TiO2 Nanotubes Research Articles

Improving the NO2 Gas Sensing Performances at Room Temperature Based on TiO2 NTs/rGO Heterojunction Nanocomposites

The development of energy-efficient, sensitive, and reliable gas sensors for monitoring NO2 concentrations has garnered considerable attention in recent years. In this manuscript, TiO2 nanotube arrays/reduced graphene oxide nanocomposites with varying rGO contents (TiO2 NTs/rGO) were synthesized via a two-step method for room temperature NO2 gas detection. From SEM and TEM images, it is evident that the rGO sheets not only partially surround the TiO2 nanotubes but also establish interconnection bridges between adjacent nanotubes, which is anticipated to enhance electron–hole separation by facilitating electron transfer. The optimized TiO2 NTs/rGO sensor demonstrated a sensitive response of 19.1 to 1 ppm of NO2, a 5.26-fold improvement over the undoped TiO2 sensor. Additionally, rGO doping significantly enhanced the sensor’s response/recovery times, reducing them from 24 s/42 s to 18 s/33 s with just 1 wt.% rGO. These enhancements are attributed to the increased specific surface area, higher concentration of chemisorbed oxygen species, and the formation of p-n heterojunctions between TiO2 and rGO within the nanocomposites. This study provides valuable insights for the development of TiO2/graphene-based gas sensors for detecting oxidizing gases at room temperature.

Preparation and Characterization of Transferable Encapsulated Dye-Sensitized Solar Cells

The increasing demand for sustainable energy as a means to combat the impact of climate change is addressed via a novel concept in the present work. Herein presented are developed transferable encapsulated dye-sensitized solar cells, canonically “solar capsules”, for photovoltaic applications on alternative surfaces, such as facades. The solar capsule assembly houses all the components necessary for photovoltaic energy conversion, enclosed within a semiconductor nanotubular array, making them truly unique in their construction. This capsule-style unit enables an easy transfer and draft onto a wide range of materials and surfaces for photovoltaic functionalization and applications. This type of dye-sensitized solar cell typically consists of transferred solar capsules and two additional electrodes. The design and construction of solar capsules means they have a high economic viability as they can seamlessly be up-scaled using commercially established techniques such as anodization and subsequent functionalization. This work demonstrates a working model of such transferable solar capsules by fabricating TiO2 nanotubes that are functionalized via facile dip- and spin-coating techniques in a wet lab at ambient conditions. These prototypes are characterized in bulk and are thoroughly investigated at the nanoscale for information on the chemical distribution of the constituents, as they may be influenced during the manufacturing process.

Photoelectrocatalytic degradation of organophosphate esters using tio2 electrodes produced from 3d-printed ti substrates.

3D printed electrode substrates with novel geometries may significantly improve the efficacy of photoelectrocatalysis for degradation of recalcitrant pollutants such as organophosphate flame retardants (OPFRs). However, the 3D printed substrates often have an irregular topology that can lead to a less uniform arrangement of nanotubes following anodisation. This study investigated the effect of polishing 3D-printed Ti substrates prior to anodisation to form TiO2 nanotube array electrodes, and their subsequent applicability for photoelectrocatalytic treatment of OPFRs in water matrices. Polished and non-polished electrodes exhibited differences in morphology in terms of average roughness, (0.38 and 3.10µm, respectively), leading to more uniform TiO2 nanotubes of the former. Water contact angle measurements revealed the non-polished electrode was super-hydrophilic and the polished electrode hydrophilic (water contact angles of 6.4˚ and 16.1˚, respectively). Despite these differences, the polished and non-polished electrodes exhibited very similar electrochemical responses. In fact, the purity and electrical conductivity of water matrices affected the photoelectrocatalytic performance more than the electrode morphology. The purified water (PW) matrix facilitated the highest degradation/removal of OPFRs, compared to tap water matrices. In particular, individual OPFR degradation levels in PW were 74% ± 9, 37% ± 10, 33% ± 9, 31% ± 11 and 3% ± 5 for triphenyl phosphate, tris(butyl) phosphate, tris(isobutyl) phosphate, tris(2-butoxyethyl) phosphate and tris(2-chloroisopropyl) phosphate, respectively. The removal of OPFRs was relative to their reactivity to hydroxyl radicals, which was higher for the aryl then alkyl straight-chain and then chlorinated compounds. This study reveals that polishing of electrode substrates is not required for the preparation of effective photoelectrocatalytic reactors to treat recalcitrant pollutants (e.g. OPFRs), Importantly, future development of novel high-profile 3D printed electrode will not be hindered by the requirement to polish the substrates prior to anodisation.

