Stability of Platinum-Group-Metal-Based Electrocatalysts in Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells (PEMFCs) have attracted significant interest as a promising alternative technology to the combustion engine to power next-generation vehicles with zero emission. Among the various technological targets, system cost and durability are currently identified as the main obstacles toward large-scale implementation of PEMFCs. Platinum-group-metal-based (PGM-based) catalysts are the most efficient catalyst for the rate-limiting cathodic oxygen reduction reaction in PEMFCs and take the highest share in the cost breakdown. Therefore, the stability of PGM-based electrocatalysts plays a significant role in the development of PEMFCs. This review will summarize the recent progress made on the understanding of both the fundamental chemical and structural stability of PGM-based catalysts, and their durability in operational PEMFC devices. It calls for systematic studies on the chemical, structural, and operational durability of the PGM-based catalyst and the need to coin practical descriptors for catalyst design with both superior activity and durability for cost-effective and high-performance PEMFCs.