Nanotube Arrays Research Articles

Efficient and stability electrochemical degradation of Bisphenol A on Ti/TiO2-NTA/PbO2-Nd anode: Mechanistic analysis

The Ti/TiO2-NTA/PbO2-Nd electrodes were fabricated using anodic oxidation and electrodeposition techniques for the electrocatalytic treatment of bisphenol A (BPA) pollutants in coking wastewater. Characterization revealed well-organized TiO2 nanotube arrays (TiO2-NTA) with a hollow structure, featuring a wall thickness of 36 nm and an inner diameter of approximately 83 nm. The TiO2-NTA interlayer restricted PbO2 growth, leading to a compact crystal structure and increased electrode surface area. Electrochemical tests showed that the Ti/TiO2-NTA/PbO2-Nd electrode outperformed Ti/TiO2-NTA/PbO2 and Ti/PbO2 electrodes, exhibiting the highest oxygen evolution potential, lowest charge transfer resistance, optimal hydroxyl radical generation, and longest service lifetime. The removal efficiencies for BPA were 95.4 % for Ti/TiO2-NTA/PbO2-Nd, 90.8 % for Ti/TiO2-NTA/PbO2, and 80.6 % for Ti/PbO2. The Ti/TiO2-NTA/PbO2-Nd electrode also achieved the lowest energy consumption at 0.157 kWh/(g·COD), a 40 % reduction compared to Ti/PbO2. The introduction of TiO2-NTA enhanced electrode stability, electron transfer, and surface area, while neodymium (Nd) doping improved oxygen evolution potential and hydroxyl radical production. Under optimized conditions, the Ti/TiO2-NTA/PbO2-Nd electrode achieved BPA removal efficiencies of 99.24 %, COD removal efficiencies of 82.77 %, and TOC removal efficiencies of 78.92 %. UV–Vis spectrophotometry, three-dimensional excitation-emission matrix fluorescence spectra (3D EEM), and gas chromatography–mass spectrometry (GC–MS) analyses revealed potential BPA degradation pathways.

Improving light harvesting and charge carrier separation enabling enhanced photoelectrochemical hydrogen production by Sb2S3-decorated TiO2 nanotube arrays on porous Ti-photoanodes

The Ag + ions doped TiO2 nanotube arrays fabricated on Ti mesh through an electrochemical anodization process, and n/n heterostructure formed by coating the TiO2 nanotube array photoanode with an n-type stibnite (Sb2S3) layer improve photoelectrochemical water splitting reaction by enhancing light harvesting and charge carrier separation. Sb2S3 is chosen because of its suitable band gap position and strong visible light response. The Ag + ion incorporated TiO2 nanotube array coated with Sb2S3 exhibits a photocurrent density of 6.5 mA cm−2 vs. RHE, whereas bare TiO2 nanotube array coated with Sb2S3 and pristine TiO2 nanotube array exhibit photocurrent densities of 3.6 and 0.27 mA cm−2, respectively, under the same conditions, which is nearly 1.8 and 24 times greater than the TiO2 nanotube array coated with Sb2S3 and pristine TiO2 nanotube array photoanodes. The applied bias photon-to-current efficiency of Ag + ion incorporated TiO2 nanotube array coated with Sb2S3 is 3.6% and the improved Photoelectrochemical performance of Ag + ion doped TiO2 nanotube array coated with Sb2S3 is attributable to higher conductivity of TiO2 nanotube array caused by increased oxygen vacancies and broad optical activity of Sb2S3. The 1-dimensional TiO2 nanotube array device structure in the Ti mesh improves charge separation and light harvesting while reducing photogenerated charge carrier recombination and the potential of this novel device structure for advanced energy conversion applications is highlighted in this study.

Electrophoretic loading of alendronate on TiO2 nanotube arrays

TiO2 nanotube arrays(TNTs) were prepared on titanium-based surfaces by electrochemical anodic oxidation method and used as drug delivery carriers. Using the principle of electrophoresis, the drug loading capacity of alendronate was significantly increased to achieve a long-term sustained release. Chitosan(CS) coating containing diclofenac sodium(DCS) on the surface of TNTs conferred anti-inflammatory and pH-smart response properties to the materials and improved antimicrobial and osseointegration properties. These findings are important for improving the performance of bone implant materials.

