Nitrogen: unraveling the secret to stable carbon-supported Pt-alloy electrocatalysts

Nitrogen functionalities significantly improve performance for metal-based carbon-supported catalysts, yet their specific role is not well understood. In this work, a direct observation of the nanoscale spatial relationship between surface nitrogen and metal catalyst nanoparticles on a carbon support is established through principal component analysis (PCA) of electron energy loss spectral (EELS) imaging datasets acquired on an aberration-corrected scanning transmission electron microscope (STEM). Improved catalyst-support interactions correlated to high substrate nitrogen content in immediate proximity to stabilized nanoparticles are first demonstrated using model substrates. These insights are applied in direct methanol fuel cell prototypes to achieve substantial improvements in performance and long-term stability using both in-house and commercial catalysts doped with nitrogen. These results have immediate impact in advanced design and optimization of next generation high performance catalyst materials.