A Z-scheme g-C3N4/TiO2 heterojunction for enhanced performance in protecting magnesium and nickel couple from galvanic corrosion

Large interfacial contact is crucial for designing novel heterostructure materials to achieve good photoelectrochemical performance. Herein, we prepared a composite photoanode consisting of titanium dioxide (TiO2) nanotubes and graphitic carbon nitride (g-C3N4) nanosheets for enhancing the photocathodic protection (PCP) capability of the nickel-coated Mg alloy (Mg/Ni). The composite g-C3N4/TiO2 (CN/TiO2) photoanode was achieved by depositing g-C3N4 on the TiO2 nanotubes grown titanium foil via a one-step thermal polymerization of melamine and thiourea mixture. A series of characterizations, including transmission electron microscope, X-ray photoelectron spectroscopy, and electron paramagnetic resonance spectra, manifested the successful deposition of g-C3N4 at the inner wall of the TiO2 nanotubes to achieve sufficient interfacial contact and the formation of a Z-scheme heterojunction to promote the charge carriers’ transfer and separation. Compared with the pure TiO2 photoanode, the heterojunction exhibited enhanced photoelectrochemical and photocathodic protection performances, which was confirmed by the electrochemical measurements. The heterojunction achieved a duration of 6.5 h to protect the Mg-Ni couple from galvanic corrosion, representing a tenfold enhancement compared with the uncoupled Mg/Ni electrode. These findings demonstrate the great potential of constructing a unique Z-scheme heterojunction with a sizeable interfacial contact area to enhance the PCP capability of metals.

Corrosion Study of TiO2 Nanotubes Decorated with Ag Silver Nanoparticles Prepared by Photoreduction Process

Corrosion Study of TiO2 Nanotubes Decorated with Ag Silver Nanoparticles Prepared by Photoreduction Process

Osteoblast Growth in Quaternized Silicon Carbon Nitride Coatings for Dental Implants.

The demand for dental implants has increased, establishing them as the standard of care for replacing missing teeth. Several factors contribute to the success or failure of an implant post-placement. Modifications to implant surfaces can enhance the biological interactions between bone cells and the implant, promoting better outcomes. Surface coatings have been developed to electrochemically alter implant surfaces, aiming to reduce healing time, enhance bone growth, and prevent bacterial adhesion. Quaternized silicon carbon nitride (QSiCN) is a novel material with unique electrochemical and biological properties. This study aimed to assess the influence of QSiCN, silicon carbide nitride (SiCN), and silicon carbide (SiC) coatings on the viability of osteoblast cells on nanostructured titanium surfaces. The experiment utilized thirty-two titanium sheets with anodized TiO2 nanotubes featuring nanotube diameters of 50 nm and 150 nm. These sheets were divided into eight groups (n = 4): QSiCN-coated 50 nm, QSiCN-coated 150 nm, SiCN-coated 50 nm, SiCN-coated 150 nm, SiC-coated 50 nm, SiC-coated 150 nm, non-coated 50 nm, and non-coated 150 nm. Preosteoblast MC3T3-E1 Subclone 4 cells (ATCC, USA) were used to evaluate osteoblast viability. After three days of cell growth, samples were assessed using scanning electron microscopy (SEM). The results indicated that QSiCN coatings significantly increased osteoblast proliferation (p < 0.005) compared to other groups. The enhanced cell adhesion observed with QSiCN coatings is likely due to the positive surface charge imparted by N+.

