Modification Of TiO2 Research Articles

Physical, optical, and radiation characteristics of bioactive glasses for dental prosthetics and orthopaedic implants applications

The melt-quench procedure was employed to create five different composition of bioactive glasses with TiO2 modifications. The optical and shielding characteristics the bioglasses have all undergone significant changes. X-ray diffraction studies were subjected to investigate the glasses' amorphous character. The absorption and transmission of the prepared glasses are measured to examine optical characteristics. The energy gap expands, whereas Urbach reduces. The physical constants basicity, polarizability, and electronegativity are all determined. Phy-X/PSD was employed to explore radiation shielding features. Because the addition of TiO2, sample G5 has the best radiation features. The outcomes show that adding TiO2 to bioactive glass compositions has a significant impact on their optical and radiation shielding features. As a result of the composition, a new bioglass system has been created that can be used in a variety of applications, including dental prosthetics and orthopaedic implants.

Dopamine Adsorption on Rutile TiO2(110): Geometry, Thermodynamics, and Core-Level Shifts from First Principles.

The modification of the rutile TiO2(110) surface with dopamine represents the best example of the functionalization of TiO2-based nanoparticles with catecholamines, which is of great interest for sunlight harvesting and drug delivery. However, there is little information on the dopamine–TiO2(110) adsorption complex in terms of thermodynamic properties and structural parameters such as bond coordination and orientation of the terminal ethyl–amino group. Here, we report a density functional theory (DFT) investigation of dopamine adsorption on the TiO2(110) surface using the optB86b-vdW functional with a Hubbard-type correction to the Ti 3d orbitals, where Ueff = 3 eV. Guided by available X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) data, our simulations identify enolate species with bidentate coordination at a submonolayer coverage, which are bonded to two neighboring 5-fold-coordinated Ti atoms at the TiO2(110) surface through both deprotonated oxygen atoms of the dopamine, i.e., in a bridging fashion. The process is highly exothermic, involving an adsorption energy of −2.90 eV. Calculated structural parameters suggest that the molecule sits approximately upright on the surface with the amino group interacting with the π-like orbitals of the aromatic ring, leading to a gauche-like configuration. The resulting NH···π hydrogen bond in this configuration can be broken by overcoming an energy barrier of 0.22 eV; in this way, the amino group rotation leads to an anti-like conformation, making this terminal group able to bind to other biomolecules. This mechanism is endothermic by 0.07 eV. Comparison of existing spectroscopic data with DFT modeling shows that our computational setup can reproduce most experimentally determined parameters such as tilt angles from NEXAFS and chemical shifts in XPS, which allows us to identify the preferred mode of adsorption of dopamine on the TiO2(110) surface.

Structure and photocatalytic activity of maleic anhydride-functionalized TiO2 nanoparticles by a simple method

Titanium dioxide (TiO2) nanoparticles were functionalized with maleic anhydride (MA). The extension of adsorbed MA on the TiO2 was evaluated by ultrasonic and magnetic stirring. Total Organic Carbon and Thermogravimetric Analysis confirmed the presence of surface MA even after the washing process. The Fourier Transform Infrared and UV-Vis Diffuse Reflectance spectra clearly showed the chemical anchored maleic anhydride on the TiO2 surface as bidentate bridging adsorption. The surface modification of TiO2 extended its light absorption range to the visible light region reducing its bandgap energy from 3.05 to 2.55 eV. X-Ray Diffraction patterns showed that the TiO2 functionalized presented a mixture of anatase and rutile phases without any crystalline phase transformation after MA chemisorption process. The functionalization percentage and the reaction efficiency for the TiO2 with 5 wt% MA sample were 3.6 and 69%, respectively, as shown by Differential Thermal Analysis and Thermogravimetric Analysis. The performance of pure and functionalized TiO2 samples were evaluated in the photocatalytic degradation of the Methyl Orange dye under ultraviolet light. TiO2 with 5 wt% MA produced a maximum degradation of 97% after 90 min, 3% higher than the commercial TiO2.

