Quantitative Determination of Titanium Lattice Defects and Solid-State Reaction Mechanism in Iron-Doped TiO2 Photocatalysts

Titanium Dioxide Nanoparticles Doped with Iron for Water Treatment via Photocatalysis: A Review

Iron-doped titanium dioxide nanoparticles are widely employed for photocatalytic applications under visible light due to their promising performance. Nevertheless, the manufacturing process, the role of Fe3+ ions within the crystal lattice of titanium dioxide, and their impact on operational parameters are still a subject of controversy. Based on these assumptions, the primary objective of this review is to delineate the role of iron, ascertain the optimal quantity, and elucidate its influence on the main photocatalysis parameters, including nanoparticle size, band gap, surface area, anatase-rutile transition, and point of zero charge. Moreover, an optimized synthesis method based on comprehensive data and insights from the existing literature is proposed, focusing exclusively on iron-doped titanium oxide while excluding other dopant variants.

Enhancement in photocatalytic selectivity of TiO2-based nano-catalyst through molecular imprinting technology

Improvement in the photocatalytic selectivity is imperative for the effective and efficient utilization of catalysts. In this study, a molecularly imprinted polymer-coated iron-doped titanium dioxide (Fe-TiO2@MIP) nanocomposite was successfully synthesized by precipitation polymerization while using RB-19 as a template. The synthesized nanocomposites (Fe-TiO2@MIP and Fe-TiO2@NIP) were characterized by Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) with energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-EMMETT-Teller (BET), and UV-visible spectrophotometry. The optimized binding experiments revealed a high imprinting factor of 5.0 for RB-19. The catalytic degradation efficiency and selectivity of Fe-TiO2@MIP enhanced to almost complete degradation of RB-19 from 70% for the parent Fe-TiO2 and 76% for Fe-TiO2@NIP. An outstanding degradation selectivity of RB-19 was achieved compared to other competitive dyes. Finally, the analysis of the non-degraded and degraded RB-19 by ESI-MS revealed the presence of different intermediates that fits well with the proposed degradation mechanism. The study opens new possibilities of selective photo-degradation of targeted contaminants that may ultimately lead to efficient use of photocatalysts.

Controlled Phase Transformation and Crystal Growth of Titanium Dioxide from Anatase/Silica Core/Shell Particles

Anatase/silica core/shell particles were prepared by the hydrolysis and condensation of tetraethyl orthosilicate on anatase particles with the sizes of 9, 22, and 111 nm, respectively. The thickness of the silica layer was designed from ca. 3 to 14 nm by repeating the coating procedure on anatase with a particle size of 22 nm. By the heat treatment at 1000 °C, though the pristine anatase particles transformed to rutile, anatase remained for the silica-coated particles. Anatase particles (111 nm) transformed to rutile upon heating at 1100 °C, while the transformation was not observed for the smaller particles (9 and 22 nm). With the increase of the silica thickness to 14 nm, anatase did not transform to rutile even after heating at 1150 °C, while resulting in varied compositions of anatase and rutile after heating at 1200 °C. The crystal growth of anatase and rutile was also suppressed for the silica-coated particles compared with that seen for pristine anatase. Thus, the thermal transformation and crystal growth of titania were controlled by the coating with silica, and the effects were shown to affect the coating.

A Review on Nano Ti-Based Oxides for Dark and Photocatalysis: From Photoinduced Processes to Bioimplant Applications

Catalysis on TiO₂ nanomaterials in the presence of H₂O and oxygen plays a crucial role in the advancement of many different fields, such as clean energy technologies, catalysis, disinfection, and bioimplants. Photocatalysis on TiO₂ nanomaterials is well-established and has advanced in the last decades in terms of the understanding of its underlying principles and improvement of its efficiency. Meanwhile, the increasing complexity of modern scientific challenges in disinfection and bioimplants requires a profound mechanistic understanding of both residual and dark catalysis. Here, an overview of the progress made in TiO₂ catalysis is given both in the presence and absence of light. It begins with the mechanisms involving reactive oxygen species (ROS) in TiO₂ photocatalysis. This is followed by improvements in their photocatalytic efficiency due to their nanomorphology and states by enhancing charge separation and increasing light harvesting. A subsection on black TiO₂ nanomaterials and their interesting properties and physics is also included. Progress in residual catalysis and dark catalysis on TiO₂ are then presented. Safety, microbicidal effect, and studies on Ti-oxides for bioimplants are also presented. Finally, conclusions and future perspectives in light of disinfection and bioimplant application are given.

