Yuehe Lin, professor at WSU's School of Mechanical and Materials Engineering. Photo: WSU.A breakthrough in splitting water into its component parts could help make renewable energy pay off, even when the sun isn't shining and the wind isn't blowing.
Using solar and wind power when it is available to split water into hydrogen and oxygen offers a simple way to store energy in the form of hydrogen fuel. Currently, the most popular system used for water splitting, or water electrolysis, relies on precious metals as catalysts. But a collaborative research team, including scientists from Los Alamos National Laboratory and Washington State University (WSU), has now developed a system that uses less expensive and more abundant materials. They report their advance in a paper in Nature Energy.
"The current water electrolysis system uses a very expensive catalyst. In our system, we use a nickel-iron based catalyst, which is much cheaper, but the performance is comparable," said Yu Seung Kim, a research scientist at Los Alamos National Laboratory and corresponding author on the paper.
Most water splitting is currently conducted using a device called a proton-exchange membrane water electrolyzer, which can produce hydrogen at a high rate. But it's expensive, works under very acidic conditions, and requires precious metal catalysts such as platinum and iridium, as well as corrosion-resistant metal plates made of titanium.
The research team worked to solve this problem by splitting water under alkaline, or basic, conditions using an anion-exchange membrane electrolyzer, which does not need a catalyst based on precious metals. In fact, a team led by Yuehe Lin, professor at WSU's School of Mechanical and Materials Engineering, created a novel catalyst based on nickel and iron, elements that are less expensive and more abundant in the environment.
Lin's team shared their development with Kim at Los Alamos, whose team in turn developed an electrode binder to use with the catalyst. This electrode binder is a hydroxide-conducting polymer that binds the catalyst and provides a high pH environment for fast electrochemical reactions.
The combination of the Los Alamos-developed electrode binder with WSU's catalyst boosted the hydrogen production rate to nearly 10 times the rate of previous anion-exchange membrane electrolyzers, making it comparable with the more expensive proton-exchange membrane electrolyzer.
About 10 million metric tons of hydrogen are currently produced in the US every year, mostly from natural gas in a process called natural gas reforming, according to the US Department of Energy. Hydrogen produced from a water splitting process that is powered by electricity from renewable energy thus holds many economic and environmental benefits.
"Water splitting is a clean technology, but you need electricity to do it," said Lin, who is a corresponding author on the paper. "Now we have a lot of renewable energy, wind and solar power, but it is intermittent. For example, at night we can't use solar, but if during the day we can use extra energy to convert it into something else, like hydrogen, that's very promising."
The global hydrogen generation market is expected reach $199.1 billion by 2023. Potential markets for hydrogen energy include everything from mass energy conversion and power grid management to fuel cells for cars. Lin estimates that there are approximately 600 wind farms in the US ready for direct connections to water electrolysis systems.
This story is adapted from material from Washington State University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.