Titania Nanotube Arrays Research Articles

Graphitic carbon nitride/titania nanotube arrays for photoelectrochemical oxidation of methanol under visible light

In this study, the fabrication of ordered and vertically oriented titanium dioxide nanotubes (TiO2 NT) array sensitized with graphitic carbon nitride (g-C3N4) nanosheets (g-C3N4 NS/TiO2 NT) was demonstrated as an attractive class of photocatalysts for the visible-light-driven photoelectrochemical oxidation of methanol. The phase and composition of the fabricated g-C3N4 NS/TiO2 NT structures and their precursors were investigated using X-ray powder diffraction (XRD). The morphological and topological characteristics of the prepared materials were studied using scanning electron microscopy (SEM). Raman spectroscopy was employed to study the electronic properties of composite material. Upon the fabrication, characterization, and use of the prepared structures for photoelectrochemical oxidation of methanol under visible-light illumination (50 W halogen lamp, 0.1 M KOH), the g-C3N4 NS/TiO2 NT array showed a significant increase in the photocurrent (96.2 μA cm−2) compared to the TiO2 NT electrode (79 μA cm−2) with 1.2 times enhancement factor. Moreover, decorating the TiO2 NT array resulted in enhanced dark light density that is 8.7 times more than that of the TiO2 NT electrode. The improved photo- and electrochemical properties of the prepared g-C3N4 NS/TiO2 NT could arise from the synergistic effects of g-C3N4 NS decoration and the unique structural properties of the fabricated vertically aligned TiO2 nanotube arrays. The TiO2 NT/g-C3N4 NS composite modified photo-electrode offers 22.55 times the ambient condition “light off” of the TiO2 NT electrode and 2.3 times the irradiated ones. The present study suggests a simple, stable, reusable, and cost-effective approach for the preparation of g-C3N4 NS/TiO2 NT photocatalyst for designing a DMFC.

Enhanced Oxalic Acid Electroreduction Selectivity toward Glyoxylic Acid on Ti3+‐Self‐Doped TiO2 Nanotube Arrays

AbstractElectroreduction of oxalic acid (OX) to glyoxylic acid (GO) is an extremely important and promising application in organic electrosynthesis. Pb cathodes, which exhibits good selectivity, need to be replace due to the severe deactivation and harmful to the environment. Herein, self‐doped titanium dioxide nanotube arrays (H‐TiO2NTs‐2) are synthesized as an alternative cathode for OX electroreduction to GO. Benefiting from two‐step anodization, the synthesized nanotube arrays are highly ordered with oriented openings. The ordered structure promotes the mass transfer of both OX and GO to ensure efficiently providing OX reactants for the diffusion‐controlled OX electroreduction and removal of GO products from the electrode to prevent the over‐reduction to glycolic acid. Additionally, the electroreduction treatment introduces more Ti3+ active sites and modulates the conduction band position of H‐TiO2NTs‐2, thereby enhancing the reduction driving force. Owing to the unique structural advantages, the Faraday efficiency of generating GO from OX reaches up to 81.3 % in an oxalic acid saturated electrolyte at 20 °C with a current density of 1500 A m−2. This designed H‐TiO2NTs‐2 holds broad application prospects in OX electroreduction.

Ultrasound-responsive ZnS:Ag QDs loaded TiO2 biointerfaces: In situ sonodynamic antimicrobial therapy for biomedical implants

Sonodynamic therapy (SDT) is extensively utilized for its profound tissue penetration capabilities in treating deep-seated infections, yet achieving precise ultrasonic treatment at the implant surface remains challenging. Herein, details the development of a novel infection microenvironment-sensitive nano-interface (TN-HHTZ), aimed at enhancing SDT efficacy for treating implant-related infections. The ZnS:Ag quantum dots (ZnS:Ag QDs) are functionalized using tyramine-modified hyaluronic acid (HA-Tyr) and horseradish peroxidase (HRP), resulting in the formation of a hydrogen peroxide (H2O2)-sensitive composite sonosensitizer (HHTZ). HHTZ is loaded onto a titanium dioxide nanotube (TN) array to form TN-HHTZ. Upon infection, ultrasonic triggering causes the rapid release of HHTZ, which interacts with H2O2 in the infected area to form a gel, thereby enabling prolonged enrichment of ZnS:Ag QDs at the site of implant infection. The doping of Ag in ZnS:Ag QDs enhances energy conversion, enabling TN-HHTZ to generate a significant amount of reactive oxygen species (ROS) during the SDT process, thereby boosting its antimicrobial efficacy and ensuring sustained antimicrobial activity throughout the infection period. The TN-HHTZ hydrogel on the implant surface promotes bone cell proliferation and recovery, providing an innovative and holistic strategy for treating and recovering from implant-associated microbial infections.

