Adsorption kinetics of small molecules on FePt metallic electrode by molecular dynamics simulation

Abstract

Understanding how long reactants remain on catalytic surfaces (adsorption time) is essential for linking interfacial dynamics to overall reaction efficiency. In complex multistep systems such as the methanol oxidation reaction (MOR), the reaction pathways and surface poisoning are strongly related to the adsorption time and molecule orientation. By employing the molecular dynamics (MD) simulation method, the methanol, sulfuric acid and water molecules on the FePt alloy exposed to (001), ( 100) and ( 111) crystal planes were studied, thereby quantitatively defining and evaluating the adsorption time. Methanol exhibits the longest adsorption time, followed by sulfuric acid and water. Molecular conformation analysis further reveals two distinct interfacial regions: a 5 Å guiding layer, where methanol molecules initially approach the surface in a Cdown configuration, and a 3 Å reaction layer, where the C-O bond reorient parallel to the surface. Facet-dependent analysis indicates that the (111) surface, with alternating Pt and Fe atoms, possesses the strongest adsorption capacity, where the adsorption time for methanol is about 18 ps longer compared to the (001) facet. These findings establish a unified framework that quantitatively connects atomic structure, adsorption time, and molecular orientation, which provides a time-resolved perspective for the rational design of FePt-based electrocatalysts.