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Nanotube/nanowire structured TiO2 samples on Ti plates were prepared by anodic oxidation in aqueous, glycerol or ethylene glycol medium under different experimental conditions and characterized by XRD, SEM‐EDX, electrochemical methods (photocurrent profiles and electrochemical impedance spectroscopy). The nanostructured TiO2 was built on relatively large Ti plates, and consequently, in some preparation conditions, different morphologic properties were observed in the underside and upside zones of the electrodes, especially in ethylene glycol medium. The electrodes were tested for selective photoelectrocatalytic oxidation of 3‐methylpyridine to 3‐pyridinemethanol, 3‐pyridinemethanal and vitamin B3 in water under UVA irradiation. The best performance was found with the electrode prepared in ethylene glycol/water/NH4F (98/2/0.3 w/w) medium at 36 V potential for 3 h, while the worst was that prepared in aqueous medium which showed the shortest nanostructure length. Unlike photoelectrocatalysis and photocatalysis, no aromatic alcohol/carbonyl products were obtained in electrocatalytic and photolytic experiments. The selectivity values of the products were similar for the various electrodes, while the morphology of the nanotubes/nanowires and their quantity which affects the total active surface area were essential for the substrate conversion. The results also show that the photocurrent intensity, XRD peak intensity, and electrical conductivity are correlated with photoelectrocatalytic activity of the Ti/TiO2 electrodes. [ABSTRACT FROM AUTHOR]

This article studies the role of electrochemical parameters in controlling the morphology of oxidized TiO2 nanotubes and the electrochemical performance of modified TiO2 nanotubes. Humidity is a key factor for fabricating TiO2 nanotubes. When the relative humidity belows 70%, the TiO2 nanotubes can be successfully prepared. What's more, by changing the anodization voltage and time, the diameter and the length of TiO2 nanotubes can be adjusted. In addition, the TiO2 nanotubes are modified through electrochemical self-doping and loading Pt metal particles on the surface of the nanotubes, which promotes the performance of the supercapacitor. The sample anodized at 100 V for 3 h has a specific capacity of up to 2.576 mF/cm² at a scan rate of 100 mV/s after self-doping, and its capacity retention rate still remains at 89.55% after 5 000 cycles, demonstrating excellent cycling stability. The Pt-modified sample has a specific capacity of up to 3.486 mF/cm² at the same scan rate, exhibiting more outstanding electrochemical performance. [ABSTRACT FROM AUTHOR]

TiO 2 is a routinely used catalyst due to its photocatalytic activity. The main problem of TiO 2 is its large band gap. Doping metal and non-metal atoms in TiO 2 crystals reduce the band gap. In this work, first-principle calculations by the full-potential numeric atom-center orbital theory were used to investigate detailed electronic properties of N-doped one monolayer (1 ML) and two monolayers (2 ML) (4,4), (8,8) and (16,16) TiO 2 (001) nanotubes. The proposed model first validated by comparing its data with the experimental available data for rutile and anatase bulk phases, and then was used to predict the electronic properties of proposed nanotubes. PBE0 hybrid method was used to align the valence and conduction bands and to predict their standard reduction potential. In addition, different routine generalized gradient approximation (GGA) and meta -GGA exchange-correlation functionals were used to show how much their errors are in predicting the band gaps of nanotubes. Hybrid data showed that a 2 ML (8,8) nanotube is a proper candidate for photocatalyst not only for its band gap but also from its formation energy point of view. Contrary to the N-doped rutile and anatase phases, there is no electron-hole recombination center for the N-doped 2 ML (8,8) TiO 2 nanotube. • Hybrid method was used to align the bands, and to predict the standard reduction potential of VB and CB of TiO2 nanotubes. • Hybrid data show that the 2 ML (8,8) fluorite-like nanotube is a proper catalyst for solar water splitting. • Contrary to the bulk phases, there is no any electron-hole recombination center in N-doped 2 ML (8,8) TiO2 nanotubes. [ABSTRACT FROM AUTHOR]

Micro/nano topological modification is critical for improving the in vivo behaviors of bone implants, regulating multiple cellular functions. Titania (TiO2) nanotubes show the capacity of promoting osteoblast-related cell differentiation and induce effective osseointegration, serving as a model material for studying the effects of micro/nano-topological modifications on cells. However, the intracellular signaling pathways by which TiO2 nanotubes regulate the osteogenic differentiation of stem cells are not fully defined. Thy-1 (CD90), a cell surface glycoprotein anchored by glycosylphosphatidylinositol, has been considered a key molecule in osteoblast differentiation in recent years. Nevertheless, whether the micro/nano topology of the implant surface leads to changes in Thy-1 is unknown, as well as whether these changes promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Here, TiO2 nanotubes of various diameters were prepared by adjusting the anodizing voltage. qPCR and immunoblot were carried out to assess the mechanism by which TiO2 nanotubes regulate Thy-1. The results revealed Ti plates harboring TiO2 nanotubes ∼100-nm diameter (TNT-100) markedly upregulated Thy-1. Subsequently, upregulated Thy-1 promoted the activation of Fyn/RhoA/MLC Ⅱ/F-actin axis, which enhanced the nuclear translocation of YAP. After Thy-1 knockdown by siRNA, the Fyn/RhoA/MLC Ⅱ/F-actin axis was significantly inhibited and TiO2 nanotubes showed decreased effects on osteogenic differentiation. Therefore, Thy-1 upregulation might be a major mechanism by which micro/nano-topological modification of TiO2 nanotubes promotes osteogenic differentiation in BMSCs. This study provides novel insights into the molecular mechanism of TiO2 nanotubes, which may help design improved bone implants for clinical application.

In this work, a highly effective separation approach mediated by 5-Lipoxygenase (5-LOX) was established for screening and isolation of anti-inflammatory ingredients from leaves of Lonicera japonica Thunb. (LLJT). Using 5-LOX immobilised on TiO2 nanotubes as a microreactor, the targeted screening was exploited by combining with HPLC-MS system. Four compounds confirmed as luteolin, luteoside, lonicerin, and isochlorogenic acid C and a fraction (M1) were screened out to be potent inhibitors of 5-LOX. Their anti-inflammatory activities were further investigated and confirmed by RAW 264.7 cells inflammation model and rat foot swelling model. Furthermore, M1 was prepared by MCI GEL CHP20P column chromatography, and further separated by Pre-HPLC. One new compound confirmed to be 5,7,3′,4′-tetrahydroxyflavone-7-O-sambubioside was first isolated from LLJT. The results provide a new method for the effective separation of active components derived from natural products.HighlightsA 5-LOX mediated separation method was established for isolation of anti-inflammatory compounds.An anti-inflammatory ingredient was separated by MCI GEL CHP20P column chromatography.One new compound was first isolated from leaves of Lonicera japonica Thunb.5-LOX was immobilised on TiO2 nanotubes and exploited by combining with HPLC-MS system.The anti-inflammatory activity of screened components was evaluated. [Figure: see text]

