TiO2 Nanotubes Research Articles

TiO2 nanoparticle seeds transformed into nanotubes for effective dye-sensitized solar cell application

Morphology plays a vital role in dye-sensitized solar cells (DSSCs) due to their high surface area, dye adsorption and electron transport. In this study, we have designed and fabricated titanate nanotube photoanodes by a simple one-step hydrothermal method. High-resolution transmission electron microscope (HRTEM) analysis revealed the transformation of nanoparticles to nanotube morphology. Brauner-Emmett-Teller (BET) method showed the enhanced surface area and pore diameter of nanotubes. TiO2 nanotube photoanode showed excellent energy conversion efficiency (2.38 %), short circuit current densities (Isc) (6.29 mA/cm2), and fill factors (FF) (0.63), respectively.

Enhanced green hydrogen production via CdS/Cu-doped TiO2 nanotubes: Advancements in photoanode performance

Cadmium Sulfide (CdS) deposited Copper (Cu) doped TiO2 nanotube hybrid photoanode (CdS/Cu-TNT) is developed via electrochemical anodization and subsequent electrochemical deposition for efficient green hydrogen production. Cu-doping of TiO2 Nanotube (TNT) is achieved in one-step anodization, which is more energy efficient than conventional arc melting. Results indicate that CdS/Cu-TNT photoanodes increased carrier density by 9 times and achieved a low bandgap of 2.46 eV which enhancing their suitability as photoanodes. Particle size distribution analysis has shown that Cu doping causes thicker nanotube walls with decreased surface area. CdS is coated over the Cu-doped TNT to enhance the photoelectrochemical properties further. The photocurrent of CdS-deposited TNT is 7.8 times higher than bare TNTs. Raman Spectral Mapping indicates the uniformity of CdS deposition and Cu doping. Photostability experiments reveal excellent performance and switching characteristics for Cu-doped, CdS-deposited, and CdS/Cu-TNT hybrid samples. The hybrid electrode with larger diameter nanotubes shows a 52.39 % increase in the Fill Factor of photocurrent response for CdS/Cu-TNT. Moreover, hydrogen production is significantly enhanced, with CdS/TNT demonstrating a 3.8-fold increase and CdS/Cu-TNT demonstrating a 4.1-fold increase. This research highlights the potential of Cu doping in TiO2 nanotubes for hydrogen generation, offering improvements over the limitations of TiO2 as a photoanode.

Facile Preparation of TiO2NTs/Au@MOF Nanocomposites for High-Sensitivity SERS Sensing of Gaseous VOC.

Surface-enhanced Raman spectroscopy (SERS) is a promising and highly sensitive molecular fingerprint detection technology. However, the development of SERS nanocomposites that are label-free, highly sensitive, selective, stable, and reusable for gaseous volatile organic compounds (VOCs) detection remains a challenge. Here, we report a novel TiO2NTs/AuNPs@ZIF-8 nanocomposite for the ultrasensitive SERS detection of VOCs. The three-dimensional TiO2 nanotube structure with a large specific surface area provides abundant sites for the loading of Au NPs, which possess excellent local surface plasmon resonance (LSPR) effects, further leading to the formation of a large number of SERS active hotspots. The externally wrapped porous MOF structure adsorbs more gaseous VOC molecules onto the noble metal surface. Under the synergistic mechanism of physical and chemical enhancement, a better SERS enhancement effect can be achieved. By optimizing experimental conditions, the SERS detection limit for acetophenone, a common exhaled VOC, is as low as 10-11 M. And the relative standard deviation of SERS signal intensity from different points on the same nanocomposite surface is 4.7%. The acetophenone gas achieves a 1 min response and the signal reaches stability in 4 min. Under UV irradiation, the surface-adsorbed acetophenone can be completely degraded within 40 min. The experimental results demonstrate that this nanocomposite has good detection sensitivity, repeatability, selectivity, response speed, and reusability, making it a promising sensor for gaseous VOCs.

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.

Neurotoxic and behavioral deficit in Drosophila melanogaster exposed to photocatalytic products of Paraquat

The Advanced Oxidative Processes have demonstrated potential for application in the degradation of organic pollutants, such as Paraquat (PQ) from water and wastewater, due to their low price, high efficiency, and non-toxic properties. In this study, we investigated whether the photodegradation of PQ with TiO2 nanotubes reduced its toxicity in Drosophila melanogaster. However, dietary ingestion of degradation products PQ for larvae resulted in a low axial ratio (pupal volume). In the adults, products of photodegradation of PQ exposure markedly diminished climbing ability in a time-dependent manner after 10 days of feeding. In addition, exposure of D. melanogaster to photodegradation of PQ reduced acetylcholinesterase and citrate synthase activities but improved oxidative stress, as evidenced by oxide nitric, protein carbonyl, and lactate production. These results suggest that the photodegradation of PQ with TiO2 nanotubes produced PQ fragments with higher toxicity than PQ, while the precise mechanism of its action needs further investigation.

