Ab initio atomic thermodynamics investigation on oxygen defects in the anatase TiO2

Abstract

In the framework of the ab initio Atomic Thermodynamics, the preliminary analysis of the annealing mechanisms of the oxygen defects in anatase TiO 2 has been done by investigating the influence of the annealing treatment under representative conditions on three typical oxygen defects, that is, oxygen vacancy, oxygen adsorption and oxygen interstitial, all of which exist during the annealing treatment by the defect chemistry, therefore, should be explored independently. Our results in this study agree well with the related experiments findings including the recent discoveries, e.g., we find that the type of the molecular ion of the adsorbed O 2 can also be determined by the initial orientation of O 2 relative to the surface (101). However, the critical annealing conditions under which the dominant oxygen defects would begin to convert to another one have not been found out due to the drawback of the current research scheme and we propose that this flaw could be compensated by studying the kinetics of the reactions, which may be the major task in the next stage of this research.

Kinetic Monte Carlo Simulations of Defects in Anatase Titanium Dioxide

“…45,73,78,141 Assuming that the Fermi energy is consistent with the kMC parameters we determined for samples 3−5, i.e. about 0.8 to 1.0 eV below the CBM for E g = 3.2 eV, in the specific temperature range, with O-rich conditions, the formation energy for V O 2+ is, for example, ∼3, 73 ∼4, 45 or ∼4.5 eV, 141 as well. (Since partial pressures were never documented in the studies we took the sample data from, a similar kMC study of defect types and concentrations in anatase samples of systematically documented growth temperature and oxygen partial pressure would be considered beneficial by the authors.)…”

Application of TiO2 Nanotubes Gas Sensors in Online Monitoring of SF6 Insulated Equipment

“…Thus, the gas molecules adsorbed in a small area of the TNTAs surface are simulated, and the nanotube-array structure is not taken into account. The prepared TNTAs are calcined at a high temperature in an oxygen-rich environment, and oxygen atoms should occupy the oxygen vacancies on the TNTAs surface [16]. The phenomenon is consistent with the findings that many thermodynamically stable (101) facets dominate the surface of most anatase nanocrystals [17].…”

Adsorptions of SO2, SOF2, and SO2F2 on Pt-modified anatase (101) surface: Sensing mechanism study

“…The results basically explain the gas-sensing mechanism of intrinsic TNTA [26,27]. However, considering the conclusions of other scholars at the same time, the sensing mechanism of Pt-modified TNTA still cannot be fully explained [28][29][30][31][32][33][34][35][36][37]. The preliminary sensing mechanism of Pt-modified TNTA is that the changes of the responses of Pt-modified TNTA to the three gases may be caused by the catalysis of the Pt nanoparticle [27].…”