Fe-doped TiO2 Research Articles

C-, N-, S-, and Fe-Doped TiO2 and SrTiO3 Nanotubes for Visible-Light-Driven Photocatalytic Water Splitting: Prediction from First Principles

The ground state electronic structure and the formation energies of both TiO2 and SrTiO3 nanotubes (NTs) containing CO, NO, SO, and FeTi substitutional impurities are studied using first-principles calculations. We observe that N and S dopants in TiO2 NTs lead to an enhancement of their visible-light-driven photocatalytic response, thereby increasing their ability to split H2O molecules. The differences between the highest occupied and lowest unoccupied impurity levels inside the band gap (HOIL and LUIL, respectively) are reduced in these defective nanotubes down to 2.4 and 2.5 eV for N and S doping, respectively. The band gap of an NO+SO codoped titania nanotube is narrowed down to 2.2 eV (while preserving the proper disposition of the gap edges relatively to the reduction and oxidation potentials, so that eHOIL < ϵO2/H2O < ϵH+/H2 < ϵLUIL), thus decreasing the photon energy required for splitting of H2O molecule. For C- and Fe-doped TiO2 NTs, some impurity levels lie in the interval between both redox po...

Photodegradtion of Methyl Orange in the Water on Undoped and Fe-doped TiO2 Nanotubes

Photodegradtion of Methyl Orange in the Water on Undoped and Fe-doped TiO2 Nanotubes

Direct microwave–hydrothermal synthesis of Fe-doped titania with extended visible-light response and enhanced H2-production performance

Fe-doped TiO2 photocatalysts were synthesized rapidly and directly by the microwave–hydrothermal method and evaluated for hydrogen production by water splitting under UV–vis irradiation. The photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption–desorption isotherms, inductively coupled plasma atomic emission spectroscopy, UV–vis spectroscopy, X-ray photoelectron spectra and photoelectrochemical experiments. The results showed that Fe-doped TiO2 photocatalysts synthesized by the microwave–hydrothermal method exhibited a smaller crystallite size and higher specific surface area than TiO2 photocatalysts. The microwave–hydrothermal method was a feasible way to increase the Fe doping concentration with enhanced electron–hole separation and electron transfer efficiency. It was also observed by first-principles density functional theory calculations that Fe can induce the formation of impurity levels near the valence band, leading to the reduction of the band gap and the improvement of photocatalytic activity. The highest photoactivity was achieved for TiO2 doped with 0.5% Fe with a hydrogen production rate of 10.95μmolh−1.

Correlation of Physicochemical Properties with the Catalytic Performance of Fe-Doped Titanium Dioxide Powders

A simple method for synthesis of Fe-doped TiO2 nanocrystalline powders, namely by coprecipitation, is described in this study. The influence of the iron content on the structural, morphological, optical and photocatalytic properties is determined. On the basis of XRD analysis, it was observed that anatase crystalline phase of TiO2 was stabilized, and the deformation of the elemental cell and strain increase with increasing of iron content due to the substitution of Ti4+ with Fe3+. The substitution process and the interaction between titanium and iron ions was also confirmed from the shifting of the Raman fundamental vibration from 144 to 149 cm–1. The absorption spectra showed that the optical response of TiO2 was red-shifted and the optical energy band gap decreased in the case of low content of Fe, whereas at high content of iron (in this case 3.11%), the optical response is blue-shifted due to the quantum size effect. The photocatalytic performance of Fe-doped TiO2 materials was correlated with the optical energy band gap. Thus, the best photocatalytic performance was obtained for the sample that contains 1.48% iron because it displays the lowest energy band gap (2.79 eV), so the material can absorb radiation from the visible range, even if this sample presents the lowest surface area. The efficiency of the degradation of Methylene Blue dye, under exposure to low intensity ultraviolet and visible radiations was 39%. Based on the characterization and performance of the Fe-doped TiO2 materials, it was concluded that the optimal iron content for our studies was 1.48%.

An ultrasensitive label-free immunosensor based on CdS sensitized Fe-TiO2 with high visible-light photoelectrochemical activity.

