DFT Calculations of the Adsorption States of O2 on OH/H2O-Covered Pt(111).

Abstract

The adsorption of O2 on Pt(111) was studied with Density Functional Theory calculations. Various adsorbed states of O2 were evaluated on clean and OH/H2O-covered Pt(111) surfaces at the solid/gas and solid/liquid interfaces. The results reveal that the adsorption of O2 on OH/H2O-covered Pt(111) surface starts with the physical adsorption of O2. Two other adsorption states are reachable from the physisorbed state, the end-on, and bridging chemisorbed O2. Analysis of the energetics of these adsorption states shows that O2 physically adsorbed at the OH/H2O-covered Pt( 111) surface is a high energy state that requires activation to transition to the end-on chemisorbed O2 state. On the other hand, the end-on chemisorbed state can transition to the bridging chemisorbed state with only a small activation energy when a nearby Pt adsorption site is available. Frequency analysis of the physisorbed, end-on, and bridging adsorption states shows that adsorbed O2 stretching frequencies are close to 1400, 1300, and 900 cm-1, respectively.