Effect of Oxygen Vacancies on Photocatalytic Efficiency of TiO₂Nanotubes Aggregation

Abstract

Aggregation of titania nanotubes (TNTs) fabricated by hydrothermal method were calcined in air and dry nitrogen; Changes in morphology and crystallinity of the nanotubes were studied by means of TEM, EDX, and XPS. EDX patterns and XPS spectra proved that there were a certain densities of oxygen vacancies in TNTs annealed in N 2 . The photocatalysis experiments revealed TNTs/N 2 possesses significantly higher photocatalytic efficiency than TNTs annealed in dry air to degrade methylene blue. The correlation between oxygen vacancies and photocatalytic property may be attributed to: 1) oxygen vacancies might have affected results on water molecules adsorption and increase of the hydroxyl concentration; and 2) oxygen vacancies resulted in some changes in electronic structure of TNTs/N 2 aggregation and Fermi level extends into the conducting band.

Control of Optical Band Gap in La Doped Bismuth Titanate with Two Stage Doping

“…Accordingly, oxygen vacancies can narrow the band gap instead of just forming active centers or trap centers [22]. In addition, oxygen vacancies were reported to cause some changes in the electronic structure of TNTs/N2 aggregation and extend the Fermi level to the conduction band [23]. For example, in a TiO 2 crystal, the Fermi surface of the total density of states (TDOS) extended into the conduction band, which led to a decrease in band gap.…”

Influence of Oxygen to Argon Ratio on the Optical Band Gap of Bi3.25La0.75Fe1Ti2O12 Thin Films Deposited by RF Sputtering

“…The formation of oxygen vacancies resulted in some changes in the electronic structure and induced band-gap narrowing. 24 On the other hand, the effects of oxygen vacancies on the band gap could not be determined due to the oxygen-rich atmosphere during deposition. Under oxygen-rich conditions, oxygen atoms fill the oxygen vacancies in the BLFT film.…”

Nanocubes of rutile titania for enhanced visible light photocatalytic applications

“…These oxygen vacancies results on water molecules adsorption and increase of the hydroxyl concentration contributes to the higher photodegradation of MB. These radicals are finally able to oxidize all organic materials to harmless CO 2 and H 2 O [43]. As a result; titania, light source and the presence of dye enhances the photocatalytic and photosensitized oxidation to occur as shown in scheme.…”