Polymer electrolyte hydrogen fuel cells and their application can contribute to a sustainable future energy landscape. A significant contribution to their costs originates from the platinum-based catalyst. To this date platinum cobalt alloy nanoparticles are the industry standard catalysts to facilitate the sluggish Oxygen reduction reaction (ORR). It has been demonstrated that platinum rare earth metal alloy nanoparticles have high ORR activities which is retained during accelerated stress tests (AST) [1].

The very negative reduction potential of the rare earth metals (-2.0 V to -2.5 V) pose great challenges on the synthesis of its respective platinum alloys with the right properties such as alloy phase and particle size distribution [2].

Last year we showed the successful synthesis of small Pt₃Y alloy nanoparticles using potassium vapor as the reducing agent at mild temperatures around 400 °C. Herein we demonstrate the synthesis of platinum alloy nanoparticles of gadolinium, cerium and lanthanum using the same method. Furthermore, we investigated the phase stability of different alloys towards acid leaching and the ORR performance before and after AST.

The Pt₃Y alloy phase appears to be stable against acid leaching, in contrast to Pt₂Y and all of the synthesized alloy phases of Gd, Ce and La. However, a lattice strain (shown by XRD) and traces of the respective rare earth element in the catalyst surface (shown by XPS) in combination with promising ORR results justify further investigation into these catalysts.

[1] Hernandez-Fernandez, P., Masini, F., McCarthy, D. N., Strebel, C. E., Friebel, D., Deiana, D., ... Chorkendorff, I. (2014). Mass-selected nanoparticles of PtxY as model catalysts for oxygen electroreduction. Nature Chemistry, 6(8), 732–738. https://doi.org/10.1038/nchem.2001

[2] Knudsen, B. P. (2016). Synthesis of Platinum Rare Earth Alloy Catalysts for Fuel Cells.