N- and Ti3+-codoped TiO2 nanotube-modified SnO2-Sb electrode for the effective degradation of caprolactam wastewater

This study prepared the N- and Ti3+-codoped TiO2 nanotube-modified(TiON) SnO2-Sb electrode. The analysis of the surface topography, structure characteristics, chemical state, electrochemical characteristics of the interlayer and active layers reveals that the doped TiO2 nanotubes arrays exhibit superior electrical conductivity and a higher surface area, which facilitates the binding of enhanced antimony tin oxide(ATO) coating. Compared with TM/ATO electrode without TiON interlayer, stability and catalytic performance of the TM/TiON/ATO electrode were substantially enhanced, which improved by 32 % and nearly 10 times. Simultaneously, influence of initial pH and current density on the degradation effectiveness and electrical energy consumption were studied, and the failure mechanisms analysis of the electrode was analyzed. Research has demonstrated that TM/TiON/ATO exhibits both stability and efficiency, rendering it a highly favorable material for the anode.

Construction of self-supported TiO2 nanotube arrays with hybrid point defect engineering: A bifunctional anode for Li+/Na+ storage

Point defect engineering has garnered widespread application for enhancing the dynamic behavior of anode materials and improving electrochemical performance. Herein, a hybrid point defect strategy is proposed in Ti-based oxide materials to achieve N doping induced oxygen vacancies (OVs) and subsequently accelerated electron mobility and perform better diffusion kinetics. This methodology culminates in the fabrication of self-supported nanotube arrays comprising N-doped OVs-rich TiO2 (denoted as N-TNTs). Density functional theory (DFT) calculations and electrochemical characterizations validate that, hybrid point defects lead to high electron mobility and perform better diffusion kinetics, as well as higher Li+/Na+ ions adsorption energy barrier and diffusion energy barrier, which in turn improves the rate performance and cycling stability. This research provides a forward-looking and feasible strategy for the application of point defect engineering in anode materials.

A pH and near-infrared light dual-responsive drug delivery system based on TiO2 nanotube arrays modified with polydopamine and Fe3+

This paper reports a novel drug delivery system based on TiO2 nanotube arrays (TNTs) modified with polydopamine (PDA) and Fe3+, which can load and release alendronate (NaAL), a drug for osteoporosis treatment, in a pH-responsive and near-infrared light-triggered manner. The samples were characterized by electron scanning microscopy(SEM/EDS), Fourier Transform infrared spectroscopy(FTIR), X-ray diffraction(XRD), X-ray Photoelectron Spectroscopy(XPS) and Thermogravimetry(TG). The drug release behavior of the samples was investigated under different pH and light conditions. The results showed that the TNTs-PDA-Fe3+ had improved drug loading capacity compared with the TNTs and TNTs-PDA. The drug release was pH-responsive and near-infrared light-triggered, the drug release from the sample with a pH of 4.6 was much greater than the pH of 11 and 7.4, and the photothermal conversion effificiency of TNTs-PDA-Fe3+-NaAL was 32.9 %. The drug release mechanism was attributed to the coordination bond between Fe3+ and NaAL, and the photothermal effect of the PDA. The cytotoxicity and biocompatibility of the samples were evaluated by MTT assay using mouse embryonic osteoblasts cells. The results indicated that the samples had no obvious cytotoxicity and could promote the cell proliferation and differentiation. The paper concludes that the TNTs-PDA-Fe3+-NaAL system is a potential implantable drug delivery platform for bone-related diseases.