Hydrogen in single-crystalline anatase TiO2

Titanium dioxide (TiO2, also known as titania) has attracted a great deal of attention since the discovery of photocatalytic splitting of water under ultraviolet light exposure by Fujishima and Honda. Three modifications of TiO2 are known to occur in nature: rutile, brookite, and anatase, of which only the first is a stable polymorph of bulk titania. The contribution of the surface free energy, however, makes anatase a stable polymorph at the nanometer scale. Compared to rutile, anatase has a longer carrier lifetime and exciton diffusion length, higher electron mobility, and is an order of magnitude more efficient in photocatalysis, which makes it a material of choice for a variety of applications. Hydrogen is a common impurity in TiO2 with a strong impact on its electrical and optical properties. In this Perspective, we discuss the application of IR absorption, Raman scattering, electron paramagnetic resonance, and ab initio theory to get insight into the properties of hydrogen in bulk single-crystalline anatase. In particular, interstitial hydrogen, hydrogen substituting for oxygen, the nature of “hidden” species, as well as complexes formed by hydrogen with acceptors are considered.

Modification strategies of polyacrylonitrile ultrafiltration membrane using TiO2 for enhanced antifouling performance in water treatment

The active application of ultrafiltration in various industries requires the development of novel membranes with tailored properties and good fouling resistance. This work is devoted to the improvement of ultrafiltration properties of polyacrylonitrile (PAN) membranes by various TiO2 modification approaches: (1) ex situ method - the introduction of pre-formed micro- or nanoparticles; (2) in situ method - the formation of TiO2 particles in the casting solution; and (3) surface modification method - dynamic deposition of TiO2 on the membrane surface. The effect of the various TiO2 immobilization techniques on the structure of PAN membranes was studied by scanning electron and atomic force microscopies, and the contact angle measurements. The introduction of TiO2 particles improved membrane performance and antifouling stability under UV irradiation in ultrafiltration of industrially important feeds - bovine serum albumin solution (BSA) and coolant lubricant emulsion. The affinity to water of TiO2-modified PAN membrane was confirmed by atomistic molecular dynamics simulations, swelling experiments, and calorimetric study of wetting. PAN membrane with 0.5 wt% TiO2 nanoparticles had the optimal transport characteristics and improved surface self-cleaning ability after UV irradiation: pure water, coolant lubricant, and BSA fluxes (849, 38, and 68 L/(m2h), respectively), and flux recovery ratio after UV-illumination (95%).

Osteogenic TiO2 composite nano-porous arrays: A favorable platform based on titanium alloys applied in artificial implants

The purpose of the nano-porous TiO2 modification on TC26 (Ti-13 Nb-13Zr) alloy is to settle the issue that the surface inertness of titanium alloys restricts bioactivity and osseointegration of artificial implants. Secondary constant current anodization was conducted to realize the efficient fabrication of the TiO2 composite nano-porous arrays containing the terminal small-diameter nanopores and the upper large-diameter nanotubes. The oxygen bubble mould theory has revealed the anodization mechanism of the TiO2 nano-porous arrays. The anodization parameters and heat treatment conditions are both able to elicit influence on morphology, chemical composition, surface properties and biocompatibility of the as-fabricated samples. The interaction of MC3TC-E1 mouse pre-osteoblasts with a series of TiO2 nano-porous arrays fabricated by primary anodization (PA) and secondary anodization (SA) was investigated by the MTT assay and alkaline phosphatase (ALP) activity assay. The response of the seeded MC3TC-E1 pre-osteoblasts to the as-fabricated samples with various nano-scale dimensions has indicated that appropriate nano-porous morphologies and heat treatment conditions have the capacity to augment cell adhesion, growth, differentiation and functionality. Such fabrication route in this research has provided a promising prospect for development of artificial implants.

Where ppm Quantities of Silsesquioxanes Make a Difference-Silanes and Cage Siloxanes as TiO2 Dispersants and Stabilizers for Pigmented Epoxy Resins.

