A new recipe for preparing oxidized TiO2(110) surfaces: An STM study

TY - JOUR

T1 - A new recipe for preparing oxidized TiO2(110) surfaces

T2 - An STM study

AU - Hansen, Jonas O.

AU - Matthiesen, Jesper

AU - Lira, Estephania

AU - Lammich, Lutz

AU - Wendt, Stefan

PY - 2017/12

Y1 - 2017/12

N2 - Using high-resolution scanning tunneling microscopy (STM), we have studied the oxidation of rutile TiO 2(1 1 0)–(1 × 1) surfaces with H ad species at room temperature. We followed the evolution of various stable species as function of the O 2 exposure, and the nature of the ultimately dominating species in the Ti troughs is described. When O 2 saturation was accomplished using a glass-capillary array doser, we found that on-top O (O ot) adatoms are the predominant surface species. In contrast, when O 2 was supplied via backfilling of the chamber the predominant surface species are tentatively assigned to terminal OH groups. We argue that unintended reactions with the chamber walls have a strong influence on the formed surface species, explaining scattered results in the literature. On the basis of our STM data we propose an alternative, easy way of preparing oxidized TiO 2(1 1 0) surfaces with O ot adatoms (o-TiO 2). It is certain that o-TiO 2(1 1 0) surfaces prepared according to this recipe do not have any residual surface O vacancies. This contradicts the situation when oxidizing reduced TiO 2(1 1 0) surfaces with O vacancies, where some O vacancies persist.

AB - Using high-resolution scanning tunneling microscopy (STM), we have studied the oxidation of rutile TiO 2(1 1 0)–(1 × 1) surfaces with H ad species at room temperature. We followed the evolution of various stable species as function of the O 2 exposure, and the nature of the ultimately dominating species in the Ti troughs is described. When O 2 saturation was accomplished using a glass-capillary array doser, we found that on-top O (O ot) adatoms are the predominant surface species. In contrast, when O 2 was supplied via backfilling of the chamber the predominant surface species are tentatively assigned to terminal OH groups. We argue that unintended reactions with the chamber walls have a strong influence on the formed surface species, explaining scattered results in the literature. On the basis of our STM data we propose an alternative, easy way of preparing oxidized TiO 2(1 1 0) surfaces with O ot adatoms (o-TiO 2). It is certain that o-TiO 2(1 1 0) surfaces prepared according to this recipe do not have any residual surface O vacancies. This contradicts the situation when oxidizing reduced TiO 2(1 1 0) surfaces with O vacancies, where some O vacancies persist.

KW - CHEMISTRY

KW - ELECTRON

KW - H-ad species (OHbr groups)

KW - H2O

KW - O-2 DISSOCIATION

KW - O-ot adatoms

KW - OH GROUPS

KW - OHt groups

KW - OXYGEN ADATOMS

KW - REDUCED RUTILE TIO2(110)

KW - Rutile TiO2(110)

KW - SCANNING-TUNNELING-MICROSCOPY

KW - Scanning tunneling microscopy (STM)

KW - TIO2 PHOTOCATALYSIS

KW - TITANIUM-DIOXIDE

KW - WATER

UR - http://www.scopus.com/inward/record.url?scp=85029697875&partnerID=8YFLogxK

U2 - 10.1016/j.susc.2017.09.001

DO - 10.1016/j.susc.2017.09.001

M3 - Journal article

SN - 0039-6028

VL - 666

SP - 113

EP - 122

JO - Surface Science

JF - Surface Science

ER -