TiO2 Nanotube Layers Research Articles

Exploiting the Bragg Mirror Effect of TiO2 Nanotube Photonic Crystals for Promoting Photoelectrochemical Water Splitting.

Exploiting the Bragg mirror effect of photonic crystal photoelectrode is desperately desired for photoelectrochemical water splitting. Herein, a novel TiO2 nanotube photonic crystal bi-layer structure consisting of a top nanotube layer and a bottom nanotube photonic crystal layer is presented. In this architecture, the photonic bandgap of bottom TiO2 nanotube photonic crystals can be precisely adjusted by modulating the anodization parameters. When the photonic bandgap of bottom TiO2 nanotube photonic crystals overlaps with the electronic bandgap of TiO2, the bottom TiO2 nanotube photonic crystal layer will act as a Bragg mirror, leading to the boosted ultraviolet light absorption of the top TiO2 nanotube layer. Benefiting from the promoted UV light absorption, the TiO2 NT-115-NTPC yields a photocurrent density of 1.4 mA/cm2 at 0.22 V vs. Ag/AgCl with a Faradic efficiency of 100%, nearly two times higher than that of conventional TiO2 nanotube arrays. Furthermore, incident photon-to-current conversion efficiency is also promoted within ultraviolet light region. This research offers an effective strategy for improving the performance of photoelectrochemical water splitting through intensifying the light-matter interaction.

TiO2 nanotubes with customized diameters for local drug delivery systems

AbstractIn this study, we evaluated the drug release behavior of diameter customized TiO2 nanotube layers fabricated by anodization with various applied voltage sequences: conventional constant applied potentials of 20 V (45 nm) and 60 V (80 nm), a 20/60 V stepped potential (50 nm [two‐diameter]), and a 20–60 V swept potential (49 nm [full‐tapered]) (values in parentheses indicate the inner tube diameter at the top part of nanotube layers). The structures of the 50 nm (two‐diameter) and 49 nm (full‐tapered) samples had smaller inner diameters at the top part of nanotube layers than that of the 80 nm sample, while the outer diameters at the bottom part of nanotube layers were almost the same size as the 80 nm sample. The 80 nm sample, which had the largest nanotube diameter and length, exhibited the greatest burst release, followed by the 50 nm (two‐diameter), 49 nm (full‐tapered), and 45 nm samples. The initial burst released drug amounts and release rates from the 50 nm (two‐diameter) and 49 nm (full‐tapered) samples were significantly suppressed by the smaller tube top. On the other hand, the largest proportion of the slow released drug amount to the total released drug amount was observed for the 50 nm (two‐diameter) sample. Thus, 50 nm (two‐diameter) achieved suppressed initial burst release and large storage capacity. Therefore, this study has, for the first time, applied TiO2 nanotube layers with modulated diameters (two‐diameter and full‐tapered) to the realization of a localized drug delivery system (LDDS) with customized drug release properties.

Surface modification of TiO2 nanotubes via pre-loaded hydroxyapatite towards enhanced bioactivity

Anodic TiO2 nanotubes (NTs) are widely established in biomedical applications, as the sub-100 nm morphology significantly impacts their biological activity. In this study, we examine the use and surface functionalization of TiO2 nanotube layers on titanium substrates to facilitate the formation of hydroxyapatite, a crucial ability for implant applications. TiO2 NT layers are grown by electrochemical anodization and the focus is on as-formed and anatase NTs with 100- and 15-nm-diameters, the latter amorphous and available in double-wall (DT) or single-wall (ST) structures. Surface modification of the TiO2 NTs is achieved through an alternate immersion method (AIM) or a simple CaCl2 immersion. The former deposits hydroxyapatite (HA) coatings on/in the NT layers, while the latter forms a thin Ca-surface-modified layer on the TiO2 surface. Both methods effectively induce the formation of an HA layer on 100-nm-diameter NTs after five days of immersion in simulated body fluid (SBF). The chemical composition of NTs is a deciding factor, as the 100-nm-diameter NTs that already contain phosphates (from the anodizing electrolyte) also lead to HA formation by modification via Ca-functionalization (CaCl2 immersion). Whereas, for smaller diameter NTs, the surface nanotopography of the DT and ST NTs is key for the HA nucleation and formation via the AIM approach, but not via immersion in a calcium-containing solution. This promising approach accelerates the growth of HA on TiO2 nanomaterials by initiating apatite nucleation on TiO2 NTs and, thus, has significant implications for increasing their bioactivity in biomedical applications.

