Nanotechnology provides safer fuel cells

The invention of bendy hydrogen sensors using nanomaterials has brought hydrogen-powered vehicles one step closer to becoming a reality.

Hydrogen sensors play a crucial role in ensuring the safety of fuel cells, enabling leaks to be detected.

Hydrogen fuel cells convert hydrogen and oxygen into water, using the chemical energy released to create an electric current.

However, hydrogen is highly flammable and its combustion is equally invisible to the human eye, making fires a considerable danger.

Scientists at the US Department of Energy's Argonne National Laboratory have now designed more efficient hydrogen sensors using single-walled carbon nanotubes.
 
The pure palladium sensors used previously are expensive to produce and also very rigid. The new sensors surpass their predecessors in terms of both efficiency and cost, with their increased flexibility also improving performance.

The sensing devices were manufactured following a two-step process.

The carbon nanotubes are first grown on a silicon surface maintained at 900ºC. They are then transferred onto a plastic sheet using a technique known as dry transfer printing.

This allows the film of nanotubes to form on the plastic, after which the palladium nanoparticles can be deposited on the nanotubes to make the sensors.

Increased sensitivity thanks to nanotech

These nanoparticles play an important role in increasing the interaction between hydrogen and the nanotubes to improve the device’s sensitivity to hydrogen molecules.

The use of plastic sheets reduces the sensors’ weight whilst increasing their mechanical flexibility and shock resistance.

This enhanced flexibility could prove particularly beneficial for use in vehicles, aircraft and portable electronic devices, as it allows the sensors to be wrapped around curved surfaces.

"The leakage of hydrogen caused by tiny pinholes in the pipe of a space shuttle, for example, could not be easily detected by individual rigid detectors because the locations of pinholes are not predetermined," said Yugang Sun, one of the researchers behind the innovation.

"However, laminating a dense array of flexible sensors on the surfaces of the pipe can detect any hydrogen leakage and alert control units to take action."

The new sensors exhibit high sensitivity, fast response and a rapid recovery time. They can detect the presence of one per cent hydrogen in only three seconds at room temperature.

Even after repeated bending, the devices remain just as effective.
 

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