Multiscale Pore Structures across Fuel Cell Components

Achieving high power density and durable operation remains a central challenge for the commercial deployment of proton exchange membrane fuel cells (PEMFCs). This challenge is closely linked to the multiscale pore structures distributed across fuel cell components. This Review examines multiscale pore structures across key PEMFC components, including porous catalysts, supports, catalyst layers, and gas diffusion layers, and discusses their roles in governing gas transport, phase distribution, and structural degradation during operation. Particular attention is given to the way pore networks link local transport limitations with component-level performance and long-term stability. Recent advances in advanced characterization and simulation are also discussed as essential tools for resolving pore-scale transport behavior and its evolution under realistic operating conditions. By consolidating reported insights across fuel cell components, this Review highlights the significance of multiscale pore structures in constraining transport behavior and operational robustness in PEMFCs.