Covalent Grafting of Tanfloc on Titania Nanotube Arrays: An Approach to Mitigate Bacterial Adhesion and Improve the Antibacterial Efficacy of Titanium Implants

Covalent Grafting of Tanfloc on Titania Nanotube Arrays: An Approach to Mitigate Bacterial Adhesion and Improve the Antibacterial Efficacy of Titanium Implants

The M2 Macrophages Derived Migrasomes From the Surface of Titania Nanotubes Array as a New Concept for Enhancing Osteogenesis (Adv. Healthcare Mater. 20/2024)

The M2 Macrophages Derived Migrasomes From the Surface of Titania Nanotubes Array as a New Concept for Enhancing Osteogenesis (Adv. Healthcare Mater. 20/2024)

Facile synthesis, characterization, and in vitro biocompatibility of free‐standing titania hollow microtubes

AbstractTitania nanotube (NT) arrays have been widely used as cell‐supporting matrices. However, cells are always seeded on the porous surface of the NT array and have very limited interactions with each individual NT in the array. In this study, titania hollow microtubes (HMTs) were synthesized via a gelatin‐template sol‐gel route and then utilized as free‐standing cell‐supporting matrices for the first time. The resultant titania HMTs were studied by field emission scanning electron microscopy, energy‐dispersed spectroscopy, X‐ray diffraction, and Fourier‐transform infrared spectroscopy. Each HMT was composed of rutile‐type titania nanoparticles with diameters of 50–100 nm and a diameter of 50–100 µm. The results from a leaching liquor assay demonstrated good biocompatibility of titania HMTs. Each HMT has been demonstrated to independently support the adhesion and proliferation of osteoblast MC3T3‐E1 cells. For comparison, titania NT arrays, not independent titania NT, only supported the adhesion of cells on their porous surface. Thus, the resultant titania HMTs are applicable to free‐standing and biocompatible cell‐supporting matrices.

Various Antibacterial Strategies Utilizing Titanium Dioxide Nanotubes Prepared via Electrochemical Anodization Biofabrication Method.

Currently, titanium and its alloys have emerged as the predominant metallic biomaterials for orthopedic implants. Nonetheless, the relatively high post-operative infection rate (2-5%) exacerbates patient discomfort and imposes significant economic costs on society. Hence, urgent measures are needed to enhance the antibacterial properties of titanium and titanium alloy implants. The titanium dioxide nanotube array (TNTA) is gaining increasing attention due to its topographical and photocatalytic antibacterial properties. Moreover, the pores within TNTA serve as excellent carriers for chemical ion doping and drug loading. The fabrication of TNTA on the surface of titanium and its alloys can be achieved through various methods. Studies have demonstrated that the electrochemical anodization method offers numerous significant advantages, such as simplicity, cost-effectiveness, and controllability. This review presents the development process of the electrochemical anodization method and its applications in synthesizing TNTA. Additionally, this article systematically discusses topographical, chemical, drug delivery, and combined antibacterial strategies. It is widely acknowledged that implants should possess a range of favorable biological characteristics. Clearly, addressing multiple needs with a single antibacterial strategy is challenging. Hence, this review proposes systematic research into combined antibacterial strategies to further mitigate post-operative infection risks and enhance implant success rates in the future.

