Nanostructured Titanium Research Articles

Toxicity evaluation of TiO2/MWCNT-CNF hybrid nanocomposites with enhanced photocatalytic activity toward freshwater microalgae: Pseudokirchneriella subcapitata

A wide range of semiconductor-assisted photocatalytic nanomaterials (NMs) are currently being considered and investigated as potential photocatalysts in water treatment. The applications of nanocomposites composed of nano-structured titania (nano-TiO2) and multi-walled carbon nanotubes (MWCNTs) nanocomposites is growing markedly on account of enhanced photocatalytic efficiency. However, concurrent with the increasing production and application comes a serious concern of these emerging nanosystems about their potential risks in aquatic systems, and thereby potentially threatening aquatic organisms via toxic mechanisms that are, at present, poorly understood. In the present study, the lethal toxic effect and oxidative stress induced by TiO2/MWCNT-CNF nanocomposite in freshwater Pseudokirchneriella subcapitata were assessed. The growth inhibition and sublethal oxidative stress produced by the nanocomposites were evaluated on green microalgae P. subcapitata after 3 days of exposure at 24 h intervals. Moreover, the nanocomposites were physicochemically characterized using a combination of analytical techniques (XRD, SEM/EDS, HRTEM, TGA, UV–Visible spectroscopy). Evaluation of the hybrid for the photocatalytic degradation of Acid Violet 7 dye indicated an enhanced dye removal performance for TiO2/MWCNT-CNF (96.2%) compared to TiO2 (75.2%) after 2 h of visible light irradiation. While the nanocomposite showed good potential for the degradation of the azo dye, overall, the findings herein indicated that acute exposure of P. subcapitata to various concentrations of TiO2/MWCNT-CNF nanocomposite may cause algal growth inhibition including undesirable sublethal oxidative stress effects. The findings of this study contribute to a better understanding of the potential hazards of the developing nanocomposites materials towards the nano-bioremediation materials to treat wastewaters.

Impact of metallic coating on the retention of 225Ac and its daugthers within core–shell nanocarriers

Currently, alpha-emitting radionuclide 225Ac is one of the most promising isotopes in alpha therapy due to its high linear energy transfer during four sequential alpha decays. However, the main obstacle preventing the full introduction of 225Ac into clinical practice is the lack of stable retention of radionuclides, leading to free circulation of toxic isotopes in the body. In this work, the surface of silica nanoparticles (SiO2 NPs) has been modified with metallic shells composed of titanium dioxide (TiO2) and gold (Au) nanostructures to improve the retention of 225Ac and its decay products within the developed nanocarriers. In vitro and in vivo studies in healthy mice show that the metallic surface coating of SiO2 NPs promotes an enhanced sequestering of radionuclides (225Ac and its daughter isotopes) compared to non-modified SiO2 NPs for a prolonged period of time. Histological analysis reveals that for the period of 3–10 d after the injections, the developed nanocarriers have no significant toxic effects in mice. At the same time, almost no accumulation of leaked radionuclides can be detected in non-target organs (e.g., in the kidneys). In contrast, non-modified carriers (SiO2 NPs) demonstrate the release of free radionuclides, which are distributed over the whole animal body with the consequent morphological changes in the lung, liver and kidney tissues. These results highlight the potential of the developed nanocarriers to be utilized as radionuclide delivery systems and offer an insight into design rules for the fabrication of new nanotherapeutic agents.

Time-Dependent Density Functional Theory Calculations of N- and S-Doped TiO2 Nanotube for Water-Splitting Applications.

On the basis of time-dependent density functional theory (TD-DFT) we performed first-principle calculations to predict optical properties and transition states of pristine, N- and S-doped, and N+S-codoped anatase TiO nanotubes of 1 nm-diameter. The host O atoms of the pristine TiO nanotube were substituted by N and S atoms to evaluate the influence of dopants on the photocatalytic properties of hollow titania nanostructures. The charge transition mechanism promoted by dopants positioned in the nanotube wall clearly demonstrates the constructive and destructive contributions to photoabsorption by means of calculated transition contribution maps. Based on the results of our calculations, we predict an increased visible-light-driven photoresponse in N- and S-doped and the N+S-codoped TiO nanotubes, enhancing the efficiency of hydrogen production in water-splitting applications.