Peri-implantitis is an inflammatory disease similar to periodontitis, caused by biofilms formed on the surface of dental implants. This inflammation can spread to bone tissues and result in bone loss. Therefore, it is essential to inhibit the formation of biofilms on the surface of dental implants. Thus, this study examined the inhibition of biofilm formation by treating TiO2 nanotubes with heat and plasma. Commercially pure titanium specimens were anodized to form TiO2 nanotubes. Heat treatment was performed at 400 and 600 °C, and atmospheric pressure plasma was applied using a plasma generator (PGS-200, Expantech, Suwon, Republic of Korea). Contact angles, surface roughness, surface structure, crystal structure, and chemical compositions were measured to analyze the surface properties of the specimens. The inhibition of biofilm formation was assessed using two methods. The results of this study showed that the heat treatment of TiO2 nanotubes at 400 °C inhibited the adhesion of Streptococcus mutans (S. mutans), associated with initial biofilm formation, and that heat treatment of TiO2 nanotubes at 600 °C inhibited the adhesion of Porphyromonas gingivalis (P. gingivalis), which causes peri-implantitis. Applying plasma to the TiO2 nanotubes heat-treated at 600 °C inhibited the adhesion of S. mutans and P. gingivalis. [ABSTRACT FROM AUTHOR]

Mass spectrometry imaging (MSI) has made the spatio-chemical characterization of a broad range of small-molecule metabolites within biological tissues possible. However, available matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) suffers from severe background interferences in low-mass ranges and inhomogeneous matrix deposition. Thus, surface-assisted LDI-MS (SALDI-MS) has been an attractive alternative for high-sensitivity detection and imaging of small biomolecules. In this study, we construct a new composite substrate, hydrophobic polydopamine (hPDA)-modified TiO2 nanotube (TDNT) coated with plasmonic gold nanoparticle (AuNP-hPDA-TDNT), as a dual-polarity SALDI substrate using an easy and cost-effective fabrication approach. Benefitting from the synergistic effects of TDNT semiconductor and plasmonic PDA modification, this SALDI substrate exhibits superior performance for dual-polarity detection of a vast diversity of small molecules. Highly reduced background interferences, lower detection limits, and spot-to-spot repeatability can be achieved using AuNP-hPDA-TDNT substrates. Due to its unique imprinting performance, various metabolites and lipids can be visualized within jatropha integerrima petals, ginkgo leaves, strawberry fruits, and latent fingerprints. More valuably, the universality of this matrix-free substrate is demonstrated for mapping spatial distribution of lipids within mouse brain tissue sections. Considered together, this AuNP-hPDA-TDNT material is expected to be a promising SALDI substrate in various fields, especially in nanomaterial development and life sciences. [ABSTRACT FROM AUTHOR]

In order to extend the visible region activity of titania nanotube array (TNAs) films, the successive ionic layer adsorption and reaction (SILAR)-ultrasonication-assisted method has been used to prepare BiOI-modified TiO2 nanotube arrays (BiOI/TNAs). The band gap of BiOI/TNAs for all the variations reveals absorption in the visible absorption. The surface morphology of BiOI/TNAs is shown in the nanoplate, nanoflake and nanosheet forms with a vertical orientation perpendicular to TiO2. The crystalline structure of BiOI did not change the structure of the anatase TNAs, with the band gap energy of the BiOI/TNAs semiconductor in the visible region. The photocurrent density of the BiOI/TNAs extends to the visible-light range. BiOI/TNAs prepared with 1 mM Bi and 1 mM KI on TNAs 40 V 1 h, 50 V 30 min show the optimum photocurrent density. A tandem dye-sensitized solar cell (DSSC)-photoelectrochemical (PEC) was used for hydrogen production in salty water. BiOI/TNAs optimum was used as the photoanode of the PEC cell. The solar to hydrogen conversion efficiency (STH) of tandem DSSC-PEC reaches 1.34% in salty water.

MoS _2 /TiO _2 nanostructure provides a lot of advantages in photoelectrochemical (PEC) applications due to the absorption of the wide spectrum solar radiation, more catalytically active sites, proper band alignment, and better separation of photogenerated charge carriers. Here we report PEC water splitting studies of MoS _2 thin film grown by chemical vapor deposition on TiO _2 nanotubes fabricated on flexible thin Ti foil. Raman and x-ray diffraction analysis confirmed the polycrystalline growth of a few layers MoS _2 on TiO _2 /Ti through their characteristic peaks. Field emission scanning electron microscopy revealed the nanotube surface morphology of TiO _2 having a diameter in the range of 200–300 nm. The chemical and electronic composition of MoS _2 and TiO _2 were investigated by x-ray photoelectron spectroscopy. PEC measurements performed in 0.5 M Na _2 SO _4 aqueous electrolyte solution under 100 mW cm ^−2 (AM 1.5G) simulated sunlight revealed 2-fold improved photocurrent density for MoS _2 /TiO _2 heterostructure (∼135.7 μ A cm ^−2 ) compared to that of bare TiO _2 (∼70 μ A cm ^−2 ). This is attributed to extended light absorption and more catalytically active surface area resulting from MoS _2 functionalization of the TiO _2 nanotubes, which results in better PEC activity. This study provides a new insight to explore the performance of thin metal foil-based photoelectrode in PEC applications that can be beneficial to develop roll-to-roll device fabrication to advance futuristic flexible electronics.

In this work, we report on the effect of anodization time on the morphology, optical, and photocatalytic properties of TiO2 nanotubes (NTs) allowing bacterial inactivation and two organic pollutant degradation under low-intensity solar-simulated light. Scanning electron microscopy (SEM) showed that the length of the TiO2 NTs increased from 2.8 to 25.8 μm as anodization time was increased from 15 to 300 min at 60 V, respectively. The X-ray diffraction (XRD) patterns showed that all samples crystallize in the anatase phase after annealing at 400 °C for 3 h. Samples anodized for 30 and 60 min exhibit low diffuse reflection at 400 nm, which was attributed to the disorder-induced exciton scattering at the molecular level. The intensity of the photoluminescence (PL) spectra was found to increase as the length of the NTs increases up to a maximum anodization time of 300 min, revealing the contribution of bulk excitonic states. A maximum photoelectric conversion efficiency of 0.55% was obtained at a potential of − 0.5 V vs. Ag/AgCl for TiO2 NTs anodized for 60 min. The optimized NTs (anodized for 60 min) showed a photocatalytic bacterial inactivation of a magnitude of 6 log within 360 min and a degradation of indole and methylene blue (MB) under low-intensity solar-simulated light (50 mW/cm2). The stability of the prepared catalyst was tested over several cycles. [ABSTRACT FROM AUTHOR]