Preparation of Iron-Doped Titania Nanoparticles and Their UV-Blue Light-Shielding Capabilities in Polyurethane

It is well known that ultraviolet (UV) and blue light cause a series of health problems and damages to polymer materials. Therefore, there are increasing demands for UV-blue light-shielding. Herein, a new type of iron-doped titania (Fe-TiO₂) nanoparticle was synthesized. Fe-TiO₂ nanoparticles with small particle size (ca. 10 nm) are composed of anatase and brookite. The iron element is incorporated into the lattice of titania and forms a hematite phase (α-Fe₂O₃). The iron doping imparted full-band UV and blue light absorption to Fe-TiO₂ nanoparticles, and greatly suppressed the photocatalytic activity. The prepared Fe-TiO₂/polyurethane (PU) films exhibited prominent UV-blue light-shielding performance and high transparency, which showed great potential in light-shielding fields.

High-Performance Lithium-Ion Storage of FeTiO3 with Morphology Adjustment and Niobium Doping

Ferrous titanate (FeTiO₃) has a high theoretical capacity and physical and chemical properties stability, so it is a potential lithium anode material. In this study, FeTiO₃ nanopowder and nanosheets were prepared by the sol-gel method and the hydrothermal method. In addition, niobium-ion doping was carried out, the radius of Nb close to Ti so the Nb can easily enter into the FeTiO₃ lattice. Nb can provide more free electrons to improve the electrochemical performance. Then, the effects of the morphology and niobium doping on the microstructure and electrochemical properties of FeTiO₃ were systematically studied. The results show that FeTiO₃ nanosheets have a better lithium storage performance than nanopowders because of its high specific surface area. A certain amount of niobium doping can improve the electrochemical performance of FeTiO₃. Finally, a 1 mol% niobium-doping FeTiO₃ nanosheets (1Nb-FTO-S) electrode provided a higher specific capacity of 782.1 mAh g^-1 at 50 mA g^-1. After 200 cycles, the specific capacity of the 1Nb-FTO-S electrode remained at 509.6 mAh g^-1. It is revealed that an increased specific surface area and ion doping are effective means to change the performance of lithium, and the proposed method looks promising for the design of other inorganic oxide electrode materials.

Recent advances in structural modifications of photo-catalysts for organic pollutants degradation - A comprehensive review

Over the last few years, industrial and anthropogenic activities have increased the presence of organic pollutants such as dyes, herbicides, pesticides, analgesics, and antibiotics in the water that adversely affect human health and the environment worldwide. Photocatalytic treatment is considered a promising, economical, effective, and sustainable process that utilizes light energy to degrade the pollutants in water. However, certain drawbacks like rapid recombination and low migration capability of photogenerated electrons and holes have restricted the use of photo-catalysts in industries. Hence, despite the abundance of lab-scale research, the technology is still not much commercialized in the mainstream. Several structural modifications in the photo-catalysts have been adopted to enhance the pollutant degradation performance to overcome the same. In this context, the present review article outlines the different advanced heterostructures synthesized to date for improved degradation of three major organic pollutants: antibiotics, dyes, and pesticides. Moreover, the article also emphasizes the degradation kinetics of photo-catalysts and the publication trend in the past decade along with the roadblocks preventing the transfer of technology from the laboratory to industry and new age photo-catalysts for the profitable implications in industrial sectors.

Photocatalytic Degradation of Thiacloprid Using Tri-Doped TiO2 Photocatalysts: A Preliminary Comparative Study

Different tri-doped TiO2 photocatalysts (Fe-N-P/TiO2, Fe-N-S/TiO2, Fe-Pr-N/TiO2, Pr-N-S/TiO2, and P-N-S/TiO2) were successfully prepared and tested in the photocatalytic removal of thiacloprid (THI) under UV-A, visible, and direct solar light irradiation. The physical-chemical properties of the prepared catalysts were analyzed by different characterization techniques, revealing that dopants are effectively incorporated into the anatase TiO2 lattice, resulting in a decrease of the energy band gap. The reduction of photoluminescence intensity indicates a lower combination rate and longer lifespan of photogenerated carriers of all doped samples in comparison with the un-doped TiO2. The doped photocatalysts not only significantly promote the photodegradation under UV-A light irradiation but also extend the optical response of TiO2 to visible light region, and consequently improve the visible light degradation of THI. Fe-N-P tri-doped TiO2 sample exhibits the highest THI photodegradation degree (64% under UV-A light, 29% under visible light and 73% under solar light).

