Mesoporous Co-N-C Supported L1-PtCo Alloy Enables Fast Mass Transport for Proton Exchange Membrane Fuel Cells.

Oxygen reduction reaction (ORR) performance of platinum can be improved through alloying transition metals, with L1-PtCo emerging as a standout option due to its balanced catalytic performance, durability, and manufacturability. However, traditional carbon supports often fail to stabilize nanoparticles, leading to performance degradation. This study introduces a mesoporous Co-N-C supported ordered L1-PtCo catalyst to overcome the above limitations. The CoN sites in the mesoporous Co-N-C (MS-CoNC) support create a strong synergy with L1-PtCo clusters, preventing nanoparticle aggregation during high-temperature synthesis. X-ray absorption spectroscopy reveals a unique shortened Pt-Pt bond length in L1-PtCo/MS-CoNC, which contributes to a mass activity of 0.54 A mg, 6.3 times that of commercial carbon-supported PtCo catalysts. Rationalised by density functional theory, L1-PtCo/MS-CoNC optimizes its d-band centre for enhancing ORR intermediate adsorption-desorption. Membrane electrode assemblies test deliver remarkably improved peak power density while with only 60 µg cm of Pt. The mesoporous structure of the Co-N-C support further reduces mass transport losses, enhancing oxygen diffusion and stability. Durability testing shows minimal performance loss after 30 000 voltage cycles, showcasing the catalyst's robustness under harsh PEMFC conditions. This work demonstrates the synergistic advantages of mesoporous Co-N-C supports and L1-PtCo catalysts, paving the way for high-performance, low-Pt fuel cell technologies.