Facile preparation of CoFe-MnO2@titania nanotube array bifunctional electrodes for high-current-density water splitting at industrial temperatures

The development of bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at high current density under industrial temperatures is crucial for large-scale industrial hydrogen production from water splitting. In this work, M-MnO2@TNTA composite electrodes were prepared by depositing various metal ion-doped manganese oxide nanoparticles on the titania nanotube array (TNTA) by successive ionic layer adsorption reaction (SILAR) method, and their HER and OER electrocatalytic performances were investigated in 1 M KOH. Results show that the CoFe-MnO2@TNTA composite electrode prepared by simultaneous doping of Co3+ and Fe3+ in MnO2 exhibits optimal catalytic performance. Compared with MnO2@TNTA without ion doping, the overpotentials of CoFe-MnO2@TNTA at 10 mA cm−2 (η10) for HER and OER are reduced by 571 and 665 mV. In addition, the electrode performance can be significantly enhanced by increasing the test temperature, and the porous array structure enables CoFe-MnO2@TNTA to exhibit better performance at high current densities. At 50 °C, which is the common industrial electrolytic water temperature, the η10 of CoFe-MnO2@TNTA for HER is almost equal to that of the Pt/C electrode. The η100 of CoFe-MnO2@TNTA for HER is reduced by 35 mV compared with the Pt/C electrode. Moreover, η200 of CoFe-MnO2@TNTA for OER is significantly lowered by 111 and 184 mV compared with IrO2 and RuO2 electrodes. Utilizing CoFe-MnO2@TNTA as both the cathode and anode for overall water splitting, the electrolysis voltage is merely 2.33 V under the current density of 200 mA cm−2, much lower than that of IrO2 (+)||Pt/C (–) (2.68 V). The present work may provide a valuable reference for the development of self-supporting bifunctional electrodes suitable for high-current-density water splitting at industrial temperatures.

Molybdenum-Modified Titanium Dioxide Nanotube Arrays as an Efficient Electrode for the Electroreduction of Nitrate to Ammonia

Electrochemical nitrate reduction (NO3−RR) has been recognized as a promising strategy for sustainable ammonia (NH3) production due to its environmental friendliness and economical nature. However, the NO3−RR reaction involves an eight-electron coupled proton transfer process with many by-products and low Faraday efficiency. In this work, a molybdenum oxide (MoOx)-decorated titanium dioxide nanotube on Ti foil (Mo/TiO2) was prepared by means of an electrodeposition and calcination process. The structure of MoOx can be controlled by regulating the concentration of molybdate during the electrodeposition process, which can further influence the electron transfer from Ti to Mo atoms, and enhance the binding energy of intermediate species in NO3−RR. The optimized Mo/TiO2-M with more Mo(IV) sites exhibited a better activity for NO3−RR. The Mo/TiO2-M electrode delivered a NH3 yield of 5.18 mg h−1 cm−2 at −1.7 V vs. Ag/AgCl, and exhibited a Faraday efficiency of 88.05% at −1.4 V vs. Ag/AgCl. In addition, the cycling test demonstrated that the Mo/TiO2-M electrode possessed a good stability. This work not only provides an attractive electrode material, but also offers new insights into the rational design of catalysts for NO3−RR.

Antimony Trisulfide with Graphene Oxide Coated Titania Nanotube Arrays as Anode Material for Lithium-ion Batteries

Antimony Trisulfide with Graphene Oxide Coated Titania Nanotube Arrays as Anode Material for Lithium-ion Batteries

Effect of graphene oxide loaded on TiO2-nanotube-modified Ti on inflammatory responses

Although a titanium matrix modified with titanium dioxide nanotube (TNT) arrays can have anti-inflammatory effects in vitro, these effects are limited. In this study, the TNT surface was modified by electrodepositing graphene oxide (GO) to enhance the anti-inflammatory effect of the material. Scanning electron microscopy (SEM), Raman spectroscopy, and x-ray diffraction were used to characterize each of these materials. Cell Counting Kit-8 (CCK-8) was used to determine the cell proliferation status. Enzyme-linked Immunosorbent Assay (ELISA), immunofluorescence staining, and RNA sequencing were used to assess the regulation of inflammation in each group. Raman spectroscopy confirmed that GO was successfully loaded onto the surface. The SEM, ELISA, fluorescence staining, and RNA sequencing results indicated that TNT-GO can effectively inhibit the inflammatory response and induce the M2 polarization of macrophages. TNT-GO can weaken the surface inflammatory responses of materials, suppress the secretion of pro-inflammatory factors, and promote the M2 polarization of macrophages. These advantageous properties render TNT-GO a promising material for dental implants.

