Ordered Pt5LaCeGdTb high-entropy alloy: tunable atomic mobility boosts proton exchange membrane fuel cells

High-entropy alloys (HEAs) have emerged as efficient electrocatalysts for the acidic oxygen reduction reaction (ORR). However, research on ordered HEAs remains limited, and the role of atomic mobility in catalytic performance is not fully understood. Here, a series of Pt 5 LaCeGdTb HEA nanoparticles with tunable atomic mobility were prepared via Joule thermal shock. We unravel the mechanism of the transformation from high to low atomic mobility in HEA nanoparticles at the single-particle level. The electrocatalytic performance is closely correlated with crystalline and electronic structures. Lowering atomic mobility significantly enhances electrocatalytic activity. The highly ordered Pt 5 LaCeGdTb (H-Pt 5 LaCeGdTb) exhibits a half-wave potential of 0.94 V in acidic ORR, a mass activity (MA) 13-fold higher than commercial Pt/C and a specific activity 8.3-fold higher. After 30k cycles of accelerated durability tests, the MA retention remains at 94.1%. Notably, the H-Pt 5 LaCeGdTb catalyst with low Pt loading exhibited superior Pt efficiency in proton exchange membrane fuel cells at elevated temperature compared to Pt/C. This order-dependent structure-performance relationship provides critical insights for the rational design of ordered HEAs catalysts.