Being cheaper is how many disruptive technologies first gain entry to the market.
Cheap catalyst can make and break hydrogen
* 10:33 07 December 2009 by Colin Barras
A cheap catalyst can both generate hydrogen and release energy from it. The new material could be a breakthrough that will allow the unpredictable energy flows from wind and solar farms to be stored.
As nations attempt to put their energy consumption in order, the need for better ways to store electrical power is becoming apparent: wind and solar power installations don't always provide power when it's most needed. Batteries are one option – although they'll have to improve before they are practical for large-scale storage – but another is converting excess electricity into hydrogen and feeding it through a fuel cell later to generate electricity.
Now Vincent Artero at Joseph Fourier University in Grenoble, France, and colleagues have shown that a cheap catalyst could be used to both generate hydrogen to store energy, and also to consume it to extract stored power.
Until now, almost all hydrogen-generating catalysts have been made with the expensive metal platinum, making scaling up their use impractical. A platinum-free catalyst for hydrogen formation was developed in 2006, but it required water-free conditions that were incompatible with conventional methods of making the gas.
Artero and his colleagues have solved that problem, coating the platinum-free catalyst in a membrane that lets hydrogen ions reach the catalyst, but not water molecules.
The team attached the catalytic molecules to a carbon nanotube electrode and sealed it in the waterproof membrane. Then they ran an electric current through the electrode and dipped it into dilute sulphuric acid. They found that hydrogen ions from the watery acid solution travelled through the membrane to the catalyst, where they picked up electrons from the circuit to become hydrogen gas.
The team also found that the new design can work in reverse, to split up gaseous hydrogen into ions, and release electrons to provide power.
"That's useful because the customer would buy just one device [that can both generate and oxidise hydrogen]," says Artero. So far, though, the device can't compete with the power output of a conventional platinum-catalysed fuel cell, although the team haven't yet begun to optimise it for that use.
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