This Letter reports in situ Fourier transform infrared (FTIR) spectroscopic data on thermal TiO films fabricated by heating titanium plates in air at 475, 700 and 800 °C. The films were studied in the dark and under UV-irradiation in aqueous 0.1MNaClO in the presence and absence of 0.1 M Na(OOC) and at 10, 25 and 50 °C. The film fabricated at 800 °C showed a broad feature near 1580cm under UV-irradiation that was not observed in the dark, whilst the films fabricated at lower temperatures, 475 and 700 °C, showed no such feature. This feature appears to be associated with the accumulation of surface-mobile holes at the complex, porous film-electrolyte interface and the capacity of such holes to enhance the absorption cross-section of optical phonons characteristic of the rutile crystal form at and near the surface of the TiO/electrolyte interface.
Christensen, P. A., Eameaim, J., Hamnett, A., & Lin, W. F. (2001). Observation of an optical phonon band in situ in TiO electrochemistry: A possible indicator of strongly trapped intermediates in the O evolution reaction. Chemical Physics Letters, 344(5-6), 488-494. https://doi.org/10.1016/S0009-2614(01)00833-8