Electronic properties of rutile and anatase TiO2 and their …
Photocatalysis is a promising technique for utilizing solar light in chemical synthesis. Among several effective photocatalysts, TiO 2 remains the archetypal representative. Using density functional theory calculations, we characterized the geometric, mechanical, electronic and optical properties of rutile and anatase TiO 2.We show that a …
Understanding the surface reduction of nano rutile and anatase …
Though black titania has been widely investigated, the influence of crystal phase during the reduction process remains unknown. In the present study, we found that the rutile phase is preferentially reduced over anatase from detailed experimental investigations and a comprehensive understanding of selective breaking of Ti-O bonds in …
Checking the Synergetic Effect between Anatase and Rutile
To check the synergetic effect between anatase and rutile, a series of anatase–rutile-coupled TiO 2 photocatalysts were prepared by calcination of the …
Tailored Preparation Methods of TiO2 Anatase, Rutile, …
Using a simple aqueous precipitation method based on a low-cost titanium oxysulfate precursor, we have prepared three TiO2 polymorphs: anatase, rutile, and brookite. Although the anatase form can be directly obtained from the thermolysis reaction of an oxysulfate solution, the rutile and the brookite have been prepared by the addition …
On Oxygen Activation at Rutile- and Anatase-TiO2 | ACS …
The rutile form of titanium dioxide (r-TiO2) usually shows a photocatalytic activity lower than that of anatase-TiO2 (a-TiO2). Nevertheless, there are numerous examples of sometimes unexpectedly high activity of r-TiO2. This material may appear to be particularly useful when a noncomplete and selective photocatalytic oxidation of organic substrates is required. …
Why is anatase a better photocatalyst than rutile?
Utilizing high –quality epitaxial TiO 2 films of the two polymorphs we evaluate the photocatalytic activity as a function of TiO 2 -film thickness. For anatase the activity increases for films up to ~5 nm thick, while rutile films reach their maximum activity for ~2.5 nm films already. This shows that charge carriers excited deeper in the ...
Efficient and Homogenous Precipitation of Sulfur Within a …
The hybridization of anatase/rutile TiO2-x and the oxygen vacancy in TiO2-x play a crucial role in enhancing the conversion kinetics of lithium polysulfides (LiPSs), mitigating the shuttle effect of LiPSs, and enhancing the overall efficiency of the Li–S battery system. Additionally, the free-standing TiO2-x/CNFs facilitate uniform deposition ...
The Role of Oxygen Vacancy in Anatase to Rutile …
Titanium dioxide (TiO2) recently has attracted a great deal of attention in different fields, such as renewable energy and pollutant removal, due to its low price and amphoteric nature. Many studies have pointed out that phase composition and oxygen vacancies play a certain role in promoting the performance of TiO2. However, the effect …
Phase evolution, morphological, optical and electrical …
A mixed-phase (anatase/rutile) TiO2 thin film was produced at a substrate temperature of 400 °C when samples are fabricated with anatase and rutile target materials. The results of this study ...
Crystal structures of TiO 2 : (a) anatase, (b) rutile
Anatase and rutile have more extensive applications because they are more stable than brookite (Figure 1). In all three forms, titanium (Ti 4+ ) atoms are coordinated to six oxygen (O 2− ) atoms ...
Quantitative analysis of anatase in Georgia kaolins using …
Anatase content was plotted versus spectral band intensity and a least-squares line was fit to the data. For our particular setup (i.e., 25% solid slurries, 128 scans, and invariant laser power), this resulted in the equation y=1.691x, where y is the weight percent anatase and x is the E g (ν 6), background-corrected band intensity at 144 cm −1.
New approach of modifying the anatase to rutile transition temperature
In pure synthetic titanium dioxide, the anatase to rutile phase transition usually occurs between the temperatures of 600 °C and 700 °C. The phase transition temperature can be altered by various methods, including modifying the precursor or by adding dopant or modifier to the TiO 2 sample. In an attempt to investigate the phase …
New understanding of the difference of photocatalytic …
In general, anatase TiO2 exhibits higher photocatalytic activities than rutile TiO2. However, the reasons for the differences in photocatalytic activity between anatase and rutile are still being debated. In this work, the band structure, density of states, and effective mass of photogenerated charge carrier
Ab initio quantum chemical studies of cluster models for doped anatase
The cluster models (Fig. 1) cut from anatase bulk structure were Ti 9 O 18, Ti 17 O 34, and Ti 21 O 42; and from rutile bulk structure were Ti 7 O 14, Ti 11 O 22 and Ti 15 O 30.One or two shells of the closest neighboring atoms or molecules surrounded the central titanium atom so that the cluster models were stoichiometric and as symmetrical …
Review of the anatase to rutile phase transformation
At all temperatures and pressures, rutile is the stable phase of TiO. 2. Anatase is metastable but it can be con- sidered to be kinetically stabilised at lower temperatures. Although rutile is the more stable phase from a thermo- dynamic point of view, anatase frequently is the product phase in the synthesis of TiO.