In this work, a highly effective separation approach mediated by 5-Lipoxygenase (5-LOX) was established for screening and isolation of anti-inflammatory ingredients from leaves of Lonicera japonica Thunb. (LLJT). Using 5-LOX immobilised on TiO2 nanotubes as a microreactor, the targeted screening was exploited by combining with HPLC-MS system. Four compounds confirmed as luteolin, luteoside, lonicerin, and isochlorogenic acid C and a fraction (M1) were screened out to be potent inhibitors of 5-LOX. Their anti-inflammatory activities were further investigated and confirmed by RAW 264.7 cells inflammation model and rat foot swelling model. Furthermore, M1 was prepared by MCI GEL CHP20P column chromatography, and further separated by Pre-HPLC. One new compound confirmed to be 5,7,3',4'-tetrahydroxyflavone-7-O-sambubioside was first isolated from LLJT. The results provide a new method for the effective separation of active components derived from natural products. [ABSTRACT FROM AUTHOR]

[Display omitted] The effect of adding strontium to nanocomposites formed of g-C 3 N 4 /TiO 2 nanotubes (TiNT) (g-C 3 N 4 : 4.0 wt%) on the photocatalytic activity was herein investigated using formic acid as a model target pollutant. g-C 3 N 4 material was prepared by a solvothermal method using a mixture of urea and cyanuric chloride as precursors and acetonitrile as a solvent at 220 °C for 15 h, while TiNT material was obtained by the alkaline hydrothermal method of P25 at 130 °C for 20 h. A series of xSr-gC 3 N 4 /TiNT nanocomposites were then synthesized through progressive incorporation of strontium (from 0.2 to 1.0 wt%) at the surface of the composites. Samples were then characterized mainly using N 2 adsorption–desorption measurements, X-ray diffraction, UV–vis diffuse reflectance, Raman and photoluminescence (PL) spectroscopies, and scanning and transmission electron microscopy (with energy-dispersive X-ray spectroscopy and Z-mapping). The Sr-containing g-C 3 N 4 /TiNT composites were then also fully characterized by electrochemical impedance spectroscopy (EIS) for their dielectric properties, while a deep kinetics analysis was also performed. Such an approach allowed us to establish a correlation between photocatalytic performance and the material's propensity to be polarized. Results emphasize the beneficial role of ferroelectricity induced by adding strontium. Indeed, enhancement of the photocatalytic activity by 2.3 times compared to a Sr-free counterpart was related to the material's ability to be polarized for Sr loadings ≤ 0.6 wt%. At higher Sr loadings, supplementary factors (decrease of the anatase crystallinity, formation of TiO 2 (B), disruption of the g-C 3 N 4 /TiO 2 interaction, or lower mobility of photogenerated charges) negatively impact the activity, counterbalancing partly the beneficial ferroelectric effect. In this way, this study emphasizes the role played by ferroelectric effects in enhancing the photocatalytic ability of a given semiconductor. [ABSTRACT FROM AUTHOR]

The technology development of electrochemical energy storage devices including lithium-ion battery is urgently needed to support the increased demand for renewable energy and production growth of portable electronic devices. Extensive research on nanostructural engineering aims to improve battery performance in terms of capacity, energy density, cycling ability, and Coulombic efficiency. This review describes the concept of atomic layer deposition (ALD) and focuses on ALD for Li-ion battery. Within the last few years, interest in the nanostructured materials synthesized by ALD to enhance battery performance has rapidly improved. Given the urgent requirement for reliable materials for high battery performance, ALD is a robust method for developing and fabricating nanostructure materials for next-generation Li-ion batteries, especially in the design of anode and cathode electrodes of the batteries.

In this paper, a Ni and diamond-like carbon (DLC)-modified TiO2 nanotube composite electrode was prepared as a glucose sensor using a combination of an anodizing process, electrodeposition, and magnetron sputtering. The composition and morphology of the electrodes were analyzed by a scanning electron microscope and energy dispersive X-ray detector, and the electrochemical glucose oxidation performance of the electrodes was evaluated by cyclic voltammetry and chronoamperometry. The results show that the Ni-coated DLC-modified TiO2 electrode has better electrocatalytic oxidation performance for glucose than pure TiO2 and electrodeposited Ni on a TiO2 electrode, which can be attributed to the synergistic effect between Ni and carbon. The glucose test results indicate a good linear correlation in a glucose concentration range of 0.99–22.97 mM, with a sensitivity of 1063.78 μA·mM−1·cm−2 and a detection limit of 0.53 μM. The results suggest that the obtained Ni-DLC/TiO2 electrode has great application potential in the field of non-enzymatic glucose sensors. [ABSTRACT FROM AUTHOR]

Anodic TiO 2 nanotube (TNT) arrays have been intensively investigated as anodes in water splitting (WS) cells because of their excellent chemical stability. However, anodic TNT is seldom considered as a cathode for the hydrogen evolution reaction (HER) in an electrochemical WS cell. This study shows that a reduced TNT (R-TNT) sample prepared with a cathodic reduction technique without loading any co-catalyst can achieve remarkable HER performance. At − 1.0 V vs reversible hydrogen electrode in 1 M NaOH in dark, R-TNT achieved a current of − 221 mA, which is 17000-times of that achieved when using TNT and 5-times of that with Ti-foil as cathode. Chronopotentiometry tests were carried out sequentially at @ −100, − 50 and − 10 mA for 24 h and decay rates of 1.3%, 5.2% and 18.4% were measured, which indicate a good stability of the R-TNT sample. [Display omitted] • Reduced TiO 2 nanotube (R-TNT) prepared with cathodic reduction technique. • R-TNT as cathode gives current (J) − 221.08 mA in dark at − 1.0 V RHE. • The J at − 1.0 V RHE is 17000 times that of TNT and 5 times that of Ti foil. • R-TNT withstands CP@ −100 mA for 24 h with a decay 1.3% in 1 M NaOH. • A Ti0-TNT/Ti composite structure is proposed to explain the cathode efficiency. [ABSTRACT FROM AUTHOR]

It is challenging to match the mutual interactions between implant and host because the biomaterials usually cannot actively adjust their performance to the changing microenvironment. Surface potential is one of the critical factors affecting the bioactivity of biomaterials, but it is difficult to be directly controlled in vivo. Magnetic stimulation has attracted much attention due to its deep penetrability, good reliability, and convenient operability. Here, titanium dioxide (TiO2) nanotubes and Terfenol‐D/P(VDF‐TrFE) composite film are prepared by anodic oxidation and solution casting methods on opposite sides of a titanium sheet, respectively. Terfenol‐D magnetostrictive microparticles deform under a magnetic field, generating surface potential on the P(VDF‐TrFE) piezoelectric matrix through magneto‐electric coupling. Correspondingly, equal opposite charges are induced on the surface of TiO2 nanotubes. Stem cells cultured on TiO2 nanotubes show that cell adhesion, proliferation, and differentiation abilities can be regulated by magnetic strength, which correlates with the absorption of charged proteins. Therefore, a cascade coupling of magnetic, mechanical, electric, biochemical, and cellular effects is established. This work demonstrates the feasibility of regulating the bioactivity of biomaterials in vivo through a magnetic field. [ABSTRACT FROM AUTHOR]

