Predictive Structure-Reactivity Models for Rapid Screening of Pt-Based Multimetallic Electrocatalysts for the Oxygen Reduction Reaction

Due to the immense phase space of potential alloy catalysts, any rigorous screening for optimal alloys requires simple and accurate predictive structure reactivity relationships. Herein, we have developed a model that allows us to accurately predict variations in adsorption energy on alloy surfaces based on easily accessible physical characteristics of the metal elements that form the alloy mainly their electro-negativity, atomic radius, and the spatial extent of valence orbitals. We have developed a scheme relating the geometric structure and local chemical environment of active Pt sites to the local chemical reactivity of the sites in the electrochemical oxygen reduction reaction (ORR). The accuracy of the model was verified with density functional theory (DFT) calculations. The model allows us to screen through large libraries of Pt alloys and identify many potentially promising ORR alloy catalysts. Some of these materials have previously been tested experimentally and shown improved performance compared to pure Pt. Since the model is grounded on validated theories of chemisorption on metal surfaces, it can be used to identify the critical physical features that characterize an optimal alloy electrocatalyst for ORR and propose how these features can be engineered.