(Invited) Designing Advanced Low-PGM Core-Shell Electrocatalysts for Fuel Cells and Electrolyzers

Abstract

The low-content Pt-based core-shell catalysts potentially alleviate the drawback in the existing Pt catalysts (i.e., high cost, slow kinetics, poor stability, etc.) and further improve the oxygen reduction reaction (ORR) activity and stability for the proton exchange membrane fuel cells (PEMFCs).1 There have been remarkable advances in both the development of promising core−shell catalysts and the understanding of the fundamental catalytic mechanisms, and it is clear that some of the low platinum-group-metal (PGM) core−shell catalysts with enhanced activity and stability have great potential for use in PEMFCs. Nevertheless, various issues still need to be clearly addressed for the advanced core−shell catalysts of the future. On the other hand, PEM electrolyzers (ELs) are desirable large-scale energy devices to produce green hydrogen toward a net-zero carbon economy. The technologies require the availability of effective catalysts, particularly for the oxygen evolution reaction (OER). However, Ir- and Ru-based catalysts are currently the best-performing OER catalysts and their cost and limited availability hamper the widespread commercialization/deployment of PEMELs. Therefore, there is also an urgent need for developing highly durable and inexpensive catalysts for the OER. This talk first focuses on synthetic strategies, catalytic mechanisms, and influencing factors of Pt- and Ir-based catalysts used for PEMFCs and PEMELs. We will then discuss effective and solid strategies/designs to employ transition-metal-nitride-based cores for the development of highly advanced low-PGM core-shell catalysts for the ORR, particularly in heavy-duty vehicle (HDV) PEMFC applications, and for the OER in PEMEL applications. R. Zhao and K. Sasaki, Advanced Pt-Based Core-Shell Electrocatalysts for Fuel Cell Cathodes, Accounts of Chemical Research. 55 (2022) 1226-1236.