Advancing low-Pt catalyst layer design from multi-scale to cross-scale synergy optimization for high-performance and durable proton exchange membrane fuel cell

Addressing renewable energy challenges through hydrogen requires the advancement of proton exchange membrane fuel cells (PEMFCs) for efficient hydrogen utilization and large-scale deployment. As the core of a PEMFC, the catalyst layer (CL) faces significant performance degradation challenges, particularly under low platinum (Pt) loading conditions. Therefore, advancing low-Pt CL designs through multi-scale to cross-scale optimization is crucial for improving both output performance and durability. This review systematically examines CL development from the perspective of multiscale design: molecular-scale manipulation of triple-phase interfaces, pore-scale optimization of water-gas transport in agglomerate structures, and macro-scale performance evaluation coupled with multi-physics fields. The chemical and mechanical degradation mechanisms of CL under dynamic operating and freeze-thaw cycles conditions are additionally reviewed. Importantly, this review highlights the applications of artificial intelligence for cross-scale bridging and synergistic reinforcement in durable low-Pt CL design, and prospect hybrid physics-informed and data-driven framework for degradation prediction. The aim of this review is to provide a novel perspective for the advancement of low-Pt PEMFC CL design, which can also offer guidance for other electrochemical renewable energy conversion technologies.