TY - JOUR
T1 - Oxygen deficiency and excess of rutile titania (1 1 0) surfaces analyzed by ion scattering coupled with elastic recoil detection
AU - Mitsuhara, Kei
AU - Matsuda, Taishi
AU - Okumura, Hideki
AU - Visikovskiy, Anton
AU - Kido, Yoshiaki
N1 - Funding Information:
The authors thank our colleagues, H. Matsumoto and H. Yamada for their experimental assistant. Thanks are also due to M. Takizawa for his valuable advice of UPS experiments. This work was partly supported by Japan Science and Technology, JST, CREST and also by Ministry of Education, Culture, Sports, Science and Technology, MEXT, Japan.
PY - 2011/8/15
Y1 - 2011/8/15
N2 - Oxygen deficiency and excess of rutile titania (TiO2) surfaces are important factors for catalytic activities of metal nano-particles on the TiO2 supports. Medium energy ion scattering (MEIS; 80 keV He +) coupled with elastic recoil detection analysis (ERD; 150 keV Ne+) can determine the numbers of bridging O (Obr) vacancies (VO) and excess O atoms adsorbed on the 5-fold Ti rows of TiO2(1 1 0) surfaces. The amounts of VO and adsorbed O were derived by H2O and 18O2 exposure followed by ERD and MEIS analyses, respectively. The present analysis revealed that only about a half of VO are filled and a comparable amount of O atoms are adsorbed on the reduced TiO2(1 1 0) surface after exposure to O 2 (1000 L; 1 L = 1 × 10-6 Torr s) at room temperature (RT). We also detected the adsorbed O for the hydroxylated TiO 2(1 1 0) after 18O2 exposure at RT. Finally, it is shown that the O adsorbed on the Ti rows reacts with CO probably to form CO2 at RT. Based on the results obtained here, we clarify the reason why only a half of VO are filled by exposing reduced surface to O2 at RT and what is the primary source of subsurface excess electronic charge, which acts as a leading part of the surface electrochemistry and gives the defect state in the band gap seen in the valence band spectra for reduced and hydroxylated TiO2(1 1 0) surfaces.
AB - Oxygen deficiency and excess of rutile titania (TiO2) surfaces are important factors for catalytic activities of metal nano-particles on the TiO2 supports. Medium energy ion scattering (MEIS; 80 keV He +) coupled with elastic recoil detection analysis (ERD; 150 keV Ne+) can determine the numbers of bridging O (Obr) vacancies (VO) and excess O atoms adsorbed on the 5-fold Ti rows of TiO2(1 1 0) surfaces. The amounts of VO and adsorbed O were derived by H2O and 18O2 exposure followed by ERD and MEIS analyses, respectively. The present analysis revealed that only about a half of VO are filled and a comparable amount of O atoms are adsorbed on the reduced TiO2(1 1 0) surface after exposure to O 2 (1000 L; 1 L = 1 × 10-6 Torr s) at room temperature (RT). We also detected the adsorbed O for the hydroxylated TiO 2(1 1 0) after 18O2 exposure at RT. Finally, it is shown that the O adsorbed on the Ti rows reacts with CO probably to form CO2 at RT. Based on the results obtained here, we clarify the reason why only a half of VO are filled by exposing reduced surface to O2 at RT and what is the primary source of subsurface excess electronic charge, which acts as a leading part of the surface electrochemistry and gives the defect state in the band gap seen in the valence band spectra for reduced and hydroxylated TiO2(1 1 0) surfaces.
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U2 - 10.1016/j.nimb.2011.05.007
DO - 10.1016/j.nimb.2011.05.007
M3 - Article
AN - SCOPUS:79959320256
SN - 0168-583X
VL - 269
SP - 1859
EP - 1864
JO - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
JF - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
IS - 16
ER -