The development of active and stable nanoparticles for the ORR is crucial for the success of hydrogen fuel cells and their application in a new energy environment. Platinum based alloy nanoparticles supported on carbon is still the most widely applied catalyst. Literature suggests that platinum alloys of the rare earth metals, including Pt₃Y, imposes a superior activity and stability towards the state of the art catalysts [1].

A number of partly successful attempts to synthesize Pt₃Y have been made [2][3][4], but unfortunately, the synthesis routes lead to unacceptable particle sizes and distributions or the formation of undesired Pt_xY phases next to Pt₃Y. In most cases, scaling up is an additional challenge.

Our synthesis approach shows promise to produce phase pure and small Pt₃Y nanoparticles with a narrow particle size distribution.

The final sample was acid washed and subsequently studied by XRD, XPS, TGA and TEM. Its ORR performance has been measured using RDE.

The XPS results in figure 1a show that metallic/alloyed yttrium exists on the surfaced of the sample confirming that platinum has indeed alloyed with Yttrium and is stable towards the acid wash. However, some yttrium oxide can also be found. It might be located within the carbon support and protected against acid leaching. The XRD spectrum in Figure 1b suggest that almost pure phase Pt₃Y nanoparticles have been formed. Only minor contributions of the patterns originating from Pt and Pt₂Y can be observed. Using the Scherrer equation, one finds an average particle diameter of 7 nm. TEM images of the the Pt₃Y sample are shown in figure 1c, while figure 1d shows a commercial Pt/C catalyst for comparison. The improvement of activity is not yet as high as anticipated, so further work is needed to understand that and to optimize the manufacturing process. The synthesis process cannot be disclosed in the abstract due to a patenting process, but it will be presented at the conference.

[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.

[3] Kanady, J. S., Leidinger, P., Haas, A., Titlbach, S., Schunk, S., Schierle-Arndt, K., … Alivisatos, A. P. (2017). Synthesis of Pt3Y and Other Early-Late Intermetallic Nanoparticles by Way of a Molten Reducing Agent. Journal of the American Chemical Society, 139(16), 5672–5675. https://doi.org/10.1021/jacs.7b01366

[4] Cui, R., Mei, L., Han, G., Chen, J., Zhang, G., Quan, Y., … Han, Z. (2017). Facile synthesis of nanoporous Pt-Y alloy with enhanced electrocatalytic activity and durability. Scientific Reports, 7(December 2016), 1–10. https://doi.org/10.1038/srep41826