Low-platinum group metal (low-PGM) intermetallics are among the best materials as active and stable electrocatalysts for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFCs). The lack of control over the particle size and size distribution limits the use of thermal annealing method in the synthesis of carbon-supported low-PGM intermetallics because of the surface atomic diffusions at elevated temperatures. Herewith, we report the synthesis of sub-3 nm intermetallic PtCo ORR catalysts using a strong electrostatic adsorption (SEA) approach. The strong adhesion of metal ion precursors ensured to anchor the PtCo nanoparticles on the carbon support, thus suppressing the atomic migration and sintering during their conversions to intermetallic phases. The mass activity of the intermetallic PtCo catalyst was 0.67 A/mg_Pt (at 0.9 V vs. RHE) which was more than double that of its alloyed counterpart. Most noticeably, the mass activity of this catalyst dropped by merely 3% of its initial value after the accelerated durability test of 10,000 cycles, in a strong acid condition. This study provides a useful strategy for preparing ultrafine low-PGM intermetallic nanocrystals for ORR and paves the way to use the SEA approach for making intermetallic ORR electrocatalysts using various metals and support materials.

低铂族金属（low-PGM）金属间化合物是最好的材料，可作为聚合物电解质膜燃料电池（PEMFC）中氧还原反应（ORR）的活性和稳定电催化剂。由于在升高的温度下表面原子扩散，对粒度和粒度分布缺乏控制限制了在碳负载的低PGM金属间化合物的合成中使用热退火方法。因此，我们报告了使用强静电吸附（SEA）方法合成亚3 nm金属间PtCo ORR催化剂。金属离子前体的强粘附力确保将PtCo纳米颗粒固定在碳载体上，从而抑制了原子迁移和金属转化为金属间相期间的烧结。金属间PtCo催化剂的质量活性为0.67A / mg_Pt（相对于RHE为0.9 V）是其合金同类产品的两倍以上。最明显的是，在强酸条件下进行10,000次循环的耐久性试验后，该催化剂的质量活性仅下降了其初始值的3％。这项研究为制备用于ORR的超细低PGM金属间纳米晶体提供了有用的策略，并为使用SEA方法使用各种金属和载体材料制备金属间ORR电催化剂铺平了道路。