Mesoporous (001)-TiO2 nanocrystals with tailored Ti3+ and surface oxygen vacancies for boosting photocatalytic selective conversion of aromatic alcohols

Mesoporous (001)-TiO₂ nanocrystals with tailored Ti³⁺ and surface oxygen vacancies exhibited remarkably boosted photoactivity for selective conversion of aromatic alcohols to carbonyl compounds in water medium under visible-light irradiation.

Transition metal mixed oxide-embedded graphene oxide bilayers as an efficient electrocatalyst for optimizing hydrogen evolution reaction in alkaline media

A novel electrocatalyst containing different percentages of iron-titanium mixed oxide onto graphene oxide (GO) support was prepared by embedding via the thermal decomposition method (TD) and was coated on a Cu substrate through facile electroless Ni–Co–P plating.

Synthesis of Fe- and Co-Doped TiO2 with Improved Photocatalytic Activity Under Visible Irradiation Toward Carbamazepine Degradation

Pure TiO₂ and Fe- and Co-doped TiO₂ nanoparticles (NPs) as photocatalysts were synthesized using wet chemical methods (sol-gel + precipitation). Their crystalline structure and optical properties were analyzed using X-ray diffraction (XRD), Raman spectroscopy and Fourier-transform infrared (FTIR) spectroscopy, ultraviolet-visible light (UV-Vis) diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The photocatalytic activity of the synthesized nanoparticles was evaluated through degradation of carbamazepine (CBZ) under UV-A and visible-light irradiations. The XRD and Raman analyses revealed that all synthesized nanomaterials showed only the anatase phase. The DRS results showed that the absorption edge was blue-shifted for Fe-doped TiO₂ NPs. The decrease in charge recombination was evidenced from the PL investigation for both Co-doped and Fe-doped TiO₂ nanomaterials. An enhancement in photocatalytic degradation of carbamazepine in aqueous suspension under both UV-A light and visible-light irradiations was observed for Fe-doped Titania NPs by comparison with pure TiO₂. These results suggest that the doping cations could suppress the electron/hole recombination. Therefore, the photocatalytic activity of TiO₂-based nanomaterials was enhanced.

Synthesis, characterization, and photocatalytic activity of silver and zinc co-doped TiO2 nanoparticle for photodegradation of methyl orange dye in aqueous solution

In this study, TiO2 nanocrystals, 1 mol% Ag-doped TiO2, and 1 mol% Ag and 0.6 mol% Zn co-doped TiO2 powders were synthesized by the sol–gel route. Their photocatalytic activities on methyl orange dye under visible irradiation were investigated. The powders were characterized by X-ray diffraction (XRD), UV–visible spectroscopy (UV–vis), Brunauer–Emmett–Teller (BET), and Fourier transform infrared spectroscopy (FTIR). The XRD results revealed the presence of a rutile phase with an average crystallite size of 9 and 11 nm. The UV–vis spectra showed a red-shift towards a longer wavelength with the corresponding decrease in band gap from 2.9 to 2.5 eV. The BET surface areas of the nanoparticles ranged from 4.7 to 11.8 m2 g−1 with an average pore size between 18.9 and 56.6 nm. The Ag-doped TiO2 has the largest surface area of 11.8 m2 g−1, whereas the Ag–Zn co-doped TiO2 was found to have the highest pore size and volume. The absorption bands at 750–500 cm−1 were attributed to the –O–Ti–O– bond in the TiO2 lattice. The photocatalytic efficiency was highest at an optimum pH of 4.1 for Ag–Zn co-doped TiO2. The results confirmed that Ag-doped and Ag–Zn co-doped TiO2 were more effective than pure TiO2. The kinetic data were fitted into a pseudo first-order equation using a Langmuir–Hinshelwood kinetic model.

Physicochemical properties and in vivo evaluation of Pt/TiO2-SiO2 nanopowders

AIM

Sol-gel is a suitable and advantageous method to synthesize mixed oxide nanomaterials with unique physicochemical and biological properties.

