TY - JOUR

T1 - Investigation of Photostimulated Oxygen Isotope Exchange on TiO2 Degussa P25 Surface upon UV–Vis Irradiation

AU - Mikhaylov, Ruslan V.

AU - Lisachenko, Andrey A.

AU - Titov, Victor V.

PY - 2012

Y1 - 2012

N2 - The interaction of oxygen molecules with TiO2 (Degussa P25) surface under UV (λ = 365 nm) and vis (λ = 436 nm) irradiation at T = 293 K was investigated by means of mass-spectrometry and thermo-programmed desorption (TPD) spectroscopy. Oxygen chemisorbed on reduced TiO2 surface consists of molecular species O2– and atomic ones. The adsorbed O2 species which are stable at 293 K are not observed on oxidized TiO2. The UV or vis irradiation in 18O enriched oxygen induces an intensive photostimulated oxygen isotope equilibration (POIEq) and exchange (POIEx) via a weakly bonded intermediate O3– due to the interaction of 18O2 with a hole center Os– (which is an exchangeable anion Os2– that captured a photogenerated hole h+). The number of surface exchangeable oxygen anions is 2 × 1011 cm–2 for oxidized TiO2 and 108 cm–2 for reduced TiO2. There is a reason to consider the observed POIEq as a multiple interaction of Os– with 18O2 molecules (in fact by means of heteroexchange). Thus, the obtained POIEq rate corresponds

AB - The interaction of oxygen molecules with TiO2 (Degussa P25) surface under UV (λ = 365 nm) and vis (λ = 436 nm) irradiation at T = 293 K was investigated by means of mass-spectrometry and thermo-programmed desorption (TPD) spectroscopy. Oxygen chemisorbed on reduced TiO2 surface consists of molecular species O2– and atomic ones. The adsorbed O2 species which are stable at 293 K are not observed on oxidized TiO2. The UV or vis irradiation in 18O enriched oxygen induces an intensive photostimulated oxygen isotope equilibration (POIEq) and exchange (POIEx) via a weakly bonded intermediate O3– due to the interaction of 18O2 with a hole center Os– (which is an exchangeable anion Os2– that captured a photogenerated hole h+). The number of surface exchangeable oxygen anions is 2 × 1011 cm–2 for oxidized TiO2 and 108 cm–2 for reduced TiO2. There is a reason to consider the observed POIEq as a multiple interaction of Os– with 18O2 molecules (in fact by means of heteroexchange). Thus, the obtained POIEq rate corresponds

U2 - 10.1021/jp305652p

DO - 10.1021/jp305652p

M3 - Article

VL - 116

SP - 23332

EP - 23341

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 44

ER -