Calculation of Coverage-Dependent Catalytic Activity for Alloy Nanoparticles with Experimentally Relevant Sizes

摘要

We present the use of ab-initio calculations to calculate the coverage-dependent catalytic activity of alloy nanoparticles with experimentally relevant sizes (5 nm - 10 nm) by explicitly predicting atomic-scale structures and adsorbate binding energies. We demonstrate our approach using Pt-Ni nanoparticles as catalysts for the oxygen reduction reaction (ORR). We achieve our results by constructing a quaternary Pt-Ni-OH-Vacancy cluster expansion model to explicitly predict OH adsorption energies on nanoparticles of varying shape, size, and atomic structure. The OH coverage-dependent ORR activity is calculated through a kinetic Monte Carlo (KMC) simulation. This model enables us to accurately investigate the catalytic activity of various surface sites with different coordination numbers and local atomic environments. Using this model, we evaluate how different parameters affect the ORR activity of Pt-Ni nanoparticles, including size (2 nm - 10 nm), Pt composition (50% - 100%), and shape. Through the use of KMC-enabled kinetic simulations of structural evolution we evaluate how the activities of the particles change due to Ni dissolution. Our approach identifies OH coverage at the atomic scale and provides theoretical insights into how to tune the structures of alloy nanoparticles to optimize catalytic activity.