We analyzed the effects of humidity on the H2S sensing ability of the undoped, Zn-doped, and Fe-doped TiO2 nanotube (TiNT)-based gas sensors. The 0.1 M Zn-doped TiNT-based gas sensor had more stable responses to 50 ppm H2S at 300°C compared to the undoped TiNT when the relative humidity (RH) ranged from 3 to 85%RH. For the 0.1 M Fe-doped TiNT sensor, the response reached the highest value (34.19-50 ppm H2S) at 70%RH. The Fe-doped TiNT sensors maintained relatively high responses when the relative humidity was below 60%RH. To determine the relationship between the sensing mechanism and TiO2 band structures and to determine the effect of water on the sensing mechanism, the systematic density functional theory (DFT) calculations for adsorption modes were performed. We found that metal ion doping was effective in improving the performance of H2S TiNT film-based gas sensors under different relative humidities. We also demonstrated the value of metal-doped TiNT gas sensors in practical environments. [ABSTRACT FROM AUTHOR]

Three-dimensional surface-enhanced Raman scattering (SERS) substrates usually provide more hot spots in the excitation light beam and higher sensitivity when compared with the two-dimensional counterpart. Here a simple approach is presented for the fabrication of arrays of Ag-nanoparticles decorated TiO2 nanotubes. Arrays of ZnO nanorods were fabricated in advance by a hydrothermal method. Then TiO2 nanotube arrays were achieved by immersing the arrays of ZnO nanorods in an aqueous solution of (NH4)2TiF6 for 1.5 h. Vertically aligned TiO2 nanotube arrays were modified with dense Ag nanoparticles by Ag mirror reaction. High density of Ag nanoparticles decorated on the fabricated TiO2 nanotubes provide plenty of hotspots for Raman enhancement. In addition, the fabricated array of Ag nanoparticles modified TiO2 nanotubes can serve as a reusable SERS substrate because of the photocatalytic activity of the TiO2 nanotubes. The SERS substrate adsorbed with analyte molecules can realize self-cleaning in deionized water after UV irradiation for 2.5 h. The sensitivity of the fabricated SERS substrate was investigated by the detection of organic dye molecules. The detectable concentration limits of rhodamine 6G (R6G), malachite green (MG) and methylene blue (MB) were found to be 10−12 M, 10−9 M and 10−8 M, respectively. The enhancement factor (EF) of the three-dimensional SERS substrate was estimated to be as high as ∼1.4×108. Therefore, the prepared Ag nanoparticles modified TiO2 nanotube arrays have promising potentials to be applied to rapid and trace SERS detection of organic chemicals.

In order to overcome the defects of high electron-hole recombination rate and narrow absorption spectrum range of TiO2 nanotubes during photoelectric conversion, TiO2 nanotubes were synergistically modified by polyoxometalates H4 SiW12 O40 (SiW12) and CsPbI3 quantum dots. SiW12/TiO2 nanotube composite films were prepared by electrodeposition of SiW12 on TiO2 nanotubes. The CsPbI3 quantum dots were synthesized by high temperature thermal injection method, and then the CsPbI3 quantum dots were deposited on the composite films by chemical bath deposition method to obtain the SiW12/CsPbI3/TiO2 nanotube composite films. The effects of SiW12 deposition time and CsPbI3 deposition frequencies on the photoelectric properties of TiO2 nanotubes were investigated. The films were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet visible spectrophotometer (UV-Vis). The photochemical properties of the films were tested by electrochemical workstation. The results show that the photoelectric conversion efficiency of TiO2 nanotubes deposited with polyoxometalates SiW12 and CsPbI3 quantum dots can be significantly improved by increasing the light absorption range and decreasing the charge transfer resistance up to 0.52%. It shows that the synergistic effect of SiW12 and CsPbI3 can effectively inhibit the electron-hole recombination of TiO2 nanotubes, broaden the absorption spectrum and improve the photoelectric conversion efficiency of TiO2 nanotubes. [ABSTRACT FROM AUTHOR]

Ilmenite (FeTiO3) is a suitable mineral to produce titanium dioxide (TiO2) for photocatalyst applications. Therefore, this research was conducted to synthesize TiO2 material from titanium oxysulfate (TiOSO4) extracted from Indonesia local ilmenite mineral (FeTiO3) and to modify this material into TiO2 nanotubes through a hydrothermal process at 150 °C for 24 hours followed by a post-hydrothermal treatment with temperature variations of 80,100, 120, and 150 °C for 12 hours. The purpose was to investigate the effect of the post-hydrothermal variations on the crystal structure, morphology, and optical properties of the TiO2 nanotubes produced. It was discovered from the scanning electron microscopy (SEM) observations that the TiO2 nanotube was successfully derived from the ilmenite precursor. Moreover, the X-Ray diffraction (XRD) analysis of the nanotube crystal structure showed that post-hydrothermal treatment enhanced the crystallinity of the anatase TiO2 phase even though the sodium titanate phase was observed to exist in the structure. The increase in the post-hydrothermal temperature from 80 to 150 °C was also discovered to have led to: 1) a reduction in the unit cell volume from 136.37 to 132.31 Å3 and a decrease in the lattice constant c from 9.519 to 9.426 Å; 2) an increase in density from 7.783 to 8.081 gr/cm3 as well as in the crystallite size from 19.185 to 25.745 nm; 3) a decrease in the bandgap energy (Eg), from 3.33 to 3.02 eV. These characteristics further indicate the ability of the photocatalytic performance of the nanotubes to enhance the degradation efficiency from 87.69 to 97.11 %. This means the TiO2 nanotubes extracted from local 3 can provide the expected crystal structure and photocatalytic performance [ABSTRACT FROM AUTHOR]

This study investigates the effects of graphene amount on TiO 2 nanotubes (TNT) synthesized on Ti6Al4V alloy via selective laser melting (SLM) to optimize corrosion resistance and biocompatibility. XRD analysis indicated the presence of anatase and rutile phases in TNTs, and the peak shifts indicated that graphene was successfully incorporated into the TNT structure. SEM images revealed that increasing the amount of graphene resulted in smaller nanotube diameters, increased contact angles, and imparted hydrophobic properties. Corrosion tests including Tafel polarization and electrochemical impedance spectroscopy (EIS) showed that graphene, especially C4-TNTs, exhibited superior corrosion resistance with high Ecorr and Rt values. Biocompatibility tests with human dermal fibroblast cells (HDFa) demonstrated cell viability with the incorporation of graphene into TNTs. The findings suggest that the optimum amount of graphene can significantly improve the corrosion resistance and biocompatibility of TiO 2 nanotubes on Ti6Al4V alloy, making them more suitable for biomedical implants. [Display omitted] • Graphene-TNTs on Ti6Al4V alloy enhance corrosion resistance significantly. • XRD and SEM confirm graphene incorporation and reduced TNT diameters. • C4-TNTs show the highest corrosion potential (-0.21 V) and lowest current density. • Graphene increases hydrophobicity; C4-TNTs reach a 135° contact angle. • Cell viability improves by 35 % with C4-TNTs, showing high biocompatibility. [ABSTRACT FROM AUTHOR]

