Structurally ordered L1₀-PtM (M = Fe, Co, Ni and so on) intermetallic nanocrystals, benefiting from the chemically ordered structure and higher stability, are one of the best electrocatalysts used for fuel cells. However, their practical development is greatly plagued by the challenge that the high-temperature (>600 °C) annealing treatment necessary for realizing the ordered structure usually leads to severe particle sintering, morphology change and low ordering degree, which makes it very difficult for the gram-scale preparation of desirable PtM intermetallic nanocrystals with high Pt content for practical fuel cell applications. Here we report a new concept involving the low-melting-point-metal (M′ = Sn, Ga, In)-induced bond strength weakening strategy to reduce E_a and promote the ordering process of PtM (M = Ni, Co, Fe, Cu and Zn) alloy catalysts for a higher ordering degree. We demonstrate that the introduction of M′ can reduce the ordering temperature to extremely low temperatures (≤450 °C) and thus enable the preparation of high-Pt-content (≥40 wt%) L1₀-Pt-M-M′ intermetallic nanocrystals as well as ten-gram-scale production. X-ray spectroscopy studies, in situ electron microscopy and theoretical calculations reveal the fundamental mechanism of the Sn-facilitated ordering process at low temperatures, which involves weakened bond strength and consequently reduced E_a via Sn doping, the formation and fast diffusion of low-coordinated surface free atoms, and subsequent L1₀ nucleation. The developed L1₀-Ga-PtNi/C catalysts display outstanding performance in H₂–air fuel cells under both light- and heavy-duty vehicle conditions. Under the latter condition, the 40% L1₀-Pt₅₀Ni₃₅Ga₁₅/C catalyst delivers a high current density of 1.67 A cm⁻² at 0.7 V and retains 80% of the current density after extended 90,000 cycles, which exceeds the United States Department of Energy performance metrics and represents among the best cathodic electrocatalysts for practical proton-exchange membrane fuel cells.

结构有序的L1 ₀ -PtM（M=Fe、Co、Ni等）金属间纳米晶，得益于其化学有序结构和较高的稳定性，是用于燃料电池的最佳电催化剂之一。然而，实现有序结构所需的高温（>600℃）退火处理通常会导致严重的颗粒烧结、形貌变化和低有序度，这使得它们的实际开发受到极大的困扰，这使得其实现非常困难。克级制备具有高 Pt 含量的理想 PtM 金属间纳米晶体，用于实际燃料电池应用。在这里，我们报告了一个新概念，涉及低熔点金属（M′ = Sn，Ga，In）诱导的键强度弱化策略，以降低E _a并促进 PtM（M = Ni，Co，Fe）的有序过程、Cu和Zn)合金催化剂具有较高的有序度。我们证明M′的引入可以将有序温度降低到极低的温度（≤450℃），从而能够制备高Pt含量（≥40wt％）L1 ₀ -Pt-MM′金属间纳米晶：以及十克规模的生产。 X射线光谱研究、原位电子显微镜和理论计算揭示了低温下Sn促进有序化过程的基本机制，其中包括通过Sn掺杂削弱键强度并因此降低E _a 、低原子团的形成和快速扩散。配位表面自由原子，以及随后的L1 ₀成核。所开发的L1 ₀ -Ga-PtNi/C催化剂在H ₂空气燃料电池中在轻型和重型车辆条件下均表现出出色的性能。 在后一种条件下，40％L1 ₀ -Pt ₅₀ Ni ₃₅ Ga ₁₅ /C催化剂在0.7 V下提供1.67 A cm ^-2的高电流密度，并在延长90,000次循环后保留80％的电流密度，这超过了美国能源部的性能指标，代表了实用质子交换膜燃料电池的最佳阴极电催化剂。