Fine Tuning Highly Active Pt3Ni7 Nanostructured Thin Films for Fuel

Polymer electrolyte membrane fuel cells (PEMFCs) are under intense research and development for transportation applications. It has been shown that a highly active, lower cost, oxygen reduction reaction (ORR) catalyst can be made by replacing a portion of the costly Pt catalyst with a transition metal, in this case Ni [1]. Further gains can be achieved through dealloying the PtNi alloy catalyst to create a Ptrich skin or shell, although spontaneous dealloying during fuel cell operation poses a significant durability issue [2]. While usually deployed in nanoparticle form, highly active Pt3Ni7 nanostructured thin films (NSTF) have also been demonstrated, and the substantial increase in both the specific activity and specific surface area has been attributed to a complex interplay between composition, grain size, lattice strain, and the catalyst nanoparticle morphology, e.g., Pt-skin, -shell or -skeleton structures [3].