Photocatalytic removal of VOCs on TiO2 nanotube layers. Effect of layer thickness and humidity

The current work is focused on the influence of TiO2 nanotube (TNT) layer thickness, texture properties and chemical nature of volatile organic compounds (VOCs) on the efficiency of their photocatalytic oxidative removal. Attention was also given to the evaluation of the degree of mineralisation and the influence of air humidity. The fabricated TNT layers have a thickness from 2to13 μm, TiO2 mass from 0.27 to 1.15 mg cm−2, tube diameter of 108 ± 17 nm and porosity of 74 ± 5 %. Values of areal SBET determined from Kr adsorption are higher than the inner surface area of the TNT layer calculated from morphology parameters, this suggests the rough nature of the inner surface of nanotubes. Acetaldehyde was more easily degraded in comparison to hexane which was explained by a simpler chemical structure. The degree of acetaldehyde mineralisation was almost 100 %, suggesting the formation of no intermediates, analysis confirmed negligible formation of formaldehyde. In contrast, degree of hexane mineralisation was lower, 80 %. An increase in humidity has a negative effect on the photocatalytic performance; this effect is more significant for non-polar hexane compared to water-miscible acetaldehyde. The conversion of hexane and absorptance of the TNT layer at 365 nm increase similarly with increasing thickness. Hexane conversion increases significantly up to a layer thickness of about 4 μm where more than 80 % of incident light is absorbed. The simultaneous degradation of four pollutants (acetaldehyde, acetone, heptane and toluene) results in the highest degradation rate of acetaldehyde and the lowest for heptane, this was attributed to their different solubility in water as well as to their different adsorption.

Morphology and Structure of TiO2 Nanotube/Carbon Nanostructure Coatings on Titanium Surfaces for Potential Biomedical Application.

Titanium is the most used material for implant production. To increase its biocompatibility, continuous research on new coatings has been performed by the scientific community. The aim of the present paper is to prepare new coatings on the surfaces of the pure Ti Grade 2 and the Ti6Al4V alloy. Three types of coatings were achieved by applying anodization and chemical vapor deposition (CVD) methods: TiO2 nanotubes (TNTs) were formed by anodization, carbon nanotubes (CNTs) were obtained through a metal-catalyst-free CVD process, and a bilayer coating (TiO2 nanotubes/carbon nanostructures) was prepared via successive anodization and CVD processes. The morphology and structure of the newly developed coatings were characterized using SEM, EDX, AFM, XRD, and Raman spectroscopy. It was found that after anodization, the morphology of the TiO2 layer on pure Ti consisted of a "sponge-like" structure, nanotubes, and nano-rods, while the TNTs layer on the Ti alloy comprised mainly nanotubes. The bilayer coatings on both materials demonstrated different morphologies: the pure Ti metal was covered by a layer of nanotubular and nano-rod TiO2 structures, followed by a dense carbon layer decorated with carbon nanoflakes, and on the Ti alloy, first, a TNTs layer was formed, and then carbon nano-rods were deposited using the CVD method.

Synthesis and Study of SrTiO3/TiO2 Hybrid Perovskite Nanotubes by Electrochemical Anodization.

Layers of TiO2 nanotubes formed by the anodization process represent an area of active research in the context of innovative energy conversion and storage systems. Titanium nanotubes (TNTs) have attracted attention because of their unique properties, especially their high surface-to-volume ratio, which makes them a desirable material for various technological applications. The anodization method is widely used to produce TNTs because of its simplicity and relative cheapness; the method enables precise control over the thickness of TiO2 nanotubes. Anodization can also be used to create decorative and colored coatings on titanium nanotubes. In this study, a combined structure including anodic TiO2 nanotubes and SrTiO3 particles was fabricated using chemical synthesis techniques. TiO2 nanotubes were prepared by anodizing them in ethylene glycol containing NH4F and H2O while applying a voltage of 30 volts. An anode nanotube array heat-treated at 450 °C was then placed in an autoclave filled with dilute SrTiO3 solution. Scanning electron microscopy (SEM) analysis showed that the TNTs were characterized by clear and open tube ends, with an average outer diameter of 1.01 μm and an inner diameter of 69 nm, and their length is 133 nm. The results confirm the successful formation of a structure that can be potentially applied in a variety of applications, including hydrogen production by the photocatalytic decomposition of water under sunlight.

