When it comes to separating hydrogen from the water molecule, it’s like the old Neil Sedaka song said: “Breaking up is hard to do.” It is so difficult, in fact, that the production of hydrogen gas has been one of the main obstacles in the deployment of fuel cell–based vehicles.
Now researchers at Stanford University have developed a nanoscale material that makes it possible to split water cheaply using just a 1.5-volt "AAA" battery, and they claim it can be done without producing any emissions.
We've previously reported on the work done by Hongjie Dai, who has spent years working on developing better catalysts for fuel cells, including some employing carbon nanotubes. But this time, instead of focusing on the fuel cell itself, Dai has turned his eye towards ways of generating the hydrogen to feed the fuel cells.
Dai’s previous work, which examined how carbon nanotubes could replace more expensive catalysts used in oxidizing the hydrogen at the anode within the fuel cell, indirectly came into play here. Since the process inside the fuel cell is the mirror opposite of what is needed to split water, this latest work, which was published in the journal Nature Communications, is somewhat along the same lines. It involves using an inexpensive nanomaterial made from nickel and iron in place of platinum as the catalyst in the water-splitting reaction.
“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," said Dai, in a press release. "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."
Dai further describes the water-splitting device and its implications in the video below.
While there has been much research into using nanomaterials for hydrogen separation, previous efforts to produce hydrogen gas on an industrial scale without first generating hot steam in an energy-intensive process with carbon dioxide as a byproduct were unsuccessful.
"It's been a constant pursuit for decades to make low-cost electrocatalysts with high activity and long durability," Dai says. "When we found out that a nickel-based catalyst is as effective as platinum, it came as a complete surprise."
A surprise indeed. In fact, the Stanford researchers don’t even understand the science that makes the novel nickel-metal/nickel-oxide nanomaterial perform the way it does.
However, the researchers do know that it works.
One area where continued research might yield improvement is durability. The material, say the Stanford engineers, doesn’t last as long as hoped, and certainly not long enough for an industrial application.
"The electrodes are fairly stable, but they do slowly decay over time," said Ming Gong, the graduate student who discovered the material, in a press release. "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"
Dai added: "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."