Sodium Titanate Nanostructures Research Articles

Defect evolution on the activity of samarium doped Na2TinO2n+1 with different sodium/titanium ratio for photocatalytic degradation of fluoroquinolones drugs, toxicity assessments and eco-toxicity prediction

In this study, samarium (Sm) doped sodium titanate (Na2TinO2n+1) with different Na/Ti molar ratios {n: 3, 6, and 9} were synthesized by using sol-gel method. The prepared nanostructures were characterized by XRD, SEM, EDS, BET, UV–vis, EIS and photoluminescence analysis. XRD analysis depicts the Na2Ti6O13 was the main substance, while Sm–Na2Ti9O19 contained a minor proportion of Na2Ti6O13, and rutile phase TiO2. The pore size distribution for all samples is between 2 nm and 20 nm, indicating that most of the pores are in the range of meso porosity. The adsorption-desorption isotherms shows the mesoporous properties of the prepared samples. The band gap energies for samarium doped sodium titanate were lower than the sodium titanate nanostructures. The productivity of hydroxyl radicals on the samarium doped sodium titanates was in the sequence Sm–Na2Ti9O19 > Sm–Na2Ti6O13 > Sm–Na2Ti3O7. The different samarium doped sodium titanates samples were utilized for degradation ofloxacin and ciprofloxacin under UV light irradiation. The results showed that the complete degradation ofloxacin (94.2 %) and ciprofloxacin (99.7 %) were obtained by using Sm–Na2Ti9O19 within 70 min, while the degradation efficiency of Sm–Na2Ti6O13 and Sm–Na2Ti3O7 were lower than Sm–Na2Ti9O19 nanostructures. Also, the marine microalgaes growth rate and biotoxicity of the Sm-doped sodium titanates were investigated on Chaetoceros calcitrans, and Nannochloropsis oculata. The results showed that high concentration of the samarium doped sodium titanates were inhibited the algae growth rate.

Optimal growth of sodium titanate nanoflower on TiO2 thin film for the fabrication of a novel Ti/TiO2/Na2Ti3O7 photoanode with excellent stability

This study reports the effect of the Ti source (Ti foil or TiO 2 thin layer) and NaOH concentration on the growth of sodium titanate nanostructures via hydrothermal treatment to improve the photoelectrochemical (PEC) water splitting performance. An optimal condition to grow sodium titanate nanoflower composed of ultrathin nanosheets on the surface of the thin TiO 2 film led to the formation of a novel nanocomposite TiO 2 /Na 2 Ti 3 O 7 photoelectrode with great adhesion of the two phases. The Ti/TiO 2 /Na 2 Ti 3 O 7 photoanode demonstrated a significant enhancement in photocurrent density and shifted the onset potential to a more negative value compared to the pure Ti/TiO 2 and Ti/Na 2 Ti 3 O 7 samples. This noticeable improvement is attributed to the suitable band alignment between the TiO 2 and Na 2 Ti 3 O 7 phases and their direct contact with the Ti foil, as well as the large surface area of nanoflower sodium titanate, which significantly facilitate the generation, separation, and transfer of photogenerated electrons from the active phases to the substrate. More interestingly, the prepared photoanode retained its initial photocurrent density even after 16 h. An ion-exchange method and calcination treatment were used at different temperatures to convert the Na 2 Ti 3 O 7 phase in the Ti/TiO 2 /Na 2 Ti 3 O 7 photoanode to TiO 2 to investigate the role of type II heterojunction for efficient photogenerated charge carrier separation in this photoanode. It was concluded that converting Na 2 Ti 3 O 7 into TiO 2 in the Ti/TiO 2 /Na 2 Ti 3 O 7 system would reduce its PEC performance due to the formation of a pure phase of TiO 2 in the Ti/TiO 2 /TiO 2 photoanode. • The Ti/TiO 2 /Na 2 Ti 3 O 7 photoanode demonstrated a significant enhancement in photocurrent density. • The Ti/TiO 2 /Na 2 Ti 3 O 7 photoanode retained its initial photocurrent density even after 16 h. • Ti/TiO 2 /Na 2 Ti 3 O 7 showed a photocurrent density of around 0.46 mA/cm 2 at 0.3 V vs. Ag/AgCl. • Any morphological and phase changes in Ti/TiO 2 /Na 2 Ti 3 O 7 reduce its photocatalytic activity.

The effect of morphology on the optical and electrical properties of sodium titanate nanostructures

Sodium based titanate nanostructures (NaTNT) are promising materials for energy storage and photoelectrode applications. We present an experimental work describing the structural, morphological and electronic properties of hydrothermally synthesized NaTNT, evaluating different synthesis conditions (synthesis temperature and time). We found a clear dependence between the synthesis condition and the observed, morphological, electrical and optical features. Increasing synthesis time and decreasing temperature allow the nanotubes to be filled. Local and extended structural analysis, and Raman spectroscopy, supported the samples stoichiometry with a pentacoordinated Ti-O polyhedral. Electrochemical impedance spectroscopy analysis revealed a predominant two-transport mechanism; however, a third process was observed for two samples with particular morphology (nanorods and nanoparticles co-existing with nanotubes). Finally, the influence on the optical properties of the structural and morphological characteristic is determined and discussed. We found a reduction of the gap energies when compared with anatase. Additionally, from the photoluminescence response we suggest different kind of defects must be present in the samples. This work presents a very complete set of experimental tools for the analysis of NaTNT, showing how the synthesis conditions allow tuning the electrical and optical responses of NaTNT for energy storage and photoelectrode applications.