In this work, silsesquioxane and spherosilicate compounds were assessed as novel organosilicon coupling agents for surface modification of TiO2 in a green process, and compared with their conventional silane counterparts. The surface-treated TiO2 particles were then applied in preparation of epoxy (EP) composites and the aspects of pigment dispersion, suspension stability, hiding power, as well as the composite mechanical and thermal properties were discussed. The studied compounds loading was between 0.005–0.015% (50–150 ppm) in respect to the bulk composite mass and resulted in increase of suspension stability and hiding power by over an order of magnitude. It was found that these compounds may be an effective alternative for silane coupling agents, yet due to their low cost and simplicity of production and manipulation, silanes and siloxanes are still the most straight-forward options available. Nonetheless, the obtained findings might encourage tuning of silsesquioxane compounds structure and probably process itself if implementation of these novel organosilicon compounds as surface treatment agents is sought for special applications, e.g., high performance coating systems.

Применение ультразвуковой обработки для повышения фотохимической активности электровзрывных бикомпонентных наночастиц TiO2-Ag

TiO2-Ag nanoparticles with thermal and chemical stability, wide band gap and low toxic are more used photocatalysts for decomposition of organic substances. However, high rate of recombination of electron-hole pairs and high energy of photoactivation significantly limit their usage. Modification of TiO2 with silver promotes surface separation of charges and increases their photochemical activity. In the present study for obtain TiO2-Ag bicomponent nanoparticles was use electric explosion of metal wires in atmosphere 85 vol.% Ar - 15 vol.% O2. This method has a high productivity (170-200 g/h) which is enough for industrial application of nanoparticles. However, electroexplosive nanoparticles are mostly agglomerates with a size of 200-500 nm, which significantly reduces their photochemical activity in the test reaction of decomposition of the model dye methylene blue under the visible light radiation. Ultrasonic treatment of nanoparticles in aqueous suspension for 15 min. contributed to an increase in the photoactivity of TiO2-Ag nanoparticles by 10%

Photocatalytic hydrogenation of acetophenone on a titanium dioxide cellulose film.

A previously developed sustainable immobilization concept for photocatalysts based on cellulose as a renewable support material was applied for the photocatalytic hydrogenation of acetophenone (ACP) to 1-phenyl ethanol (PE). Four different TiO2 modifications (P25, P90, PC105, and PC500) were screened for the reaction showing good performance for PC25 and PC500. PC500 was selected for a detailed kinetic study to find the optimal operating conditions, and to obtain a better understanding of the photocatalytic pathway in relation to conventional and transfer hydrogenation. The kinetic data were analyzed using the pseudo-first-order reaction rate law. A complete conversion was obtained for ACP concentrations below 1 mM using a 360 nm filter and argon as the purge gas within 2–3 hours. High oxygen concentrations slow down or prevent the reaction, and wavelengths below 300 nm lead to side-products. By investigating the temperature dependency, an activation energy of 22 kJ mol−1 was determined which is lower than the activation energies for conventional and transfer hydrogenation, because the light activation of the photocatalyst turns the endothermic to an exothermic reaction. PC500 was immobilized onto the cellulose film showing a 37% lower activity that remains almost constant after multiple use.

Microbiological evaluation for antifungal activity of some metal oxides nanofillers incorporated into cold cured soft lining materials: clinical based study

Objective: The aim of the current study was to evaluate the efficacy of addition of zirconium oxide (ZrO2), titanium oxide(TiO2), and silica oxide (SiO2) nanoparticles to cold-cured soft liner on adhesion of Candida albicans (CA). Material andMethods: Fifty-four patients had been selected and divided into three groups according to the modification of soft linerwith ZrO2, TiO2, and SiO2 nanoparticles (18 each of). Each patient received maxillary complete denture having threecavities, the cavities were lined using cold cured soft liner modified with different concentration (0%, 3%, and 7%) ofmetal oxide nanoparticles. On days 14 and 28, swaps were taken out from relining site and immediately cultured forfungal evaluation. The number of colonies were counted, data collected and explored for normality using Shapiro-Wilktest, logarithmic transformation of CA count was performed. Repeated and one-way ANOVA were used followed byTukey HSD. Independent-t test used to compare between CA counts at different periods. Results: The CA adhesionwas significantly decreased by the addition of ZrO2, TiO2 and SiO2 nanoparticles in comparison with control group, alsothe antifungal coverage increased with nanoparticles concentration increased (P<0.005). The highest CA count wasidentified in group SiO2 followed by ZrO2, while TiO2 showed the lowest CA count (P <0.001). Conclusion: Additionof different nanoparticles; ZrO2, TiO2 and SiO2 to cold-cured soft liner is an effective method for reducing CA adhesion.KEYWORDSAntifungal agent; Candida albicans; Denture liners; Nanoparticles.