H2O2-assisted photo-electrocatalytic and photocatalytic degradation of methyl violet by CuO-modified TiO2 nanotube arrays

Photoelectrocatalytic degradation is an environmental friendly and efficient technique providing solutions for the dire issue of water pollution. TiO2 nanotubes are widely used as the photocatalyst but its efficiency is restricted by the wide band gap. This study deals with the fabrication of CuO-modified TiO2 nanotubes by electrochemical anodization following the hydrothermal method to enhance the photocatalytic degradation. Optical studies revealed a reduction in the bandgap (2.12 eV) of CuO-modified TiO2 nanotubes, which plays an important role in increasing the photocatalytic activity. The effect of CuO loading on TiO2 nanotubes in photocatalytic degradation as well as the effect of bias and H2O2 on photo-electrocatalytic degradation were studied. In photocatalytic degradation, 0.05 M CuO–TiO2 photocatalyst produced a maximum degradation of 49.5 % in 8 h. Compared with the pristine TiO2 nanotubes, the photodegradation of CuO-loaded TiO2 nanotubes increased by 16 %. Furthermore, when an external bias was applied, the photodegradation efficiency increased by 36 %. In addition of H2O2 to the PEC system, 0.05 CuO–TiO2 photocatalyst produced 100 % degradation of methyl violet in 2.5 h. Reusability studies showed that the photocatalysts are stable and can therefore be used for practical applications such as photocatalytic degradation and photoelectrochemical degradation of methyl violet.

Photocatalytic activity of molybdenum disulfide nanotube arrays with different wall thicknesses under visible light

Light trapping based on nanostructure has emerged as an effective method to improve light absorption of the photocatalytic devices. Herein, molybdenum disulfide nanotube arrays with different wall thicknesses were successfully synthesized by changing reactant concentration from 50 % to 150 %. The nanotubes overcame aggregation of the nanosheets, offered multiple scattering centers and enabled multiple refraction of light, leading to excellent light harvest in the visible range and molecule absorption efficiency as high as 21.0 %. The photodegradation efficiency of methylene blue as catalyzed by the nanotubes was modulated by the wall thickness, in which the highest degradation efficiency of 69.6 % and the largest kinetic constant of 5.516×10−3min−1·cm−2 were achieved for the thinnest wall. The analysis revealed that the photocatalytic activity of the nanotube arrays was dominated by the dye absorption, environment, light excitation and charge recombination, which would provide structural design for their applications in optoelectronics and photocatalysis.

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.

Bamboo-like MnO2/TiO2 Nanotube Arrays with Enhanced Photocatalytic Degradation

Bamboo-like MnO2/TiO2 Nanotube Arrays with Enhanced Photocatalytic Degradation

Carbon cloth with lithiophilic carbon-coated ZnO nanotubes as anode current collector for hybrid lithium ion/lithium metal battery

Reasonable design of light-weight carbon-based current collector is a promising strategy to enable high-energy-density lithium batteries. Herein, carbon-coated ZnO nanotube arrays with good lithiophilicity are constructed on carbon cloth, which is used as anode current collector to construct hybrid lithium ion/lithium metal battery. The modified carbon cloth effectively promotes the formation of robust and inorganic-rich solid electrolyte interphase, which consists of mixed ionic-electronic conductive (MIEC) interface with ion-conductive Li2O/LiC6 and electron-conductive LiZn alloy. Rapid electron/ion transportation during repeated lithium plating/stripping is realized by the Li2O/LiZn/LiC6 MIEC arrays, which homogenizes the lithium deposition and ensures uniform dendrite-free Li deposition. The three-dimensional structure of the current collector also provides enough space to constrain the lithium deposition and avoid the huge volume change. As a result, continuous anode-electrolyte interfacial side reactions and active lithium loss are effectively suppressed. Uniform Li deposition and high average Coulombic efficiency are achieved in the hybrid lithium ion/lithium metal cell. The capacity retention of full cell with carbonate-based electrolyte maintains 47.0 % after 600 cycles, and the full cell also shows superiority in rate performance and energy density. This work provides a promising alternative for light-weight anode current collector to enable high-energy-density lithium batteries.

