Scientists at the Georgia Institute of Technology have developed a way to give fuel cell catalysts better catalytic activity and longevity using platinum and graphene.
In a study featured in the journal Advanced Functional Materials, researchers at Georgia Tech's School of Materials Science and Engineering successfully combined two atom-thick platinum films with graphene to produce fuel cell catalysts with superior stability over bulk platinum.
Using Platinum-Based Fuel Cell Catalysts
Fuel cell manufacturers often use platinum to make catalysts because of its ability to reduce oxidation reaction. However, the material is very expensive to use, especially in large quantities. This inspired researchers to look into ways on how to utilize platinum is smaller amounts without sacrificing catalytic activity during experiments.
Faisal Alamgir, an associate professor at Georgia Tech and one of the authors of the study, discussed the challenges that scientists face when developing platinum-based fuel cell catalysts.
"There's always going to be an initial cost for producing a fuel cell with platinum catalysts, and it's important to keep that cost as low as possible," Alamgir said.
"But the real cost of a fuel cell system is calculated by how long that system lasts, and this is a question of durability."
Alamgir added that recent studies have focused on using catalytic systems without including platinum. However, there is still no alternative method that could yield the same catalytic activity and durability of the material.
Combining Platinum Films With Graphene
For their work, Alamgir and his colleagues developed new systems that make use of atomically-thin platinum films combined with a layer of graphene. The method allowed the researchers to maximize the available surface area of platinum when trigger catalytic reactions. It also helped lower the amount of the material needed for experiments.
Catalytic systems that make use of platinum often depend on metal nanoparticles that have been chemically bonded to a support surface. The atoms found in this surface are the ones responsible for triggering the catalytic activity, leaving the atoms beneath it relatively underutilized during the process.
Alamgir and his team were also able to show that films of platinum that are at least two atoms thick performed better than nanoparticle platinum in terms of dissociation energy. This measures the energy cost when dislodging platinum atoms on a given surface. The researchers found that these films could yield catalytic systems that can last longer.
Results suggest that the bond between neighboring atoms in the platinum film came together with another bond, this time between the film itself and the graphene layer. This gave the catalytic system better durability throughout the process.
Alamgir explained that metallic films below a certain thickness are often unsuitable for experiments because the bonds between them are not directional. Most of the time, these films roll over each other and often conglomerate to form a particle.
The researcher said this was not the case with graphene, which has been proven to be stable in two-dimensional forms even when they are only one atom thick. The material is known to have particularly strong covalent directional bonds between its neighboring atoms.
Alamgir and his team believe their new catalytic system could take advantage of graphene's directional bonding to help support atomically-thin platinum films.