Comparative Study of Nanostructured TiO2 and SLA Surface Modifications for Titanium Implants: Surface Morphology and in vitro Evaluation

Our work presents a comparative study of morphological characteristics and the osteogenic potential of MC3T3-E1 cells on different modified surfaces of titanium: nanostructured TiO2 with 20 and 100 nm nanotube diameter, and sandblasting and acid etching, commercially known as SLA. Nanostructured TiO2surface was prepared by anodizing of titanium plates, while SLA surface was provided by commercial supplier. Surfaces were characterized by SEM, EDS, AFM, and water contact angle measurements. In order to evaluate cell response,in vitrotests of MTT, alkaline phosphatase and staining with alizarin red were performed. From the results ofin vitro tests, 100 nm nanotubular surface showed lower levels of cell mineralization, differentiation and adhesion. In general, 20 nm TiO2nanotubular and SLA surfaces promoted similar response from osteoblasts. As a result, 20 nm nanotubular surface proved to be a possible alternative to SLA surface with potential for use in oral implantology market.

Adsorption characteristics of 2,4-dichorophenoxy acetic acid onto surfactant modified titania nanoparticles

The present study investigated adsorption of 2,4-dichorophenoxy acetic acid (2,4-D) on titania (TiO2) nanoparticles with surface modification by cationic surfactant, cetyltrimethylammonium bromide (CTAB). Titania nanoparticles which were successfully synthesized by sol-gel method, were characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). Surface modification of TiO2 with CTAB enhanced the removal of 2,4-D significantly. Some effective conditions affect to the removal of 2,4-D using CTAB modified TiO2 such as pH and adsorbent dosage were systematically studied and found to be 5 and 10 mg/mL, respectively. Adsorption mechanisms of 2,4-D onto CTAB modified TiO2 was suggested based on the change in surface charge after adsorption.

Synthesis and electron irradiation modification of anatase TiO2 with different morphologies

Anatase TiO2 samples with three different morphologies were successfully prepared by the solvothermal method, and their photoelectric properties were tested. The mixed anatase TiO2 demonstrated the best photoelectrochemical water splitting performance with a photocurrent density of 0.84 mA/cm2 (1.23V vs. reversible hydrogen electrode (RHE)), carrier concentration of 1.29 × 1022 cm-3, and interface resistance of 29.20 Ω. Further, the anatase TiO2 samples with different morphologies were doped with nitrogen ions by electron beam irradiation in order to modify the defect concentration in these samples. Among them, the photocurrent density of mixed anatase TiO2 irradiated by 100 kGy obtained the highest current density at 0.99 mA/cm2 (1.23 V vs. RHE). Moreover, its carrier concentration reached 2.46 × 1022 cm-3 and interface resistance was reduced to 11.24 Ω. The photocatalytic properties of TiO2 with different morphologies and the effects of irradiation and nitrogen doping on the properties of the samples were investigated.

