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

ABSTRACT: 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 (TiO₂) (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 a

SUBMITTER: Cao Y 

PROVIDER: S-EPMC5045268 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature