Fe-doped TiO2 Research Articles

Visible Light-Driven Photocatalytic Activity and Kinetics of Fe-Doped TiO2 Prepared by a Three-Block Copolymer Templating Approach.

Fe-doped titania photocatalysts (with 1, 2.5, and 3.5 wt. % Fe nominal content), showing photocatalytic activity under visible light, were prepared by a soft-template assisted sol–gel approach in the presence of the triblock copolymer Pluronic P123. An undoped TiO2 photocatalyst was also prepared for comparison. The photocatalysts were characterized by means of X-ray powder Diffraction (XRPD), Quantitative Phase Analysis as obtained by Rietveld refinement, Diffuse Reflectance (DR) UV−Vis spectroscopy, N2 adsorption/desorption at −196 °C, electrophoretic mobility in water (ζ-potential), and X-ray photoelectron spectroscopy (XPS). The physico-chemical characterization showed that all the samples were 100% anatase phase and that iron was present both in the bulk and at the surface of the Fe-doped TiO2. Indeed, the band gap energy (Eg) decreases with the Fe content, with Tauc’s plot determined values ranging from 3.35 (undoped TiO2) to 2.70 eV (3.5 wt. % Fe). Notwithstanding the obtained Eg values, the photocatalytic activity results under visible light highlighted that the optimal Fe content was equal to 2.5 wt. % (Tauc’s plot determined Eg = 2.74 eV). With the optimized photocatalyst and in selected operating conditions, under visible light it was possible to achieve 90% AO7 discoloration together with a TOC removal of 40% after 180 min. The kinetic behavior of the photocatalyst was also analyzed. Moreover, the tests in the presence of three different scavengers revealed that the main reactive species are (positive) holes and superoxide species. Finally, the optimized photocatalyst was also able to degrade phenol under visible light.

Oxygen vacancy control of electrical, optical, and magnetic properties of Fe0.05Ti0.95O2 epitaxial films* *Project supported by the National Natural Science Foundation of China (Grant No. 11504192) and the Natural Science Foundation of Shandong Province, China (Grant Nos. ZR201910230017 and BSB2014010).

High-quality Fe-doped TiO2 films are epitaxially grown on MgF2 substrates by pulsed laser deposition. The x-ray diffraction and Raman spectra prove that they are of pure rutile phase. High-resolution transmission electron microscopy (TEM) further demonstrates that the epitaxial relationship between rutile-phased TiO2 and MgF2 substrates is 110 TiO2 ∥ 110 MgF2. The room temperature ferromagnetism is detected by alternative gradient magnetometer. By increasing the ambient oxygen pressure, magnetization shows that it decreases monotonically while absorption edge shows a red shift. The transport property measurement demonstrates a strong correlation between magnetization and carrier concentration. The influence of ambient oxygen pressure on magnetization can be well explained by a modified bound magnetization polarization model.

Synthesis, characterization of novel Fe-doped TiO2 activated carbon nanocomposite towards photocatalytic degradation of Congo red, E. coli, and S. aureus

Synthesis, characterization of novel Fe-doped TiO2 activated carbon nanocomposite towards photocatalytic degradation of Congo red, E. coli, and S. aureus

Visible light active Fe-Pr co-doped TiO2 for water pollutants degradation

Fe–Pr co-doped TiO2 photocatalysts are synthetized by sol–gel method using titanium tetraisopropoxide, praseodymium nitrate and iron acetylacetonate as precursors of titania, praseodymium and iron, respectively. The chemical-physical properties of all prepared samples are analysed by X-ray diffraction (XRD), Raman spectroscopy, UV–vis diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence (PL) spectroscopy and N2 adsorption at −196 °C. XRD patterns show the main peaks of anatase phase in all photocatalysts and evidence that Fe and Pr ions are effectively introduced into the TiO2 lattice. UV–vis DRS spectra indicate the reduction of the band gap value of Fe-Pr co-doped TiO2 with respect to TiO2 and Pr-doped TiO2 thank to co-doping of TiO2 with Pr and Fe ions. The photocatalytic performances of all prepared samples are investigated for the degradation of Acid Orange 7 azo dye (AO7) and also of phenol under visible light irradiation. Photocatalytic efficiency obtained using Fe–Pr co-doped TiO2 markedly increases compared to un-doped TiO2, Pr-doped TiO2 and Fe-doped TiO2 photocatalysts. Fe-Pr co-doped TiO2 prepared with 8.5 mg of praseodymium nitrate gave the best photocatalytic activity. The enhanced photocatalytic activity should be associated with the simultaneous doping of TiO2 with Pr3+ and Fe3+ ions that induces a marked decrease of band gap value together with an enhanced generation of oxygen vacancies, which can trap electrons, and therefore reducing their recombination with photogenerated positive holes. Indeed, using the optimized Fe-Pr co-doped TiO2, the dye discoloration and mineralization is about 87 and 80 %, respectively, after 60 min of LEDs visible light irradiation, underlining the best performances of the optimized Fe–Pr co-doped TiO2 in terms of treatment time. Finally, the optimized Fe-Pr co-doped TiO2 is tested for visible light degradation of phenol in aqueous solution, confirming the absence of possible sensitization phenomena of photocatalyst surface by the AO7 dye.

Construction and characteristics of a novel green photocatalyst:iron (III) doped titania nanomesh

In this work, a green Fe-doped TiO2 photocatalyst was successfully synthesized on Ti mesh through the chemical impregnation and anodization method. The influence of sample Fe-content on the photocatalytic performance was investigated in detail. Ordered TiO2 nanomesh was compactly decorated with nanospheres to form a novel photocatalyst Fe-doped TiO2 with anatase phase. Simultaneously, it exhibits higher light absorption intensity compared to the pristine TiO2 within the visible light range, and its absorption peak has a redshift. The VSM results showed that the sample has excellent magnetic properties. It is hard to achieve magnetic agglomeration after magnetic field removal, which benefits the strong recyclability and reusability of Fe-doped TiO2 photocatalyst. Importantly, this higher visible-light photoresponse of TiO2 was clearly obtained after Fe doping. When the Fe-content was 0.6 wt%, the degradation rate of methylene blue reached 87.9% under simulated sunlight irradiation for 2.5 h. The prepared nanocrystalline photocatalyst demonstrated excellent photocatalysis because of its prominent crystal morphology, strengthen light-absorption capacity, and commendable inhibition recombination of photo-induced electron-hole.

Visible light assisted degradation of Atenolol by Fe-TiO2: Synthesis, characterization, optimization and mechanism

Photo stimulation of Fe doped TiO2 (Fe-TiO2) under visible light irradiation (i.e. 300 W Halogen lamp) was employed for atenolol (ATL) removal from domestic wastewater effluent. As a first step, Fe nanoparticles (NPs) were synthesized using Acacia Catechu pods, doped with TiO2, characterized using UV–vis spectrometry, SEM, TEM, FT-IR, XRD and XPS, and subsequently, used for photo degradation experiments. The experimental variables, viz., initial contaminant concentration (10–50 mg/L), pH (6–12), photocatalyst concentration (500–2000 mg/L) and reaction time (30–180 min.) were optimized using response surface methodology (RSM). A positive correlation between catalyst dosage and ATL degradation was observed in RSM up to a catalyst dose of 1.25 g/L when pH was between 7 and 9. After 105 min, a maximum of 85 % ATL removal was achieved at pH 9, 1.25 g/L of Fe-TiO2 dosage at an initial ATL concentration of 10 mg/L. The obtained RSM model demonstrated a high correlation between experimental and predicted values of ATL removal (R2∼0.95). Cleavage of ether bond, hydroxylation of aromatic ring and oxidation of amine moieties were responsible for the degradation of ATL by visible light activated Fe-TiO2. The electrical energy consumed per order (EE/O) was evaluated to ascertain the efficiency of irradiation intensity and EE/O values were found to increase with increase in the initial ATL concentration. Overall, the green synthesized Fe-TiO2 could be an useful alternative for commercial photocatalysts.

