Creating Favorable Pt/Co Interfaces via a Two‐Step Approach for Constructing Highly Durable PtCo Intermetallic Fuel Cell Catalysts

Abstract Structurally ordered PtCo intermetallics are one of the most promising oxygen‐reduction catalysts in proton exchange membrane fuel cells (PEMFCs) due to their intrinsically improved catalytic activity and stability relative to PtCo solid‐solution alloys. However, increasing the heating temperature to achieve a desirable high degree of ordering results in severe particle agglomeration and low mass activity and stability. Herein, a two‐step synthesis approach is developed to create an L1 2 ‐Pt 3 Co intermetallic structure with an increased ordering degree and well‐dispersed ultrafine particles. The first step of the synthesis yields ultrafine Pt nanoparticles that are well‐dispersed on the ZIF‐8‐derived carbon support. The second adsorption step enables us to fine‐tune the Pt and Co interfaces, assisted by optimal amino acids, to establish a favorable Co‐rich environment around fine Pt nanoparticles, facilitating Co diffusion into the Pt crystalline under mild thermal conditions (<800 °C). This two‐step ordered L1 2 ‐Pt 3 Co catalyst is systematically evaluated using membrane electrode assemblies under heavy‐duty vehicle (HDV) conditions and demonstrated exceptional performance and durability, retaining 1.35 A cm ‐ 2 only a 7% loss in current density at 0.7 V after an extensive accelerated stress test of 150,000 voltage cycles.