Proton exchange membrane fuel cells (PEMFCs) are efficient energy converting devices and have great potentials in alternative energy applications. Nanoscale materials have been extensive applied in fuel cell technologies. For example, to increase the surface area of the catalysts so to maximize the power output, fuel cell catalysts are fabricated in the nanoparticle form. A long time puzzle is whether the catalytic activity depends on the particle size and the particle spacing. To address this question, we used uniform arrays of Pt nanoparticles with control size and interparticle spacing. It will be shown that the particle size and interparticle spacing play important roles in oxygen reduction, which is the cathode reaction in PEMFCs. One of the overarching challenges in PEMFCs development is to reduce the amount of Pt used in the catalysts.
Nanotechnology also plays an important role in this area. In this talk, Pt-based new catalysts for oxygen reduction will be discussed. The first are PtNi alloy nanoparticles with size and shape controlled. The other is dealloyed PtNi particles. These new catalysts show significantly higher activity for oxygen reduction. Methanol and formic acid oxidation on PtCu particles will also be discussed. It will be demonstrated that in addition to the particle composition, the shape of the particle plays an important role in catalyst activity.