Copper-Decorated Titanium Electrodes: Impact of Surface Modifications of Substrate on the Morphology and Electrochemical Performance.

This study investigates the effect of surface modifications of the titanium substrate on the growth of electrochemically deposited copper. These materials are intended to serve as cathodes in the electroreduction of nitrates in aqueous solutions. Surface modifications included the use of hydrogen fluoride for titanium etching and anodization to promote the growth of a structured titania nanotube array. The effect of an intermediate calcination step for the nanotubes before deposition was assessed along with a comparison to an untreated substrate electrode. The materials were comprehensively characterized by SEM, XRD, contact angle, potentiodynamic tests, EIS, and cyclic voltammetry. Their electrocatalytic ability was tested in the reduction of aqueous solutions containing nitrates. The results reveal that surface finishing impacted the shape and size of the Cu microparticles, as well as the nucleation mechanism enabling a crystal-facet-controllable synthesis. All the materials exhibited microsized copper particles with a spherical shape with some clusters. On the etched titanium surface, a high number of heterogeneous submicroscopic particles were also present. The thermally treated anodized substrate promoted the development of a combination of sparse microparticles corresponding to defect sites in amorphous titanium and the presence of a diffuse coating of octahedral nanosized particles whose growth was promoted by the tetragonal structure of anatase crystals. Electrochemical tests display reduced charge transfer resistance upon copper deposition on the modified substrates, which is indicative of the enhanced conductivity of the coated materials. Additionally, cyclic voltammetry and electrolysis experiments reveal the electrodes' potential for nitrate reduction, showing a better response for the etched titanium substrate (30% nitrate removal, after 2 h at 25 mA cm-2).

Molecularly imprinted polymer photoelectrochemical sensor for the detection of triazophos in water based on carbon quantum dot-modified titanium dioxide.

Widely used organophosphorus pesticide triazophos (TAP) can easily cumulate in aquatic system due to its high stability chemically and photochemically and thus posing significant threat to aquatic creatures and humans' health. Urging demand for rapid determiningTAP in water has risen. Photoelectrochemical (PEC) sensing turns out to be a good candidate for its simplicity in fabrication and swiftness in detection. Nevertheless, traditional PEC sensors often lack selectivity as their signal generation primarily relies on the oxidation of organic compounds in the electrolyte by photo-induced holes. To address this limitation, molecularly imprinted polymers (MIPs) can be in combined with PEC sensors to significantly enhance the selectivity. Here, we present a novel approach utilizing a PEC sensor enhanced by carbon-modified titanium dioxide molecularly imprinted polymers (MIP/C/TiO2 NTs). Carbon quantum dot (CQD) modification of titanium dioxide nanotube arrays (C/TiO2 NTs) was achieved through a one-step anodization process, effectively enhancing visible light absorption by narrowing the band gap of TiO2, and CQDs also function as sensitizer accelerating charge transfer for improved and stable photocurrent signals during detection. Our method further incorporates MIPs to heighten the selectivity of the PEC sensor. Electro-polymerization using cyclic voltammetry was employed to polymerize MIPs with pyrrole as the functional monomer and triazophos as the target molecule. The resultant MIP/C/TiO2 NT sensor exhibited remarkable sensitivity, with a detection limit of 0.03nM (S/N = 3), alongside exceptional selectivity and stability for triazophos detection in water. This offers a promising avenue for efficient, cost-effective, and rapid monitoring of pesticide contaminants in aquatic environments, contributing to the broader goals of environmental preservation and public health.

The M2 Macrophages Derived Migrasomes From the Surface of Titania Nanotubes Array as a New Concept for Enhancing Osteogenesis.