MATERIALS & METHODS

In this work, TiO₂-SiO₂ nanopowders cogeled with platinum acetylacetonate were developed and studied in the perspective of nanomedicine. The physicochemical properties of the Pt/TiO₂-SiO₂ nanopowders, named NanoRa²-Pt, were evaluated in detail by means of complementary spectroscopic and microscopic tools. The nanopowder's biocatalytic efficiency in wound healing was evaluated in a Type I diabetes animal model.

RESULTS

These are TiO₂-SiO₂ submicron mesoporous particles with variable size and shape containing ultra-small platinum nanoparticles with catalytic properties.

CONCLUSION

The use of NanoRa²-Pt catalyzes the natural healing processes with a faster remodeling stage. These sols, which we call nanobiocatalysts, belong to an emerging and very promising research field known as catalytic nanomedicine.

Effect of Mixed Valence States of Platinum Ion Dopants on the Photocatalytic Activity of Titanium Dioxide under Visible Light Irradiation

Titanium dioxide doped with the Pt ion (Pt-TiO₂) was synthesized by a sol-gel method using only water as the solvent and conducting dialysis. The photocatalytic activity for the degradation of 4-chlorophenol (4-CP) on Pt-TiO₂ was not affected by the Brunauer-Emmett-Teller specific surface area under visible light (VL) irradiation. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure measurements revealed that only the Pt(IV) ion existed in the TiO₂ bulk and both Pt(II) and Pt(IV) were present near the Pt-TiO₂ surface. Pt(IV) is most likely substituted in the Ti(IV) site of the TiO₂ lattice because of their similar ionic sizes. Quantitative analysis of Pt(II) was performed in the XPS measurements, indicating that the amount of Pt(II) on the surface increased with an increase in the doping amount from 0.2 to 1.0 atom %. We synthesized 0.5 atom % Pt-TiO₂ with various Pt(II)/Pt(IV) ratios by changing the Ti(OC₃H₇)₄ concentration used in the sol-gel synthesis. The 4-CP conversion on Pt-TiO₂ increased linearly with an increase in the Pt(II)/Pt(IV) ratios. A similar relationship was obtained with Pt-TiO₂, which was prepared by a conventional sol-gel method in ethanol-water mixed solvent. Therefore, the Pt(II)/Pt(IV) ratio is a key factor affecting the photocatalytic activity of Pt-TiO₂ under VL irradiation. Our results indicate that controlling the mixed valence states of the doped metal ions is a new strategy to developing highly active metal-ion-doped TiO₂ under VL irradiation.

C–N–S tridoping into TiO2matrix for photocatalytic applications: observations, speculations and contradictions in the codoping process

C–N–S-tridoped TiO₂: behind and beyond the codoping process.

TiO2@Carbon Photocatalysts: The Effect of Carbon Thickness on Catalysis

Nanocomposites composed of TiO2 and carbon materials (C) are widely popular photocatalysts because they combine the advantages of TiO2 (good UV photocatalytic activity, low cost, and stability) to the enhanced charge carrier separation and lower charge transfer resistance brought by carbon. However, the presence of carbon can also be detrimental to the photocatalytic performance as it can block the passage of light and prevent the reactant from accessing the TiO2 surface. Here using a novel interfacial in situ polymer encapsulation-graphitization method, where a glucose-containing polymer was grown directly on the surface of the TiO2, we have prepared uniform TiO2@C core-shell structures. The thickness of the carbon shell can be precisely and easily tuned between 0.5 and 8 nm by simply programming the polymer growth on TiO2. The resulting core@shell TiO2@C nanostructures are not black and they possess the highest activity for the photodegradation of organic compounds when the carbon shell thickness is 1-2 nm, corresponding to ∼3-5 graphene layers. Photoluminescence and photocurrent generation tests further confirm the crucial contribution of the carbon shell on charge carrier separation and transport. This in situ polymeric encapsulation approach allows for the careful tuning of the thickness of graphite-like carbon, and it potentially constitutes a general and efficient route to prepare other oxide@C catalysts, which can therefore largely expand the applications of nanomaterials in catalysis.

Visible-light photocatalytic performances of TiO2nanobelts decorated with iron oxide nanocrystals

Anatase TiO₂nanobelts supported on Ti sheet and decorated by hematite Fe₂O₃nanocrystals were prepared by an easy-to-achieve three-step soft chemistry route and evaluated for its visible-light photocatalytic performances.