Development of a novel photocatalyst: Titania nanostructure bunches decorated on graphene oxide for enhanced photocatalytic efficiency

Titania decorated on graphene oxide nano-sheets (TiO2-GO-N) was developed by a two-step procedure. The TiO2-GO-N was then characterized by energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) analyses. Scherrer equation analysis revealed that the crystallite size of TiO2 nanoparticles decorated on graphene oxide (GO) was 3.37 nm. The TEM images showed that the particle size of TiO2 decorated on the GO nano-sheets ranges from 3-5 nm. Photocatalytic degradation of Congo red (CR) by TiO2-GO-N was studied experimentally by varying the pH values from 4.0–10.0. The highest photocatalytic efficiency of nearly 92% for the initial Congo red dosage of 15 × 10−3 mmol/l was observed at a pH of 4. The photocatalytic efficiency was 73.28% at the nearest environmentally relevant pH = 6 has been chosen for further studies.

Electrochemical synthesis of titanium dioxide nanostructures and its application in the in dye photocatalytic removal

By electrochemical anodization to titanium sheets, titanium dioxide nanostructures were sintered for 10 V and 20 V and times of 3 hours and 5 hours. For the electrolytic solution, 0.3 g of ammonium fluoride, 97 mL of ethylene glycol and 3 mL of distilled water were used. The sheets (51 mm × 21 mm × 0.4 mm) were treated using abrasive paper and cleaned with a 1:1 solution of ethanol water by means of ultrasound and dried using hot air. A stirring frequency of 300 rpm was used during anodizing. For the sintering of the titanium dioxide anatase phase, heat treatment was applied at 550 °C for 3 hours by means of an electric muffle, with heating speed of 10 °C/min. The crystallinity index, and the quantification of the sintered phases was carried out by means of X-ray diffraction, while the nanoporosities and their distribution were carried out using imageJ software to the images taken by means of scanning electron microscopy. For the photocatalytic treatment of the methylene blue dye in water, the titanium dioxide nanostructures that reported the highest anatase phase were used, where ultraviolet C radiation from a led lamp was applied for 4 direct hours. The efficiency in the removal of the dye was studied by UV-Vis spectrophotometry, finding the highest degradation of the dye for the wavelength of 644 nm.

Optimization and characterization of immobilized laccase on titanium dioxide nanostructure and its application in removal of Remazol Brilliant Blue R

The objective of this study was to determine optimum condition for immobilizing laccase onto porous TiO 2 nanostructure, and to characterize the immobilized enzyme. XRD and FTIR analyses revealed that laccase was successfully immobilized. The maximum recovery activity of 85.30 ± 0.89% was achieved when immobilization conditions were: 1.5 mg/mL laccase concentration, pH 7.0, and 18 h contact time. Shifting of optimum temperature and pH were observed after immobilization. Kinetics revealed that the immobilized form had lower substrate specificity and catalytic rate compared to the free enzyme. Storage stability of the immobilized form were improved compared to the free enzyme. Interestingly, the immobilized laccase could preserve 31.84 ± 1.86% of enzyme activity after keeping the enzyme at room temperature continuously for 14 days. Maximum RBBR removal of 76.09 ± 0.47% was achieved at pH 5.0, and repeatability of the immobilized enzyme in decolorization was performed for 3 cycles with 40% decrease in efficiency. The immobilized laccase can be removed easily from the solution using forceps without further separation processes. • Combination of laccase enzyme and nanostructure was applied to produce the nanobiocatalyst. • Laccase was successfully immobilized on nano TiO 2 using covalent binding method. • Stability, durability, and reusability of the immobilized laccase were improved. • Maximum RBBR decolorization of the immobilized laccase was 76.09 ± 0.47% at pH 5.0. • After completion of the reaction, the immobilized laccase can be easily separated.