A practical method for incorporation of Fe (III) in Titania matrix for photocatalytic applications

The unprecedented catalytic role of Iron (III) nitrate nonahydrate (Fe (NO3)3·9H2O) has been explored in a top-down technique for the synthesis and Iron (III) doping of Titanium dioxide nanoparticles (TiO2-NPs). In the experimental procedure, the chosen 1:1 ratio of Fe (NO3)3·9H2O and TiO2 bulk powder is allowed to work hydrothermally in top-down synthesis and Fe-doping of (TiO2) nanoparticles. Field emission scanning electron microscopy (FESEM) shows the particle structure or morphology of the Fe-doped TiO2-NPs. Raman and x-ray photoelectron spectroscopy (XPS) is used to study the composition and iron-content at the surface of the synthesized nanoparticles. X-ray diffraction (XRD) pattern has several peaks for α-Fe2O3 corresponds to Iron doping in the synthesized nanoparticles of (TiO2). The current technique provides a practical method for maximum yield and high quality of Fe-doped TiO2 nanoparticles for its potential photovoltaic and photocatalytic applications in modern technologies.

Photocatalytic oxidation of gas-phase Hg0 by Fe-doped TiO2 hollow microspheres

Fe-doped TiO2 hollow microspheres were prepared by the hydrothermal method and characterized by the X-ray diffraction (XRD), the Scanning Electronic Microscopy (SEM), the Energy Dispersive X-Ray (EDX), the Brunauer-Emmett-Teller (BET), and the UV–visible diffuse-reflectance spectrum (UV–Vis). The as-prepared samples were evaluated for photocatalytic removal of Hg0 under ultraviolet light irradiation. The results showed that the sample had a good photocatalytic performance. When M* (the molar ratio of Fe/Ti) was 0.05, the mercury removal efficiency reached up to 100%. It was found that the incorporation of iron narrowed the energy band gap of TiO2 (from 3.11 eV to 2.58 eV) and the absorbing boundary increased from 398 nm to 480 nm. While too much Fe3+ may occupy the capture sites of electrons and holes, which leads to a decrease of photocatalytic efficiency.

Accelerated Neurite Outgrowth and Neurogenesis of PC12 Cells on an Fe-doped TiO2 Nanorod Film Triggered by Visible Light.

Acceleration of neurite outgrowth and neuronal differentiation of neural cells are critical for effective neural tissue regeneration. In addition to biochemical cues, biomaterials have proven to be a valuable tool for engineering neural cellular physiological processes. However, strategies with convenient potential spatiotemporal control are still desirable. We here design a novel Fe-doped TiO2 nanorod film using hemoglobin as the Fe source to endow it with visible-light-responsive regulated surface hydroxyl groups (-OH), which was demonstrated as the central role in mediating cell-material interactions in our previous study. The acceleration of neurite outgrowth and neuronal differentiation of PC12 cells might be attributed to the upregulated distinct terminal hydroxyl groups triggered by visible light. We also demonstrate that the actin cytoskeletal system plays a pivotal role during these processes, approved by the inhibition experiment results. This study therefore sheds light on the regulation of neurite outgrowth and neuronal differentiation of neural cells using a convenient spatiotemporal controllable strategy.

