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Homogeneous Anodic TiO <sub/>2</sub> Nanotube Layers on Ti–6Al–4V Alloy with Improved Adhesion Strength and Corrosion Resistance
摘要： Hexagonal TiO2 nanotubes (TNTs) arrays are generally fabricated on Ti-based substrates for some biomedical purposes, but the TNT layers constructed on conventionally processed Ti alloys are usually inhomogeneous because the substrates typically contain both the α and β phases. In this work, high-pressure torsion (HPT) is applied to obtain a saturated single α-phase microstructure in Ti–6Al–4V alloys via strain-induced β phase dissolution. Homogeneous anodic TNT layers with three different morphologies, one-step nanoporous, one-step nanotubular, and two-step nanoporous structures, are electrochemically fabricated on the ultrafine-grained (UFG) Ti–6Al–4V alloy substrates after HPT processing, whereas the TNT layers prepared on coarse-grained substrates are normally inhomogeneous. More notably, the TNT layers show significantly improved adhesion strength to the UFG substrate as well as better corrosion resistance compared to those on the conventionally processed Ti–6Al–4V substrates. X-ray diffraction analysis, scanning electron microscopy in combination with electron backscatter diffraction, and transmission electron microscopy indicate that the improvement is due to a larger dislocation density in the UFG substrate as well as strain-induced β phase dissolution.
关键词： high-pressure torsion,homogeneity,TiO2 nanotubes,adhesion strength,strain-induced phase transformation
更新于2025-11-21 11:03:13
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Synthesis of Ag nanoparticles decorated on TiO2 nanotubes for surface adsorption and photo-decomposition of methylene blue under dark and visible light irradiation
摘要： TiO2 nanotubes and Ag/TiO2 nanotubes (TNT) have been synthesized by simple hydrothermal and solvothermal method and were characterized by XRD, UV, ICP, TEM, SEM, BET and XPS. In this study the photocatlytic activity of Ag/TNT (contain 3.33% Ag) was investigated through decolorization of MB (standard methylene blue tablets for milk testing) in aqueous solution. Because of the surface plasmon resonance (SPR) effect of Ag nanoparticles, under visible light, Ag/TNT showed superior photocatalytic activity, and due to high surface area of TNT, it showed high surface absorption in dark conditions. In this study, the photocatalytic effect of Ag/TNT for the destruction and absorption of MB in aqueous solution indicated good application.
关键词： Absorption,Destruction,Ag/TiO2 nanotubes,Photocatlytic activity,MB
更新于2025-09-23 15:23:52
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Photocatalysis as an advanced reduction process (ARP): the reduction of 4-nitrophenol using titania nanotubes-ferrite nanocomposites
摘要： TiO2 photocatalysis is an advanced process, employed worldwide for the oxidation of organic compounds, that leads to significant technological applications in the fields of health and environment. The use of the photocatalytic approach in reduction reactions seems very promising and can open new horizons for green chemistry synthesis. For this purpose, titanium dioxide nanotubes (TNTs) were developed in autoclave conditions using TiO2 P25 as a precursor material. Based on these nanotubular substrates, TiO2/CoFe2O4 (TCF) nanocomposites were further obtained by wet impregnation method. The materials were thoroughly characterized and their structural, textural, vibrational, optoelectronic and magnetic properties were determined. The composite materials combine absorbance in the visible optical range and high BET surface area values (~100 m2/g), showing extremely high yield in the photocatalytic reduction of 4-nitrophenol (4-NP), exceeding 94% within short illumination time (only 35 min). The developed nanocomposites were successfully reused in consecutive photocatalytic experiments and were easily removed from the reaction medium using magnets. Both remarkable recycling ability and high-performance stability in the photocatalytic reduction of nitrophenol were observed, thus justifying the significant economic potential and industrial perspectives for this advanced reduction process.
