Cobalt-graphene material to rival platinum?

Researchers at Brown University have engineered a new material that could be a cheaper and more durable alternative to platinum as the catalyst for hydrogen fuel cells.

According to lead researcher Shouheng Sun, the material – a graphene sheet covered by cobalt and cobalt-oxide – has the best oxygen reduction performance of any non-platinum catalyst reported to date. The oxygen reduction reaction occurs on the cathode side of a hydrogen fuel cell. Oxygen functions as an electron sink, stripping electrons from hydrogen fuel at the anode and creating the electrical pull that keeps the current running through electrical devices powered by the cell. "The reaction requires a catalyst, and platinum is currently the best one," said Sun. "But it's very expensive and has a very limited supply, and that's why you don't see a lot of fuel cell use aside from a few special purposes." Lab tests performed by Sun and his team showed that although the new graphene-cobalt material was a bit slower than platinum in getting the oxygen reduction reaction started, once the reaction was going, it actually reduced oxygen at a faster pace. The new catalyst also proved to be more stable, degrading much more slowly than platinum over time. After about 17 hours of testing, the graphene-cobalt catalyst was performing at around 70% of its initial capacity. The platinum catalyst the team tested performed at less than 60% after the same amount of time. Sun and his team are optimistic that with more study their material could one day be a suitable replacement for platinum catalysts. "Right now, it's comparable to platinum in an alkaline medium," he said, "but it's not ready for use yet. We still need to do more tests." Ultimately, Sun believes finding a suitable non-platinum catalyst will be the key to getting fuel cells out of the laboratory phase and into production as power sources for cars and other devices.