Photoinduced Dissociation of O2 on Rutile TiO2(110)

Oxygen plays an important but often poorly understood, role in many photocatalytic processes. Here, we investigate the adsortption and photon-stimulated reactions of O-2 on reduced rutile TiO2 (110). After adsortption at 28K and anneling to 100 K, at least 85% of the O-2 has not dissociated. Typically less than 50% of this molecularly adsorbed O-2 desorbs via hole-mediated reactions during irradiation with ultraviolet (UV) photons. However, UV irradiation dissociates similar to 20-40% of the chemisorbed O-2, which we propose to occur through electron attachment reactions. In addition wealy bound (physisorbed) O-2 readily reacts with chemisorbed O-2 during UV irradiation. These results show that the photochemistry of oxygen on TiO2 (110) is both diverse and more complicated than previously appreciated.