Programmable Two-Phase Transport and Interfacial Mechanics in Hierarchical Electrodes for High-Current-Density AEM Water Electrolysis

Green hydrogen is central to achieving a carbon-neutral energy future. Operating water electrolyzers at high current densities (≥4 A cm⁻²) lowers the levelized cost of hydrogen by boosting productivity, enabling compact stacks, and reducing balance-of-plant costs. However, such high-rate operation remains constrained by two coupled bottlenecks: bubble-induced transport losses that block ionic pathways and increase overpotential, and mechanical degradation from cyclic bubble detachment that weakenscatalyst–substrate adhesion. Existing strategies—micro/nano-texturing for bubble release, ordered porous networks for gas evacuation, and interlayer bonding for adhesion—have been effective individually but remain decoupled. In practice, these approaches address only isolated aspects of the problem: electrodes that remove bubbles efficiently often lose adhesion under stress, while those with strong interfaces trap bubbles and suffer transport losses. Consequently, mass transport and mechanical robustness have rarely been optimized simultaneously, leaving bubble nucleation, detachment, and in-pore transport uncontrolled at high current operation.To overcome these challenges, we propose a three-tier hierarchical electrode integrating a Ni TPMS substrate, a micro-cavity interlayer, and a conformal NiFe-LDH catalyst. This architecture unifies efficient gas evacuation, coalescence-induced early detachment, and robust interfacial anchoring. Preliminary studies demonstrate exceptional AEM-cell performance and durability—achieving 8.5 A cm⁻² @ 2.0 V and 14.8 A cm⁻² @ 2.3 V with stable operation for 6000 h @ 1 A cm⁻²—among the best reported for alkaline anodes, confirming the promise of geometry-driven co-optimization.Nevertheless, the underlying mechanisms remain poorly understood, particularly the coupling between cavity geometry and bubble kinetics, TPMS topology and in-pore gas transport, and interfacial structure and cyclic stress tolerance. Resolving these gaps requires a unified framework linking geometric design to both transport and mechanical responses under high-rate operation. This project will develop an integrated dual-scale approach combining modeling, fabrication, and characterization to reveal how geometry governs two-phase transport and interfacial mechanics. The modeling framework will link pore-scale transport with cavity-scale bubble evolution, generating predictive design maps for optimized architectures. These predictions will drive the fabrication of hierarchical electrodes via additive manufacturing and electrodeposition, followed by high-speed imaging, electrochemical and nanomechanical tests, and AEM validation—completing a closed loop from modeling to device-level performance.By uniting fundamental understanding and device-scale validation, we will establish geometry-based design rules for durable, high-rate AEM electrolysis—advancing both the science of multiscale bubble–structure interactions and the engineering of scalable green-hydrogen technologies.