Studying the Photoactivity of Ag-Decorated TiO2 Nanotubes with Combined AFM and Raman Spectroscopy

The drive for the development of systems that can simultaneously investigate chemical and morphological information comes from the requisite to fully understand the structure and chemical reactivity relationships of materials. This is particularly relevant in photocatalysis, a field ruled by surface interactions. An in-depth understanding of these complex interactions could lead to significant improvements in materials design, and consequently, in photocatalytic performances. Here, we present a first approach to a combined atomic force microscopy (AFM) and Raman spectroscopy characterization of anodic TiO2 nanotubes arrays decorated with Ag nanoparticle electrodeposition from either the same anodizing organic electrolyte or from an aqueous one. Photocatalytic substrates were used in up to 15 consecutive photocatalysis tests to prove their possible deterioration with reuse. Sample aging can, in principle, produce changes in both the morphology and the chemical compounds that characterize the photocatalyst surface. Adopting multiple characterization techniques, such as a combination of AFM and Raman spectroscopy in an original setup, can profitably enable the observation of surface contamination. A significant drop in photocatalytic activity was observed after 10 cycles on samples where silver was deposited from the organic electrolyte, while the others remained stable. Such a drop was ascribed to photocatalyst deactivation. While in other cases, a simple recovery treatment allowed the initial photoactivity to be restored, this deactivation was not restored even after chemical and thermal cleaning treatments.

Fundamental study on the construction of anti-wear drug delivery system through the design of titanium surface morphology

The durability of dental implant carrier coatings is of paramount importance for the expeditious and predictable osseointegration process. The present work is based on a bionic micro/nano hierarchy structure, which consists of titanium surface microstructures and their internal TiO2 nanotubes (TNTs) with drug-carrying capacity. This effectively increases the wear resistance of the drug-carrying coating on the titanium surface. In comparison to untextured samples, the wear volume and wear depth of the optimal texture group are markedly diminished, resulting in a significant enhancement of wear resistance. This improvement was primarily attributed to the smaller contact area of the microstructure. Concurrently, the microstructure serves to safeguard the TNTs from damage during friction. The hydrophilic biomimetic anti-wear micro/nano hierarchies demonstrated the capacity to promote MC3T3-E1 cell adhesion and proliferation, while also exhibiting no cytotoxic effects. Moreover, the micro/nano hierarchical structure can be directly applied to the surface of commercialized implants. In simulated clinical conditions, the implant was inserted into a fresh Bama porcine mandible, and the structure of the drug-loading coatings remained intact. This structure enhances the abrasion resistance of the drug coating while minimizing alterations to the original treatment process of the implant, which is of great significance in the clinical application of implant-loaded drug delivery.

Engineering Cl vacancies in lead-free halide double perovskites decorated on TiO2 nanotubes for highly sensitive NO2 sensing at room temperature

Engineering Cl vacancies in lead-free halide double perovskites decorated on TiO2 nanotubes for highly sensitive NO2 sensing at room temperature

MXene/TiO2 NAs on CC flexible electrode for electrocatalytic tigecycline degradation: Performance, Mechanistic insights, and toxicological assessment

In this study, a composite electrode (MXene/TiO2 NAs@CC) based on TiO2 nanotube arrays (NAs) and two-dimensional MXene-coated carbon cloth (CC) was prepared. The electrode greatly improved the catalytic activity by capturing protons through the abundant active sites of TiO2 nanotube arrays and promoting proton reduction with the high conductivity of MXene. Moreover, the composite electrode possessed the largest specific surface area (9.1660 m2·g−1) according to the results of the BET test. Under optimal conditions, the composite electrode degraded tigecycline (TGC) up to 86.66 % in 20 min. Furthermore, the electrocatalytic performance was not affected after 10 cycling experiments and 60 days of exposure to air, indicating its excellent stability. In addition, the cathodic co-catalytic reaction mechanism involving anode ·OH, HClO, and cathode H* was proposed. The degradation pathways of TGC and the toxicity of possible intermediates were also analyzed. Finally, a two-stage continuous wastewater reactor with high efficiency and low consumption (90.46 % removal rate, 0.061 kWh/m3) was designed. This study provides a new idea for designing an electrocatalytic reactor with high efficiency, stability, and low consumption, enriching the field of electrocatalytic treatment strategies for antibiotic wastewater. It is of great significance for the protection of the water environment and human health.