Low‐Temperature Atomic Layer Deposition Synthesis of Vanadium Sulfide (Ultra)Thin Films for Nanotubular Supercapacitors

Herein, the synthesis of vanadium sulfide (VxSy) by atomic layer deposition (ALD) based on the use of tetrakis(dimethylamino) vanadium (IV) and hydrogen sulfide is presented for the first time. The (ultra)thin films VxSy are synthesized in a wide range of temperatures (100–225 °C) and extensively characterized by different methods. The chemical composition of the VxSy (ultra)thin films reveals different vanadium oxidation states and sulfur‐based species. Extensive X‐ray photoelectron spectroscopy analysis studies the effect of different ALD parameters on the VxSy chemical composition. Encouraged by the rich chemistry properties of vanadium‐based compounds and based on the variable valences of vanadium, the electrochemical properties of ALD VxSy (ultra)thin films as electrode material for supercapacitors are further explored. Thereby, nanotubular composites are fabricated by coating TiO2 nanotube layers (TNTs) with different numbers of VxSy ALD cycles at low temperature (100 °C). Long‐term cycling tests reveal a gradual decline of electrochemical performance due to the progressive VxSy thin films dissolution under the experimental conditions. Nevertheless, VxSy‐coated TNTs exhibit significantly superior capacitance properties as compared to the blank counterparts. The enhanced capacitance properties exhibited are derived from the presence of chemically stable and electrochemically active S‐based species on the TNTs surface.

Ultrathin TiO2 Coatings via Atomic Layer Deposition Strongly Improve Cellular Interactions on Planar and Nanotubular Biomedical Ti Substrates.

This work aims to investigate the chemical and/or structural modification of Ti and Ti-6Al-4V (TiAlV) alloy surfaces to possess even more favorable properties toward cell growth. These modifications were achieved by (i) growing TiO2 nanotube layers on these substrates by anodization, (ii) surface coating by ultrathin TiO2 atomic layer deposition (ALD), or (iii) by the combination of both. In particular, an ultrathin TiO2 coating, achieved by 1 cycle of TiO2 ALD, was intended to shade the impurities of F- and V-based species in tested materials while preserving the original structure and morphology. The cell growth on TiO2-coated and uncoated TiO2 nanotube layers, Ti foils, and TiAlV alloy foils were compared after incubation for up to 72 h. For evaluation of the biocompatibility of tested materials, cell lines of different tissue origin, including predominantly MG-63 osteoblastic cells, were used. For all tested nanomaterials, adding an ultrathin TiO2 coating improved the growth of MG-63 cells and other cell lines compared with the non-TiO2-coated counterparts. Here, the presented approach of ultrathin TiO2 coating could be used potentially for improving implants, especially in terms of shading problematic F- and V-based species in TiO2 nanotube layers.

Can electrodeposited Ti replace rolled Ti as substrate for the growth of anodic TiO2 nanotube layers?

This study conducted a deep investigation of TiO2 nanotube (TNT) layers of two different thicknesses anodically grown on electrodeposited Ti films. The Ti films were grown from molten salts on Ni foils. The structure of the starting metals was compared by XRD (X-Ray Diffraction) and EBSD (Electron Backscatter Diffraction analyses), which showed a strong orientation towards the titanium (101) for the electrodeposited substrate, compared to the rather polycrystalline structure of the rolled Ti. The photoelectrochemical and electrochemical properties of 1 μm and 5 μm thick TNT layers anodically grown on these substrates were examined and compared with TNT layers of the same thickness. No significant morphological and compositional differences were found using SEM (Scanning Electron Microscopy) and XPS (X-ray Photoelectron Spectroscopy) between the TNT layers grown on the two substrates. However, higher photocurrent densities and ICPE values were observed for TNT layers grown on electrodeposited Ti. An in-depth investigation using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) analyses showed increased conductivity of the TNT layers produced on electrodeposited Ti compared to their counterparts. The carrier density (ND) for the TNT layers on electrodeposited Ti, calculated from Mott-Schottky measurements, showed a higher doping level than the TNT layers grown on Ti foils. This increase in ND results in more optimal photoelectrochemical performance of the TNT layers grown on electrodeposited Ti. All in all, the results presented herein pave the way for the use of electrodeposited Ti, with all its inherent benefits, and allow the further study of its promising properties in a wide range of applications.

