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

The adsorption of O(2)on Pt(111) was studied with density functional theory calculations. Various adsorbed states of O(2)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 O(2)on OH/H2O-covered Pt(111) surface starts with the physical adsorption of O-2. Two other adsorption states are reachable from the physisorbed state, the end-on, and bridging chemisorbed O-2. The analysis of the energetics of these adsorption states shows that O(2)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 O(2)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 O(2)stretching frequencies are close to 1400, 1300, and 900 cm(-1), respectively.