Optical, electrical and structural properties of Fe doped sodium titanate nanostructures

In this work we present the synthesis, optical and electrical characterization of nanoparticles of iron doped anatase and iron doped sodium titanate high aspect ratio nanostructures (Na2Ti2O5·H2O). Our study focused mainly in the study of the electronical structure and the derived properties of the dielectric function by DFT (Density Functional Theory) means and their relationship with experimental measurements of optical band gap and electric impedance spectroscopy. Also, structural and morphological characterizations of the systems were carried on by X-ray powder diffraction, high resolution transmission electron microscopy and Raman spectroscopy. It was possible for the doped nanostructures to observe a slight red shift in the band gap of about 0.2 eV and an order of magnitude decrease in the global resistance in the doped system.

Hydrothermal treatment of layered sodium titanate nanostructures and their conversion to Li4Ti5O12

Lithium titanate spinel (Li4Ti5O12) has been successfully prepared via a simple hydrothermal treatment of layered sodium titanate Na2Ti3O7 nanostructures in LiOH aqueous solution. The pure phase of α-Li2TiO3 intermediate product is formed due to ion exchange Na+→ Li+ accompanied by chemical interaction of components under hydrothermal conditions. The intermediate product is formed by one-dimensional elongated nanostructures and nanostructured particles up to 250 nm in size. Annealing at 550 °C leads to their conversion to a nanostructured Li4Ti5O12 spinel. The combination effect of one-dimensional elongated structures and non-compact architectures allows one to obtain a nanostructured material with a decreased grain boundary resistance compared to pure LTO.

Three-Dimensional Chestnut-Like Architecture Assembled from NaTi3O6(OH)·2H2O@N-Doped Carbon Nanosheets with Enhanced Sodium Storage Properties.

The application of sodium titanate anodes of low cost, feasible operating voltage, and nontoxic nature were severely hindered by their inferior cycling stability and poor rate capability. Here, three-dimensional (3D) chestnut-like NaTi3O6(OH)·2H2O@N-doped carbon nanospheres (NTOH@CN) with loose crystal structures were prepared by a self-sacrificed template method. The nanospheres were composed of nanosheets and linked with nanowires, which interweaved to construct a meshwork structure. The growth mechanism of unique 3D NTOH@CN nanospheres was investigated by tracking the synthesis process of different hydrothermal durations. The rate performances of 3D NTOH@CN were superior to that of NaTi3O6(OH)·2H2O irregular spheres assembled from nanosheets (3D NTOH) and NaTi3O6(OH)·2H2O nanosheets (two-dimensional NTOH). Excellent cycling and rate performance were obtained due to their open crystal structure, unique 3D nanosphere morphology with short diffusion paths, N-doped carbon surrounding, and the solid solution reaction. In addition, the reaction mechanism, morphology change, and dynamics research during the sodium insertion/desertion process have been carefully studied. Based on varying ex situ analyses, the irreversible metallic titanium formation and the excellent structural stability of nanosphere morphology have been evidenced. The pseudocapacitive phenomenon was also detected, which effectively enhanced Na+ ion storage capability. The systematical and comprehensive study provide a holograph for the design and synthesis of sodium titanate nanostructures.

Nanostructured Titanate with Different Metal Ions on the Surface of Metallic Titanium: A Facile Approach for Regulation of rBMSCs Fate on Titanium Implants

Titanium (Ti) is widely used for load-bearing bio-implants, however, it is bio-inert and exhibits poor osteo-inductive properties. Calcium and magnesium ions are considered to be involved in bone metabolism and play a physiological role in the angiogenesis, growth, and mineralization of bone tissue. In this study, a facile synthesis approach to the in situ construction of a nanostructure enriched with Ca(2+) and Mg(2+) on the surface of titanium foil is proposed by inserting Ca(2+) and Mg(2+) into the interlayers of sodium titanate nanostructures through an ion-substitution process. The characteriz 0.67, and 0.73 nm ation results validate that cations can be inserted into the interlayer regions of the layered nanostructure without any obvious change of morphology. The cation content is positively correlated to the concentration of the solutions employed. The biological assessments indicate that the type and the amount of cations in the titanate nanostructure can alter the bioactivity of titanium implants. Compared with a Na(+) filled titanate nanostructure, the incorporation of divalent ions (Mg(2+) , Ca(2+) ) can effectively enhance protein adsorption, and thus also enhance the adhesion and differentiation ability of rat bone-marrow stem cells (rBMSCs). The Mg(2+) /Ca(2+) -titanate nanostructure is a promising implantable material that will be widely applicable in artificial bones, joints, and dental implants.