Photocatalytic TiO2 Nanotube Layers on 3D Substrates Using Bipolar Electrochemistry

Self-organized TiO2 nanotube (TNT) layers have attracted considerable scientific and technological interest over the past almost 20 years, due to their wide range of applications, including (photo-) catalysis, hydrogen generation and biomedical uses [1,2]. The synthesis of these TNT layers is usually carried out by electrochemical anodization of valve Ti metal substrates in various F--containing electrolytes using a conventional 2-electrode set-up with the Ti substrate as anode and a Pt-foil as cathode.By now, the TiO2 nanotube layer modification of Ti substrates is mainly focused on planar substrates, such as Ti foils and 2D Ti meshes, as these substrates can easily be connected to the potentiostat during anodization. However, for the real application in photocatalytic cleaners, 3D Ti substrates, such as 3D meshes or Ti spheres, are of high interest due to their significantly increased surface area compressed in a small volume.To anodize such 3D Ti substrates towards TiO2 nanotube layers, bipolar electrochemistry can be employed instead of using a conventional set-up [3-5]. In such a bipolar set-up, the Ti substrate is not directly connected to the potentiostat but placed in an electrolyte between two so-called feeder electrodes. Due to the electric field between the feeder electrodes, the Ti substrate is polarized and can be anodized if the applied potential between the feeder electrodes is high enough. This method opens the door for the preparation of TNT layers with gradients in dimensions (i.e. diameter and length of the nanotubes) [3-5] as well as for the preparation of TNT layers on Ti substrates, which cannot be directly connected to the potentiostat, e.g. small Ti spheres [6] and complicated 3D printed structures [7].In this presentation, the preparation of TNT layers on small Ti spheres [6] as well as on 3D printed Ti substrates [7] using bipolar electrochemistry will be shown. Their application in liquid and gas phase photocatalysis will be discussed. Furthermore, we will also show the possibility of using closed bipolar electrochemical cells, consisting of two closed half-cells with the Ti substrate as obstacle between the cells for the preparation of TiO2 nanotube layers with different dimensions on the two sides of a classical Ti foil [8].

(Invited) Atomic Layer Deposition on 1D Nanomaterials for Various Applications

One-dimensional nanomaterials – materials with one dimension outside the nanoscale, further noted as 1D NMs – represent a class of very important nanomaterials with continuously increasing importance. Due to their intrinsic features, unique properties and diversity of functionalities, they count among the most widely studied materials nowadays. While considerable research efforts have been spent to synthesize various 1D NMs (e.g. nanopores, nanotubes or nanofibers), limited efforts have been devoted to surface modification and property tailoring of these materials.However, it is their surface that comes into direct contact with various media (air, gases, liquids, solids) and influences the reactivity, stability and biocompatibility of these materials. The surface and aspect ratio (defined as their diameter to length ratio) influence the performance of these materials in various applications. Considering these facts, it is more relevant to tailor the surface of these materials and to be able to influence their properties and reactivity at the nanoscale, rather than to deal with tailoring their own bulk material composition.The focus of this presentation is on the modification of two types of 1D nanomaterials – nanotubes and nanofibers. Numerous techniques can be utilized for this purpose, such as for example wet chemical or physical deposition techniques. However, it is only the Atomic Layer Deposition (ALD) that is capable of really uniform and homogenous coating of these 1D nanomaterials, in particular those of very high-aspect ratio.The presentation will be mainly focused on modification of TiO2 nanotube layers and various nanofibers of different aspect ratios via ALD.Experimental details and some very recent application examples in photocatalysis, catalysis, sensors, batteries, nanorobots, etc. [1-11] and structural characterizations of these modified materials will be discussed. Sopha et al (2017), Appl. Mater. Today, 9, 104.Sopha et al. (2018), Electrochem. Commun.,97, 91.Ng et al. (2017), Adv. Mater. Interfaces, 1701146.Dvorak et al. (2019), Appl. Mater. Today, 14, 1.Sopha et al. (2019), FlatChem 17, 100130.Motola et al. (2019), Nanoscale 11, 23126.Ng et al. (2020), ACS Appl. Mater. Interfaces, 12, 33386.Motola et al. (2020) ACS Appl. Bio Mater. 3, 6447.Rihova & M. Knez & J. M. Macak et al. (2021), Nanoscale Adv., 3, 4589Galstyan, T. Djenizian, J. M. Macak (2022), Appl. Mater. Today, 29, 101613Villa & M. Pumera & J. M. Macak et al. (2022), Small, 2106612

