Credit: Caltech

Caltech researchers have made a discovery that they say could lead to the economically viable production of solar fuels in the next few years.

For years, solar-fuel research has focused on developing catalysts that can split water into hydrogen and oxygen using only sunlight. The resulting could be used to power , electrical plants, and fuel cells. Since the only thing produced by burning hydrogen is water, no carbon pollution is added to the atmosphere.

In 2014, researchers in the lab of Harry Gray, Caltech's Arnold O. Beckman Professor of Chemistry, developed a water-splitting made of layers of nickel and iron. However, no one was entirely sure how it worked. Many researchers hypothesized that the nickel layers, and not the iron atoms, were responsible for the water-splitting ability of the catalyst (and others like it).

To find out for sure, Bryan Hunter (PhD '17), a former fellow at the Resnick Institute, and his colleagues in Gray's lab created an experimental setup that starved the catalyst of water. "When you take away some of the water, the reaction slows down, and you are able to take a picture of what's happening during the reaction," he says.

Production of solar fuels inches closer with discovery by Caltech scientists
Gas generation by a solar-fuel catalyst. Credit: Caltech

Those pictures revealed the active site of the catalyst—the specific location where is broken down into oxygen—and showed that iron was performing the , not nickel.

"Our experimentally supported mechanism is very different than what was proposed," says Hunter, first author of a paper published February 6 in Joule, a journal of sustainable-energy research, describing the discovery. "Now we can start making changes to this material to improve it."

Gray, whose work has focused on for decades, says the discovery could be a "game changer" for the field.

"This will alert people worldwide that iron is particularly good for this kind of catalysis," he says. "I wouldn't be at all shocked if people start using these catalysts in commercial applications in four or five years."

The paper describing the research in Joule is titled, "Trapping an Iron(VI) Water Splitting Intermediate in Nonaqueous Media."

Explore further: New method efficiently generates hydrogen from water

More information: Trapping an Iron(VI) Water-Splitting Intermediate in Nonaqueous Media, DOI: 10.1016/j.joule.2018.01.008 , http://www.cell.com/joule/fulltext/S2542-4351(18)30036-9

Related Stories

Ultrathin black phosphorus for solar-driven hydrogen economy

January 17, 2018

Hydrogen as a fuel source, rather than hydrocarbons like oil and coal, offers many benefits. Burning hydrogen produces harmless water with the potential to eliminate carbon dioxide emissions and their environmental burden. ...

Recommended for you

The changing shape of DNA

May 24, 2018

The shape of DNA can be changed with a range of triggers including copper and oxygen—according to new research from the University of East Anglia.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.