Further enhanced performance of platinum nanocatalysts towards the oxygen reduction reaction (ORR) in fuel cells can be achieved by alloying platinum with a secondary metallic element, typically late transition metals such as Ni and Co.(1-4) Recent theoretical and experimental studies have shown that Pt- Rare earth (RE) metal alloys exhibit remarkable ORR activities, among the highest of all ORR catalysts ever reported. (5-7) Due to the substantial difference of standard reduction potentials between Pt and RE metals as well as the extremely high oxophilicity of RE metals, alloying of the two metals as nanoparticles meets great challenges by usual chemical routes.

Here we report a simple method of synthesizing Pt-RE alloy catalysts by one-step heat-treatment of common precursors. A long series of Pt-RE alloy catalysts with single alloy phases, e.g., Pt₃Y, Pt₂Gd, Pt₂Sm, Pt₅Ce, or Pt₅La, have been successfully synthesized, which exhibit narrow particle size distributions and excellent ORR performance. The highest ORR activities, achieved as far, are around 6 times (by Pt surface area) and 3 times (by Pt mass) higher than the start-of-the-art Pt/C catalysts. Several alloy catalysts such as Pt₅Ce/C and Pt₅La/C have showed also excellent stabilities by the standard accelerated stability tests. Furthermore, the synthesis mechanism has been clarified by investigation of intermediate products of the synthesis. The synthesis scale has been increased to 5-10 per batch for specific catalysts. As such, fuel cell tests with this type of catalysts become feasible, which have yielded promising results.

1. V. R. Stamenkovic et al., Science 315, 493-497 (2007).
2. X. Q. Huang et al., Science 348, 1230-1234 (2015).
3. B. Han et al., Energy & Environmental Science 8, 258-266 (2015).
4. C. Cui et al., Nat. Mater. 12, 765-771 (2013).
5. M. Escudero-Escribano et al., Science 352, 73-76 (2016).
6. M. Escudero-Escribano et al., J. Am. Chem. Soc. 134, 16476-16479 (2012).
7. J. Greeley et al., Nature Chemistry 1, 552-556 (2009).