(Invited) TiO2 Single Nanotubes Decorated with Fe3O4 Nanoparticles for Photocatalytical Environmental Applications

Self-organized TiO2 nanotubes arrays, formed by electrochemical anodization of Ti, have attracted tremendous scientific and technological attention, due to their remarkable properties such as the tunability of dimensions, their directionality, high surface area, high stability, and ability to absorb a significant amount of incident light [1,2].The most widely used electrolyte for the synthesis of TiO2 nanotube layers is based on ethylene glycol containing small amounts of water and fluoride ions. However, nanotubes prepared in these electrolytes present a double-walled structure. The outer wall consists of almost pure TiO2, and the inner wall consists of TiO2 contaminated with carbon and fluoride species [3,4]. In recent years, the selective etching of the inner nanotube wall on Ti layer enabled the synthesis of single-wall nanotubes that showed superior photo-electrochemical performance compared to their double-walled counterparts [5]. An extensive etching also enabled the synthesis of single-tube powders, which can be in turn effectively decorated with Fe3O4 nanoparticles to act as magnetically guidable photocatalysts [6,7].The presentation will discuss the synthesis of these nanotube morphologies and their performance in the photocatalytic degradation of model dye in the liquid phase as well as model drugs that are problematic in wastewaters. We will demonstrate how the photocatalytic performance is influenced by the single nanotubes and single nanotubes decorated with Fe3O4 magnetic particles. Experimental details and photocatalytic results will be presented and discussed.

Recent advances in TiO2 nanotube layers – A mini review of the latest developments in nanotube preparation and applications in photocatalysis and microwave sensing

AbstractSelf‐organized anodic TiO2 nanotube (TNT) layers prepared by anodization of Ti substrates have attracted great interest within the last 20 years, due to their unique properties and low‐cost synthesis. This mini review article aims to shortly summarize the most recent developments in the TNT layer synthesis and applications. It presents the synthesis of high aspect ratio (HAR) TNT layers in a short time by accelerating the TNT layer growth rates in lactic acid containing electrolytes. Furthermore, the etching of TNT layers towards TNT bundles of homogeneous size and single tube powders is discussed, as well as the possibility to grow TNT layers on non‐planar Ti substrates, which cannot be directly connected to the potentiostat (e.g., Ti spheres or 3D Ti meshes). As a relatively new application, the employment of TNT layers in microwave resonator sensors is introduced. Last, but not least, approaches of upscaling the TNT layer size from the laboratory scale towards significantly larger scale are outlined and reviewed.

Non-thermal regimes of laser annealing of semiconductor nanostructures: crystallization without melting

As-prepared nanostructured semiconductor materials are usually found in an amorphous form, which needs to be converted into a crystalline one for improving electronic properties and achieving enhanced application functionalities. The most utilized method is thermal annealing in a furnace, which however is time- and energy-consuming and not applicable for low-temperature melting substrates. An alternative is laser annealing, which can be carried out in a relatively short time and, additionally, offers the possibility of annealing localized areas. However, laser-annealed nanostructures are often distorted by melting, while preserving the as-prepared morphology is essential for practical applications. In this work, we analyze conditions of non-thermal ultrafast laser annealing of two kinds of nanostructures: anodic TiO2 nanotube layers and Ge/Si multilayer stacks. For both cases, regimes of crystallization have been found, which yield in preserving the initial nanomaterial morphologies without any melting signs. On these examples, ultrafast non-thermal mechanisms of structural material transformation are discussed, which can provide new opportunities for conversion of amorphous semiconductor nanomaterials into a desired crystalline form that is of high demand for existing and emerging technologies.