Synthesis of Heterostructured TiO2 Nanopores/Nanotubes by Anodizing at High Voltages.

This paper reports on the coating of heterostructured TiO2 nanopores/nanotubes on Ti substrates by anodizing at high voltages to design surfaces for biomedical implants. As the anodized voltage from 50 V to 350 V was applied, the microstructure of the coating shifted from regular TiO2 nanotubes to heterostructured TiO2 nanopores/nanotubes. In addition, the dimension of the heterostructured TiO2 nanopores/nanotubes was a function of voltage. The electrochemical characteristics of TiO2 nanotubes and heterostructured TiO2 nanopores/nanotubes were evaluated in simulated body fluid (SBF) solution. The creation of heterostructured TiO2 nanopores/nanotubes on Ti substrates resulted in a significant increase in BHK cell attachment compared to that of the Ti substrates and the TiO2 nanotubes.

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

Photo-assisted selective oxidation of monoterpenes by a covalently supported dioxo-molybdenum complex on TiO2: Effect of electron donor ligands

High-valent dioxo-Mo species have demonstrated the ability to catalyze industrially interesting alkene-to-epoxide transformations via oxygen atom transfer (OAT) reactions. The impact of electron donor ligands of dioxo-molybdenum complexes [MoO2Ln] covalently supported on TiO2 nanotubes (MoO2Ln/TiO2NT) on OAT to α-pinene, β-pinene, (R)-limonene and camphene has been investigated through the use of UV–vis radiation and molecular oxygen. Molybdenum complexes with electron donor ligands, such as bipyridine, bispyrazole, and terpyridine, exhibited high conversion and selectivity towards epoxide formation. This suggests that electron donation enhances the efficiency of photostimulated OAT. The photonic efficiency (ξ) demonstrates a linear correlation between the ligand structure and the OAT activity, indicating that the electron donation of the ligands enhances electron mobility towards the Mo=O bond. This correlation is evident in the position of the IR and Raman νsym(O=Mo=O) and vasym(O=Mo=O) vibrations of the complex Mo.

Boosting visible-light-driven photocatalysis of nitrogen oxide degradation by Mott–Schottky Pd/TiO2 heterojunctions

One of the main air pollutants is NOx gas, which is emitted into the atmosphere by burning fossil fuels and vehicle exhaust. The application of the photocatalytic technique to mitigate the concentration of NOx in the atmosphere is preferable because it is environmentally friendly, simple, and inexpensive method. In this work, palladium nanoparticles (Pd NPs) were decorated on TiO2 nanotubes (TNTs) by gamma-ray irradiation, and degradation of nitrogen monoxide (NO) was applied to evaluate the photocatalysis of the as-prepared Pd/TNT materials under atmospheric conditions. The results demonstrated that the Pd/TNT material with a 14 kGγ dose is the best photocatalyst, achieving 53.30 % NO removal efficiency, which is 1.6 times greater than that of pure TNTs. Furthermore, the decomposition of NO on the Pd/TNT catalysts also generated less NO2 poisoning under both solar and visible light conditions. Additionally, they possess desirable properties such as reusability, low toxicity, and high apparent quantum efficiency (AQE).

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.

Mn-N codoped TiO2 nanotubes with enhanced photocatalytic activity: An integrated experimental and theoretical investigation

The efficient enhancement of the photocatalytic activity of TiO2 nanotubes under visible light remains a significant challenge in current research. This study, employing density functional theory, systematically investigates the impact of Mn-N co-doping on the morphology, electronic structure, and optical properties of Hydrothermal composite treatment of TiO2 nanotubes. The successful introduction of Mn-N co-doping into the nanotubes induces impurity energy levels, reducing the bandgap while enhancing absorption capability and reflectance of visible light. Mn and N are partially incorporated into the TiO2 lattice, resulting in a reduction of the bandgap from 2.98 eV to 2.81 eV. The degradation efficiency of methylene blue solution under UV light and visible light is improved by approximately 31 % and 25 %, respectively.

