Tetraoxygen on reduced TiO2(110):: Oxygen adsorption and reactions with bridging oxygen vacancies

Oxygen adsorption on reduced TiO(2)(110) is investigated using temperature programed desorption and electron-stimulated desorption. At low temperatures, 2 O(2) molecules can be chemisorbed in each oxygen vacancy. These molecules do not desorb upon annealing to 700 K. Instead, for 200 K < T < 400 K, the 2 O(2) convert to another species, which has four oxygen atoms, i.e., tetraoxygen, that decomposes at higher temperatures. In contrast, when only 1 O(2) is adsorbed in an oxygen vacancy, the molecule dissociates upon annealing above similar to 150 K to heal the vacancy in agreement with previous results.