"Damaging" carbon nanotubes can give them catalytic properties at par with the expensive platinum currently used for key fuel cell reactions.

Scientists at Stanford University found that multi-walled carbon nanotubes riddled with defects and impurities allow for the formation of catalytic sites while maintaining the material's good electric conductivity.

In a fuel cell, a catalyst triggers a chemical reaction to convert hydrogen and oxygen to water, creating an electric current.

Currently, catalysts used tend to be made up of expensive precious metals such as platinum or palladium. Platinum goes for $800 to $2,200 an ounce.

As carbon-based materials are easy and cheap to produce, the catalytic carbon nanotubes from Stanford are seen as a potential replacement for precious-metal catalysts.

To produce their catalytic nanotubes, Yanguang Li, a postdoctoral fellow, and his colleagues used multi-walled carbon nanotubes - two or three concentric tubes of the material nested together.

They treated these tubes in a chemical solution that caused the first layer to shred, leaving catalytic sites with iron and nitrogen impurities on the outside, while the inner tube remained intact. The intact inner tube retains its electrical conductivity, providing a path for electrons to move around.

Because the catalytical activity of the nanotubes is close to platinum, the researchers believe that these could also be used in fuel cells. They have sent samples to fuel cell experts for testing.

The multi-walled nanotubes could also have applications in metal-air batteries made of lithium or zinc. These batteries use a catalyst to trigger the oxidation of metal with oxygen from air to produce electricity.

The work was supported by a grant from the Precourt Institute for Energy at Stanford, Intel, Lawrence Berkeley and Oak Ridge National laboratories, the Department of Energy, and the National Science Foundation. – EcoSeed Staff