Bio-AFM exploits enhanced response of human gingival fibroblasts on TiO2 nanotubular substrates with thin TiO2 coatings

The present work studies anodic TiO2 nanotube (TNT) layers and their surface modifications for enhancing the cell behavior of human gingival fibroblast cells (hGFs) with the contribution of bio-AFM (Atomic Force Microscopy) method. TNT layers, prepared via electrochemical anodization of Ti, with an average tube diameter of 15, 30, and 100 nm, were used as primary substrates for the study. Flat Ti foils were used as reference substrates. Part of the substrates was coated by ultrathin TiO2 coatings (≈ 0.3 nm thin) using Atomic Layer Deposition (ALD). The cell growth and adhesion of hGFs on the TNT layers and Ti foils were compared between ALD coated and uncoated ones. The supplemental coatings altered the surface chemistry of the TNT layers, particularly shading the fluorine and carbon impurities within anodic TiO2, while preserving the original structure and morphology. The presented approach of very mild surface modification remarkably effects the material's biocompatibility and possess great prospect as implant materials. For the first time, the TNT/cell interface was investigated using bio-AFM in terms of Young's modulus, stiffness, cell adhesive force and roughness. Improved biocompatibility was studied in terms of increased cell viability, density, cell cytoskeleton orientation and overall stiffness of the hGFs.

Bipolar Anodization for the Synthesis of TiO2 Nanotube Layers: New Concepts and Cell Designs

Self-organized TiO2 nanotube (TNT) layers have attracted considerable scientific and technological interest over the past almost 20 years, due to their wide range of applications, including (photo-) catalysis, hydrogen generation and biomedical uses [1,2]. The synthesis of these TNT layers is usually carried out by electrochemical anodization of valve Ti metal substrates in various F--containing electrolytes using a conventional 2-electrode set-up with the Ti substrate as anode and a Pt-foil as cathode.By now, the TiO2 nanotube layer modification of Ti substrates is mainly focused on planar substrates, such as Ti foils and 2D Ti meshes, as these substrates can easily be connected to the potentiostat during anodization. However, for the real application in photocatalytic cleaners, 3D Ti substrates, such as 3D meshes or Ti spheres, are of high interest due to their significantly increased surface area compressed in a small volume.To anodize such 3D Ti substrates towards TiO2 nanotube layers, bipolar electrochemistry can be employed instead of using a conventional set-up [3-5]. In such a bipolar set-up, the Ti substrate is not directly connected to the potentiostat but placed in an electrolyte between two so-called feeder electrodes. Due to the electric field between the feeder electrodes, the Ti substrate is polarized and can be anodized if the applied potential between the feeder electrodes is high enough. This method opens the door for the preparation of TNT layers with gradients in dimensions (i.e. diameter and length of the nanotubes) [3-5] as well as for the preparation of TNT layers on Ti substrates, which cannot be directly connected to the potentiostat, e.g. small Ti spheres [6] and complicated 3D printed structures [7].In this presentation, the preparation of TNT layers on small Ti spheres [6] as well as on 3D printed Ti substrates [7] using bipolar electrochemistry will be shown. Their application in liquid and gas phase photocatalysis will be discussed. Furthermore, we will also show the possibility of using closed bipolar electrochemical cells, consisting of two closed half-cells with the Ti substrate as obstacle between the cells for the preparation of TiO2 nanotube layers with different dimensions on the two sides of a classical Ti foil [8].