关键词： Cobalt ferrite,4-nitrophenol reduction.,Nanocomposite photocatalyst,TiO2 nanotubes
更新于2025-09-23 15:23:52
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Enhanced photoelectrochemical performance of CdO-TiO2 nanotubes prepared by direct impregnation
摘要： A direct impregnation technique was adopted to prepare a series of CdO-TiO2 nanotubes. Self-organized TiO2 nanotubes were prepared using an optimized two-step anodization process. The morphology, crystallinity, elemental composition, and photoelectrochemical properties of the CdO-TiO2 nanotubes were characterized by scanning electron microscopy (SEM), transimission electron microscopy (TEM), UV-Vis diffuse reflection spectra (UV-Vis DRS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and photoelectric cell (PEC) measurements. At lower Cd(NO3)2 concentration, no obvious CdO crystalline particle formed on the TiO2 NTbs surface, while the EDS and XPS measurements shows the increasing doping amount of CdO as the Cd(NO3)2 concentration increasing. At a relatively high precursor concentration (800 mM), the formation of particle clusters and nanocrystals on the surface of the TiO2 nanotubes could be easily detected, and the sample presented XRD diffraction peaks indicative of CdTiO3. Meanwhile, the Ti 2p XPS spectra displayed an obvious shift (~0.3 eV), which could be attributed to the change in the lattice structure. A negative shift in the flatband potential (Vfb) and a decrease in charge carrier density were observed after doping. The maximum incident photon to charge carrier efficiency (IPCE) value calculated for the CdO-TiO2 nanotubes was 10.16%, much higher than that of pure TiO2 nanotubes.
关键词： Cadmium oxide,Photoelectrochemical,Impregnation-Calcination,TiO2 nanotubes
更新于2025-09-23 15:23:52
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EFFECT OF VOLTAGE ON TIO2 NANOTUBES FORMATION IN ETHYLENE GLYCOL SOLUTION
摘要： Anodization of Ti foils in ethylene glycol (EG) containing ammonium fluoride (NH4F), and hydrogen peroxide (H2O2) was carried out to study the effect of voltage on the formation of TiO2 nanotubes. The crystalline phase of the TiO2 nanotubes without further heat treatment were studied. The TiO2 nanotube arrays were produced by anodization of Ti foil at three different voltage; 10, 40, and 60 V in a bath with electrolytes composed of ethylene glycol (EG), ammonium fluoride (NH4F), and hydrogen peroxide (H2O2). The H2O2 is a strong oxidizing agent which was used as oxygen provider to increase the oxidation rate for synthesizing highly ordered and smooth TiO2 nanotubes. Anodization at voltage greater than 10 V leads to the formation of tubular structure where higher anodization voltage (~ 60 V) yield to larger tube diameter (~ 180 nm). Crystallinity of the nanotubes is improved as the voltage was increased. The transformation of amorphous to anatase can be obtained for as anodized TiO2 without any heat treatment. The Raman spectra results show the anodization at 40 V and 60 V gives anatase peak in which confirms the crystalline phase. The stabilization of the crystalline phase is due to the oxygen vacancies and ionic mobilities during the anodization at high voltage.
关键词： anatase,TiO2 nanotubes,crystallization,anodization
更新于2025-09-23 15:23:52
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Growth orientation Mechanism of TiO<sub>2</sub> Nanotubes Fabricated by Anodization
摘要： TiO2 nanotube fabricated by anodization has been extensively researched in the past decades. However, the mechanism that controls the growth orientation of anodic TiO2 nanotube is still not clear. Here we firstly dig into their growth orientation systematically. Combining with previous literatures, the results of anodization on rotated Ti foil and thin Ti wire confirm that almost all of the TiO2 nanotubes grow vertically to the local Ti substrate surface. Their growth orientation predominantly depends on the local electric field around the nanotube bottom. The distribution of local electric field is regulated by the shape of initial nano-scale local Ti substrate surface. Mostly, the initial nano-scale local Ti substrate surface is nearly flat, which leaves vertical, circle and straight TiO2 nanotubes. In terms of evolution of TiO2 nanotubes fabricated on micron-scale convex surface, the vertical growth of TiO2 nanotubes leads to a continuous decrease in the oxide/substrate interface area, and a few TiO2 nanotubes are crushed and detached periodically from oxide/substrate interface. For micron-scale concave surface, due to the ever-increasing of oxide/substrate interface area, Y-branched TiO2 nanotubes occurred periodically as a response to avoid the vacancy on oxide/substrate interface.
关键词： growth orientation,anodic TiO2 nanotubes,concave surface,convex surface
更新于2025-09-23 15:22:29
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TiO2 Nanotubes with Nanograss Structure: The Effect of the Anodizing Voltage on the Formation Mechanism and Structure Properties
摘要： Titanium dioxide nanotubes (TiO2 NTs) with a nanograss structure were synthesized in a fluoride organic electrolyte based on ethylene glycol under a potentiostatic anodization regime. By varying the anodization voltage, significant morphological differences were obtained, and the upper NTs’ surface has a nanograss appearance caused by the thinning of top tube walls, the result of the vertical splitting mechanism of nanograss growth. The samples were characterized using techniques such as scanning electron microscopy, x-ray diffraction, UV–visible spectroscopy and Mott–Schottky (MS) analysis. The obtained results show that samples annealed at 500°C for 3 h crystallized into anatase form and displayed the apparition of rutile phase at higher anodization voltage, where the morphology was significantly improved with thicker tube walls. The MS measurement of all samples displays a n-type semiconductor nature and the flat band potential (Ufb) takes less negative values by the increasing anodization voltage. As a result, TiO2 NTs with a nanograss structure expedite electron–hole separation, therefore, providing a lower recombination rate.
