A research team led by scientists at the US Department of Energy’s Pacific Northwest National Laboratory reports that it has designed a highly active and durable fuel cell catalyst that doesn’t rely on costly platinum to trigger the chemical reaction, Kallanish reports.

The new catalyst contains cobalt interspersed with nitrogen and carbon and has proven to be more four times more durable that a similarly structured catalyst made from iron, the PNNL says.

The research, which is promising for fuel cells used in transportation, was published in Nature Catalysis on 30 November.

At present, platinum group metals serve as the most productive catalyst material for proton exchange membrane or PEM fuel cells, but they account for half of the fuel cell cost, says the PNNL that is located in Richland, Washington.

Cobalt is abundant and, compared to platinum, in expensive. Previous studies had shown that cobalt is far less active than iron-based catalysts.

“We knew that the configuration of cobalt with nitrogen and carbon was key to how effectively the catalyst reacts and that the active site density was critically important for performance,” says PNNL materials scientist Yuyan Shao, who led the study. “Our goal was to really improve the reaction activity of the cobalt-based catalysts.”

The multi-institutional team immobilised cobalt-based molecules in the micropores of zeolitic imidazolate frameworks, which served as protective fences to decrease the cobalt atoms’ mobility and to prevent them from clustering together. The team then used high-temperature pyrolysis to convert the atoms to catalytically active sites within the framework.

The researchers found that the density of the active sites significantly increased, in turn increasing the reaction activity, the PNNL said in a DOE article about the cobalt findings. That work achieved the highest activity in fuel cells reported for non-iron, platinum group metal-free catalysts, to date.

“In the end, we were able to not only improve the activity of the cobalt-based catalyst, bur we significantly improved the durability,” Shao says. “Our further investigation led us to discover the mechanisms that typically degrade these types of catalysts.”