An ultrasensitive label-free immunosensor was developed for the detection of squamous cell carcinoma antigen (SCCA) based on CdS sensitized Fe-TiO2 nanocomposites with high visible-light photoelectrochemical (PEC) activity. In this protocol, ascorbic acid was used as an efficient electron donor for scavenging photogenerated holes. The Fe-doped TiO2 improved the absorption of TiO2 in the visible light region and promoted the photocurrent production distinctly. Especially, 0.1% Fe-TiO2 showed the highest photocurrent, which was 7.4 times that of pure TiO2. Carboxyl functionalized CdS nanoparticles (CdS NPs) were bonded onto Fe-TiO2 composite through interactions between carboxyl groups and TiO2, which further enhanced the PEC signal strength by approximately 2.9 fold compared with 0.1% Fe-TiO2. The specific binding between SCCA and antibody resulted in a decrease in photocurrent intensity and the intensity decreased linearly with the logarithm of SCCA concentration in the range of 0.001-75 ng mL(-1) with a detection limit of 0.22 pg mL(-1). The developed CdS enhanced Fe-TiO2 PEC immunosensor exhibited high sensitivity, good reproducibility, and low cost, which may have potential applications in clinical diagnosis of cancers, aptasensors, photocatalysis, and other related fields.

Investigation of TiO2 photocatalyst performance for decolorization in the presence of hydrodynamic cavitation as hybrid AOP

In this article, an acoustic cavitation engineered novel approach for the synthesis of TiO2, cerium and Fe doped TiO2 nanophotocatalysts is reported. The prepared TiO2, cerium and Fe doped TiO2 nanophotocatalysts were characterized by XRD and TEM analysis to evaluate its structure and morphology. Photo catalytic performance of undoped TiO2 catalyst was investigated for the decolorization of crystal violet dye in aqueous solution at pH of 6.5 in the presence of hydro dynamic cavitation. Effect of catalyst doping with Fe and Ce was also studied for the decolorization of crystal violet dye. The results shows that, 0.8% of Fe-doped TiO2 exhibits maximum photocatalytic activity in the decolorization study of crystal violet dye due to the presence of Fe in the TiO2 and it may acts as a fenton reagent. Kinetic studies have also been reported for the hybrid AOP (HAOP) that followed the pseudo first-order reaction kinetics.

Rapid photo- and photo-Fenton-like catalytic removals of malachite green in aqueous solution on undoped and doped TiO2 nanotubes

Undoped and Fe-doped TiO2 nanotubes with Fe content of 0–3.86 at.% were fabricated by hydrothermally treating sol–gel-derived undoped and Fe-doped TiO2 nanoparticles in NaOH aqueous solution. The Fe doping narrowed the optical band gap of the nanotubes from 3.17 to ~2.76 eV as the increase in Fe-doping content from 0 to 3.86 at.%. The nanotubes showed a large specific surface area of ~274–303 m2 g−1, which increased as the increase of Fe content. The sunlight-excited degradation experiments of malachite green in the water indicated that the nanotubes had a high photocatalytic activity. The Fe doping further enhanced the photocatalytic activity of the nanotubes, increased as increasing Fe-doping content. Moreover, the photodegradation of the dye became more fast as H2O2 was used, showing remarkable Fenton-like photocatalytic activity. This Fenton-like reaction also enhanced as increasing Fe content. An optimal H2O2 dosage was also observed. The quasi-kinetic first-order rate constant of the photodegradation of the malachite green aqueous solution with the concentrations of 1 × 10−6 and 1×10−5 mol l−1 were in the range of ~1.61–2.03 and ~0.41–0.65 min−1, respectively. These constants further increased to ~2.81–3.51 and ~1.71–2.04 min−1 as the H2O2 with a concentration of 10 ml l−1 is used.

Fabrication, characterization and photocatalytic performance of Fe-doped TiO2 nanotube composite for efficient degradation of water pollutants

Pure TiO2 nanotube and Fe-doped TiO2 nanotube composite were fabricated by the electrochemical anodic oxidation process and the impregnating-calcination method, respectively. The structural and spectral properties were characterized by scanning electron microscopy, energy dispersive X-ray spectrometer, X-ray diffraction, Fourier transform infrared spectroscopy, photoluminescence, and UV–vis spectrum. These results showed that Fe was effectively deposited on the surface of TiO2 nanotube. It is demonstrated that the Fe-doped TiO2 nanotube composite can inhibit the recombination of electron–hole pairs and enhance the light harvesting ability. The photocatalytic activity of Fe-doped TiO2 nanotube composite under UV irradiation was examined in terms of color and UV–vis absorbance for the degradation of methyl orange. The photocatalytic performance of UV-C irradiation in presence of Fe-doped TiO2 nanotube composite increased obviously for the removal efficiency of color and UV–vis absorbance compared to that of UV-A irradiation, and the reaction rate constant was about 6.8 times faster than that of UV-A irradiation. This can be ascribed to the effective separation of the photo-generated charge carriers.

