Unlocking the oxygen transport challenges in PEM fuel cells and water electrolysis

The quest for sustainable and clean energy has propelled the development of hydrogen-based technologies. Proton exchange membrane (PEM) fuel cells and water electrolysis (PEMWEs) are at the forefront of this transition, offering efficient hydrogen utilization and production. However, their large-scale commercialization is hindered by high costs, primarily due to the use of noble metal catalysts. A comprehensive review published in Nano-Micro Letters by Professor Shuiyun Shen and Professor Junliang Zhang from Shanghai Jiao Tong University, China, provides a detailed analysis of the oxygen transport challenges within the catalyst layers of PEM fuel cells and PEMWEs. Their work offers critical insights and innovative solutions to enhance performance and reduce costs, paving the way for more sustainable hydrogen technologies.

Why Oxygen Transport Matters

• Enhanced Oxygen Transport in PEM Fuel Cells: The reduction of platinum loading in PEM fuel cells is crucial for cost reduction but is limited by oxygen transport resistance in the cathode catalyst layers (CCLs). Recent studies have shown that optimizing the pore structure and ionomer distribution can significantly improve oxygen transport efficiency. For example, the use of pore-forming agents and novel carbon supports has led to a substantial decrease in bulk oxygen transport resistance.
• Formation of High-Quality SEI Layer in PEMWEs: In PEM water electrolysis, the anode catalyst layers (ACLs) also face oxygen transport challenges. The formation of a high-quality interlayer through the optimization of ionomer and catalyst interactions can enhance the stability and efficiency of the ACLs, similar to the advancements seen in PEM fuel cells.

Innovative Design and Mechanisms

• Controlled Growth of Pore Structures: Researchers have developed various methods to control the pore structure in CCLs and ACLs, including the use of hard and soft templating techniques. These methods create well-defined pore channels that facilitate oxygen transport, improving both bulk and local oxygen transport properties.
• Conversion Reaction and Ionomer Design: The interaction between ionomers and catalysts plays a critical role in oxygen transport. Studies have shown that modifying the ionomer structure, such as using high oxygen permeability ionomers (HOPI), can enhance local oxygen transport. Additionally, the use of additives like polybenzimidazole (PBI) can improve ionomer distribution and reduce oxygen transport resistance.

Future Outlook

• Scalability and Practical Applications: The scalable synthesis of optimized catalyst layers and ionomer structures highlights their potential for practical PEM fuel cell and PEMWE applications. The insights gained from this review can guide the development of more efficient and cost-effective hydrogen technologies.
• Further Research: Future work may focus on exploring new materials and structures to further enhance oxygen transport and durability. Additionally, the integration of advanced characterization techniques and computational modeling can provide deeper insights into the oxygen transport mechanisms.

Conclusion: This comprehensive review provides a detailed analysis of the oxygen transport challenges in PEM fuel cells and PEMWEs, offering valuable insights and innovative solutions. By addressing these challenges, we can pave the way for the development of high-performance, low-cost hydrogen technologies, contributing to a more sustainable energy future.

Stay tuned for more groundbreaking advancements from Professor Shuiyun Shen and Professor Junliang Zhang at Shanghai Jiao Tong University as they continue to push the boundaries of hydrogen and fuel cell technologies!