Rapid and morphology controlled synthesis of anionic S-doped TiO2 photocatalysts for the visible-light-driven photodegradation of organic pollutants

In recent years, growing concerned has been raised to the global problem of the drainage of organic pollutants into water steams.

Combined cytotoxic effect of UV-irradiation and TiO2 microbeads in normal urothelial cells, low-grade and high-grade urothelial cancer cells

The differentiation of urothelial cells results in normal terminally differentiated cells or by alternative pathways in low-grade or high-grade urothelial carcinomas. Treatments with traditional surgical and chemotherapeutical approaches are still inadequate and expensive, as bladder tumours are generally highly recurrent. In such situations, alternative approaches, using irradiation of the cells and nanoparticles, are promising. The ways in which urothelial cells, at different differentiation levels, respond to UV-irradiation (photolytic treatment) or to the combination of UV-irradiation and nanoparticles (photocatalytic treatment), are unknown. Here we tested cytotoxicity of UV-irradiation on (i) normal porcine urothelial cells (NPU), (ii) human low-grade urothelial cancer cells (RT4), and (iii) human high-grade urothelial cancer cells (T24). The results have shown that 1 minute of UV-irradiation is enough to kill 90% of the cells in NPU and RT4 cultures, as determined by the live/dead viability assay. On the other hand, the majority of T24 cells survived 1 minute of UV-irradiation. Moreover, even a prolonged UV-irradiation for 30 minutes killed <50% of T24 cells. When T24 cells were pre-supplemented with mesoporous TiO2 microbeads and then UV-irradiated, the viability of these high-grade urothelial cancer cells was reduced to <10%, which points to the highly efficient cytotoxic effects of TiO2 photocatalysis. Using electron microscopy, we confirmed that the mesoporous TiO2 microbeads were internalized into T24 cells, and that the cell's ultrastructure was heavily compromised after UV-irradiation. In conclusion, our results show major differences in the sensitivity to UV-irradiation among the urothelial cells with respect to cell differentiation. To achieve an increased cytotoxicity of urothelial cancer cells, the photocatalytic approach is recommended.

Characterization and photocatalytic performance evaluation of various metal ion-doped microstructured TiO2 under UV and visible light

Commercially available microcrystalline TiO2 was doped with silver, ferrous and ferric ion (1.0 mol %) using silver nitrate, ferrous sulfate and ferric nitrate solutions following the liquid impregnation technology. The catalysts prepared were characterised by FESEM, XRD, FTIR, DRS, particle size and micropore analysis. The photocatalytic activity of the prepared catalysts was tested on the degradation of two model dyes, methylene blue (3,7-bis (Dimethylamino)-phenothiazin-5-ium chloride, a cationic thiazine dye) and methyl blue (disodium;4-[4-[[4-(4-sulfonatoanilino)phenyl]-[4-(4-sulfonatophenyl)azaniumylidenecyclohexa-2,5-dien-1-ylidene]methyl]anilino]benzene sulfonate, an anionic triphenyl methane dye) under irradiation by UV and visible light in a batch reactor. The efficiency of the photocatalysts under UV and visible light was compared to ascertain the light range for effective utilization. The catalysts were found to have the anatase crystalline structure and their particle size is in a range of 140-250 nm. In the case of Fe(2+) doped TiO2 and Fe(3+) doped TiO2, there was a greater shift in the optical absorption towards the visible range. Under UV light, Ag(+) doped TiO2 was the most efficient catalyst and the corresponding decolorization was more than 99% for both the dyes. Under visible light, Fe(3+) doped TiO2 was the most efficient photocatalyst with more than 96% and 90% decolorization for methylene blue and methyl blue, respectively. The kinetics of the reaction under both UV and visible light was investigated using the Langmuir-Hinshelwood pseudo-first-order kinetic model. Kinetic measurements confirmed that, Ag(+) doped TiO2 was most efficient in the UV range, while Fe(3+) doped TiO2 was most efficient in the visible range.