[Display omitted] • TiO 2 NTs@Fe 3 O 4 NPs-assisted open-channel device for viral RNA extraction. • Direct viral RNA detection via simple fluorescence status evaluation. • Method validated by 145 SARS-CoV-2 samples against PCR-based method. • Nanomaterial-assisted device meets the criteria of point-of-care testing. Most routine viral RNA detection assays available today rely on RNA amplification steps. The sensitivity of such methods comes at the expense of time, cost, and equipment availability. Given the constraints during the COVID-19 pandemic, such as the limited capacity of RNA amplification instruments and the global shortage of isolation kits, there has been a demand for amplification-free assays which should meet POCT criteria: affordable, sensitive, specific, user-friendly, rapid, and equipment-free. This study aims to design and validate a microanalytical system for direct viral RNA detection which meets these criteria. The presented RNA detection assay consists of four consecutive steps: immunocapturing viral particles, viral particles lysis, TiO 2 NTs@Fe 3 O 4 NPs-assisted RNA extraction, and finally viral RNA detection. The last three steps occur within a microfluidic device with open channels (OC-MFD). The OC-MFD is manufactured from polycarbonate film by unique mechanical replication techniques in a roll-to-roll setup. This method has been experimentally validated to offer the advantages of low-cost and extremely rapid production (1 mil. pieces of OC-MFDs per hour). Two permanent magnets situated under the application/extraction zones enabled to fix magnetically active particles/nanotubes. At first, viral particles are quantitatively captured from the entire sample volume using immunomagnetic particles. The lysed viral particles are transferred to the application zone of OC-MFD, followed by RNA extraction using magnetic TiO 2 nanotubes decorated with Fe 3 O 4 nanoparticles (TiO 2 NTs@Fe 3 O 4 NPs). The effectivity of the nanomaterial to attract viral RNA molecules was evaluated against a standard RT-qPCR-based laboratory test. Equivalence tests were performed with 143 positive and negative SARS-CoV-2 samples. Spearman rank correlation coefficients demonstrated high agreement for both measured biomarker genes (the E gene equaled 0.76, the RdRp gene equaled 0.73 , the p-value < 0.001). To fulfill POCT criteria, viral RNA captured directly on the surface of TiO 2 NTs@Fe 3 O 4 NPs and fixed by permanent magnet in the extraction zone of OC-MFD was visualized in situ using SYBR Green II fluorescent dye. This strategy allows to achieve a sensitivity of 0.3 ng of RNA per µL−1. Additionally, this test can be easily adapted for direct detection of any other RNA virus simply by choosing a suitable immunosorbent with the corresponding antibody specificity. Besides, the most significant advantages of this microanalytical system for direct viral RNA detection and outlook for future applications are also discussed and summarized. [ABSTRACT FROM AUTHOR]

In this study, different chemical methods were used to synthesize ZnO nanorod, TiO2 nanotube and ZnO/TiO2 nanostructure as high sensitivity vapor sensor for ethanol. The surface topography of ZnO nanorod, TiO2 nanotube and ZnO/TiO2 was studied by using the scanning electron microscopy (SEM). The X-rays diffraction showed the appearance of (101) ZnO which has single crystalline with a hexagonal wurtzite while TiO2 has been crystallized in a tetragonal with the preferential orientation of the crystallinity with the prominent (111). The relation between resistance-time showed high sensitivity for ZnO/TiO2 and was found to be around 20-80% at different working temperature. ZnO/TiO2 sensor was the most sensitive to ethanol vapor.

Peri-implantitis is an inflammatory disease similar to periodontitis, caused by biofilms formed on the surface of dental implants. This inflammation can spread to bone tissues and result in bone loss. Therefore, it is essential to inhibit the formation of biofilms on the surface of dental implants. Thus, this study examined the inhibition of biofilm formation by treating TiO2 nanotubes with heat and plasma. Commercially pure titanium specimens were anodized to form TiO2 nanotubes. Heat treatment was performed at 400 and 600 °C, and atmospheric pressure plasma was applied using a plasma generator (PGS-200, Expantech, Suwon, Republic of Korea). Contact angles, surface roughness, surface structure, crystal structure, and chemical compositions were measured to analyze the surface properties of the specimens. The inhibition of biofilm formation was assessed using two methods. The results of this study showed that the heat treatment of TiO2 nanotubes at 400 °C inhibited the adhesion of Streptococcus mutans (S. mutans), associated with initial biofilm formation, and that heat treatment of TiO2 nanotubes at 600 °C inhibited the adhesion of Porphyromonas gingivalis (P. gingivalis), which causes peri-implantitis. Applying plasma to the TiO2 nanotubes heat-treated at 600 °C inhibited the adhesion of S. mutans and P. gingivalis.

In this paper, internal anodization of porous Ti was performed to fabricate immobilized TiO2 nanotubes with a high specific surface area. The results showed that complete internal anodization of porous Ti was achieved, self-ordered and open-topped TiO2 nanotube arrays were successfully formed within the whole region of porous Ti by applying high anodizing voltage, long oxidation time and enhancing mass transfer. The BET specific surface area of anodized porous Ti reached 16.96 m2/g, which was almost 60 times that before anodic oxidation. Moreover, due to the potential drop and mass transfer, the nanotube growth was larger at the front surface than the back surface, and decreased as they were inward further away from the surface. The anodized porous Ti with a high specific surface area not only benefits the designing of highly active TiO2-based photocatalysts, but also shows great potential for applications in adsorption and electrocatalysis etc.

The relatively small specific capacitance along with poor electrochemical activity and weak electrical conductivity of TiO2 has resulted in several studies on the methods of modifying TNTs(TiO2 nanotube arrays). In this study, different mechanisms for improving the electrochemical properties of TiO2 nanotubes are employed; Nitrogen doping of TNTs in different concentrations of ammonia solution (named N-TNTs), then conducting electrochemical reductive doping on optimized TNTs (named N-R-TNTs). .Nitrogen doping of TNTs fabricated using two-step anodization was used to narrow the bandgap of TNTs as a non-metal doping technique. To better demonstrate the impact of the nitrogen content on enhancing the electrochemical activity, TNTs were immersed in 0.5, 1, 2, 4, and 8 molars of ammonia solution. Electrochemical reductive doping was implemented on TNTs and N-TNTs. The phase structure and surface morphologies of the asprepared TNTs were identified by X-ray diffraction (XRD), Field Emission Electron Microscope (FESEM) and Fourier transformed infrared spectroscopy (FT-IR) measurements. The electrochemical response of the TNTs following nitrogen and electrochemical doping was evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge tests, and electrochemical impedance spectroscopy (EIS). The electrochemical measurements of the modified samples confirmed that a noticeable improvement was achieved in the electrochemical behavior and that the areal capacitance of R-N-TNT was roughly 400 orders of magnitude greater than that of TNTs with long-term stability (93% of its initial capacitance after 500 cycles). [ABSTRACT FROM AUTHOR]

