Photocatalytic oxidation of the organic monolayers on TiO2 surface investigated by in-situ sum frequency generation spectroscopy

Yujin Tong, Qiling Peng, Tongsen Ma, Takuma Nishida, Shen Ye

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4 Citations (Scopus)


In-situ vibrational sum frequency generation (SFG) spectroscopy has been employed to investigate the photocatalytic oxidation of two types of well-ordered organic monolayers, namely, an arachidic acid (AA) monolayer prepared by the Langmuir-Blodgett method and an octadecyltrichlorosilane (OTS) monolayer prepared by the self-assembling method, on a TiO2 surface under ultraviolet (UV) irradiation. The extremely high sensitivity and unique selectivity of the SFG spectroscopy enabled us to directly probe the structural changes in these monolayers during the surface photocatalytic oxidation and further elucidate their reaction mechanisms at a molecular level. It was revealed that the ordering of the monolayers during the photocatalytic reaction is strongly dependent on their interaction with the substrate; the AA monolayer maintains its ordered conformation until the final oxidation stage, while the OTS monolayer shows a large increase in disordering during the initial oxidation stage, indicating a different photocatalytic reaction mechanism of the two monolayers on the TiO2 surface.

Original languageEnglish
Article number104402
JournalAPL Materials
Issue number10
Publication statusPublished - 2015 Oct 1
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)

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