Graphene aerogels optimised with boron and nitrogen

Rice University scientists have found that metal-free aerogels made from graphene nanoribbons and optimised with boron and nitrogen can serve as catalysts to produce fuel cells.

 

The team used various levels of boron and nitrogen with graphene nanoribbons, to test their electrochemical properties.

 

During tests, which involved half of the catalytic reaction, researchers identified that a version with around 10% boron and nitrogen is efficient at catalysing oxygen reduction reactions.

 

Oxygen reduction reaction is a step in producing energy from feedstocks such as methanol.

 

Researchers said graphene's potential as a catalyst stands along the edges where molecules prefer to interact.

 

Scientists unzipped carbon nanotubes into ribbons and structured them into three-dimensional aerogels with boron and nitrogen molecules on the ribbon's edges.

 

The material is said to provide a number of active sites along the exposed edges for oxygen reduction reactions.

 

Scientist Pulickel Ajayan said: "The key to developing carbon-based catalysts is in the doping process, especially with elements such as nitrogen and boron.

 

"The graphitic carbon-boron-nitrogen systems have thrown many surprises in recent years, especially as a viable alternative to platinum-based catalysts."

 

Rice theoretical physicist Boris Yakobson and the team found that neither boron nor nitrogen doping alone could produce the desired reactions.

 

Aerogels enhanced with boron / nitrogen are said to be better at avoiding the crossover effect over platinum, where fuel such as methanol saturate the polymer electrolyte that splits electrodes and degrades performance.

 

The project was backed by the Welch Foundation, the Air Force Office of Scientific Research, Multidisciplinary University Research Initiative grants from the US Army Research Office, the Air Force Office of Scientific Research and the Office of Naval Research, and the Department of Energy's Oak Ridge National Laboratory.