Enhancement of photocatalytic degradation of Malachite Green using iron doped titanium dioxide loaded on oil palm empty fruit bunch-derived activated carbon

Iron-doped titanium dioxide loaded on activated carbon (Fe–TiO2/AC) was successfully synthesized from oil palm empty fruit bunch (OPEFB) using sol-gel method. The properties of the synthesized pure TiO2, Fe-doped TiO2, AC, TiO2/AC and Fe–TiO2/AC were examined by various techniques such as field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) and nitrogen adsorption-desorption analyses at 77 K. FE-SEM revealed that Fe-doped TiO2 particles were dispersed homogeneously on the AC surface. FT-IR demonstrated high surface hydroxylation after Fe doping on TiO2 and UV–Vis DRS showed that Fe–TiO2/AC had the lowest band gap energy. Catalytic performance results proved that Fe dopants could restrict the recombination rate of hole and electron pairs, whereas AC support improved the Malachite Green (MG) adsorption sites and active sites of the hybrid catalyst. Photocatalytic degradation of 100 mg/L MG in the presence of 1.0 g/L 15 wt% Fe–TiO2 incorporated with 25 wt% AC, initial solution pH of 4 and 3 mM H2O2 could achieve the highest removal efficiency of 97% after 45 min light irradiation. This work demonstrates a promising approach to synthesis an inexpensive and efficient Fe–TiO2/AC for the photocatalytic degradation of organic dye.

Kinetic Study on the Crystal Transformation of Fe-Doped TiO2 via In Situ High-Temperature X-ray Diffraction and Transmission Electron Microscopy.

Titanium dioxide (TiO2) is widely used in various major industries owing to its different crystal forms and functions. Therefore, fabricating suitable crystalline TiO2 through reasonable processes is necessary. In this study, Fe-doped TiO2 precursors were prepared via hydrolysis. Further, in situ high-temperature X-ray diffraction and transmission electron microscopy were used to transform the synthesized precursor in its crystal form. The Rietveld full-spectrum fitting method could accurately yield two different crystal forms at instant temperatures. Additionally, the rate relation between the crystal form transformation and reaction conditions was obtained. Results showed that the addition of Fe increased the temperature of phase transition of TiO2 anatase to rutile and accelerated the anatase → rutile transformation process. Further, crystal phase transition kinetic analysis showed that the phase transition kinetic model of Fe-doped TiO2 matched the Johnson–Mehl–Avrami–Kohnogorov (JMAK) model and that its phase transition was affected by crystal defects. Finally, Fe3+ in Fe-doped TiO2 was reduced to Fe2+ to generate oxygen vacancies, thus promoting the rate of transformation from titanium ore to rutile.

Synthesis and material characterization of TiO2 nanoparticles doped with iron (Fe)

Titanium dioxide (TiO2) doped with iron (Fe) atom are investigated using X-Ray diffraction, field emission scanning electron microscopy (FESEM), and photocatalysts measurements. Fe-TiO2 nanoparticles with different concentration of iron were formed using the conventional co-precipitation technique from two different chemical solutions. The precursors of TiO2 were prepared using titanium tetrachloride (TiCl4) of 50 ml, and iron trichloride (FeCl3) was used as a dopant source. X-ray diffraction results show that diffraction pattern have two phases structures anatase and rutile phase structures where the intensity of the rutile structures are superior to that the anatase phase intensities. The results from FESEM micrograph indicate that the agglomerations were taken place, forming into clusters. Irradiation of ultraviolet (UV) with varying the time from 30 minutes to 120 minutes to the Fe-doped TiO2 nanoparticles using methylene blue shows that the absorption intensity reduces as time irradiation increased. The results indicate that the TiO2 nanoparticles doped with iron are suitable as photocatalysts.

Peroxy titanium complex derived Fe-doped TiO2 Nanoparticles: Synthesis, properties and antibacterial activity

The synthesis of Fe3+-TiO2 nanoparticles (NPs) derived from peroxytitanium complex carried out using hydrothermal method. Pure TiO2 and Fe3+ doped TiO2 powders were characterized to study their structural, compositional, morphological and optical properties. The X-ray diffraction patterns shows crystalline pure anatase TiO2 and crystallite size decreases from 10.17 to 8.25 nm with addition of Fe3+ ion. FE-SEM micrographs reveal well diffused aggregates with nanograin morphology. The efficiency of antibacterial activity against E. coli was studied under different physicochemical parameters. The antibacterial activity varies with concentration of Fe3+ in TiO2 matrix against E. coli bacteria. The antibacterial activity was increased with increasing Fe3+ content in TiO2 NPs and the highest antibacterial activity was observed for 2.15 wt.% Fe3+-TiO2.

