Laser-burned graphene could replace platinum as catalyst for fuel cells

Rice University chemists have found a way to embed metallic nanoparticles that turn laser-induced graphene into a functional catalyst for fuel cells and other applications.

Laser-induced graphene, created by the Rice lab of chemist James Tour, is a flexible film with a surface of porous graphene made by exposing a common plastic known as polyimide to a commercial laser-scribing beam.

With the discovery, the material that the researchers call 'metal oxide-laser induced graphene' (MO-LIG) becomes a new candidate to replace expensive metals like platinum in catalytic fuel-cell applications in which oxygen and hydrogen are converted to water and electricity.

"The wonderful thing about this process is that we can use commercial polymers, with simple inexpensive metal salts added," Tour said. "We then subject them to the commercial laser scriber, which generates metal nanoparticles embedded in graphene.

"These composites, which have less than 1% metal, respond as 'super catalysts' for fuel-cell applications. Other methods to do this take far more steps and require expensive metals and expensive carbon precursors."

Initially, the researchers made laser-induced graphene with commercially available polyimide sheets. Later, they infused liquid polyimide with boron to produce laser-induced graphene with a greatly increased capacity to store an electrical charge, which made it an effective supercapacitor.

For the latest iteration, they mixed the liquid and one of three concentrations containing cobalt, iron or molybdenum metal salts. After condensing each mixture into a film, they treated it with an infrared laser and then heated it in argon gas for half an hour at 750°C.

That process produced robust MO-LIGs with metallic, 10nm particles spread evenly through the graphene. Tests showed their ability to catalyse oxygen reduction, an essential chemical reaction in fuel cells. Further doping of the material with sulphur allowed for hydrogen evolution, another catalytic process that converts water into hydrogen.

Author
Tom Austin-Morgan

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