关键词： nanograss,TiO2 nanotubes,anodization process,nanomaterials,properties
更新于2025-09-23 15:22:29
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The effects of growth TiO <sub/>2</sub> nanotubes on forged Ti <sub/>6</sub> Al <sub/>4</sub> V alloy and selectivelaser sintered Ti <sub/>6</sub> Al <sub/>4</sub> V alloy surfaces for environment and medical applications
摘要： The paper describes the effect of growth TiO2 nanotubes on titanium surfaces by anodic oxidation for environmental and medical applications. The importance of the metallurgical state of TiAl6V alloy on the growing of TiO2 nanotubes by anodization will be highlighted. Starting from the possibility of obtaining the TiO2 nanotubes, the paper presents results on TiO2 nanotubes grown by electrochemical anodization method, using a solution containing HF 0,4% and having as electrodes, graphite as cathode and titanium alloy specimens obtained by two technologies: by cold plastic deformation as well as by additive manufacturing process SLS, as anode. So, the nanotubes were produced by anodization and analysed by scanning electron microscopy. The aim of this paper is to compare the electrochemical formation of TiO2 on the surface of both specimens knowing that the titanium alloys and its oxides are used in many biomedical and environmental applications, thus providing the importance of nanotubes and the fact that their properties open doors in these fields.
关键词： medical applications,TiO2 nanotubes,environmental applications,anodic oxidation,Ti6Al4V alloy
更新于2025-09-23 15:21:01
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Differences in the local structure and composition of anodic TiO2 nanotubes annealed in vacuum and air
摘要： This work is dedicated to the influence of thermal treatment procedures in vacuum and air atmosphere on the structural features of multiwalled TiO2 anodic nanotubes (NTs) formed in fluorine-containing ethylene glycol (EG) based electrolyte investigated by high-resolution transmission electron microscopy (HRTEM) in conjunction with EDX and electronic nanodiffraction (STEM nanodiffraction), IR and Raman spectroscopy, XPS and ToF SIMS. Using electron nanodiffraction technique, there were estimated TiO2 nanocrystallite sizes for the inner layer of the NTs after annealing in air and vacuum for the first time. The differences in carbon distribution profiles in TiO2 nanotube crosscut after thermal treatments in air and vacuum were discussed. It was found that thermal treatment in vacuum leads to different phase composition of TiO2 NTs IL comparing to annealing in air. A sequential thermal treatment (firstly in vacuum and then in air) enables to remove carbon from TiO2 NTs surface and partly from TiO2 NTs IL and prevent detachment of IL from OL at the same time. The obtained data will be useful for understanding the mechanisms of structural modifications during thermal treatments as well as for functional properties optimization of such nanostructures.
关键词： Anodizing,TiO2 nanotubes,Thermal treatment,Electron nanodiffraction,HAADF-STEM
更新于2025-09-23 15:19:57
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TiO2 nanotubes modified with polydopamine and graphene quantum dots as a photochemical biosensor for the ultrasensitive detection of glucose
摘要： Rapid and sensitive detection of glucose concentrations is very important for human health. Herein, an ultrasensitive photoelectrochemical dual-electron-acceptor biosensor was constructed by modifying the TiO2 nanotubes (NTs) with polydopamine (PDA) and amino-functionalized graphene quantum dots (N-GQDs)/GOx. PDA is grown on the top of the TiO2 NTs by the electropolymerization, and N-GQDs are loaded into the inner of the TiO2 NTs by a microwave-assisted method. The TiO2 NTs/PDA/N-GQD dual-electron-acceptor biosensor exhibited a highly enhanced photoelectric response, excellent electron–hole separation efficiency, low detection limit (0.015 mM), wide linear range (0–11 mM) and ultrahigh sensitivity (13.6 lA mM-1 cm-2). The prepared biosensor reflected high selectivity and excellent stability. This work also provides new insights into other optoelectronic biosensors.
关键词： photochemical biosensor,polydopamine,graphene quantum dots,TiO2 nanotubes,glucose detection
更新于2025-09-23 15:19:57