Titanate Nanomaterials Research Articles

Perovskite-structured ceramic zinc titanate nanomaterials: A comparative study of photovoltaic and synthetic approaches

Ternary metal oxide materials are being explored as potential electrode materials for dye-sensitized solar cells due to their adjustable electronic band structures through elemental composition modifications. Perovskite materials based on zinc and titanium have been utilised in DSSC and show moderate performance. Considerable research has been dedicated to this field to improve their performances. The focus was primarily on the synthetic variabilities due to their impact on performance under varying synthetic conditions. According to this perspective, no comparative studies have found superior methodologies for utilising zinc titanate as a potential photoanode in DSSC. We synthesised a zinc titanate material using thermal, sol-gel, and plasma irradiation techniques. The materials' structural variability was analysed using PXRD and FT-IR techniques. A mixed-phase composition of spinel cubic and hexagonal has been identified. The SEM images provide insights into the particle distribution and morphology of the zinc titanate materials. Investigating absorption properties, band gap energy levels and aggregation behaviours provided initial insights into the potential use of the three zinc titanate materials. The DSSC devices were fabricated using zinc titanate materials with varying properties, and the results are detailed in this discussion. Based on the findings, the plasma and thermal irradiation techniques yielded more favourable zinc titanate materials for dye-sensitized solar cell use. The efficiency reached 0.04 % when operating with polymeric gel electrolytes.

Recent advances in processing, morphological evolution and applications of bismuth sodium titanate nanoceramics

Nanostructured hybrid functional perovskite materials are an exciting domain of electroceramic materials and have created attention among researchers due to the coexistence of multiple properties like piezo and ferroelectricity. It offers a broad range of applications in optics and electronics technology. One of its kinds, bismuth sodium titanate (Bi0·5Na0·5TiO3-BNT) nanomaterials, possesses an integral and significant role in advanced electronic industries. This article aims to systemize the deliberation related to the development of bismuth sodium titanate-based nanomaterials, including the study of nanomaterial morphology mechanism, fabrication methods, crystal structure, and its role in many other novel applications. This work focuses on analyzing behavior based on synthesis methods, the proposed approaches for optimizing morphology, and current challenges. Challenges and opportunities connected with the BNT nanomaterials are elaborated. This study could motivate young researchers to study and develop novel BNT-based nanomaterials so that we could get the best out of the research.

Synthesis of cobalt doped nickel titanate nanomaterials for enhanced photocatalytic reduction of chromium

A series of cobalt doped nickel titanate nanomaterials where cobalt % is varied from 1 to 10% have been successfully synthesized by solvothermal method followed by calcination at 600 °C. Synthesized materials are characterized by XRD, FE-SEM, HR-TEM, BET surface area, DRS UV-Vis-NIR, XPS and PL spectroscopy. XRD and HR-TEM confirm the existence of NiTiO3 ilmenite structure with crystallite size in the range of 20–30 nm. HR-TEM of cobalt doped NiTiO3 shows the presence of tiny single atom cobalt metal sitting on NiTiO3, surface which induces the surface plasmon resonance effect. XPS of the doped NiTiO3 exhibits Ti3+ formation accompanied with oxygen vacancies resulting in the extended light absorption in the Vis-NIR region. The photocatalytic efficiency is studied monitoring the photoreduction of carcinogenic Cr (VI) under visible light. 3% cobalt doped NiTiO3 achieves 100% reduction of 30 ppm Cr (VI) solution within 60 min whereas pristine NiTiO3 shows only 50% efficiency under identical conditions. The trapping experiment shows the direct transfer of photogenerated electrons for the reduction of Cr (VI) following a first order kinetics. The two-fold enhanced activity of cobalt doped NiTiO3 is due to the collective effect of oxygen vacancies, efficient Vis-NIR absorption and surface plasmon resonance effect.

