(Invited) Development and Application of Core-Shell Cathode Catalysts in PEM Fuel Cell

Platinum group metals (PGM) catalysts are presently the most promising catalysts for the oxygen reduction reaction (ORR). However, the total PGM content in the PEM fuel cell should be reduced. To meet longer term passenger vehicle automotive targets, catalyst with at least 4 times higher mass activity over the currently available commercial Pt/C is required. One promising approach to meet this goal is the development of Pt monolayer core-shell catalysts through electro under-potential deposition of Cu onto a core (Pd, PdAu, etc.), followed by galvanic replacement of the Cu by Pt salt [1]. It is widely accepted that Pt monolayer catalysts exhibit at least 4-8 times higher mass activity vs. Pt/C, while also demonstrating excellent durability during accelerated stress testing on rotating disk electrodes (RDE) [2]. However, the scale-up synthesis of the platinum monolayer core-shell catalysts and the retention of favorable catalytic performance in the membrane electrode assemblies (MEA) are still quite challenging [3]. In this work, we will present the results of Pd@Pt/C core-shell catalysts successfully scaled up (in-house) from a conventional synthetic approach (micro gram level) to a large 3-electrodes reactor (gram level). It is demonstrated that this scale up is successful, with the gram level batch showing comparable activity to the small scale batch, based on RDE testing. In addition, preliminary in-situ MEA tests of commercial core-shell catalysts will be presented, demonstrating the performance and durability of these monolayer core-shell catalysts under fuel cell operating conditions. [1] R. R. Adzic. Electrocatalysis, 2012, 3 (3-4):163-169. [2] J. Hu, L. Wu, K. A. Kuttiyiel, K. R. Goodman, C. Zhang, Y. Zhu, M. B. Vukmirovic, M. G. White, K. Sasaki, R. R. Adzic, J. Am. Chem. Soc. 2016, 138: 9294-9300. [3] L. L. Zhang, S. Zhu, Q. Zhang, D. Su, J. Yue, Z. Du, M. Shao. ACS Catal. 2016, 6: 3428 −3432.