Iron-doped titanium dioxide hollow nanospheres for efficient nitrogen fixation and Zn–N2 aqueous batteries

A shell-engineering strategy is proposed for the design of vacancy-laden Fe-doped TiO2 hollow nanospheres, such as “breathing alveolus”, enabling highly efficient and sustainable electrocatalytic N2 reduction and realizing Zn–N2 aqueous batteries.

Enhancement of pyridine derivatives containing symmetrical substituents on the photocatalytic degradation of phenol and antibiotics by Er-Fe-TiO2

Eight composite photocatalysts were synthesized. Er- and Fe-doped TiO2 photocatalysts were prepared first, and their photocatalytic performance for phenol degradation was investigated. Furthermore, three pyridine derivatives and 1,10-phenanthroline were bonded to Er-Fe-TiO2, which greatly improved the efficiency and rate of photocatalytic degradation of phenol and chlortetracycline hydrochloride. The absorption spectra, fluorescence spectra, photocurrent density, impedance spectra, and ESR radical measurements of eight different photocatalysts were investigated. On this basis, combined with a discussion on the matching of the molecular orbital energy levels of pyridine derivatives and 1,10-phenanthroline with the band gap of Er-Fe-TiO2, a possible mechanism of electron transport was proposed for the photocatalysis process. We studied the degradation of chlortetracycline hydrochloride or a mixture of phenol and four antibiotics using four composite photocatalysts. The possible degradation sites of chlortetracycline hydrochloride were predicted by theoretical calculations, and some results were consistent with those detected by HPLC-MS.

Photosynthesis of a Photocatalyst: Single Atom Platinum Captured and Stabilized by an Iron(III) Engineered Defect.

Single atom (SA), noble metal catalysts are of interest due to high projected catalytic activity while minimizing cost. Common issues facing many synthesis methodologies include complicated processes, low yields of SA product, and production of mixtures of SA and nanoparticles (NPs). Herein we report a simple, room-temperature synthesis of single Pt-atom decorated, anatase Fe-doped TiO2 particles that leverages the Fe dopant as an engineered defect site to photodeposit and stabilize atomically dispersed Pt. Both particle morphology and Fe dopant location are based on thermodynamic principles (Gibbs-Wulff construction). CO-DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) reveals absence of bridge-bonded CO signal, confirming atomically dispersed Pt. XAS (X-ray absorption spectroscopy) of both Pt and Fe indicates Fe-O-Pt bonding that persists through catalytic cycling. Mass balance indicates that the Pt loading on single particles is 2.5 wt % Pt; the single Pt-atom decorated nanoparticle yield is 17%. Pt-containing particles show more than an order-of-magnitude increased photooxidation efficiency relative to particles containing only Fe. High single-atom-Pt yield, ease of synthesis, and high catalytic activity demonstrate the utility and promise of this method. The principles of this photodeposition synthesis allow for its generalizability toward other SA metals of catalytic interest.

Structural Properties of Fe Doped TiO2 Nanorods Prepared by Low Cost Hydrothermal Method

In this work, titanium dioxide films were deposited on fluorine tin oxide (FTO)-glass substrates using Hydrothermal method. A low-cost homemade autoclave was used to fabricate pure TiO2 and Fe-doped (0.1%, 0.3%, 0.5%, 0.7% and 1.5%) films. X-ray diffraction patterns showed that the predominant phase is rutile (R-TiO2) with peaks at (101), (002) and (112). The Field Emission Scanning Electron Microscope (FESEM) top and cross-sectional images indicated that the films have vertically aligned nanorods structures with parallelogram cross-sectional areas and aspect ratio range (9.2-15.3).