As newly discovered substrate anchored extracellular vesicles, migrasomes (Migs) may bring a new opportunity for manipulating target cells bioactivities. In this study, the M2 macrophages derived Migs are obtained by titania nanotubes surface (NTs). Due to the benefits of nanostructuring, the NTs surface is not only able to induce RAW264.7 for M2 polarization but also to generate more Migs formation, which can be internalized by following seeded mesenchymal stem cells (MSCs). Then, the NTs surface induced Migs are collected by density-gradient centrifugation for MSCs treatment. As indicated by immunofluorescence staining, alkaline phosphatase activity, and alizarin red staining, the osteogenic differentiation capacity of MSCs is significantly enhanced by Migs treatment, in line with the dosage. By RNA-sequence analysis, the enhancement of osteogenic differentiation is correlated with PI3K-AKT pathway activation that may originate from the M2 polarization state of donor cells. Finally, the Migs are coated onto Ti surface for therapeutic application. Both the in vitro and in vivo analysis reveal that the Migs coated Ti implant shows significant enhancement of osteogenesis. In conclusion, this study suggests that the nanosurface may be a favorable platform for Migs production, which may bring a new concept for tissue regeneration.

Double-sided semitransparent titania photoelectrode with enhanced light harvesting

In this work, unique semitransparent electrodes were prepared by the anodization of titanium layers (540 nm thick) initially deposited on the both sides of glass substrates employing indium-tin oxide interface layers serving as a current collector for the induced photocurrent. The anodization strategy used in this study enables fabrication of semitransparent titanium dioxide nanotube arrays with either aligned or spaced architecture on the two sides of the planar substrate. This study aims to perform a detailed investigation of this novel photoelectrode system (crystal structure, morphology and optical properties) to reveal their photoelectrochemical features. It was found that the photoelectrode exhibits enhanced photocurrent density about 1.9 times higher (4.6 μAcm−2 at +0.5 V) for aligned nanotubes compared to a substrate overgrown symmetrically by separated nanotubes (2.4 μAcm−2 at +0.5 V). This can be effectively explained by the higher tube density in the case of aligned nanostructures, which provide more channels for charge percolation. In addition, both the high donor concentration (6.4 × 1020 cm−3) together with the low charge transfer resistance of the semitransparent electrode of the aligned nanotubes make the material promising for application in photoelectrochemical systems and smart light management.

Electro-assisted photocatalytic reduction of CO2 in ambient air using Ag/TNTAs at the gas-solid interface

The direct conversion of atmospheric CO2 into fuel via photocatalysis exhibits significant practical application value in advancing the carbon cycle. In this study, we established an electro-assisted photocatalytic system with dual compartments and interfaces, and coated Ag nanoparticles on the titanium nanotube arrays (TNTAs) by polydopamine modification. In the absence of sacrificial agent and alkali absorption liquid conditions, the stable, efficient and highly selective conversion of CO2 to CO at the gas-solid interface in ambient air was realized by photoelectric synergy. Specifically, with the assistance of potential, the CO formation rates reached 194.9 μmol h−1 m−2 and 103.9 μmol h−1 m−2 under ultraviolet and visible light irradiation, respectively; the corresponding CO2 conversion rates in ambient air were 30% and 16%, respectively. The excellent catalytic effect is mainly attributed to the formation of P–N heterojunction during the catalytic process and the surface plasmon resonance effect. Additionally, the introduction of solid agar electrolytes effectively inhibits the hydrogen evolution reaction and improves the electron utilization rate. This system promotes the development of photocatalytic technology for practical applications and provides new insights and support for the carbon cycle.

Long-Term Stability of Light-Induced Ti3+ Defects in TiO2 Nanotubes for Amplified Photoelectrochemical Water Splitting.

This study shows that the simple approach of keeping anodic TiO2 nanotubes at 70 °C in ethanol for 1 h results in improved photoelectrochemical water splitting activity due to initiation of crystallization in the material amplified by the light-induced formation of a Ti3+ -Vo states under UV 365 nm illumination. For the first time, the light-induced Ti3+ -Vo states are generated when oxygen is present in the reaction solution and are stable when in contact with air (oxygen) for a long time (two months). We confirmed here that the amorphous or nearly amorphous structure of titania supports the survival of Ti3+ species in contact with oxygen. It is also shown that the ethanol treatment substantially improves the morphology of the titania nanotube arrays, specifically, less surface cracking and surface purification from C- and F-based contamination from the electrolyte used for anodizing.

