SI 1. A series of TEM images c.a. 3 nm Pt/Ru nanoparticles deposited on Pt-Rh APT tips for 2 seconds, 3seconds and 6 seconds at 1.5V. It reveals that the amount of Pt/Ru nanoparticles increases with the deposition time.

No abstract

Pt and Pt alloy catalysts for the PEMFC cathode fall short of the high activities per gram of Pt required to enable large scale automotive PEMFC commercialization. Thrifting of the active Pt component in the ORR catalyst via the formation of core shell catalysts is an exciting approach to resolve this issue. Pt monolayers have been deposited onto Pd3Co, Pd3Fe and Ir cores using scaleable proprietary methods. Characterisation of these materials, via cyclic voltammetry, LEIS and XPS, showed successful Pt coating of the surface and enhanced catalyst stability in liquid electrolyte cycling tests compared to the bare cores. Electrolyte analysis indicated leaching of base metals and Pd/Ir, so further optimisation is required to generate a uniform pinhole free Pt shell. RDE testing showed 3.7 x Pt activity for PtML/Pd3Co and preliminary MEA tests show great promise, with mass activity up to 2 x that of Pt only.