Influence of Fe3+ ions doping on TiO2 thin films: Defect generation, d-d transition and band gap tuning for optoelectronic device applications

In this article, we have explored the influence of Fe3+ ion on the surface morphological, structural, optical and electrical properties of TiO2 thin films grown on glass substrates by thermal spray pyrolysis technique. The FESEM micrographs of the deposited TiO2 thin films reveal that the surface consists of agglomerates of small grains. The anatase and rutile phase is confirmed by XRD and Debye-Scherer (D-S), Uniform Deformation Model (UDM) and Halder-Wagner (HW) method are employed to determine the structural parameters using XRD peak profile analysis. A red shift occurs in absorption spectra and band gap decreases with Fe content. The optical parameters such as skin depth, optical static dielectric constant, Urbach energy, etc and Electron-phonon interaction are increased with increasing Fe contents, whereas steepness parameter decreases. The electrical properties are studied by Hall Effect measurements. The paramount study is useful for standardizing the Fe-doped TiO2 thin films for optoelectronic device applications.

Synthesis and Application of Fe-Doped TiO2 Nanoparticles for Photodegradation of 2,4-D from Aqueous Solution

2,4-Dichlorophenoxyacetic (2,4-D) is a toxic herbicide used to control weeds in agricultural sector. However, its residuals in soil and water are harmful for human and aquatic life. Therefore, the aim of this study was to evaluate the photocatalytic degradation of 2,4-D from aqueous solution using the Fe-doped TiO2 nanoparticles in the presence of UV and sunlight irradiation. The nanoparticles were synthesized via a mild hydrothermal process. The characteristics of the synthesized nanoparticles were determined using powder X-ray diffraction, Fourier transform infrared and scanning electron microscopy techniques. The effects of different parameters, including pH, nanoparticle dosage, initial 2,4-D concentration and dopant percentage on the degradation of 2,4-D, were investigated. The results demonstrated that the successfully doped nanoparticles had likely pseudo-spherical morphology. The optimum conditions for photocatalytic degradation of 2,4-D obtained at pH 7, nanoparticle dosage = 0.4 g/l, initial 2,4-D concentration = 10 mg/l, dopant percentage = 1.5% and contact time = 120 min. Under the optimal conditions, the photocatalytic degradation efficiencies of 2,4-D under UV and sunlight irradiation were 65 and 72%, respectively. In addition, the findings showed that 2,4-D degradation efficiency increased with increasing dosage of nanoparticles, while it decreased with increasing initial concentration of 2,4-D and initial pH. Therefore, the Fe-doped TiO2 nanoparticles could be used for the photodegradation of 2,4-D, and it is recommended for the degradation of other organic pollutants from aqueous media especially in tropical areas where a free energy source, i.e., sunlight, is available.

Local structural investigations of Fe-doped TiO2 amorphous thin films

The present study deals with the local structure of amorphous TiO2 and Fe-doped TiO2 thin films deposited on Si substrate using magnetron sputtering. The absence of long range order is confirmed by grazing incidence x-ray diffraction and the short range order is studied using x-ray absorption near edge structure (XANES) measurements at Ti, Fe and O K-edges and Fe and Ti L3-edge. The XANES provides understanding about the electronic transition induced from the short range ordering and dependence of electronic hybridization of the central Ti-p orbitals with the Ti-d orbitals. The XANES measurements also show that maximum Fe doping concentration allowed to replace Ti is 2 at.% and after that separate phase starts appearing, which is consistent with simulation by ab-initio multiple scattering theory based code FEFF9. Ellipsometry measurements show gradual decrease in band-gap energy upto 2 at.% Fe doping from pristine TiO2, however a drastic decrease in band-gap energy is observed at 4 at.% or higher doping concentration due to formation of other phases.