Large-Scale Anodic TiO2 Nanotube Layers: Gas Phase Photocatalysis and Virus Killing

Self-organized TiO2 nanotube layers have attracted considerable scientific and technological interest over the past 15 years motivated for their wide range of applications including (photo-) catalysis, hydrogen generation and biomedical uses [1,2]. The synthesis of the 1D TiO2 nanotube layers is carried out by a conventional electrochemical anodization of valve Ti metal sheets in various electrolytes.By now, the synthesis of TiO2 nanotube layers with different nanotube dimensions (diameter, length) and the application of these nanotube layers is well established on the laboratory scale. However, for real applications outside the laboratory scale, such as photocatalysis [3], TiO2 nanotube layers of much larger size are necessary. To date, just a few efforts were carried out to scale up the size of the nanotube layers to more than a few cm2 [3-7] due to the difficulty of controlling the parameters of the anodization process on a larger scale. The main challenge is the huge current received during the anodization of large substrates. This, in turn, leads to an increase in the electrolyte temperature that may result in dielectric breakdown of the growing nanotube layers.In this presentation, the preparation of TiO2 nanotube layers on larger area titanium substrates (dozens of cm2) will be discussed, taking into account the control of the anodization parameters. The TiO2 nanotube layers with different thicknesses and nanotube diameters were employed for gas phase photocatalysis, following the ISO standards [3,8]. In addition, results from antivirotic tests of these layers will be demonstrated. Experimental details and photocatalytic results will be presented and discussed.

Evaluation of osseointegration of Ti-6Al-4V alloy orthodontic mini-screws with ibandronate-loaded TiO2 nanotube layer.

Recently, the use of orthodontic mini-screws as an anchorage for orthodontic treatment is increasing, and the degree of osseointegration of the mini-screws affects the performance of orthodontic treatment. This study aimed to evaluate the biocompatibility and osseointegration of Titanium 6Aluminum 4Vanadium (Ti-6Al-4V) alloy orthodontic mini-screws with an ibandronate-loaded TiO2 nanotube (TNT) layer. The TNT layer was formed on the surface of the Ti-6Al-4V alloy orthodontic mini-screws and loaded with ibandronate. The TNT formed by anodic oxidation formed a completely self-organized and compact structure and was stably released for 7 days after loading with ibandronate. Mini-screws loaded with ibandronate were implanted into both tibias of rats, confirming rapid initial bone regeneration. We demonstrate that the release of stable ibandronate from the TNT layer of Ti-6Al-4V alloy orthodontic mini-screws can effectively improve biocompatibility and osseointegration.

Flow-through Gas Phase Photocatalysis Using TiO2 Nanotubes on Wirelessly Anodized 3D-Printed TiNb Meshes.

In this work, for the first time 3D Ti-Nb meshes of different composition, i.e., Ti, Ti-1Nb, Ti-5Nb, and Ti-10 Nb, were produced by direct ink writing. This additive manufacturing method allows tuning of the mesh composition by simple blending of pure Ti and Nb powders. The 3D meshes are extremely robust with a high compressive strength, giving potential use in photocatalytic flow-through systems. After successful wireless anodization of the 3D meshes toward Nb-doped TiO2 nanotube (TNT) layers using bipolar electrochemistry, they were employed for the first time for photocatalytic degradation of acetaldehyde in a flow-through reactor built based on ISO standards. Nb-doped TNT layers with low concentrations of Nb show superior photocatalytic performance compared with nondoped TNT layers due to the lower amount of recombination surface centers. High concentrations of Nb lead to an increased number of recombination centers within the TNT layers and reduce the photocatalytic degradation rates.

Decrypting the growth of anodic TiO2 nanotube layers in eco-friendly fluoride-free nitrate-based electrolyte for enhanced photocatalytic degradation of organic pollutants

Anodic TiO2 nanotube (TNT) layers were prepared in eco-friendly fluoride-free organic-aqueous-based electrolytes containing cerium ammonium nitrate. Nanotubes with controllable morphology (tube diameter and tube length) and surface features (porosity and surface roughness) were obtained by varying percentual ratios of ethylene glycol (Ex%) and water (Wy%) in the electrolyte (Ex%Wy%). Obtained TNT layers were studied for photocatalytic degradation of methylene blue (MB) under UVA irradiation. The most promising, TNT layers were prepared in E75%W25% electrolyte with a thickness of approx. 1.9 μm with a tube diameter of approx. 33 nm, and exhibited the highest photocatalytic degradation rate (k = 0.0151 min−1).