Experimental study and theoretical modeling of coating-speed-dependent optical properties of TiO2-graphene-oxide thin films

Nanostructured titanium dioxide–graphene oxide (TiO2-GO) thin films have been successfully synthesized and deposited on glass substrates using spin coating technique. TiO2-GO nanocomposites were prepared using Titanium Tetra Isopropoxide (TIP) and Graphene Oxide (GO) nanosheets. The influences of spin coating deposition speed on the structural, morphological, and optical features of the resulting TiO2-GO samples have been investigated. X-ray diffraction (XRD) patterns showed an amorphous structure of all deposited films. Scanning electron microscopy (SEM) images demonstrated that these films are homogeneous and all free from cracking over the entire surface of the sample, regardless of the number of rotations used. Atomic force microscopy (AFM) topography images reveal that all samples are smooth with very small surface roughness. Optical data obtained from UV–Vis spectrophotometer measurement together with theoretical modeling using Tauc–Lorentz (TL) oscillator model showed that all films display high transmittance level around 85% from the visible to the near-infrared region. It is also shown that an increase in spin coating speed results in a decrease in the film thickness and the optical band gap. The observed optical features reveal that TiO2-GO thin films are promising candidate that can be used as transparent conducting oxide electrode in solar cells.

Photocatalytic and Antibacterial Properties of a 3D Flower-Like TiO2 Nanostructure Photocatalyst.

Flower-like titanium dioxide (TiO2) nanostructures are successfully synthesized using a hybrid sol-gel and a simple hydrothermal method. The sample was characterized using various techniques to study their physicochemical properties and was tested as a photocatalyst for methyl orange degradation and as an antibacterial material. Raman spectrum and X-ray diffraction (XRD) pattern show that the phase structure of the synthesized TiO2 is anatase with 80-100 nm in diameter and 150–200 nm in length of flower-like nanostructures as proved by field emission scanning electron microscope (FESEM). The energy-dispersive X-ray spectroscopy (EDS) analysis of flower-like anatase TiO2 nanostructure found that only titanium and oxygen elements are present in the sample. The anatase phase was confirmed further by a high-resolution transmission electron microscope (HRTEM) and selected area electron diffraction (SAED) pattern analysis. The Brunauer-Emmett-Teller (BET) result shows that the sample had a large surface area (108.24 m2/g) and large band gap energy (3.26 eV) due to their nanosize. X-ray photoelectron spectroscopy (XPS) analysis revealed the formation of Ti4+ and Ti3+ species which could prevent the recombination of the photogenerated electron, thus increased the electron transportation and photocatalytic activity of flower-like anatase TiO2 nanostructure to degrade the methyl orange (83.03%) in a short time (60 minutes). These properties also support the good performance of flower-like titanium dioxide (TiO2) nanostructure as an antibacterial material which is comparable with penicillin which is 13.00 ± 0.02 mm inhibition zone against Staphylococcus aureus.

In Vitro Corrosion of SiC-Coated Anodized Ti Nano-Tubular Surfaces.

Peri-implantitis leads to implant failure and decreases long-term survival and success rates of implant-supported prostheses. The pathogenesis of this disease is complex but implant corrosion is believed to be one of the many factors which contributes to progression of this disease. A nanostructured titanium dioxide layer was introduced using anodization to improve the functionality of dental implants. In the present study, we evaluated the corrosion performance of silicon carbide (SiC) on anodized titanium dioxide nanotubes (ATO) using plasma-enhanced chemical vapor deposition (PECVD). This was investigated through a potentiodynamic polarization test and bacterial incubation for 30 days. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze surface morphologies of non-coated and SiC-coated nanotubes. Energy dispersive X-ray (EDX) was used to analyze the surface composition. In conclusion, SiC-coated ATO exhibited improved corrosion resistance and holds promise as an implant coating material.

Microbial Decontamination and Antibacterial Activity of Nanostructured Titanium Dental Implants: A Narrative Review.