TiO2 nanotubes with customized diameters for local drug delivery systems

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

Enhanced 1,2-dichloroethane removal using g-C3N4/Blue TiO2 nanotube array photoanode in microbial photoelectrochemical cells

The compound 1,2-dichloroethane (1,2-DCA), a persistent and ubiquitous pollutant, is often found in groundwater and can strongly affect the ecological environment. However, the extreme bio-impedance of C–Cl bonds means that a high energy input is needed to drive biological dechlorination. Biotechnology techniques based on microbial photoelectrochemical cell (MPEC) could potentially convert solar energy into electricity and significantly reduce the external energy inputs currently needed to treat 1,2-DCA. However, low electricity-generating efficiency at the anode and sluggish bioreaction kinetics at the cathode limit the application of MPEC. In this study, a g-C3N4/Blue TiO2-NTA photoanode was fabricated and incorporated into an MPEC for 1,2-DCA removal. Optimal performance was achieved when Blue TiO2 nanotube arrays (Blue TiO2-NTA) were loaded with graphitic carbon nitride (g-C3N4) 10 times. The photocurrent density of the g-C3N4/Blue TiO2-NTA composite electrode was 2.48-fold higher than that of the pure Blue TiO2-NTA electrode under light irradiation. Furthermore, the MPEC equipped with g-C3N4/Blue TiO2-NTA improved 1,2-DCA removal efficiency by 45.21% compared to the Blue TiO2-NTA alone, which is comparable to that of a microbial electrolysis cell. In the modified MPEC, the current efficiency reached 69.07% when the light intensity was 150 mW cm−2 and the 1,2-DCA concentration was 4.4 mM. The excellent performance of the novel MPEC was attributed to the efficient direct electron transfer process and the abundant dechlorinators and electroactive bacteria. These results provide a sustainable and cost-effective strategy to improve 1,2-DCA treatment using a biocathode driven by a photoanode.

Effect of Precursors Concentration on The Optical and Photoelectrochemical Properties of Bi₂S₃/TiO₂ Nanotubes Arrays Photoanode Synthesized by the SILAR Technique

The use of robust solar energy-driven photocatalysis materials to address the global energy and environmental crisis has gained significant attention in recent years. However, the wide band gaps in many robust semiconductor photocatalysts hinder their absorption of visible light from the solar spectrum. To address this issue, the modification of the large band gap semiconductor with the lower band gap material using the Successive Ionic Layers Adsorption and Reaction (SILAR) technique has emerged as an economical, accessible, and reproducible method for depositing nanoscale materials onto semiconductor substrates. This research aims to know how the concentration variation of cation and anion precursors in the SILAR technique affects the optical and photoelectrochemical properties of the resulting composite materials. Bi₂S₃ serves as a modifier for TiO₂ nanotube arrays (NTAs). The result shows that the cation-anion concentration ratio of 1:1.5 mM with five SILAR cycles gives the best photoelectrochemical performance, with a stable current density of 0.12 mA/cm², compared to pristine TiO₂ NTAs the current density of Bi₂S₃/TiO₂ NTAs is 15-fold. In addition, at each variation, the concentration ratio of cation and anion precursors decreases bandgap energy with each increase in the SILAR cycle.

Nitrogen-doped TiO2 nanotubes obtained by anodizing for photodegradation of glycerol

Nitrogen-doped TiO2 nanotubes obtained by anodizing for photodegradation of glycerol

Chemical bath co-deposition of Co3O4 and In2O3 on TiO2 nanotubes, aiming for photoanodes with improved photoelectrochemical properties

This study investigates the implications of the deposition of Co3O4 and In2O3 onto TiO2 nanotube thin films for the photoelectrochemical activity of TiO2 nanotubes (TNTs). Initially, TiO2 nanotubes were fabricated through an electrochemical anodizing process. Subsequently, a facile chemical bath deposition (CBD) method was used to deposition Co3O4 and In2O3 oxides. The resulting composites are used as photoanodes for the photoelectrochemical cathodic protection of AISI304 stainless steel (304SS) in marine environments. The surface morphology, compositions, crystalline structures, and optical characteristics of samples were examined using a combination of FESEM, TEM, EDX, XPS, XRD, and UV-Vis absorption spectroscopy. Electrochemical measurements under both illuminated and dark conditions were conducted to assess the photoelectrochemical characteristics of synthesized samples. The optimal co-deposited photoanode, significantly shifted the open circuit potential of the coupled AISI 304SS to −708 mV under intermittent light exposure, demonstrating appropriate photocathodic protection (PCP) performance. This potential was further enhanced and maintained at −720 mV for an hour in continuous light tests. Additionally, the photoanodes showed some degrees of delayed cathodic protection even after the light was switched off. The Co3O4-In2O3-modified TNTs composite exhibits superior photoelectrochemical cathodic protection activity due to the synergistic effects of Co3O4 and In2O3 nanoparticles.