Fe doped TiO2-graphene nanostructures: synthesis, DFT modeling and photocatalysis

In this work, Fe-doped TiO(2) nanoparticles ranging from a 0.2 to 1 weight % were grown from the surface of graphene sheet templates containing -COOH functionalities using sol-gel chemistry in a green solvent, a mixture of water/ethanol. The assemblies were characterized by a variety of analytical techniques, with the coordination mechanism examined theoretically using the density functional theory (DFT). Scanning electron microscopy and transmission electron microscopy images showed excellent decoration of the Fe-doped TiO(2) nanoparticles on the surface of the graphene sheets >5 nm in diameter. The surface area and optical properties of the Fe-doped photocatalysts were measured by BET, UV and PL spectrometry and compared to non-graphene and pure TiO(2) analogs, showing a plateau at 0.6% Fe. Interactions between graphene and Fe-doped anatase TiO(2) were also studied theoretically using the Vienna ab initio Simulation Package based on DFT. Our first-principles theoretical investigations validated the experimental findings, showing the strength in the physical and chemical adsorption between the graphene and Fe-doped TiO(2). The resulting assemblies were tested for photodegradation under visible light using 17β-estradiol (E2) as a model compound, with all investigated catalysts showing significant enhancements in photocatalytic activity in the degradation of E2.

Preparation, structural and morphological studies of Ni doped titania nanoparticles

TiO2 nanoparticles doped with different weight percentages (4%, 8%, 12% and 16%) of nickel contents were prepared by a modified sol-gel method using Titanium tetra iso propoxide and nickel nitrate as precursors and 2-propanol as a solvent. X-ray diffraction studies show that the as prepared and annealed products show anatase structure with average particle sizes running between of 8 and 16 nm. FTIR results demonstrate the presence of strong chemical bonding at the interface of TiO2 nanoparticles. The optical properties of bare and doped samples were carried out using UV-DRS and photoluminescence measurements. The surface morphology and the element constitution of the nickel doped TiO2 nanoparticles were studied by scanning electron microscope attached with energy dispersive X-ray spectrometer arrangement. The non linear optical properties of the products were confirmed by Kurtz second harmonic generation (SHG) test and the output power generated by the nanoparticle was compared with that of potassium di hydrogen phosphate (KDP).

FTIR and UV-vis diffuse reflectance spectroscopy studies of the wet chemical (WC) route synthesized nano-structure CoFe(2)O(4) from CoCl(2) and FeCl(3)

Nano-structure CoFe(2)O(4) has been fabricated by wet chemical route using CoCl2 and FeCl3 as simple precursors. The prepared nano-structure samples was calcined at 600°C and characterized by fourier transform infrared spectra (FTIR), UV-vis diffuse reflectance spectroscopy (DRS), X-ray powder diffractometry (XRD), and field emission scanning electron microscopy (FESEM). X-ray diffraction patterns confirmed the presence of the spinel phases with average crystallite sizes of 47nm. Field emission scanning electron microscopy investigations showed spherical morphology of nanoparticles with average particle size of 46nm. The FTIR spectra of CoFe(2)O(4) nanoparticles showed absorption bands at about 594cm(-1) and 401cm(-1) due to the stretching vibrations of Co-O and Fe-O respectively. Investigation of the optical properties of the produced nano-structure CoFe(2)O(4) confirmed its semiconducting properties by revealing two optical band gaps at 1.4 and 2.0eV.

Ultrafine single-crystal TiOF2 nanocubes with mesoporous structure, high activity and durability in visible light driven photocatalysis

Single crystal TiOF2 nanocubes assembled into a mesoporous structure were synthesized by alcoholysis of TiF4 under solvothermal conditions, which displayed spectral response in the visible area owing to the intrinsic narrow energy band gap. Mechanism studies revealed that TiOF2 was formed via consecutive hydrolysis reactions and the H2O produced by condensation between two alcohols played a key role in determining the TiOF2 crystal growth and its transformation to anatase TiO2. The TiOF2 nanocube size could be easily adjusted by changing either alcoholysis time, or solvothermal temperature, or alcohol kind owing to the different H2O production rate and amount. The small-sized TiOF2 nanocubes with large surface area exhibited high activity in photocatalytic degradation of Rhodamine B (RhB) and 4-chlorophenol (4-CP) owing to the enhanced adsorption for reactant molecules and the reduced photoelectron-hole recombination rate. Meanwhile, they also showed strong durability since the mesoporous structure enhanced the stability against either the phase transformation from TiOF2 crystal to anatase TiO2 or the agglomeration of TiOF2 nanocubes.