Peri-implantitis is the major cause of the failure of dental implants. Since dental implants have become one of the main therapies for teeth loss, the number of patients with peri-implant diseases has been rising. Like the periodontal diseases that affect the supporting tissues of the teeth, peri-implant diseases are also associated with the formation of dental plaque biofilm, and resulting inflammation and destruction of the gingival tissues and bone. Treatments for peri-implantitis are focused on reducing the bacterial load in the pocket around the implant, and in decontaminating surfaces once bacteria have been detached. Recently, nanoengineered titanium dental implants have been introduced to improve osteointegration and provide an osteoconductive surface; however, the increased surface roughness raises issues of biofilm formation and more challenging decontamination of the implant surface. This paper reviews treatment modalities that are carried out to eliminate bacterial biofilms and slow their regrowth in terms of their advantages and disadvantages when used on titanium dental implant surfaces with nanoscale features. Such decontamination methods include physical debridement, chemo-mechanical treatments, laser ablation and photodynamic therapy, and electrochemical processes. There is a consensus that the efficient removal of the biofilm supplemented by chemical debridement and full access to the pocket is essential for treating peri-implantitis in clinical settings. Moreover, there is the potential to create ideal nano-modified titanium implants which exert antimicrobial actions and inhibit biofilm formation. Methods to achieve this include structural and surface changes via chemical and physical processes that alter the surface morphology and confer antibacterial properties. These have shown promise in preclinical investigations.

Photocatalytic efficiency of titania nonylphenol ethoxylate composite thin films under solar irradiation

Photocatalytic efficiency of titania thin-films on ITO synthesized in the presence of nonylphenol-surfactants containing different numbers of ethoxylate-units was investigated under solar-irradiation. A colorless transparent titania-gel formed in the non-aqueous medium in the presence of nonylphenol-10-ethoxylates while milky white opaque gel was observed with nonylphenol-35-ethoxylates. They were coated on ITO plate by dipping method and calcined at 350, 500 and 700 °C. The XRD, IRRAS, EDS, SEM and AFM analyses revealed that different composite nanostructures are formed by calcinations of Ti-nonylphenol-35-ethoxylates at 350 and 500 °C. The photocatalytic-efficiencies of the composite films are better than the other titania nanostructures. Transparency and band-gap energy evaluated from transmittance measurements demonstrated that visible-light responsive Ti-nonylphenol-35-ethoxylates composites are more efficient catalysts than UV-absorbable Ti-nonylphenol-10-ethoxylates films. The photocatalytic degradation rate of the methylene-blue on the catalysts was calculated using the Langmuir-Hinshelwood equation and its modified form derived in this study by considering intensity changes in solar light. The dye degradation efficiency of the Ti-nonylphenol-ethoxylate films changes in the 58–74% range after 2 h of irradiation in 0.02 mM MB solution. The solution completely decolorized after 8 h of irradiation on the TiNP-35 catalysts calcined at 350 °C.

Synthesis of Palladium and Copper Nanoparticles Supported on TiO2 for Oxidation Solvent-Free Aerobic Oxidation of Benzyl Alcohol

The use of metal oxides as supports for palladium and copper (Pd–Cu) nanoalloys constitutes a new horizon for improving new active catalysts in very important reactions. From the literatures, Pd-based bimetallic nanostructures have great properties and active catalytic performance. In this work, nanostructures of titanium dioxide (TiO2) were used as supports for Pd–Cu nanoparticles catalysts. Palladium and copper were deposited on these supports using the sol-immobilisation method. The composite nanoalloys were characterized using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The catalyst was evaluated for the oxidation of benzyl alcohol. The effect of the Cu–Pd ratio using sol-immobilization methods supported on TiO2 was investigated. The results show that monometallic Cu/TiO2 was observed to have a low activity. However, as soon as the catalyst contained any palladium, the activity increased with a significant increase in the selectivity towards isomerization products. The influence of support and temperature were investigated. Furthermore, the catalyst reusability was also tested for oxidation of benzyl alcohol reactions, by repeatedly performing the same reaction using the recovered catalyst. The Pd–Cu/TiO2 catalyst displayed better reusability even after several reactions

Design and development of defect rich titania nanostructure for efficient electrocatalyst for hydrogen evolution reaction in an acidic electrolyte

Cost-effective, efficient and stable electrocatalyst for water splitting in the acidic electrolyte medium has been developed. The acidic electrolyte could be a support for the high purity hydrogen production via water splitting. Accordingly, we have prepared the defect-rich titania nanostructure via electrochemical anodization and cathodization routes using the titanium plate, which showed highly effective and durable electrocatalyst of hydrogen evolution reaction (HER) in an acidic medium. This hybrid compound showed a low onset potential of −0.17 V for HER with a current density of −150 mA cm−2 in 1 M H2SO4. Moreover, the stability test has been performed with the defect-rich titania nanostructure as cathode for 6 h in the two electrodes system.