Assessment of some characteristics, properties of a novel waterborne acrylic coating incorporated TiO2 nanoparticles modified with silane coupling agent and Ag/Zn zeolite

Effect of rutile TiO2 nanoparticles modified with 3-(trimethoxysilyl) propyl methacrylate silane - TMSPM (m-TiO2) and Ag/Zn zeolite on the properties, and durability of acrylic waterborne coatings was studied. The obtained results indicated that m-TiO2 nanoparticles and Ag/Zn zeolite could disperse regularly in the acrylic polymer matrix. Consequently, the acrylic coating's abrasion resistance was improved in the presence of m-TiO2 or/and Ag/Zn zeolite. The acrylic coating's abrasion resistance depended on the content of m-TiO2 nanoparticles as well as the initial TMSPM content for modification of rutile TiO2 nanoparticles. The abrasion resistance of the m-TiO2 nanocomposite coating was higher than that of the unmodified TiO2 nanocomposite coating. The acrylic coating filled by 2 wt% TiO2 modified with 3 wt% TMSPM had the highest abrasion resistance value, leveling off at 187.2 L/mil. The abrasion resistance of acrylic coating filled by m-TiO2 reduced with increasing too high m-TiO2 nanoparticles content and using initial TMSPM content in high level for TiO2 modification. The starting temperature of weight loss of acrylic coating filled by m-TiO2 was lower than that of the neat acrylic coating. In comparison with the m-TiO2 nanoparticles, the Ag/Zn zeolite particles showed a lower improvement for acrylic coating properties, i.e. abrasion resistance, weathering durability, but the Ag/Zn zeolite particles expressed an excellent antibacterial activity. Hence, combination of the m-TiO2 nanoparticles and Ag/Zn zeolite particles could enhance the acrylic waterborne coatings' properties. The acrylic coating filled by 2 wt% m-TiO2 nanoparticles and 1 wt% Ag/Zn zeolite particles illustrated high abrasion resistance, good weather durability, and superior antibacterial activity for both of E. coli and S. aureus. This coating is promising for environmental friendly building materials application.

Мо-модифицированный диоксид титана как перспективный фотокаталитически активный материал

The oxide composites based on titanium dioxide modified by molybdenum have been synthesized. The peculiarities of the formation of these composites their physico-chemical and photocatalytic properties have been studied. It is shown that the modification of TiO2 with molybdenum provides obtaining nanodispersed powders (from 8.3 to 12.1 nm) with a free specific surface from 279 to 190 m2/g, respectively. It is shown that the synthesized composites have significantly higher photocatalytic activity (PCA) relative to unmodified TiO2 of similar genesis and industrial titanium dioxide P-25 of Degussa by the example of decomposition of various dyes.

Comparison of Anatase and Rutile for Photocatalytic Application: the Short Review

The dioxide titanium (TiO2) is attracting a great attention as semiconductor photocatalyst because of its high photoreactivity, non-toxicity, corrosion resistance, photostability, cheapness. It can be used in wide range of applications: air and water purification, hydrogen (H2) generation, CO2 reduction, in photovoltaic application and others. The efforts of scientists were applied to use solar light for dioxide titanium photocatalysis and to enhance the photocatalytic efficiency. In this article we review the properties difference of anatase and rutile modifications of TiO2. The anatase has a higher photoefficiency. The higher photoefficiency of anatase is due to longer lifetime of charge carriers (lifetime of e-/h+ in anatase on 3 order higher than in rutile). But anatase has higher band gap energy (3.2 eV or 388 nm) in comparison with rutile (3.0 eV or 414 nm). Thus, anatase becomes photosensitive in ultraviolet (UV) diapason of light, meanwhile rutile - in violet spectrum of visible light. It is desirable to obtain TiO2 semiconductor with properties combining best ones from anatase and rutile: higher photoreactivity and smaller band gap. It can be made by using external factors such as electric or magnetic fields, doping and etc.

Thermo-Optical Characterization of Cu- and Zr-Modified TiO2 Photocatalysts by Beam Deflection Spectrometry

Cu/Zr-modified TiO2 photocatalysts were prepared in the form of nanopowders and characterized by photothermal spectrometry, UV–Vis spectrophotometry and X-ray diffraction (XRD) to investigate the effect of Cu/Zr content on their thermo-optical and transport properties. Adding Cu (0.05%) caused a change in the light absorption range limit, which reduced from 3.25 eV for pure TiO2 to 2.85 eV for Cu-modified TiO2. The decrease in energy band gap was accompanied by a 19.5% decrease in the charge carrier lifetime, which is not favorable for photocatalysis. The decrease in charge carrier lifetime can be minimized by additional modification of TiO2 with Zr (1%), which showed insignificant effects on the energy band gap of the investigated materials. Furthermore, modification of TiO2 with Zr affected the material’s structure and increased its specific surface area, which improved the adsorption of degraded compounds as well as the absorption of light. Altogether, these effects resulted in higher photocatalytic degradation rate constants of the investigated TiO2-based photocatalyst. It was also found that modification of TiO2 with Cu and/or Zr increases both the material’s thermal diffusivity and conductivity due to changes in the band gap and structure of material. Beam deflection spectrometry (BDS) has demonstrated high potential in materials’ characterization which stems from its high sensitivity and precision.