Why is Anatase a Better Photocatalyst than Rutile? The
Anatase is generally considered to be more active than rutile phase using as a photocatalyst. It excels in higher crystallinity preferred for photocatalysis; due to these properties, fewer defects ...
A Branched Rutile/Anatase Phase Structure Electrode with …
A photoelectrochemical (PEC) detection platform was built based on the branched rutile/anatase titanium dioxide (RA-TiO2) electrode. Theoretical calculations proved that the type-II band alignment of rutile and anatase could facilitate charge separation in the electrode. The self-generated electric field at the interface of two …
Strongly bound excitons in anatase TiO2 single crystals and …
Figure 8 a,b, respectively show the normalised Δ A of anatase TiO 2 NPs in aqueous solution and of doped anatase TiO 2 single crystals ( n = 2 × 10 19 cm −3 ), as a function of the probe ...
Reduced extrinsic recombination process in anatase and rutile …
Although the effective density of states of anatase (N C,anatase ~ 7.8 × 10 20 cm −3) 36 is larger than that of rutile (N C,rutile ~ 2.5 × 10 19 cm −3) 37, the slope of anatase (0.87 k B T/q ...
Preparation and photoactivity of samarium loaded anatase, brookite and
Highlights Pure and samarium loaded anatase, brookite and rutile nanopowders were synthesized by thermohydrolysis of TiCl 4. The beneficial effect of samarium on the photodegradation of 4-nitrophenol was attributed to an increased separation efficiency of the photogenerated electron–hole pairs. The presence of …
Review of the anatase to rutile phase transformation
The present work aims to clarify the differences between the two main polymorphs of titanium dioxide, the nature of the anatase to rutile transformation, and …
Metal-organic framework-derived mixed-phase anatase/rutile …
The fourth factor is that the anatase/rutile mixed phase interface effect leads to charge separation at the boundary, providing additional good lithium storage sites, while enhancing the charge transfer kinetics and providing high-rate capability at the same time. Among them, the crystal phase transition caused by the temperature change is the ...
Unraveling the photocatalytic activation of …
The details of the used chemicals were provided in the Supporting Information.A simple solvothermal method was proposed to prepare the TiO 2 samples using precursor solutions containing Pluronic surfactant F127, titanium tetraisopropoxide, ethanol and HCl (Fig. 1 A). [35] The anatase/rutile (A/R) ratio was controlled by …
Synthesis of anatase and rutile mixed phase titanium …
The anatase and rutile planes of TiO 2 nanoparticles made with 0.6 M of Ti precursors exhibit the same XRD peak intensity. This can be attributed to TiO 2 crystal phase transformation from rutile to anatase with increase in titanium precursor. Anatase is more stable at low temperature and transfers to rutile phase at high temperature.
Heterophase Polymorph of TiO2 (Anatase, Rutile, Brookite, …
TiO2 exists naturally in three crystalline forms: Anatase, rutile, brookite, and TiO2 (B). These polymorphs exhibit different properties and consequently different photocatalytic performances. This paper aims to clarify the differences between titanium dioxide polymorphs, and the differences in homophase, biphase, and triphase properties in …
Comparative study of the effects of anatase and rutile …
The anatase and rutile titanium dioxide (TiO 2) were prepared and characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscope and UV–vis spectrophotometer.Then they were introduced into waterborne polyurethane (WPU) to prepare hybrid films. The effects of anatase and rutile TiO 2 on …
Why is anatase a better photocatalyst than …
Generally, anatase is moreactive than rutile, but no consensus exists to explain this difference. Here we demonstrate that it is the bulk transport of excitons to the surface …
Band Alignment and Controllable Electron Migration between Rutile …
Difference in surface states for anatase and rutile nanoparticles. Figure 4a shows the TIRA-ESS for anatase nanocrystals of three different size, i.e., 8, 19 and 200 nm respectively, where the E ...
Brookite vs. rutile vs. anatase: What`s behind their …
The results of investigating the morphological, optical and electronic properties of three synthesized TiO 2 polymorphs (anatase (A and A2), brookite (B and …
Why is anatase a better photocatalyst than rutile?
for the anatase (001) and rutile (101) samples, respectively. For the anatase sample a 4 3 1 superstructure is observed in the RHEED pattern. This is the typical surface reconstruction for the anatase
