Photocatalysis on TiO₂ Surfaces Investigated by Atomic Force Microscopy:  Photodegradation of Partial and Full Monolayers of Stearic Acid on TiO₂(110)

Abstract

We have studied the nature and surface morphological changes associated with the photodegradation of stearic acid LB films on TiO2(110). Interestingly, submonolayers of stearic acid consisted of circular domains of various sizesa feature very attractive for monitoring TiO2 photocatalysis by AFM. We noted that there was no bulk differential reactivity at island edges compared to the interior. This suggests that the rate of photodegradation of the stearic acid molecules is independent of their location in the island. Accordingly, the overall surface reactivity trends were similar for both partial films and complete films. Likewise, the observed inhomogeneous reactivity patterns appear to be a reflection of the transient distribution of the reaction centers.

Photocatalytic Evidence of the Rutile‐to‐Anatase Electron Transfer in Titania

“…[4][5][6][7][8] Stearic acid is highly stable under UV irradiation in the absence of an underlying, effective photocatalyst fi lm. The overall degradation reaction is given by Equation ( 1) and can be easily monitored for transparent samples via infrared spectroscopy, following the disappearance of typical C-H bands at 2958, 2923 and 2853 cm −1 (Figure 6 (a) …”

Improved Power Conversion Efficiency of Organic Photovoltaic Cell Fabricated by Electrospray Deposition Method by Mixing Different Solvents

“…Figure 4 shows the atomic force micrograph (AFM) images of monolayer stearic acid prepared on a TiO 2 rutile (110) single crystal by the Langmuir-Blodgett method. 22,23) The thickness of the organic substance was about 2 nm, and the number of stearic molecules was roughly estimated to be 10 16 -10 17 / cm 2 . When this was exposed to UV light of about 2.5 mW/ cm 2 , surface morphological changes were clearly observed, i.e., the inhomogeneous pitting of the film was very distinct.…”

X-ray Absorption Spectral Analyses by Theoretical Calculations for TiO2 and Ni-Doped TiO2 Thin Films on Glass Plates

“…According to a theoretical calculation introducing the manybody theory by van der Laan et al 20 and van Elp et al, 22 it has been reported that the large peak at 853 eV is assigned to the 2p -3/2 -3d 9 character and that the next peak at around 855 eV is assigned to 3d 9 L or hybrid ( 3d 9 and 3d 10 L -) characters. Also, the changes in the feature and position of the peak around 855 eV indicate that the spectral features are directly related to the oxidized form, or are reflected in multiplet splittings.…”

“…[1][2][3][4][5][6][7] Because the photocalalytic reaction is carried out at the surface of titanium oxides where UV light (< 380 nm wavelength) is irradiated, the surface structures of titanium oxides have also been of interest and studied. [7][8][9][10] The X-ray absorption spectroscopy (XAS) at the L-edges and the X-ray absorption near edge structure (XANES) at the Kedges for 3d transition metals is a powerful tool for investigating the steric and electronic structures of an absorbing atom center. [11][12][13][14][15][16][17] Since the core-hole lifetime of L-edge transitions is longer than that of K-edges, the L-edge XAS has very narrow inherent linewidths, which lead to better resolved features in the spectra, compared to the K-edge XANES.…”