Objectives:In this study, the treatment potential of ammonia in wastewater generated by S company odor removal process was tested by using electrochemical reactor with RuO2/Ti anode and TiO2 nanotube cathode. The effect of chlorine ion concentration and current density on ammonia oxidation were investigated by comparing the treatment efficiencies. Methods:380 mL of wastewater was electrolyzed for 3 h using 4 anodes and 5 cathodes and pH, NH3-N, NO3--N, and TN were measured and analyzed every 30 minutes. Results and Discussion:As the addition of chlorine ion increases, about 1,700 mg/L of ammonia in the wastewater was found to increase in oxidation reaction rate due to an increase in chlorine based oxidizing agent. An increase in chlorine based oxidizing agent leads to an increase in indirect oxidation. As a result, total nitrogen removal was increased. Ammonia oxidation rate was increased as the current density increased. Nitrate, ammonia oxidation byproduct, was accumulated at a current density from 20 to 40 mA/cm2. At higher than 50 mA/cm2, nitrate was accumulated for a while and then decreased. Total nitrogen removal rate increased as the current density increased. During electrochemical oxidation of ammonia to nitrate, hydroxyl ions were consumed by the reaction. The hydroxyl ion consumed during ammonia oxidation was less than that produced from nitrate reduction. Conclusions:Thus, ammonia in actual wastewater was completely removed using RuO2/Ti anode and TiO2 nanotube cathode and the possibility of reducing nitrate was confirmed. We confirmed the applicability of the two electrodes to the real industry.

Bo Chen,1 Yapeng You,1 Aobo Ma,1 Yunjia Song,1 Jian Jiao,2 Liting Song,1 Enyu Shi,1 Xue Zhong,1 Ying Li,1 Changyi Li1 1School of Dentistry, Stomatological Hospital, Tianjin Medical University, Tianjin, People’s Republic of China; 2Department of Stomatology, Tianjin Medical University General Hospital, Tianjin, People’s Republic of ChinaCorrespondence: Ying Li; Changyi LiStomatological Hospital, Tianjin Medical University, No. 12 of Observatory Road, Heping District, Tianjin 300070, People’s Republic of ChinaTel +86-22-23332034; +86-22-23332003Fax +86-22-23332122Email yingli@tmu.edu.cn; lichangyi@tmu.edu.cnPurpose: Zinc (Zn), an essential trace element in the body, has stable chemical properties, excellent osteogenic ability and moderate immunomodulatory property. In the present study, a Zn-incorporated TiO2 nanotube (TNT) was fabricated on titanium (Ti) implant material. We aimed to evaluate the influence of nano-scale topography and Zn on behaviors of murine RAW 264.7 macrophages. Moreover, the effects of Zn-incorporated TNT surface-regulated macrophages on the behaviors and osteogenic differentiation of murine MC3T3-E1 osteoblasts were also investigated.Methods: TNT coatings were firstly fabricated on a pure Ti surface using anodic oxidation, and then nano-scale Zn particles were incorporated onto TNTs by the hydrothermal method. Surface topography, chemical composition, roughness, hydrophilicity, Zn release pattern and protein adsorption ability of the Zn-incorporated TiO2 nanotube surface were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), surface profiler, contact angle test, Zn release test and protein adsorption test. The cell behaviors and both pro-inflammatory (M1) and pro-regenerative (M2) marker gene and protein levels in macrophages cultured on Zn-incorporated TNTs surfaces with different TNT diameters were detected. The supernatants of macrophages were extracted and preserved as conditioned medium (CM). Furthermore, the behaviors and osteogenic properties of osteoblasts cultured in CM on various surfaces were evaluated.Results: The release profile of Zn on Zn-incorporated TNT surfaces revealed a controlled release pattern. Macrophages cultured on Zn-incorporated TNT surfaces displayed enhanced gene and protein expression of M2 markers, and M1 markers were moderately inhibited, compared with the LPS group (the inflammation model). When cultured in CM, osteoblasts cultured on Zn-incorporated TNTs showed strengthened cell proliferation, adhesion, osteogenesis-related gene expression, alkaline phosphatase activity and extracellular mineralization, compared with their TNT counterparts and the Ti group.Conclusion: This study suggests that the application of Zn-incorporated TNT surfaces may establish an osteogenic microenvironment and accelerate bone formation. It provided a promising strategy of Ti surface modification for a better applicable prospect.Keywords: titanium surface modification, TiO2 nanotube, zinc nanoparticles, immunomodulatory function, osseointegration

Bone marrow mesenchymal stem cells (BMSCs) play a critical role in bone formation and are extremely sensitive to external mechanical stimuli. Mechanical signals can regulate the biological behavior of cells on the surface of titanium-related prostheses and inducing osteogenic differentiation of BMSCs, which provides the integration of host bone and prosthesis benefits. But the mechanism is still unclear. In this study, BMSCs planted on the surface of TiO2 nanotubes were subjected to cyclic mechanical stress, and the related mechanisms were explored. The results of alkaline phosphatase staining, real-time PCR, and Western blot showed that cyclic mechanical stress can regulate the expression level of osteogenic differentiation markers in BMSCs on the surface of TiO2 nanotubes through Wnt/β-catenin. As an important member of the histone acetyltransferase family, GCN5 exerted regulatory effects on receiving mechanical signals. The results of the ChIP assay indicated that GCN5 could activate the Wnt promoter region. Hence, we concluded that the osteogenic differentiation ability of BMSCs on the surface of TiO2 nanotubes was enhanced under the stimulation of cyclic mechanical stress, and GCN5 mediated this process through Wnt/β-catenin.

A combined electrochemical anodization and ultraviolet light-assisted photochemical preparation technique has been used to prepare Cu/TiO2, Ag/TiO2, Cu@Ag/TiO2, and Ag@Cu/TiO2 nanotubes. X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) were used to systematically characterize the crystalline phase and morphology, respectively, of the prepared nanotube films. The optical absorption properties of the samples were also studied using ultraviolet-visible (UV-Vis) absorption spectroscopy. The photoelectrochemical activity and photocathodic protection properties of 403 stainless steel were investigated using photogenerated open circuit potential, photogenerated current density, Tafel curves, and J-V curves. The effects of the type of particles deposited and the deposition sequence on their photocathodic protection properties were also studied. According to the results, the morphology and photoelectrochemical and photocathodic protection properties of the prepared samples are affected by the photodeposition sequence of the particles. The results also show that photodeposited TiO2 nanotubes enhance the light absorption and photoelectrochemical properties under light illumination, thus greatly increasing the photocurrent density of the Cu/TiO2 and Ag/TiO2 nanotubes in comparison with bare TiO2 nanotubes. In addition, the photogenerated potential drop of the photodeposited TiO2 was greater than that of bare TiO2. The open circuit potential (OCP) values of 403SS coupled with Cu/TiO2, Ag/TiO2, Cu@Ag/TiO2, and Ag@Cu/TiO2 under irradiation were −695 mV, −665 mV, −594 mV, and −574 mV, respectively. Silver- and copper-photodeposited TiO2 nanotubes can be applied as new photoanode materials to provide good photogenerated cathodic protection for metals under light illumination. [ABSTRACT FROM AUTHOR]