Red-light-excited TiO2/Bi2S3 heterojunction nanotubes and photoelectric hydrogels mediate epidermal-neural network reconstruction in deep burns

Inspired by the strong light absorption of carbon nanotubes, we propose a fabrication approach involving one-dimensional TiO2/Bi2S3 QDs nanotubes (TBNTs) with visible red-light excitable photoelectric properties. By integrating the construction of heterojunctions, quantum confinement effects, and morphological modifications, the photocurrent reached 9.22 µA/cm2 which is 66 times greater than that of TiO2 nanotubes (TNTs). Then, a red light-responsive photoelectroactive hydrogel dressing (TBCHA) was developed by embedding TBNTs into a collagen/hyaluronic acid-based biomimetic extracellular matrix hydrogel with good biocompatibility, aiming to promote wound healing and skin function restoration. This approach is primarily grounded in the recognized significance of electrical stimulation in modulating nerve function and immune responses. Severe burns are often accompanied by extensive damage to epithelial-neural networks, leading to a loss of excitatory function and difficulty in spontaneous healing, while conventional dressings inadequately address the critical need for nerve reinnervation. Furthermore, we highlight the remarkable ability of the TBCHA photoelectric hydrogel to promote the reinnervation of nerve endings, facilitate the repair of skin substructures, and modulate immune responses in a deep burn model. This hydrogel not only underpins wound closure and collagen synthesis but also advances vascular reformation, immune modulation, and neural restoration. This photoelectric-based therapy offers a robust solution for the comprehensive repair of deep burns and functional tissue regeneration. Statement of significanceWe explore the fabrication of 1D TiO2/Bi2S3 nanotubes with visible red-light excitability and high photoelectric conversion properties. By integrating heterojunctions, quantum absorption effects, and morphological modifications, the photocurrent of TiO2/Bi2S3 nanotubes could reach 9.22 µA/cm², which is 66 times greater than that of TiO2 nanotubes under 625 nm illumination. The efficient red-light excitability solves the problem of poor biosafety and low tissue penetration caused by shortwave excitation. Furthermore, we highlight the remarkable ability of the TiO2/Bi2S3 nanotubes integrated photoelectric hydrogel in promoting the reinnervation of nerve endings and modulating immune responses. This work proposes an emerging therapeutic strategy of remote, passive electrical stimulation, offering a robust boost for repairing deep burn wounds.

Nanoporous Titanium Implant Surface Accelerates Osteogenesis via the Piezo1/Acetyl-CoA/β-Catenin Pathway.

Osseointegration is the most important factor determining implant success. The surface modification of TiO2 nanotubes prepared by anodic oxidation has remarkable advantages in promoting bone formation. However, the mechanism behind this phenomenon is still unintelligible. Here we show that the nanomorphology exhibited open and clean nanotube structure and strong hydrophilicity, and the nanomorphology significantly facilitated the adhesion, proliferation, and osteogenesis differentiation of stem cells. Exploring the mechanism, we found that the nanomorphology can enhance mitochondrial oxidative phosphorylation (OxPhos) by activating Piezo1 and increasing intracellular Ca2+. The increase in OxPhos can significantly uplift the level of acetyl-CoA in the cytoplasm but not significantly raise the level of acetyl-CoA in the nucleus, which was beneficial for the acetylation and stability of β-catenin and ultimately promoted osteogenesis. This study provides a new interpretation for the regulatory mechanism of stem cell osteogenesis by nanomorphology.

Highly selective sensing of toxic NOx gases for environmental monitoring using Ru-doped single walled TiO2 nanotube: A density functional theory study

Applying density functional theory simulations, in this study, we examine the sensing properties of Ru-TNT surface towards NOx molecules such as NO and NO2. The obtained results show that Ru doping creates a large-spin density over the Ru-TNT surface, which hints at an increase in the adsorption energy of NOx molecules. The electronic properties of the Ru-TNT surface are significantly altered after NO and NO2 molecule adsorption, as proven by the larger change in the energy gap values. Moreover, the selectivity study indicates that the Ru-TNT is capable of selectively sensing the NOx molecules in the presence of other gases, e.g., CO2, CO, NH3 and H2O. Using an external positive electric field can resist the strong anchoring of NOx molecules over the Ru-TNT surface, suggesting that material recovery is feasible. Thus, the Ru-TNT structure can be applied as a selective, sensitive, and promising ambient temperature gas sensor for NOx molecules.