Modeling of nitrate removal from aqueous solution by Fe-doped TiO2 under UV and solar irradiation using response surface methodology

&lt;div&gt; &lt;p&gt;Nitrate is a common groundwater pollutant all over the world. In some regions of Iran, its levels are high enough to cause serious problems to human health and the environment&lt;span dir="RTL"&gt;.&lt;/span&gt; The objectives of this work were to evaluate the efficiency of Fe-doped TiO&lt;sub&gt;2&lt;/sub&gt; nanoparticles at removing nitrate from aqueous solutions under UV and solar radiation and to model nitrate removal using response surface methodology techniques. In this study, a response surface methodology based on the Box&amp;ndash;Behnken design matrix was used to describe the process of nitrate removal from an aqueous solution with four independent parameters, namely Fe-doped TiO&lt;sub&gt;2&lt;/sub&gt; (dose 1-2 g l&lt;sup&gt;-1&lt;/sup&gt;), nitrate concentration (25-100 mg l&lt;sup&gt;-1&lt;/sup&gt;), contact time (10-120 min), and pH (4-9). The results indicated that the removal efficiency of nitrate in the presence of ultraviolet and solar radiation was 56.5 % and 21.8%, respectively. The removal efficiency of nitrate increased with time and initial concentration of nitrate. Analysis of variance (ANOVA) indicated that the proposed model was essentially in accordance with the experimental results with the correlation coefficient R&lt;sup&gt;2 &lt;/sup&gt;= 0.9237 and Adj-R&lt;sup&gt;2&lt;/sup&gt; = 0.8347. Response surface methodology (RSM) proved to be a powerful statistical tool for investigating the operating conditions for nitrate removal under UV irradiation.&lt;/p&gt; &lt;/div&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Enhanced photocatalysis using side-glowing optical fibers coated with Fe-doped TiO2 nanocomposite thin films

Abstract This study characterized and evaluated photocatalytic efficiency of Fe-doped TiO 2 (Fe–TiO 2 ) nanocomposite thin films coated on side-glowing optical fibers (SOFs) for organic contaminant degradation. For the first time Fe–TiO 2 thin films with mixed anatase and rutile phases were successfully grown on SOFs using polymer assisted hydrothermal deposition (PAHD) method. The photocatalyst films were characterized using transmission and scanning electron microscopes, energy-dispersive X-ray, X-ray diffraction, and X-ray photoelectron spectroscopes. The photocatalytic efficiencies of the catalysts coated SOFs were studied by the degradation of Rhodamine B as a representative organic contaminant. The results showed that 5% Fe–TiO 2 thin films (Fe:TiO 2 molar ratio), mixture of anatase and rutile phases, achieved the highest photocatalytic activity under the irradiation of ultraviolet (UV) and visible light. The coupled adsorption and photocatalytic oxidation of Rhodamine B by the SOFs coated with photocatalyst nanocomposite thin films followed the Langmuir–Hinshelwood kinetic model, and the apparent first-order rate constants achieved 0.50 h −1 and 0.33 h −1 under UV and visible light irradiation, respectively. Photocatalytic degradation efficiency was affected by pH and initial organic concentration. Reactivation and regeneration of the used catalysts, and long-term photoactivity testing of catalysts coated SOFs demonstrated the durability of synthesized photocatalysts for water treatment.

