Insights into the adsorption of oxygen and water on low-index Pt surfaces by molecular dynamics simulations

Abstract

Adsorption of molecular oxygen on platinum surfaces is an important process of the Pt-catalyzed oxygen reduction reaction (ORR). In this work, classical molecular dynamics simulations were used to investigate adsorption of oxygen molecules on three low-index Pt surfaces, namely, (111), (100) and (110) surfaces, considering the coadsorption of the water molecules. The dynamic structures of the adsorbed species (O₂ and H₂O) were investigated. The results showed that the configurations and compositions of the adsorbed species varied on the three surfaces, and a strong correlation was found between the adsorption stability and adsorbed species structure at the interface. Pt(111) was the most favorable for oxygen adsorption, whereas Pt(100) was the most favorable for water adsorption. Our results also revealed the competitive adsorption between oxygen and water. Thus, this study provided new insight into the adsorption layer structure at the Pt/O₂/H₂O interface. And the attained knowledge will be useful for designing high performance ORR catalysts.