Study of Effect of the Chrome Additive on the Structural, Morphology and Optical Properties of Nanostructured Titanium dioxide Thin Film

Undoped Titanium dioxide (TiO2) and Cr-doped TiO2 films were prepared by Spray Pyrolysis Technique (SPT). XRD styles showed that TiO2 films were grown along dominant orientation of (111). Crystallite size increases from 8.95 nm to 9.70 nm as vanadium concentration increase, whereas the strain(%) parameter increased from 3.87 to 3.57. the AFM imaging shows that the Undoped TiO2 and TiO2: Cr thin films was discontinuous surface with spherically grains decreased from (65.95-44.23 nm) with increase doping from 0% to 3%, and root-mean square (rms) roughness of surface is about (9.70-2.41) nm. Spectrometric analysis of deposited films showed high transmittance in spectral range from 300 to 900 nm, whereas the corresponding value of bandgaps was ranged from 3.48 to- 3.38 eV by Cr doping. Results show that doping of TiO2 with Cr enhances the optical properties. the absorption coefficient (α), extinction coefficient (k) and refractive index (n) are increased when Cr additive is increasing.

Synthesis and Photoelectrocatalytic Activity of Anodic Nanostructured TiO₂ Films

Nanostructured titanium dioxide films were prepared by electrochemical oxidation technique, anodization voltage effect on structure morphology, optical and photoelectrocatalytic performances of the nanotubes were studied. The anodization voltage is shown to significantly affect structure of nanofilms and, accordingly, their photoelectrocatalytic activity. An active heterojunction photoanode was synthesised with electrodeposition of Cu₂O onanodized TiO₂. The anode photoelectroact ivityunder bias 1V (Ag/AgCl/3,5M KCl) is found to be 15 % higher than that of the original nanostructured TiO₂ film

Comprehensive review on ultrasound-responsive theranostic nanomaterials: mechanisms, structures and medical applications.

The field of theranostics has been rapidly growing in recent years and nanotechnology has played a major role in this growth. Nanomaterials can be constructed to respond to a variety of different stimuli which can be internal (enzyme activity, redox potential, pH changes, temperature changes) or external (light, heat, magnetic fields, ultrasound). Theranostic nanomaterials can respond by producing an imaging signal and/or a therapeutic effect, which frequently involves cell death. Since ultrasound (US) is already well established as a clinical imaging modality, it is attractive to combine it with rationally designed nanoparticles for theranostics. The mechanisms of US interactions include cavitation microbubbles (MBs), acoustic droplet vaporization, acoustic radiation force, localized thermal effects, reactive oxygen species generation, sonoluminescence, and sonoporation. These effects can result in the release of encapsulated drugs or genes at the site of interest as well as cell death and considerable image enhancement. The present review discusses US-responsive theranostic nanomaterials under the following categories: MBs, micelles, liposomes (conventional and echogenic), niosomes, nanoemulsions, polymeric nanoparticles, chitosan nanocapsules, dendrimers, hydrogels, nanogels, gold nanoparticles, titania nanostructures, carbon nanostructures, mesoporous silica nanoparticles, fuel-free nano/micromotors.

Structural and optical properties of titania nanostructures obtained from oxime-modified titanium(IV) precursor

ABSTRACT Spray pyrolytic deposition (SPD) of titania films on borosilicate glass substrates has been carried out using oxime-modified titanium(IV) isopropoxide, [Ti(O i Pr)2{ONC(CH3)2}2]. Thermal study of the above complex indicates one step decomposition to TiO2 at low temperature (< 250 °C), making it a versatile SPD precursor to deposit titania film at low temperature. The XRD analyses of the deposited titania films indicate presence of amorphous titania over glass substrate. The deposition of titania films was further confirmed by the EDX analyses. The SEM images of the titania films over glass substrates indicate presence of crack-free titania films having thickness in the range of 1.28–1.45 µm. AFM images of titania-coated glass sample represent growth of smooth structures of titania. The transmittance of the deposited titania films over glass lies in the range of 77–86% in the visible region.