High quality sulfur-doped titanium dioxide nanocatalysts with visible light photocatalytic activity from non-hydrolytic thermolysis synthesis

A non-hydrolytic route for monodisperse S-doped TiO₂ nanocatalysts with enhanced visible light activation is demonstrated.

Degradation of paracetamol by advance oxidation processes using modified reticulated vitreous carbon electrodes with TiO(2) and CuO/TiO(2)/Al(2)O(3)

The degradation of paracetamol in aqueous solutions in the presence of hydrogen peroxide was carried out by photochemistry, electrolysis and photoelectrolysis using modified 100 pores per inch reticulated vitreous carbon electrodes. The electrodes were coated with catalysts such as TiO(2) and CuO/TiO(2)/Al(2)O(3) by electrophoresis followed by heat treatment. The results of the electrolysis with bare reticulated vitreous carbon electrodes show that 90% paracetamol degradation occurs in 4 h at 1.3 V vs. SCE, forming intermediates such as benzoquinone and carboxylic acids followed by their complete mineralisation. When the electrolysis was carried out with the modified electrodes such as TiO(2)/RVC, 90% degradation was achieved in 2 h while with CuO/TiO(2)/Al(2)O(3)/RVC, 98% degradation took only 1 h. The degradation was also carried out in the presence of UV reaching 95% degradation with TiO(2)/RVC/UV and 99% with CuO/TiO(2)/Al(2)O(3)/RVC/UV in 1 h. The reactions were followed by spectroscopy UV-Vis, HPLC and total organic carbon analysis. These studies show that the degradation of paracetamol follows a pseudo-first order reaction kinetics.

Iron insertion and hematite segregation on Fe-doped TiO2 nanoparticles obtained from sol-gel and hydrothermal methods

Iron-doped TiO(2) (Fe:TiO(2)) nanoparticles were synthesized by the sol-gel method (with Fe/Ti molar ratio corresponding to 1, 3, and 5%), followed by hydrothermal treatment, drying, and annealing. A similar methodology was used to synthesize TiO(2) and α-Fe(2)O(3) nanoparticles. For comparison, a mixture hematite/titania, with Fe/Ti = 4% was also investigated. Characterization of the samples using Rietveld refinement of X-ray diffraction data revealed that TiO(2) consisted of 82% anatase and 18% brookite; for Fe:TiO(2), brookite increased to 30% and hematite was also identified (0.5, 1.0, and 1.2 wt % for samples prepared with 1, 3, and 5% of Fe/Ti). For hematite/titania mixture, Fe/Ti was estimated as 4.4%, indicating the Rietveld method reliability for estimation of phase composition. Because the band gap energy, estimated as 3.2 eV for TiO(2), gradually ranged from 3.0 to 2.7 eV with increasing Fe content at Fe:TiO(2), it can be assumed that a Fe fraction was also inserted as dopant in the TiO(2) lattice. Extended X-ray absorption fine structure spectra obtained for the Ti K-edge and Fe K-edge indicated that absorbing Fe occupied a Ti site in the TiO(2) lattice, but hematite features were not observed. Hematite particles also could not be identified in the images obtained by transmission electron microscopy, in spite of iron identification by elemental mapping, suggesting that hematite can be segregated at the grain boundaries of Fe:TiO(2).

The Influence of Carbon Doping on TiO2 Nanoparticle Size, Surface Area, Anatase to Rutile Phase Transformation and Photocatalytic Activity

Visible light-sensitive carbon doped titanium dioxide nanoparticles (C-TiO2) were prepared by a sol-gel method. The carbon dopant was obtained from glucose. The dopant level incorporated into the TiO2lattice structure was varied by using different concentrations of the carbon source solution. The nanoparticles were characterized by X-ray diffraction (XRD), BET Surface area, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Scanning X-ray photoelectron spectroscopy (SXPS) and Diffuse reflectance spectroscopy (DRS). The presence of carbon in the TiO2lattice was determined by SXPS. The DRS results revealed that carbon doping reduced the band gap of TiO2. Doping was also found to cause a reduction in the particle size of the TiO2nanoparticles and enhance anatase to rutile phase transformation. The photocatalytic activities of the prepared samples were evaluated by the photocatalytic degradation of methyl orange. The carbon doped TiO2showed a higher photocatalytic activity than degussa P25 and undoped TiO2.