This study compared the topography of different titanium surface structures (TiO2 nanotube and grain) with similar elemental compositions (TiO2 and fluorine [F]) on the Ti surface. High magnification indicated that the surfaces of the control and etching groups were similar to each other in a flat, smooth form. The group anodized for 1 h was observed with TiO2 nanotubes organized very neatly and regularly. In the group anodized for 30 min after etching, uneven wave and nanopore structures were observed. In addition, MTT assay showed that the F of the surface did not adversely affect cell viability, and the initial cell adhesion was increased in the 2.8% F‐incorporated TiO2 nanograin. At the edge of adherent cells, filopodia were observed in spreading form on the surfaces of the anodizing and two‐step processing groups, and they were observed in a branch shape in the control and etching groups. Moreover, cell adhesion molecule and osteogenesis marker expression was increased at the F‐incorporated TiO2 nanostructure. In addition, it was found that the expression of p‐extracellular signal‐regulated kinase (ERK) and p‐cAMP response element‐binding protein (CREB) increased in the TiO2 nanograin with the nanopore surface compared to the micro rough and nanotube surfaces relative to the osteogenic‐related gene expression patterns. As a result, this study confirmed that the topographic structure of the surface is more affected by osteogenic differentiation than the pore size and that differentiation by specific surface composition components is by CREB. Thus, the synergy effect of osteogenic differentiation was confirmed by the simultaneous activation of CREB/ERK. [ABSTRACT FROM AUTHOR]

Mixed-matrix membranes (MMMs) possess the unique properties and inherent characteristics of their component polymer and inorganic fillers, or other possible types of additives. However, the successful fabrication of compact and defect-free MMMs with a homogeneous filler distribution poses a major challenge, due to poor filler/polymer compatibility. In this study, we use two-dimensional multi-layered Ti3C2Tx MXene nanofillers to improve the compatibility and CO2/CH4 separation performance of cellulose triacetate (CTA)-based MMMs. CTA-based MMMs with TiO2-based 1D (nanotubes) and 0D (nanofillers) additives were also fabricated and tested for comparison. The high thermal stability, compact homogeneous structure, and stable long-term CO2/CH4 separation performance of the CTA-2D samples suggest the potential application of the membrane in bio/natural gas separation. The best results were obtained for the CTA-2D sample with a loading of 3 wt.%, which exhibited a 5-fold increase in CO2 permeability and 2-fold increase in CO2/CH4 selectivity, compared with the pristine CTA membrane, approaching the state-of-the-art Robeson 2008 upper bound. The dimensional (shape) effect on separation performance was determined as 2D > 1D > 0D. The use of lamellar stacked MXene with abundant surface-terminating groups not only prevents the aggregation of particles but also enhances the CO2 adsorption properties and provides additional transport channels, resulting in improved CO2 permeability and CO2/CH4 selectivity.

In this paper, a Ni and diamond-like carbon (DLC)-modified TiO2 nanotube composite electrode was prepared as a glucose sensor using a combination of an anodizing process, electrodeposition, and magnetron sputtering. The composition and morphology of the electrodes were analyzed by a scanning electron microscope and energy dispersive X-ray detector, and the electrochemical glucose oxidation performance of the electrodes was evaluated by cyclic voltammetry and chronoamperometry. The results show that the Ni-coated DLC-modified TiO2 electrode has better electrocatalytic oxidation performance for glucose than pure TiO2 and electrodeposited Ni on a TiO2 electrode, which can be attributed to the synergistic effect between Ni and carbon. The glucose test results indicate a good linear correlation in a glucose concentration range of 0.99–22.97 mM, with a sensitivity of 1063.78 μA·mM−1·cm−2 and a detection limit of 0.53 μM. The results suggest that the obtained Ni-DLC/TiO2 electrode has great application potential in the field of non-enzymatic glucose sensors.

In this study, a new material obtained from titanium ingots residue was coated with natural carotenoids having antibacterial properties. The waste is a no recycling titanium scrap from technological production process which was pressed and transformed into disks titanium samples. Through anodization and annealing procedures of the titanium disk, a nanostructured titanium dioxide surface with photocatalytic and antibacterial properties was successfully obtained. The titanium scrap impurities (V, Al, and N), unwanted for production process, have shown to improve electrochemical and semiconductor properties of the residue surfaces. The nanostructured titanium scrap surface was modified with two different carotenoids, torularhodin and β-carotene, to potentiate the antibacterial properties. The bactericidal tests were performed against Salmonella typhimurium and Escherichia coli, both Gram-negative. The best bactericidal effect is obtained for nanostructured titanium scrap disks immersed in torularhodin, with a percentage of growth inhibition around 60% against both tested bacteria. The results suggest that this low-cost waste material is suitable for efficient reuse as antibacterial surface after a few simple and inexpensive treatments. [ABSTRACT FROM AUTHOR]

The mechanical measurements of nanostructures are crucial to the development and processing of novel nanodevices. In this study, TiO2 nanotubes were synthesised using an electrospinning method combined with subsequent heat treatment. A simple experimental method is established to measure theelastic modulus of a single nanotube based on atomic force microscopy (AFM) technology. Subsequently, the finite element method (FEM) is employed to evaluate the effect of the elastic modulus of TiO2 and dimensional size on the mechanical behaviours of the TiO2 nanotubes. The results show that, by combining AFM with FEM technology. the mechanical behaviour of a single TiO2 nanotube can be predicted efficiently in the linear elastic region. [ABSTRACT FROM AUTHOR]

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In this study, one-dimensional titanium dioxide (TiO 2) nanotube arrays (NTAs) with different tube lengths are synthesized via anodic oxidation of Ti foils and their ultraviolet (UV) light detection properties are investigated to determine their optimum growth conditions. A TiO2 nanotube ultraviolet photodetector based on photoelectrochemical cell is fabricated using the optimum TiO2 nanotubes and its characteristics in the ultraviolet region are determined. The photodetector is examined under a UV illumination intensity of 10 mW/cm2and at a wavelength of 368 nm. Its responsivity is measured to be about 96 μ A/cm2 and its response time is less than 0.2 s under an applied bias of 0.5 V. [ABSTRACT FROM AUTHOR]