Novel strategies for 2,8-dichlorodibenzo-p-dioxin degradation using ternary Au-modified iron doped TiO2 catalysts under UV–vis light illumination

Polychlorinated dibenzo-p-dioxins (PCDDs), characterized by their extreme toxicity, high persistency and bioaccumulation, regard as one of the most concerned environmental pollutants on the priority list. In this study, microwave-hydrothermal and photoreduction methods were adopted for fabrication of ternary Au@Fe/TiO2 composites for removal of 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD) under UV–Vis light irradiation. The acquired materials were characterized and analyzed by XRD, TEM, XPS, UV–Vis DRS, PL, etc. As a result, the 1%Au@1%Fe/TiO2 exhibited much higher photocatalytic activity that 96.3% of 2,8-DCDD was removed within 160 min with respect to that of Fe/TiO2 (3.0 times) and TiO2 (5.5 times). It revealed the active substances might be produced, which were verified by ESR analysis. In a comparison, the 1%Au@1%Fe/TiO2 also exhibited high activity in that 97.2% of 2,8-DCDD was removed within 240 min under an anoxic atmosphere. The 1%Au@1%Fe/TiO2 systems were all pH-dependent that 2,8-DCDD could be fully degraded in neutral conditions. The results of repeatability on 1%Au@1%Fe/TiO2 showed that the sample was high stability. Fe doping improved the charge separation of TiO2 and Au modification improved the activity via SPR effect and Mott-Schottky barrier. The degradation mechanisms and pathways were proposed and discussed in detail. The current work develops a new approach on photocatalytic oxidation and reductive dechlorination of dioxins and may open a new opportunity to extend the application range of TiO2 catalysts.

Study of particles of plasma dynamic synthesis product in the Ti-O system by high-resolution transmission electron microscopy

The paper demonstrates the possibility of obtaining a dispersed product in the Ti-O system by the method of plasma dynamic synthesis. It was revealed that the product consists of two modifications of TiO2: anatase and rutile. The degree of crystallinity is at a level of ~ 98.0%, which indicates the practical absence of an amorphous component. The predominant phase is anatase, which is confirmed by the results of quantitative X-ray phase analysis and high-resolution transmission electron microscopy.

Enhanced performance of photocatalytic treatment of Congo red wastewater by CNTs-Ag-modified TiO2 under visible light.

In order to improve the treatment efficiency of printing and dyeing wastewater, the carbon nanotubes-silver-modified-titanium dioxide (CNTs-Ag-TiO2, CAT) ternary composite was prepared by a mechanical mixing method. It was found that the morphology of the prepared CAT sample was uniformly coated with strips of CNTs, speckled Ag, and lumpy TiO2. The (002) crystal plane of CNTs, the (101) crystal plane of TiO2, and the (111) crystal plane of Ag were observed, which possessed functional groups such as Ti-OH and Ti-O-C, indicating that the prepared CAT sample had photocatalytic reaction sites. The visible light utilization of titanium dioxide can be improved. The treatment effect of different proportions of CNTs-Ag-TiO2 on Congo red wastewater was tested, and the results showed that the optimum degradation effect of Congo red wastewater was CNTs: Ag = 10:1, and the doped amount of CNTs/Ag was 15%, and the removal rate of Congo red wastewater could reach 100% within 140 min. The excellent removal effect of CAT ternary composite on Congo red wastewater provided a new idea and way for the modification of TiO2 and its composites for the potential of organic dyes degradation.