Simultaneous tartrazine-tetracycline removal and hydrogen production in the hybrid electrocoagulation-photocatalytic process using g-C3N4/TiNTAs

This study aimed to investigate the removal of tartrazine dye & tetracycline antibiotic and hydrogen (H2) production simultaneously through the hybrid electrocoagulation-photocatalytic process using g-C3N4/TiO2 nanotube arrays (TiNTAs) nanocomposite. The g-C3N4/TiNTAs was used as the photocatalyst. The melamine as the precursor of g-C3N4 was varied to obtain the optimal loading on the removal of tartrazine dye & tetracycline antibiotic and hydrogen (H2) production simultaneously. The integrated acrylic photoreactor was equipped with two 250-W mercury lamps. The nanotubular morphology of TiNTAs and nanostructure features of g-C3N4/TiNTAs were examined using FESEM/EDX and HR-TEM/SAED. The XRD patterns indicated the composition of TiNTAs, confirming the presence of anatase and rutile crystalline phases. UV-Vis DRS also showed a redshift in the composite absorbance and a reduced bandgap with g-C3N4 introduction. The results showed that when tartrazine and tetracycline were treated simultaneously, tartrazine was more dominantly degraded compared to tetracycline. In mixed pollutant system condition, the H2 production increased by 17.0% and 41.1% compared to single pollutant system of tartrazine and tetracycline, respectively. The photocatalyst used in the hybrid process was the g-C3N4/TiNTAs (3 g) which provide the optimum H2 production.

Interface States in Gate Stack of Carbon Nanotube Array Transistors.

A deep understanding of the interface states in metal-oxide-semiconductor (MOS) structures is the premise of improving the gate stack quality, which sets the foundation for building field-effect transistors (FETs) with high performance and high reliability. Although MOSFETs built on aligned semiconducting carbon nanotube (A-CNT) arrays have been considered ideal energy-efficient successors to commercial silicon (Si) transistors, research on the interface states of A-CNT MOS devices, let alone their optimization, is lacking. Here, we fabricate MOS capacitors based on an A-CNT array with a well-designed layout and accurately measure the capacitance-voltage and conductance-voltage (C-V and G-V) data. Then, the gate electrostatics and the physical origins of interface states are systematically analyzed and revealed. In particular, targeted improvement of gate dielectric growth in the A-CNT MOS device contributes to suppressing the interface state density (Dit) to 6.1 × 1011 cm-2 eV-1, which is a record for CNT- or low-dimensional semiconductors-based MOSFETs, boosting a record transconductance (gm) of 2.42 mS/μm and an on-off ratio of 105. Further decreasing Dit below 1 × 1011 cm-2 eV-1 is necessary for A-CNT MOSFETs to achieve the expected high energy efficiency.

Investigation of a visible-light-driven molecularly imprinted photoelectrochemical sensing platform for ultrasensitive and selective detection of diflubenzuron utilizing an in-situ grown 3D hierarchical structure

An ultrasensitive molecularly imprinted polymer-photoelectrochemical (MIP-PEC) sensing platform has been successfully fabricated for the detection of diflubenzuron (DBZ) under visible-light irradiation. The noval photoactive material was a ternary Bi2S3/BiVO4/TiO2 nanotube arrays (BVT) heterojunction, grown in-situ on a Ti substrate. The distinct architecture of BVT featured BiVO4 nanoparticles anchored onto TiO2 nanotube arrays and wrapped by Bi2S3 nanofibers. This innovative design, coupled with the aligned energy bands of BVT, significantly boosted visible-light absorption, and photo-induced charge separation and transfer, leading to an enhanced photocurrent response surpassing that of binary and single-component systems. The sensing platform displayed remarkable sensitivity and a broad detection range for DBZ with a linear range of 0.01–1000 ng mL−1 and a limit of detection of 1.25 pg mL−1. Its selectivity was further validated by comparable photocurrent responses in the presence of interfering substances, highlighting its accuracy in detecting DBZ in complex matrices. Additionally, the sensing platform demonstrated excellent stability and reproducibility, ensuring reliable results over multiple measurements. Evaluation of the sensing platform in real samples, including tap water and apples, has confirmed its high accuracy with recovery rates between 94.4 % and 103.4 %. Therefore, this visible-light-driven MIP-PEC sensing platform exhibits considerable potential for application in ultrasensitive detection of DBZ. This work offers novel insights into the in-situ preparation of high-performance sensors for applications in food safety and environmental monitoring.