2D MXene nanosheet dispersed Mn, Ru NPs loaded Ti composite electrodes for electrocatalytic synergistic degradation of antibiotics in high-salt mariculture wastewater

In this study, a composite electrode based on etched TiO2 nanotube arrays and two-dimensional (2D) MXene nanosheets was successfully designed for efficient degradation of antibiotics in mariculture wastewater. The composite electrode effectively dispersed Mn and Ru nanoparticles (NPs) by introducing 2D MXene nanosheets as an intermediate layer, which significantly enhanced the catalytic performance. The bifunctional properties of Mn and Ru NPs in catalysis and the contribution of d-orbital electrons to the formation of metal‑hydrogen bonds were revealed in depth by analyzing the electron transfer mechanism at the electrodes. The experimental results demonstrated a synergistic catalytic effect between Mn and Ru bimetals and MXene, resulting in an effective increase in the degradation rate. Under the optimal conditions, the degradation rate of Tetracycline (TC) by Mn/Ru/MXene/Ti composite electrode could reach 90.69 % in 60 min. In addition, it still shows excellent stability after 45 days of air exposure, 10 cycling experiments, and 10,000 s of timed current testing. Mechanistic studies have demonstrated that anode hydroxyl radical (·OH), HClO, and cathode activated hydrogen atoms (H*) all play catalytic roles in the degradation process. The degradation pathways were analyzed using density-functional theory (DFT) calculations and liquid-liquid-mass spectrometry (LC-MS) techniques, with further experiments confirming that this degradation process effectively reduces the biotoxicity of intermediate products, improving the safety of wastewater discharge. Finally, we designed the reactor and calculated the energy consumption to verify the feasibility and economy of the system in practical applications. This research proposes a novel multi-metal co-catalysis and cathode and anode co-catalysis system for the efficient degradation of antibiotics in mariculture wastewater, with potential applications in the electrocatalytic degradation of antibiotics.

Effect of chemical bath deposited V2O5 on TiO2 nanotubes for supercapacitor application

Effect of chemical bath deposited V2O5 on TiO2 nanotubes for supercapacitor application

Boosted photoelectrochemical activity of anodic titanium dioxide nanotubes by electrophoretically decorated nickel–aluminum layered double hydroxide

The splitting of water using photoelectrochemical (PEC) processes is a promising method for generating renewable hydrogen. However, the practical efficiency of converting solar energy to fuel in PEC systems remains limited by inadequate light absorption and the swift recombination of photogenerated charge carriers within the photoelectrode material. In our research, we present a photoanode that addresses these challenges. In this work, we report on the electrophoretic deposition of nickel–aluminum layered double hydroxide (NiAl-LDH) under different voltages onto anodic TiO2 nanotube arrays (TNTAs) as a convenient and economically viable fabrication route of versatile and durable photoanodes. PEC and optical spectroscopy examinations, including linear sweep voltammetry, electrochemical impedance spectroscopy, Mott-Schottky plots, and diffuse reflectance spectroscopy, reveal that NiAl-LDH/TNTAs composites exhibit a superior enhancement of visible light absorption and consequently water splitting photocurrent. We interpret the improvement of PEC water splitting performance of the NiAl-LDH/TNTAs with the band structure speculated by the binding energy and the flat-band potential and band-gap measurements which features this nanocomposite as a novel photocatalyst for future hydrogen energy applications.

