Interface Design and Optimization of Anode Catalyst Utilization in Water Electrolysis: Tomography-Based Modeling

Engineering the complex transport electrodes within proton exchange membrane water electrolysis (PEMWE) is a complex task: the anode catalyst layer (ACL) properties such as activity, electrical and ionic conductivities, permeability, thickness, contact angle, and its interface with the porous transport layer (PTL) significantly influence the performance of PEMWEs. To enable better exploitation of this interplay, this study presents a two-dimensional, two-phase model to capture the ACL dependence on its PTL interface structure, quantifying catalyst utilization. The model is validated against reference polarization curves, literature-based tomographic data, and an in-house constructed digital twin of the ACL. Simulation results reveal that catalyst utilization decreases with increasing electrode potential due to pronounced product transport limitations, which can already provide impulses to future electrode engineering. To mitigate these effects, balanced and high electrical and ionic conductivities and optimal pore size at the interface are analyzed by the model. The simulation results suggest an optimal pore size of ~3 μm at ACL/PTL interface under constrained electrical conductivity, while larger pores (~6 μm) are favored when conductivity is moderate. With an improved interface, the model shows that cell performance can be improved by 11.7% and 3.2%, respectively.