Fast Response UV Photodetector Based on Aligned Arrays of Anodic Anatase TiO2 Nanotubes

Fast Response UV Photodetector Based on Aligned Arrays of Anodic Anatase TiO2 Nanotubes

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.

Mathematical Modeling of Diffraction and Parametric Instability Thresholds for Magnetic Nanostructures Based on Magnetically Functionalized Carbon Nanotube Arrays

Mathematical Modeling of Diffraction and Parametric Instability Thresholds for Magnetic Nanostructures Based on Magnetically Functionalized Carbon Nanotube Arrays

Honeycomb-shaped vertically aligned carbon nanotubes decorated with molybdenum trioxide as an electrochemical sensor for glucose

In this study, an electrode based on transition metal oxide molybdenum trioxide (MoO3) was fabricated and applied to electrochemical biosensing for glucose. In the process of making electrodes with relatively larger specific surface areas, an array of carbon nanotubes (CNTs) was deposited on a silicon substrate, and then, MoO3 was coated on the array of CNTs by chemical vapor deposition to produce a MoO3/CNTs/Si structure of three-dimensional electrochemical biosensing electrodes. Biosensing measurement was carried out in the concentration region from 20 μM to 7 mM of sodium hydroxide (NaOH). The highest sensitivity of 17.4 μA/μM cm2 was measured in the concentration range of 20–100 μM. The correlation coefficient of linear response (R2) was 0.9929, thus showing that MoO3/CNTs/Si is an excellent nonenzymatic glucose electrochemical sensor.

Preparation and photocatalytic performance of BiOCl nanosheet–TiO2 nanotube array composites

Combining BiOCl with TiO2 nanomaterials is beneficial to enhance the photocatalytic activity and optoelectronic activity. In this paper, BiOCl nanosheet–TiO2 nanotube array composites were synthesized to enhance the photocatalytic degradation performance for methyl orange (MO) of TiO2 under ultraviolet light irradiation. BiOCl nanosheets were deposited on TiO2 nanotube arrays by the straightforward impregnation method. X-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and photocurrent (i–t) were used to evaluate the composites of BiOCl nanosheets–TiO2 nanotube arrays. The results showed that the tetragonal BiOCl nanosheets clustered together on the surface of the TiO2 nanotubes and grew along the (110) crystal plane. The composites outperformed pure TiO2 regarding outstanding structure and overall photocatalytic performance, and the MO photocatalytic degradation rate was 98.5%. For the 30-BiOCl–TiO2, its photocurrent intensity (58 µA) was 4.5 higher than TiO2 (13 µA). The degradation rate of 87% can still be reached after three cycles.

Electro-assisted photothermal synergy for removal of volatile organic compounds over Au single atoms anchored TiO2 nanotubes

Gas-phase photoelectrocatalysis (GPEC) systems for treating gas pollution may lead to a Joule-heat effect and form photothermal synergy under an external bias voltage. However, such a synergistic effect and mechanism remain unclear. Herein, a electro-assisted photothermal synergistic removal of VOCs by defective TiO2 nanotube array decorated with atomically dispersed Au species was chosen as a prototypical illustration. By introducing single Au atoms, the carrier concentration and mobility of the catalytically active layer, i.e., TiO2 nanotube arrays anchored with Au single atoms, were substantially increased to the semi-metal level through an electrochemical reduction step and square-wave pulse method for anchoring single atoms. This not only contributes to the photogenerated carrier separation at low external bias but also significantly enhances the Joule heating effect on the catalyst surface. As a result, the catalyst used exhibited an excellent electro-assisted photothermal synergistic effect and outstanding efficiency in toluene removal in the designed tubular reactor. SynopsisA novel electro-assisted photothermal synergy system was constructed, which combines the advantages of gas-phase photoelectrocatalysis and electrothermal catalysis to remove VOCs with high efficiency and low energy consumption.