Performance and uniformity enhancement in low‑platinum PEMFCs via synergistic dual‑segment power‑law platinum and ionomer gradients: A physics‑informed multi‑objective optimization approach

Low platinum loading severely restricts the performance and durability of proton exchange membrane fuel cells (PEMFCs). To overcome this, a physics-informed analysis and optimization framework is proposed to condense high-dimensional distribution spaces into interpretable parameters for efficient gradient cathode catalyst layer (CCL) designs. Drawing on regional sensitivity analyses, a dual-segment power-law profile (DSPLP) is introduced to address region-specific demands for Pt and ionomer. A three-dimensional multiphase PEMFC model with agglomerate submodel evaluates net output power and current density uniformity across DSPLP configurations. Independent and interactive DSPLP-based Pt loading and ionomer-to-carbon (I/C) ratio distributions are sequentially analyzed to identify critical parameters and influencing mechanisms, followed by multi-objective optimization for synergistic Pt-ionomer designs. Results show that compared to linear distribution, independent DSPLP-based Pt and ionomer gradients primarily mitigate ohmic and concentration losses, respectively, boosting net performance. However, both degrade current density uniformity by modulating proton availability and oxygen transport resistance, particularly steep ionomer gradients. The Pt-ionomer gradient interaction flattens the optimal Pt distribution to near-linear and lowers the mean I/C ratio from 0.70 to 0.60. Ultimately, at a Pt loading of 0.1 mg·cm⁻², the optimized DSPLP CCL reduces concentration loss by 0.04 V via ionomer gradient, supplemented by Pt-driven ohmic mitigation, yielding a 5.26% increase in peak net power over uniform CCL, exceeding the 3.52% gain from linear CCL. Synergistic effects further suppress extreme local current zones, improving uniformity by 5.65% at 1.5 A·cm⁻². This work provides a broadly applicable approach and valuable insights to support membrane electrode assembly design for next-generation PEMFCs.