Suppression of Photoinduced BBO Defects Generation on TiO2(110) by Water

Abstract

We have investigated creation of variable concentrations of defects on TiO 2 (110)-(1×1) surface by 266 nm laser using temperature programmed desorption technique. Oxygen-vacancy defects can be easily induced by ultraviolet light, the defects concentration has a linear dependence on power density higher than 50 mW/cm 2 for 90 s irradiation. No observation of O 2 molecule and Ti atom desorption suggests that UV induced defects creation on TiO 2 (110)-(1×1) is an effective and gentle method. With pre-dosage of thin films of water, the rate of defects creation on TiO 2 (110)-(1×1) is slower at least by two orders of magnitude than bare TiO 2 (110)-(1×1) surface. Further investigations show that water can be more easily desorbed by UV light, and thus desorption of bridging oxygen is depressed.

Active Species in Photocatalytic Reactions of Methanol on TiO2(110) Identified by Surface Sum Frequency Generation Vibrational Spectroscopy

“…Here, 267 nm was used because the photon energy dependence shows that the photocatalytic reactivity with 267 nm is much higher than that with 400 nm. However, a previous result shows that 267 nm UV light higher than 50 μJ/cm 2 can induce O b vacancies on TiO 2 (110), so we used low UV intensity (0.3 mW, diameter 1.5 mm, that is ∼13 μJ/cm 2 ; the same way to generate UV light in the literature) to reduce this effect in our experiment. Figure shows the SFG vibrational spectra with ssp polarization combination of methoxy at O b sites on TiO 2 (110) before and after variant UV irradiation times.…”

“…Due to very high adsorption energy of methoxy at O b sites, it might be completely inactive with 267 nm light. UV light of 267 nm could induce desorption of the surface O b , 52 so it is possible that here the depletion of the CH 3 resonance features could be attributed to the direct desorption of CH 3 radical induced by 267 nm light.…”

A novel photo-thermochemical cycle for the dissociation of CO 2 using solar energy

“…However, UV-induced defects of the crystal faces on the surface of TiO 2 other than rutile TiO 2 (1 1 0) (e.g. anatase) have not been reported in the literature by STM [21,22]. For the reason that large single crystals are required in STM.…”

“…8(b)). Both phenomena can be attributed to the generation of Ti 3+ by UV light illumination [22,35]. The results of the XPS peak differentiation imitating analysis of State A and State B are shown in Fig.…”

“…These line defects were produced by UV light [21]. Xu et al discovered that TiO 2 (1 1 0)-(1 Â 1) on the rutile surface can construct controllable numbers of V O under illumination by a 266 nm pulse laser [22]. A line defect formation mechanism is assumed, whereby the photo-induced electron-hole pairs (EHPs) alter the material surface.…”