Reaction kinetics for the oxygen hydrogenation process on Pt(111) derived from temperature-programmed XPS

Oxygen hydrogenation under ultra high vacuum conditions at the platinum surface was explored using temperature-programmed X-ray photoelectron spectroscopy. Through modeling of the oxygen consumption, information on the reaction kinetics was obtained indicating that the reaction rate of the oxygen hydrogenation process depends on the hydrogen diffusion and on the lifetime of hydroxyl intermediates. The reaction rate is, however, enhanced when an autocatalytic process stabilizes the hydroxyl intermediates through hydrogen bonding to neighboring water molecules. The overall activation energy for the hydrogenation of atomic oxygen to form water was determined to be 0.20eV with a frequency factor of only 103s−1. [Display omitted] •O/Pt(111) consumption at H2 exposure obtained from temperature-programmed XPS.•Neither the first nor the second H addition step is the rate determining process.•The rate-determining process is the lifetime of the Pt-OH intermediate.•The reaction rate is enhanced through H-bonding between Pt-OH and neighboring H2O.•The energy barrier for the hydrogenation process of O is 0.20eV.