Optimization on composition and structure of catalyst layer for high-temperature polymer electrolyte membrane fuel cells

High-temperature polymer membrane fuel cells (HT-PEMFCs) are considered as the trend of PEMFC future development due to their accelerated electrochemical reaction kinetics, simplified water/thermal management, and improved tolerance to impurities (CO). As the core part of membrane electrode assembly in HT-PEMFC, the catalyst layer significantly affects the cost, performance, and lifetime of HT-PEMFC. However, due to the high temperature and acid environment in HT-PEMFC, platinum (Pt) catalyst degradation and carbon corrosion are accelerated. Moreover, the loss of phosphoric acid (PA) which serves as the proton conductor is observed after long-term operation. In addition, the adsorption of phosphate on Pt surface leads to the poor Pt utilization. Thus, high cost and fast performance decay must be addressed for the commercialization of HT-PEMFC. Optimizing the composition and structure of catalyst layer are demonstrated as effective strategies to resolve the problems. In this review, we first summarize the latest progress in the optimization of catalyst layer composition for HT-PEMFC, including catalysts, binders, electrolyte (PA), and additives. Thereafter, the structural characteristics of catalyst layer are introduced and the optimization strategies are reviewed. Finally, the current challenges and research perspectives of catalyst layer in HT-PEMFC are discussed.