A planer π-conjugated spacer is one of the strategies used to develop the performance of the dye-sensitized solar cell (DSSC). This study focuses on describing the effect of the nitrogen-based heterocycles as π-linker on the properties of novel photosensitizers based on diphenylthienylamine (DPTA). The π-linker is five- (5M), or six-membered rings (6M) contains none (D0), one (D1), two (D2), and three (D3) nitrogen atoms. The geometrical structures, electronic properties, and photovoltaic parameters are calculated using the DFT/B3LYP and TD-DFT/CAM-B3LYP functional with 6-31G+(d,p) basis set. As well, the polarised continuum model (PCM) is used to simulate the solvation effects. To understand the mechanism of electrons injection to semiconductor, the adsorbed dyes on titanium dioxide nanotube (TiO2NT) are studied, using B3LYP/6-31G(d) and LANL2DZ basis sets. The results revealed that 6M is better than 5M dyes due to the extended conjugation in the 6M dyes. As well, the 5M-D0 (cyclopenta-1,3-diene) shows a broad absorption band from 400 to 850 nm at the near-infrared (NIR) region with an absorption wavelength of 561.24 nm. Besides, 5M-D0, 6M-D3 (1,2,4-triazine) can be considered promising photosensitizers due to their unique electronic properties that will be expected to improve the power conversion efficiency of the DSSC device. [ABSTRACT FROM AUTHOR]

Arsenic in groundwater caused the black‐foot disease (BFD) in many countries in the 1950–1960s. It is of great importance to develop a feasible method for removal of arsenic from contaminated groundwater in BFD endemic areas. Photocatalytic oxidation of As(III) to less toxic As(V) is, therefore, of significance for preventing any arsenic‐related disease that may occur. By in situ synchrotron X‐ray absorption spectroscopy, the formation of As(V) is related to the expense of As(III) disappearance during photocatalysis by TiO2 nanotubes (TNTs). Under UV/Vis light irradiation, the apparent first‐order rate constant for the photocatalytic oxidation of As(III) to As(V) is 0.0148 min−1. It seems that As(III) can be oxidized with photo‐excited holes while the not‐recombined electrons may be scavenged with O2 in the channels of the well defined TNTs (an opening of 7 nm in diameter). In the absence of O2, on the contrary, As(III) can be reduced to As(0), to some extent. Cu(II) (CuO), as an electron acceptor, was impregnated on the TNTs surfaces in order to gain a better understanding of electron transfer during photocatalysis. It appears that As(III) can be oxidized to As(V) while Cu(II) is reduced to Cu(I) and Cu(0). The molecular‐scale data are very useful in revealing the oxidation states and interconversions of arsenic during the photocatalytic reactions. This work has implications in that the toxicity of arsenic in contaminated groundwater or wastewater can be effectively decreased via solar‐driven photocatalysis, which may facilitate further treatments by coagulation. [ABSTRACT FROM AUTHOR]

TiO2 nanotubes arrays with dominant (001) facets were fabricated by multi-anodic oxidation technology. The influence factor of the electrolyte composition on the ratio of different facets for anatase TiO2 and the bioactivity were investigated. Besides, the characterization of the surface morphologies and crystal structures were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD),etc. Finally, the bioactivity was estimated by the CaP salt deposition vis biomin-eralization process and protein adsorption experiment. The results show that the relative proportions of different facets in the TiO2 nanotubes can be adjusted by changing the content of H2O in the electrolyte. The (004) facet texture coefficient of TiO2 nanotubes arrays prepared in 2% H2O(volume fraction) electrolyte reaches up to 4.76. The TiO2 nanotubes with dominant (001) facets can accelerate the deposition of hydroxyapatite and raise the amount of protein adsorption in the humanoid environment by providing more active sites for biomineralization and protein adsorption. The TiO2 nanotubes with a higher proportion of (001) facets have the more excellent biological activity.

Novel ternary nanocomposite photocatalysts based on g-C3N4/Bi2MoO6/TiO2 nanotube were synthesized using simple solid combustion, hydrothermal and wetness impregnation methods. The structural and morphological properties of the synthesized photocatalysts were systematically characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). The crystal structure and phase purity of unitary, binary, and ternary photocatalysts were confirmed by XRD analysis. The SEM analysis reveals the tubular morphology of the TiO2 nanotube, and the presence of Ti, C, N, Bi, Mo, O, C, and N in the ternary composites was confirmed by EDX analysis. The photocatalytic decolorization efficiency of the ternary composites was evaluated by monitoring the decolorization of reactive black 5 and methylene blue dyes under visible light and direct sunlight irradiation, and these ternary composites were compared with binary composites and unitary photocatalysts in terms of the decolorization efficiency. After five cycles of adsorption and decolorization reactions, it was confirmed that the ternary composite photocatalysts were highly stable and reusable. From the results, we conclude that ternary composites (g-C3N4/Bi2MoO6/TiO2 nanotube) are efficient photocatalysts for the decolorization of dyes.

Abstract TiO2 nanotubes (TNTs) have drawn tremendous attention owing to their unique architectural and physical properties. Anodizing of titanium foil has proven to be the most efficient method to fabricate well-aligned TNTs, which, however, usually produces amorphous TNTs and needs further thermal annealing. Recently, a water-assisted crystallization strategy has been proposed and investigated by both science and engineering communities. This method is very efficient and energy saving, and it circumvents the drawbacks of thermal sintering approach. In this paper, we review the recent research progress in this kind of low-temperature crystallization approach. Here, various synthetic methods are summarized, and the mechanisms of the amorphous–crystalline transformation are analyzed. The fundamental properties and applications of the low-temperature products are also discussed. Furthermore, it is proved that the water-assisted crystallization approach is not only applicable to TNTs but also to crystallizing other metal oxides.

The well-ordered titanium dioxide (TiO 2) nanotube array surfaces were formed at different voltages such as 20 V, 40 V, 60 V, 80 V and 100 V for 1 h on cp-Ti by anodic oxidation (AO) technique. And then, to improve crystallinity of the surface, heat treatment was applied at 450 °C for 1 h to all surfaces without any morphological changing. The surface and cross sectional morphology, elemental structure, phase composition, functional groups, roughness and thickness, wettability and mechanical results were investigated by SEM, EDX, XRD, FT-IR, AFM, contact angle measurement device and nanoindentation tester, respectively. Mainly, anatase- and rutile-TiO 2 phases were obtained at post-heat treatment whereas only, Ti phase was detected on AO surfaces at pre-heat treatment. All nanotube structures and the elements of Ti and O were uniformly distributed through the whole surface. The roughness and thickness of tube structures usually increased with increasing voltage values and measured. The roughness and thickness values were measured as 10.67–111.97 nm and 0.21–1.92 μm, respectively. TiO 2 nanotube surfaces exhibited hydrophobic behaviors with respect to plain Ti surface. Furthermore, mechanical properties such as hardness and elastic modulus of the coating produced at minimum voltage were great compared to ones at higher voltage and plain Ti surface under a Berkovich indenter due to phase structure, homogeneity and density of nanotube structures. [ABSTRACT FROM AUTHOR]