Dramatic CO2 photoreduction with H2O vapors for CH4 production using the TiO2 (bottom)/Fe–TiO2 (top) double-layered films

This paper reports the production of a catalyst for the efficient photoreduction of CO2 to CH4. TiO2 and xmol.% Fe-doped TiO2 (Fe–TiO2, x=0.5, 1.0, 5.0, 10.0mol.%) were prepared using a conventional solvothermal method. The prepared powders were fabricated as TiO2 (bottom)/Fe–TiO2 (top) double-layered films for applications to the photoreduction of CO2. The amount of CH4 generated from the photoreduction of CO2 with H2O increased remarkably over the TiO2/Fe–TiO2 double-layered photocatalytic films compared to the TiO2 (bottom)/TiO2 (top) double layered film. In particular, the amount of CH4 gas evolved over the TiO2/1.0mol.% Fe–TiO2 doubled layered film was 7 times higher than that produced over the TiO2 (bottom)/TiO2 (top) double layered film. A proposed model suggested that the photoactivity over the TiO2/Fe–TiO2 double layered films can be enhanced by the effective charge separation and inhibited recombination of photogenerated electron–hole (e−/h+) pairs on interfacial transfer between TiO2 and Fe–TiO2.

Typical Application of Sound Field in Wastewater Treatment with Fluidized Bed Photocatalytic Reactor.

The effect of a sound field on wastewater treatment with a fluidized bed photocatalytic reactor (FBPR) was investigated. With Alizarin Green (AG) being the sole infectant, the Fe-doped TiO2 catalyst prepared was used as the fluidized media. According to the Langmuir-Hinshelwood model, the photocatalytic degradation follows the pseudo-first-order reaction kinetics with respect to the concentration of AG. Sound field application allowed the fluidization of the fine powder at high liquid flow rates; thus, the mass transfer rate between organic pollutant and particle photocatalyst was enhanced and the efficiency of degradation was increased. As expected, the degradation rate constant increased with increasing sound pressure level, as well as increased with increasing sound frequency ranging from 50 to 100 Hz, then further decreased with increasing sound frequency from 100 to 200 Hz. In addition, Fe doping is also responsible for the enhanced photocurrent response of the Fe-doped TiO2 nanoparticle in FBPR relative to pure TiO2.

Highly effective Fe-doped TiO2 nanoparticles photocatalysts for visible-light driven photocatalytic degradation of toxic organic compounds

This paper reports the synthesis of various molar concentrations of iron (Fe)-doped TiO2 nanoparticles and their efficient use as potential photocatalysts for photocatalytic degradation of toxic and harmful chemical, paranitrophenol. The nanoparticles were synthesized by a novel and facile ultrasonic assisted hydrothermal method and characterized in detail by various analytical techniques in terms of their morphological, structural, compositional, thermal, optical, pore size distribution, etc properties. The photocatalytic activities of the as-prepared Fe-doped TiO2 nanoparticles were examined under visible light illumination using para-nitrophenol as target pollutant. By detailed experimental findings revealed that the Fe dopant content crucially determines the catalytic activity of TiO2 nanoparticles. The maximum degradation rate of para-nitrophenol observed was 92% in 5h when the Fe3+ molar concentration was 0.05mol%, without addition of any oxidizing reagents. The prepared nanoparticles demonstrated excellent photocatalytic response because of their small size, excellent crystalline structure, increase in threshold wavelength response and maximum separation of photogenerated charge carriers. Further, the determination of reaction intermediates has also been carried out and plausible mechanism of photocatalytic degradation of para-nitrophenol has been proposed.

Photoelectrochemical properties of iron (III)-doped TiO2 nanorods

Fe (iron)-doped TiO2 nanorods were grown on fluorine doped tin oxide (FTO) substrates with various Fe doping concentrations using modified chemical bath deposition (M-CBD). We investigated the effects of Fe doping concentration on the morphological, structural, optical, and photoelectrochemical (PEC) properties of the TiO2 nanorods. From this study, it was found that the PEC properties were mainly dependent on the morphological and optical properties of the Fe-doped TiO2 nanorods. At low Fe doping concentration, the PEC properties were highly affected by the optical properties. On the other hand, the PEC properties were significantly affected by the morphological properties at high doping concentration. We observed a maximum photocurrent density of 0.48mA/cm2 at a Fe doping concentration of 2at% from this study. In addition, the donor density and flat-band potential of the Fe doping concentration from the Mott–Schottky plot were analyzed.

