Scientists create water splitter that runs on a single AAA battery
By Richard Moss
August 25, 2014
A new emissions-free device created by scientists at Stanford University uses an ordinary 1.5-volt battery to split water into hydrogen and oxygen at room temperature, potentially providing a low-cost method to power fuel cells in zero-emissions vehicles and buildings.
The water splitter is made from the relatively cheap and abundant metals nickel and iron. It works by sending an electric current from a single-cell AAA battery through two electrodes.
"This is the first time anyone has used non-precious metal catalysts to split water at a voltage that low," chemistry professor and lead researcher Hongjie Dai says. "It's quite remarkable, because normally you need expensive metals like platinum or iridium to achieve that voltage."
The technology has huge potential as a source for powering hydrogen fuel cells, long held as a likely successor to gasoline. Unlike gasoline combustion, which emits large quantities of the greenhouse gas carbon dioxide, fuel cells combine stored hydrogen gas with oxygen from the air to produce electricity, leaving only water as a byproduct.
Fuel cell vehicles have been around since the 1960s, albeit mostly as research projects and demonstration cars and buses. But we may soon see them in commercial production, with Toyota and Honda both committed to selling fuel cell cars in 2015 and Hyundai already leasing fuel cell vehicles in Southern California.
Fuel cell vehicles have been widely criticized for their high cost, the lack of infrastructure around their fuel delivery, and their low energy efficiency after accounting for the effort it takes to produce compressed hydrogen (often involving large industrial plants that use an energy-intensive process that combines steam and natural gas).
But the new Stanford research, which latches onto a previously unknown method for splitting water, could help account for all these issues.
"It's been a constant pursuit for decades to make low-cost electrocatalysts with high activity and long durability," Dai explains. "When we found out that a nickel-based catalyst is as effective as platinum, it came as a complete surprise."
The nickel-metal/nickel-oxide catalyst, discovered by Stanford graduate student Ming Gong, also requires significantly lower voltages to split water when compared to pure nickel or pure nickel oxide. This new technique is not quite ready for commercial production, though.
"The electrodes are fairly stable, but they do slowly decay over time," Gong says. "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 next step is to improve that decay rate and to test a version that runs on electricity produced by solar energy instead of the AAA battery.
The researchers believe that their water splitter could save hydrogen producers billions of dollars, and the electrolytic device could be used to make chlorine gas and sodium hydroxide as well as hydrogen fuel cells.
A paper published in the journal Nature Communications describes the research in more detail.
You can see Dai himself demonstrating the device in the video below.
Source: Stanford University
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