Layered sodium titanate nanostructures as a new electrode for high energy density supercapacitors

A flower-shaped hydrated layered sodium titanate material, Na2Ti2O4(OH)2, have been synthesized through a facile hydrothermal method and subsequently converted into sodium free titania (anatase). Potential application of the Na2Ti2O4(OH)2 as an electrode for supercapacitors under pseudo-capacitance storage mode is evaluated. The Na2Ti2O4(OH)2 showed sixfold higher specific capacitance (CS ∼ 300 F g−1) in an aqueous electrolyte than the anatase and demonstrated stable electrochemical cycling. This high CS is originated from a combination of electrochemical double layer and pseudo-capacitance storage mechanisms. The presence of hydrated layered within some loose interlayer plays an important role in assisting the diffusion process of ions as confirmed in electrical impedance spectroscopy analysis.

Morphology-controlled synthesis and growth mechanism of lead-free bismuth sodium titanate nanostructures via the hydrothermal route

Lead-free bismuth sodium titanate (Bi0.5Na0.5TiO3, BNT) perovskite nanostructures including nanoplates, nanocubes and nanowires were synthesized by a facile hydrothermal method without any additives or templates. The crystallization and morphologies of the hydrothermal derived BNT were controlled by simply adjusting the reaction time and NaOH concentration, which were examined by XRD, SEM, TEM and HRTEM techniques in detail. The BNT nanoplates of 400 nm in length and several nanometers in thickness were obtained at 200 °C for 48 h with NaOH concentration of 8–12 M. The uniformly BNT cubes of 1–2 μm in length were synthesized at 200 °C with NaOH concentration of 16–18 M for 36–48 h. The BNT nanowires with 50–100 nm in diameter and more than 5 μm in length were obtained when the holding time was prolonged to 60 h. The probable growth mechanisms of the BNT nanostructures with various morphologies were proposed.

Facile Fabrication of Sodium Titanate Nanostructures Using Metatitanic Acid (TiO2 · H2O) and Its Adsorption Property

Fluffy sodium titanate nanostructures have been fabricated by a simple hydrothermal method with metatitanic acid as precursor. The obtained nanostructures exhibit as the aggregation of nanosheets, and the surface area of the nanostructure is about 110.59 m2/g. Such nanoarchitecture indicates high adsorption capacity to some metal ions, such as Cd2+, and the maximum adsorption capacity has been estimated to be 255.18 mg/g. The possible reasons that are responsible after its high adsorption ability, have been ascribed to the tiny structure, the ion‐exchange ability and the large surface area of the sodium titanate nanostructures. And this may greatly enlarge its application potential as an adsorbent.

Morphology, crystal structure and adsorption performance of hydrothermally synthesized titania and titanate nanostructures

Titania (TiO2) and sodium titanate nanostructures with controllable phases and morphologies were synthesized by a hydrothermal method with titanium disulfide (TiS2) as the starting material. Sodium titanate nanobelts could be synthesized under a relatively low alkaline concentration (1 mol L(-1) NaOH) and short duration (6 h). At 3 mol L(-1) HCl, rutile TiO2 nanorods were synthesized. Anatase TiO2 nanoparticles were obtained at pH values ranging between 2 and 13. FTIR analysis confirmed the phase change as the pH of the reacting medium increased from highly acidic to highly alkaline. The adsorption of Methylene Blue (MB) on the as-synthesized sodium titanate nanobelts fitted well with the Langmuir monolayer model, with an adsorption capacity as high as 312.5 mg g(-1). The kinetics of MB adsorption was found to be a pseudo-second-order kinetic model. In brief, this study demonstrates a simple method to control the phase and morphology of titanium-based oxides. Excellent performance has been shown in the MB adsorption test by the sodium titanate nanostructures.

Synthesis of One-Dimensional Sodium Titanate Nanostructures

We synthesized sodium titanate nanotubes and nanowires using TiB2 and TIN as the starting materials, respectively in a hydrothermal process. The experimental results indicate that the reaction temperature influences the morphology of the product significantly. The nanowires were formed above 170 degrees C. Nanotubes were obtained below 140 degrees C. The synthesized nanotubes exhibit a crystallized multi-wall structure. The inner diameter was found to be ca. 5 nm. The diameter of the nanowires was found to be ca. 50 nm. The characteristic lengths was in the order of tens micrometers.

Chemical composition and phase identification of sodium titanate nanostructures grown from titania by hydrothermal processing

Fine titanium dioxide particles were hydrothermally treated in a sodium hydroxide aqueous solution. The treatment extended from 1 to 6 days leading to belt-like and wire-like structures of a metastable phase of sodium titanate, with typical widths and diameters between 8 and 40 nm, and lengths from 100 nm to several micrometers. These conclusions are supported by X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy and high resolution transmission electron microscopy. The latter method revealed two set of space fringes with characteristic distances of 0.29 and 0.34 nm. These distances could correspond to the lattice spacing of [ - 3 1 1 ] and [ - 1 1 1 ] planes in Na 2 Ti 6 O 13 compounds. The nanomaterial was found to be stable up to temperatures as high as 200 or 400 ∘ C depending on the reaction time and the concentration.