AC conductivity studies of Fe doped TiO2 nanotubes

Fe-doped TiO2 nanotubes are prepared by the combination of sol-gel process with hydrothermal treatment. The morphology and crystalline structure of TiO2 nanotubes are characterized by transmission electron microscopy (TEM), X-ray diffraction respectively (XRD). Fe doping induces a structural transformation from anatase to rutile. The temperature dependence of the ac electrical conductivity is investigated in the temperature range 303-413 K. Positive temperature coefficient of resistance is observed in the Fe doped TiO2 nanotubes. PL spectrum shows the presence of oxygen vacancies and self trapped excitons in Fe doped TiO2 nanotubes and undoped samples.

Local structure and optical absorption characteristic investigation on Fe doped TiO2 nanoparticles**Supported by National Basic Research Program of China (2012CB825801), Science Fund for Creative Research Groups of NSFC (11321503), National Natural Science Foundation of China (11321503, 11179004) and Guangdong Natural Science Foundation (S2011040003985)

The local structures and optical absorption characteristics of Fe doped TiO2 nanoparticles synthesized by the sol-gel method were characterized by X-ray diffraction (XRD), X-ray absorption fine structure spectroscopy (XAFS) and ultraviolet-visible absorption spectroscopy (UV-Vis). XRD patterns show that all Fe-doped TiO2 samples have the characteristic anatase structure. Accurate Fe and Ti K-edge EXAFS analysis further reveal that all Fe atoms replace Ti atoms in the anatase lattice. The analysis of UV-Vis data shows a red shift to the visible range. According to the above results, we claim that substitutional Fe atoms lead to the formation of structural defects and new intermediate energy levels appear, narrowing the band gap and extending the optical absorption edge towards the visible region.

Effects of Fe doping on the optical and magnetic properties of TiO2 films deposited on Si substrates by a sol–gel route

Fe-doped TiO2 films were deposited on Si(100) substrates by a sol–gel technique. X-ray diffraction measurements show that all the films contain both anatase and rutile phases, and Fe doping promotes the anatase–rutile transformation of TiO2 films. The optical constants of the films were attained by tackling spectroscopic ellipsometry data. With increasing Fe content, the refractive indices n values at 2 eV photon energy first increases, then decreases, and finally increases again, and the optical band gap of the films sharply reduces from 3.60 to 3.30 eV. These results may be not only related to Fe contents but also to the phase composition changed by Fe doping. In addition, the undoped TiO2 film showed feeble ferromagnetic character. Ferromagnetic behaviors were clearly observed for x = 0.01 Fe-doped TiO2 film. When x > 0.01, the magnetizations of the samples, firstly decrease and then increase with the increment Fe content, which may be due to an anatase-to-rutile junction destroying an F-center bound magnetic polaron. The n values at 2 eV photon energy first increases, then decreases, and finally increases again with the increase of Fe composition, which suggested the complicated polarity mechanism of the present samples. The abnormal changes of refractive indices may be related to not only Fe doping but also the outcome of the anatase/rutile junctions

Characterization and Photocatalytic Evaluation (UV-Visible) of Fe-doped TiO2 Systems Calcined at Different Temperatures

AbstractThere is growing interest in obtaining compounds with photocatalytic activity in the solar spectrum, and this has led to intense research on the topic. In our laboratory, Fe-doped TiO

Fe-doped anatase TiO2/carbon composite as an anode with superior reversible capacity for lithium storage

This paper reports an economic and effective wet chemistry process to prepare Fe-doped anatase TiO2/carbon composite with excellent performance in lithium-ion batteries.

Investigation of the Preparation and Characterization of Fe-doped TiO2 Nanoparticles

Fe-doped TiO2 nanoparticles were synthesized by sol–gel method. The synthesized nanopowders were characterized by powder X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), Ultraviolet Visible (UV-Vis) and Dielectric studies. The crystallite size and phase were determined by X-ray diffraction (XRD) analysis. The morphology and particle size were studied using the scanning electron microscope (SEM) and transmission electron microscopy (TEM). There is a slight variation in numerical value of crystallite size measured by the two techniques: TEM and XRD peak broadening. The optical properties were obtained from UV-Vis absorption spectrum. The UV-Vis absorption spectrum demonstrated an absorption shift in Fe-doped TiO2 nanoparticles to longer wavelengths, thus showing an enhancement of the absorption in the visible spectrum. The dielectric studies were carried out at different frequencies and at different temperatures for the prepared Fe-doped TiO2 nanoparticles. The frequency dependence of the dielectric constant and dielectric loss is found to decrease with an increase in the frequency at different temperatures.