Hierarchical TiN‐Supported TsFDH Nanobiocatalyst for CO2 Reduction to Formate

AbstractThe electrochemical reduction of CO2 to value‐added products like formate represents a promising technology for the valorization of carbon dioxide. We propose a proof‐of‐concept bioelectrochemical system (BES) for the reduction of CO2 to formate. For the first time, our device employs a nanostructured titanium nitride (TiN) support for the immobilization of a formate dehydrogenase (FDH) enzyme. The hierarchical TiN nanostructured support exhibits high surface area and wide pore size distribution, achieving high catalytic loading, and is characterized by higher conductivity than other oxide‐based supports employed for FDHs immobilization. We select the oxygen‐tolerant FDH from Thiobacillus sp. KNK65MA (TsFDH) as enzymatic catalyst, which selectively reduces CO2 to formate. We identify an optimal TiN morphology for the enzyme immobilisation through enzymatic assay, reaching a catalyst loading of 59 μg cm−2 of specifically‐adsorbed TsFDH and achieving a complete saturation of the anchoring sites available on the surface. We evaluate the electrochemical CO2 reduction performance of the TiN/TsFDH system, achieving a remarkable HCOO− Faradaic efficiency up to 76 %, a maximum formate yield of 44.1 μmol mg−1FDH h−1 and high stability. Our results show the technological feasibility of BES devices employing novel, nanostructured TiN‐based supports, representing an important step in the optimization of these devices.

Effect of Conditions of Sol-Gel Synthesis and Post-Synthetic Treatment on Photoelectrochemical and Electro-Catalytic Properties of Titanium Oxide Nanostructures and Tio2-Au Nanocomposites

Carbon-doped mesoporous TiO2 nanostructures and TiO2-Au nanocomposites with stabilized Au nanoparticles have been synthesized by the sol-gel template method and characterized by X-ray diffraction, scanning and transmission electron microscopies, Fourier-transform infrared spectroscopy, N2 adsorption/desorption, ultraviolet-visible spectroscopy, and photoelectrochemical current spectroscopy. The synthesis hydrothermal treatment conditions affected the particle size, electronic structure, morphology, phase, and chemical compositions, as well as the texture of the synthesized materials. The TiO2 and TiO2-Au based electrodes were light-sensitive in a wavelength range of 250–412 nm and were distinguished by a high catalytic activity during oxygen electroreduction. The presence of -ol and carboxylate groups in the amorphous phase is the main factor affecting the photosensitivity of TiO2 nanostructures to visible light and an increase in their photoactivity during the decomposition of methylene blue upon irradiation with ultraviolet and visible light relative to pure anatase. The higher photosensitivity and photoactivity of TiO2-Au nanocomposites compared with those of the corresponding starting TiO2 is due to the synergistic effect of Au nanoparticles and interstitial Ti-O-C groups, which depends on the Au nanoparticle content of the composite and on the mesopore size.

Molecular interaction of natural dye based on Zea Mays and Bixa Orellana to nanocrystalline TiO2 into dye sensitized solar cells.

This work studies the interaction between natural dyes obtained from Peruvian Zea mays and Bixa orellana seeds and nanostructured titanium dioxide in order to evaluate their function as sensitizers into solar cell devices. The effective attachment of dyes to the TiO2 layer is corroborated by the comparison of UV-Visible absorption and FT-IR spectra of the extracted dye solutions and sensitized TiO2 electrodes. The principal compounds from the seed extraction of Zea mays and Bixa orellana are cyanidin-3-glucoside (C3G) and bixin, respectively, which were analyzed in an isolated dye/cluster TiO2 system by molecular dynamic simulation. The results showed that the chemisorption is carried out through a consecutive deprotonation process and Ti-O bond formation by the monodentate OH and COOH anchoring groups, for C3G and bixin, respectively. Finally, we tested the effect of the dye – TiO2 interaction on the charge transfer by the comparison of the current-voltage (I-V) curves and incident photon-to-current conversion efficiency (IPCE) of the cells. We found that dye agglomeration in films with Bixa orellana and the high charge recombination of films with Zea mays are critical points to be solved. For this reason, we propose the pretreatment of the TiO2 film before sensitization with Bixa orellana and analyze the effects of pH in Zea Mays solution, in order to obtain better device efficiencies.