Insights Into Atomic Ordering and Morphological Control Integration Design for Next-Generation Proton Exchange Membrane Fuel Cells.

Proton exchange membrane fuel cells (PEMFCs) are emerging as key energy conversion systems for heavy-duty vehicles, stationary power plants, and high-load infrastructures such as data centers. However, their long-term durability remains critically constrained by transition metal dissolution and structural degradation in alloy catalysts, particularly under heavy-duty target operation (90°C-120°C). Recent studies reveal that the fundamental origin of degradation lies not simply in alloy composition but in the instability of atomic ordering within each grain. Long-range ordered (LRO) intermetallic phase enhances thermodynamic stability through strong atomic bonding, yet their high-temperature synthesis often induces particle coarsening and structural defects. Conversely, short-range ordered (SRO) phase arranges at lower energies, enabling morphology preservation while providing locally stabilized chemical environments that suppress dissolution. Advances in operando microscopy and three-dimensional atomic electron tomography have clarified how atomic-scale ordering, strain distribution, and site occupancy govern degradation pathways. Building on these insights, low-temperature atomic rearrangement strategies coupled with morphology engineering offer a unified framework for achieving stable electronic structures, minimized defect density, and enhanced durability. This review consolidates the mechanistic understanding of ordering-dependent degradation and proposes atomic ordering-morphology integration design for next-generation PEMFC catalysts capable of sustaining high performance under demanding conditions.