Synthesis and Characterization of Bi2S3 Deposited on TiO2 Nanotubes (TiO2NTAs) as Photoanode in the Tandem DSSC-PEC System for Hydrogen Evolution

Synthesis and Characterization of Bi2S3 Deposited on TiO2 Nanotubes (TiO2NTAs) as Photoanode in the Tandem DSSC-PEC System for Hydrogen Evolution

Synthesis and Characterization of TiO2 Nanotubes for High-Performance Gas Sensor Applications

In this study, we investigated the fabrication, properties, and sensing applications of TiO2 nanotubes. A pure titanium metal sheet was used to demonstrate how titanium dioxide nanotubes can be used for gas-sensing applications through the electrochemical anodization method. Subsequently, X-ray diffraction indicated the crystallization of the titanium dioxide layer. Scanning electron microscopy and transmission electron microscopy then revealed the average diameter of the TiO2 nanotubes to be approximately 100 nm, with tube lengths ranging between 3 and 9 µm and the thickness of the nanotube walls being about 25 nm. This type of TiO2 nanotube was found to be suitable for NO2 gas sensor applications. With an oxidation time of 15 min, its detection of NO2 gas showed a good result at 250 °C, especially when exposed to a NO2 gas flow of 100 ppm, where a maximum NO2 gas response of 96% was obtained. The NO2 sensors based on the TiO2 nanotube arrays all exhibited a high level of stability, good reproducibility, and high sensitivity.

Comparative Analysis of Anodized TiO2 Nanotubes and Hydrothermally Synthesized TiO2 Nanotubes: Morphological, Structural, and Photoelectrochemical Properties.

This study presents a comparative analysis of anodization and hydrothermal techniques for synthesizing TiO2 nanotubes directly on titanium foil. It emphasizes its advantages as a substrate due to its superior conductivity and efficient charge transfer. Optimized synthesis conditions enable a thorough evaluation of the resulting nanotubes' morphology, structure, and optical properties, ultimately assessing their photoelectrochemical and photocatalytic performances. Scanning electron microscopy (SEM) reveals differences in tube diameter and organization. An X-ray diffraction (XRD) analysis shows a dominant anatase (101) crystal phase in both methods, with the hydrothermally synthesized nanotubes exhibiting a biphase structure after annealing at 500 °C. UV-Vis and photoluminescence analyses indicate slight variations in band gaps (around 0.02 eV) and recombination rates. The anodized TiO2 nanotubes, exhibiting superior hydrophilicity and order, demonstrate significantly enhanced photocatalytic degradation of a model pollutant, amido black (80 vs. 78%), and achieve a 0.1% higher photoconversion efficiency compared to the hydrothermally synthesized tubes. This study underscores the potential advantages of the anodization method for photocatalytic applications, particularly by demonstrating the efficacy of direct TiO2 nanotube growth on titanium foil for efficient photocatalysis.

Exploiting the Bragg Mirror Effect of TiO2 Nanotube Photonic Crystals for Promoting Photoelectrochemical Water Splitting.

Exploiting the Bragg mirror effect of photonic crystal photoelectrode is desperately desired for photoelectrochemical water splitting. Herein, a novel TiO2 nanotube photonic crystal bi-layer structure consisting of a top nanotube layer and a bottom nanotube photonic crystal layer is presented. In this architecture, the photonic bandgap of bottom TiO2 nanotube photonic crystals can be precisely adjusted by modulating the anodization parameters. When the photonic bandgap of bottom TiO2 nanotube photonic crystals overlaps with the electronic bandgap of TiO2, the bottom TiO2 nanotube photonic crystal layer will act as a Bragg mirror, leading to the boosted ultraviolet light absorption of the top TiO2 nanotube layer. Benefiting from the promoted UV light absorption, the TiO2 NT-115-NTPC yields a photocurrent density of 1.4 mA/cm2 at 0.22 V vs. Ag/AgCl with a Faradic efficiency of 100%, nearly two times higher than that of conventional TiO2 nanotube arrays. Furthermore, incident photon-to-current conversion efficiency is also promoted within ultraviolet light region. This research offers an effective strategy for improving the performance of photoelectrochemical water splitting through intensifying the light-matter interaction.

