Evolution of anatase surface active sites probed by in situ sum-frequency phonon spectroscopy

Surface active sites of crystals often govern their relevant surface chemistry, yet to monitor them in situ in real atmosphere remains a challenge. Using surface-specific sum-frequency spectroscopy, we identified the surface phonon mode associated with the active sites of undercoordinated titanium i...

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Bibliographic Details
Published in:Science advances 2016-09, Vol.2 (9), p.e1601162
Main Authors: Cao, Yue, Chen, Shiyou, Li, Yadong, Gao, Yi, Yang, Deheng, Shen, Yuen Ron, Liu, Wei-Tao
Format: Article
Language:English
Subjects:
Anatase surface
Catalysis
Catalytic Domain
Chemistry
Hydrogen - chemistry
in situ surface spectroscopy
Methanol - chemistry
Nanostructures - chemistry
Oxygen - chemistry
Phonons
PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
SciAdv r-articles
Science & Technology - Other Topics
Spectrum Analysis
sum-frequency phonon spectroscopy surface photochemistry
surface active sites
surface oxygen vacancies
Surface Properties
Titanium - chemistry
Water - chemistry
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Summary:Surface active sites of crystals often govern their relevant surface chemistry, yet to monitor them in situ in real atmosphere remains a challenge. Using surface-specific sum-frequency spectroscopy, we identified the surface phonon mode associated with the active sites of undercoordinated titanium ions and conjoint oxygen vacancies, and used it to monitor them on anatase (TiO ) (101) under ambient conditions. In conjunction with theory, we determined related surface structure around the active sites and tracked the evolution of oxygen vacancies under ultraviolet irradiation. We further found that unlike in vacuum, the surface oxygen vacancies, which dominate the surface reactivity, are strongly regulated by ambient gas molecules, including methanol and water, as well as weakly associated species, such as nitrogen and hydrogen. The result revealed a rich interplay between prevailing ambient species and surface reactivity, which can be omnipresent in environmental and catalytic applications of titanium dioxides.
ISSN:2375-2548
2375-2548
DOI:10.1126/sciadv.1601162