Battery-powered water splitter delivers low-cost emissions-free fuel cells
The low-cost, emissions-free electrolytic device was developed by Stanford University Professor Hongjie Dai and uses an AAA battery to send an electric current through two electrodes that split liquid water into hydrogen and oxygen gas at room temperature. The water splitters do not use expensive precious-metal catalysts because the electrodes in the Stanford device are made of inexpensive nickel and iron.
"Using nickel and iron, which are cheap materials, we were able to make the electrocatalysts active enough to split water at room temperature with a single 1.5-volt battery," explained Hongjie Dai, a professor of chemistry at Stanford. "This is the first time anyone has used non-precious metal catalysts to split water at a voltage that low. It’s quite remarkable, because normally you need expensive metals, like platinum or iridium, to achieve that voltage."
Prof Dai and his colleagues describe the new device in a study published in the journal Nature Communications.
"It’s been a constant pursuit for decades to make low-cost electrocatalysts with high activity and long durability," Dai said. "When we found out that a nickel-based catalyst is as effective as platinum, it came as a complete surprise."
The discovery was made by Stanford graduate student Ming Gong, co-lead author of the study. "Ming discovered a nickel-metal/nickel-oxide structure that turns out to be more active than pure nickel metal or pure nickel oxide alone," explained Dai. "This novel structure favors hydrogen electrocatalysis, but we still don’t fully understand the science behind it."
The nickel/nickel-oxide catalyst lowers the voltage required to split water, which could eventually save hydrogen producers billions of dollars in electricity costs, according to Gong. His next goal is to improve the durability of the device.
"The electrodes are fairly stable, but they do slowly decay over time," said Gong. "The current device would probably run for days, but weeks or months would be preferable. That goal is achievable based on my most recent results"
The researchers are also looking to develop a water splitter than runs on electricity produced by solar energy.
"Hydrogen is an ideal fuel for powering vehicles, buildings and storing renewable energy on the grid," said Dai. "We’re very glad that we were able to make a catalyst that’s very active and low cost. This shows that through nanoscale engineering of materials we can really make a difference in how we make fuels and consume energy."
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