Turing-Patterned Catalyst-Ionomer Architectures for Enhanced Mass Transport in Anion Exchange Membrane Fuel Cells

The membrane electrode assembly, a core component of anion exchange membrane fuel cells (AEMFCs), faces critical challenges in maintaining operational stability under fluctuating humidity conditions due to the insufficient environmental adaptability of conventional catalyst layers (CLs). Typically, ionomers within CLs simultaneously serve as ionic conductors and structural binders. However, their random distribution often leads to transport bottlenecks that compromise the triple-phase interface effectiveness. Herein, we introduce a molecular engineering strategy to construct Turing-patterned ionomer networks through precisely controlled cross-linking chemistry. Advanced microstructural characterization (transmission electron microscopy and atomic force microscopy) confirms the formation of a distinctive pendant-cross-linked architecture with periodic nanochannels (∼8 nm width), establishing interconnected pathways for simultaneous ion, water, and O₂ transport under low-humidity operating conditions. Combined theoretical modeling and electrochemical diagnostics reveal that this Turing-patterned architecture effectively reduces mass transport resistance compared to conventional systems while maintaining better single-cell durability. The engineered CL enables AEMFCs to achieve a record-high peak power density of 1.39 W cm^-2 under practical low relative humidity (70 °C, 60% RH, 0.1 MPa backpressure).