Hydrogen evolution reaction catalyzed by Co-based metal-organic frameworks and their derivatives

In this study, Co-bearing Metal-Organic Frameworks (MOFs) are grown via a facile solvothermal process on the surface of two kinds of conductive substrates – titanium dioxide nanotubes (TiO2NT) and fluorine-doped tin oxide (FTO) glass and tested as electrodes in the electrochemical hydrogen evolution reaction (HER). The materials derived from three organic linkers - terephthalic acid (Co-BDC), 2-aminoterephthalic acid (Co-BDCNH2), and trimesic acid (Co-BTC) are characterized by FTIR, Raman, XRD, SEM-EDS, BET, and XPS. Among the layers on FTO without post-synthesis treatment, Co-BTC shows the highest activity (overpotential of HER 1.72 V vs. Ag/AgCl/KCl). The effects of substrate change on TiO2NT and annealing of Co-BTC layers in air and argon on their electrocatalytic properties are also studied. Using TiO2 nanotubes as a substrate and annealing the material in air results in a reduction of the hydrogen evolution overpotential to 1.44 V vs. Ag/AgCl/KCl and a significant reduction in the exchange current density.

Anodic Synthesis of Highly Ordered TiO2 Nanotube Arrays: Role of Electrolyte Composition on the Structural, Morphological, Optical, and Photo-electrochemical Properties

The fluoride species present in two different anodizing electrolytes were used to produce TiO2 nanotube arrays (TiO2 NTAs) by simultaneous anodic reaction and chemical dissolution. In this investigation, two different electrolytes were used for the preparation; [Eth-TiO2 NAs: 95 ml ethylene glycol+0.5% NH4F+5 ml DI water] and [Gly-TiO2 NAs: 75 ml glycerine+0.5% NH4F+25 ml DI water]. The effects of the prepared electrolytes used in the synthesis of TiO2 nanotube arrays on structural element composition, morphology, and optical properties are the focus of this study and are characterized by X-ray diffraction (XRD), scanning electron microscopy field emission (FE-SEM), energy-dispersive X-ray spectroscopy (EDX) and UV-vis diffusion reflection spectroscopy (DRS), respectively. The photoelectrochemical properties of TiO2 NTAs prepared in different electrolytes were investigated. The photoelectrochemical performance of TiO2 NTAs in Na2SO3 (0.1 M) and Na2S (0.1) was examined under the light of 100 mW/cm2 from a xenon lamp. Comparing the photoelectrochemical (PEC) results of both electrolytes, we find that Eth-TiO2 NTAs contribute a wide surface area resulting in an enhanced PEC response. TiO2 NTs, which were prepared with Eth-TiO2 NTAs, exhibited the highest photocurrent density, 0.326 mA cm–2, and photoconversion efficiency (0.22%).

Mechanism and growth kinetics of hexagonal TiO2 nanotubes with an influence of anodizing parameters on morphology and physical properties

Hexagonal TiO2 nanotubes (hTNTs) mimic a honeycomb structure, indicating their high potential as implantable materials due to their superior mechanical, chemical, and biological properties. However, the fabrication of hTNTs with a hexagonal base and six rectangular sides poses significant challenges, underscoring the importance of this research. This study developed a novel sonoelectrochemical method for synthesizing uniform hTNTs and evaluated the influence of anodizing parameters on their morphology. The effects of electrolyte concentration (ethylene glycol 90–97.5% and ammonium fluoride 0.1–0.5 wt%) and anodizing parameters (time 5–90 min, potential 10–80 V) on the morphology (diameter and length) and physical properties (porosity, specific surface area, growth factor) of hTNTs were investigated using scanning electron microscopy and anodization analysis. The methodology enabled the synthesis of hTNTs with diameters ranging from 33 ± 3 nm to 203 ± 33 nm and lengths from 1.16 ± 0.04 μm to 20.93 ± 2.37 μm. The study demonstrated that the concentrations of ethylene glycol and ammonium fluoride influenced the diameter and length of hTNTs depending on the anodizing potential. Moreover, the anodizing potential significantly affected the diameter, while both potential and time impacted the length of hTNTs. The proposed method can modify material surfaces for diverse applications.