Polydopamine-Modified Titanium Dioxide Nanotube Arrays Doped with Calcium as a Sustained Drug Delivery System.

Titanium nanotube (TNT) arrays manufactured via electrochemical anodization have been widely used as local drug carriers due to their excellent biocompatibility and customizable nanotubular structures. However, the uncontrollable and abrupt drug release at the early stage decreases the drug release duration, leading to excessive drug concentration at the implantation site. In this study, a continuous drug delivery system based on TNTs was created. Initially, a basic ultrasound-assisted approach was utilized to deposit a polydopamine (PDA) coating onto TNTs to obtain PDA-modified TNTs. Next, TNTs-PDA were submerged in a calcium chloride solution to include Ca2+ through Ca2+ coordination between the PDA layer's catechol groups. Sodium alendronate (NaAL) was used as a model drug and loaded onto TNTs-PDA-Ca2+ by immersing them in an NaAL solution. In the final step, NaAL was covalently attached to TNTs-PDA-Ca2+ through coordination bonds with Ca2+. The samples underwent characterization through the use of various techniques, including field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction patterning, X-ray photoelectron spectroscopy, and inductively coupled plasma emission spectrometry. The results indicated that the bioactivity of TNTs improved, and there was an enhancement in drug loading capacity and release performance due to modification with PDA and Ca2+. Furthermore, acidic conditions can cause significant drug release due to the cleavage of coordination bonds between the drug and Ca2+ ions. Thus, the aforementioned drug delivery system represents a potentially promising approach for achieving sustained and controllable drug release.

Novel portable photoelectrochemical sensor based on CdS/Au/TiO2 nanotube arrays for sensitive, non-invasive, and instantaneous uric acid detection in saliva

Uric acid (UA) monitoring is the most effective method for diagnosis and treatment of gout, hyperuricemia, hypertension, and other diseases. However, challenges remain regarding detection efficiency and rapid on-site detection. Here, we first synthesized a CdS/Au/TiO2-NTAs Z-scheme heterojunction material using a titanium dioxide nanotube array (TiO2-NTAs) as the substrate and modified with gold nanoparticles (Au) and cadmium sulfide particles (CdS). This material achieves bandgap alignment to generate a large number of electron-hole pairs under illumination. Then, using CdS/Au/TiO2-NTAs as the working electrode and molecularly imprinted polymers (MIP) as the recognition unit, we constructed a portable photoelectrochemical (PEC) sensor for non-invasive instant detection of UA concentration in human saliva, which has unique advantages in the field of high-sensitivity PEC instant detection. The portable MIP-PEC sensor achieves a linear range of 0.01–50 μM and a detection limit as low as 5.07 nM (S/N = 3). At the same time, the portable MIP-PEC sensor exhibits excellent sensitivity, specificity as well as stability, and shows no statistically significant difference compared to traditional high-performance liquid chromatography (HPLC) in practical sample detection. Compared to traditional PEC modes, this work demonstrates a novel and universal method for high-sensitivity instant detection in the field of PEC.

Surface characterization and antibacterial efficiency of well-ordered TiO2 nanotube surfaces fabricated on titanium foams

Titanium (Ti)-based implants are not compatible enough due to their bio-inert character, insufficient antibacterial capabilities and stress-shielding problem for dental and orthopaedic implant applications. Thus, this work focused to fabricate, analyze and improve antibacterial properties titanium dioxide (TiO2) nanotube array surfaces on Ti foam by anodic oxidation (AO) process. The well-ordered nanotube arrays with approximately 75 nm were successfully fabricated at 40 V for 1 h on Ti foams. Ti and O were observed as major elements on AO-coated Ti foam surfaces. In addition, the existence of TiO2 structure was proved on AO-coated foam Ti surfaces. For potential dental and orthopedic implant application, in vitro antibacterial properties were investigated versus Staphylococcus aureus and Escherichia coli. For both bacteria, antibacterial properties of TiO2 nanotube surface were greater than bare Ti foam. The bacterial inhibition versus Staphylococcus aureus and Escherichia coli of TiO2 nanotube surfaces are improved as 53.3% and 69.4% compared to bare Ti foam.