Optimization of Oxygen Transport and Performance of PEM Water Electrolyzers with a Gradient Porous Transport Layer: A Numerical Investigation

In the proton exchange membrane water electrolyzer (PEMWE), a porous transport layer (PTL) regulates the oxygen transport path and rate at the anode of PEMWE, significantly affecting the efficiency and durability of electrolysis. In this study, a three-dimensional numerical model is constructed, coupling its simulation results as boundary conditions with a two-dimensional Lattice Boltzmann model (LBM) to account for the differences in performance and oxygen transport caused by the gradient PTL. The results suggest that the PTL with cis-gradient porosity leads to a performance enhancement of 44.6mv than the trans-gradient porosity PTL at 1.9 A/cm 2 by minimizing oxygen accumulation near the catalyst layer and establishing more uniform pressure and diffusion pathways. The optimized structure increases oxygen saturation at the PTL–channel interface by 23.7% and decreases it at the CL–PTL interface by 9.7%, significantly enhancing the mass transfer and operational stability. These insights provide a foundational guideline for designing high-efficiency, durable PTL architectures and advancing next-generation PEMWE technology.