Acetone-Assisted Oxygen Vacancy Diffusion on TiO₂(110)

Abstract

We have studied the dynamic relationship between acetone and bridge-bonded oxygen (Ob) vacancy (VO) defect sites on the TiO2(110)-1 × 1 surface using scanning tunneling microscopy (STM) and density function theory (DFT) calculations. We report an adsorbate-assisted VO diffusion mechanism. The STM images taken at 300 K show that acetone preferably adsorbs on the VO site and is mobile. The sequential isothermal STM images directly show that the mobile acetone effectively migrates the position of VO by a combination of two acetone diffusion channels: one is the diffusion along the Ob row and moving as an alkyl group, which heals the initial VO; another is the diffusion from the Ob row to the five-coordinated Ti(4+) row and then moving along the Ti(4+) row as an acetone, which leaves a VO behind. The calculated acetone diffusion barriers for the two channels are comparable and agree with experimental results.

A DFT-based study of surface chemistries of rutile TiO2 and SnO2(110) toward formaldehyde and formic acid

“…For acetone adsorption and diffusion, we found an almost perfect agreement between STM and DFT results. [12] In contrast, the relative stabilities and adsorption configurations for formaldehyde on TiO 2 (110) predicted by DFT, although agrees with previous theoretical results, were not in line with the STM results [15]. Formic acid can be produced from oxidation of formaldehyde.…”

“…Therefore, the study of the adsorption and conversion of formaldehyde and formic acid is of great interests not only in terms of fundamental research but also the practical applications. Previously, we reported combined density functional theory (DFT) and scanning tunneling microscopic (STM) studies of the diffusion of Vo on TiO 2 (110) [11] as well as its role of the vacancy in adsorption and diffusion of acetone [12] and formaldehyde [13,14]. For acetone adsorption and diffusion, we found an almost perfect agreement between STM and DFT results.…”

Adsorption and dissociation of methanol on defective rutile TiO2 (110) surface with bridging oxygen-vacancy pairs

“…An additional attractive interaction between O b and H atoms exists in the more stable cases, which is indicated by the O b atom protruding from the row where it is located ( Figure 2B1-M1). This interaction has an important role in stabilizing the structures, as pointed by Xia et al in a previous study [33]. However, the orientations of the methyl do not affect the stability since the similar stability of B1-M1 and B1-M2.…”

Function ofTiO2Lattice Defects toward Photocatalytic Processes: View of Electronic Driven Force

“…Here a hypothesis is made that such heat do not or has little influence on the separation and migration of charge carriers. [64] and it could be seen that the potential field of the neighbouring Ti is The atomic lattice is blurred Maybe exists [72,123] Ultraviolet-visible spectroscopy (UV-vis) An optical absorption band above 400 nm Maybe exists [30] Photoemission spectroscopy (PL) The emission position and intensity Type, relative concentration of defects [124] Raman spectroscopy Variation in vibration of O and Ti-related region Type of defects [30,38,72] X-ray photoelectron spectroscopy (XPS) Valence state variation Type of defects mainly Ti 3+ [30,37,72,89] Electron paramagnetic resonance (EPR) factor calculated from the position of the sharp signal Type of paramagnetic defects [35,123,125,126] Positron annihilation lifetime spectroscopy (PALS) The lifetime of the positrons Size, type, and relative concentration of defects [68] Scanning tunneling microscopy (STM) Light dot in pictures The type, position of defects [31,113,120] Atomic force microscopy (AFM) Comparison of pictures The type, position of defects [38] Temperature programmed deoxidation (TPD) A narrow peak related to partial oxygen loss according to temperature. the most influenced site whereas the variations die largely in distance.…”

“…Defect state caused by OTDs was also found to influence the electronic structure of pristine TiO 2 , and visible light response was clearly observed in reduced TiO 2− specimens [11,30]. OTDs were found to be the active response sites from the scanning tunneling microscopy (STM), which came out to be one of the powerful techniques in detecting surface configuration in materials [31][32][33]. The formation of OTDs is called "self-doping. "…”