Microwave-assisted homogeneous precipitation route for the synthesis of La2Ti2O7:Tb3+ nanophosphors

Herein, a facile homogeneous coprecipitation strategy followed by calcination has been demonstrated to prepare La2Ti2O7:Tb3+ nanophosphors. Assisted by microwave irradiation, crystal water in La(NO3)3·6H2O was homogeneously released and ensured the coprecipitation of Ti4+, La3+ and Tb3+ via hydrolysis reactions. Pure perovskite La2Ti2O7 was obtained at a low annealing temperature of 800 °C, and the sample showed good dispersity with an average particle size of approximately 45.5 nm. By doping with Tb3+, the La2Ti2O7 nanoparticles exhibited green emission and the optimal Tb3+ concentration was 5 mol%. Our work offers an emergent and effective strategy for the synthesis of titanate nanomaterials.

Multielement Doped Barium Strontium Titanate Nanomaterials as Capacitors

Due to the growing demand of energy and wastage of energy, there exists an interest of storing energy so that it could be utilized efficiently. Capacitors are materials designed for such an application. Ferroelectric materials are known for their application as capacitors. Of such materials, perovskites are the preferable classes of materials that have been used as capacitors. Barium strontium titanate nanomaterial is a member of perovskites which encompasses a smaller dielectric loss, elevated dielectric constant, and good thermal stability. Research studies also clarified that incorporating dopants into a barium strontium titanate nanomaterial of high dielectric materials including metal/metal oxides enhances their efficiency and effectiveness. Moreover, multielement doping or codoping has shown better dielectric properties as compared to the unidoping of BST. In this review, barium strontium titanate capacitors codoped with more than one metal/metal oxides have been studied most of which have shown that the codoped barium strontium titanate materials possess improved and sufficient dielectric properties to be utilized as capacitors. We believe that this work will have of its own contribution on understanding the doped barium strontium titanate nanomaterial by clarifying the most probable and detail reasons behind the enhancement of dielectric properties of codoped barium strontium titanate nanomaterials.

Current Achievements in Flexible Piezoelectric Nanogenerators Based on Barium Titanate

Harvesting ambient mechanical energy at the nanometric scale holds great promise for powering small electronics and achieving self-powered electronic devices. The current review is focused on kinetic energy harvesters, particularly on flexible piezoelectric nanogenerators (p-NGs) based on barium titanate (BaTiO3) nanomaterials. p-NGs based on nanotubes, nanowires, nanofibres, nanoplatelets, nanocubes or nanoparticles of BaTiO3 fabricated in vertical or lateral orientation, as well as mixed composite structures, are overviewed here. The achievable power output level is shown to depend on the fabrication method, processing parameters and potential application conditions. Therefore, the most widely studied aspects, such as influence of geometry/orientation, BaTiO3 content, poling process and other factors in the output performance of p-NGs, are discussed. The current standing of BaTiO3-based p-NGs as possible candidates for various applications is summarized, and the issues that need to be addressed for realization of practical piezoelectric energy harvesting devices are discussed.

Electrochemical Properties of Composites Based on Lithium Titanate and Carbon Nanomaterials

Electrochemical Properties of Composites Based on Lithium Titanate and Carbon Nanomaterials

Terbium doped zinc ortho titanate nanocomposite for optical application – A complementary theoretical calculations

Zinc ortho titanate nanomaterial was synthesized hydrothermally under surfactant free conditions. The crystalline nature of the synthesized nano composite has been affirmed by PXRD analysis. FTIR analysis reports the existence of Ti-O and Zn-O metal organic bonds at 495 and 558 cm-1 respectively. UV cut off wavelength was found to be 232 nm which is evident that the narrow transparent window was in the entire visible region. The structural morphology and elemental analyses have been confirmed by SEM and EDX respectively and as well characterized by photoluminescence, scanning electron microscopy and thermal analysis. The SEM image is further analyzed and compared with laser speckle image processing. Thermal analysis evidenced the stability of the nano composite up to 990 °C which suitable to thermal devices. To reinforce the experimental findings, theoretical calculations were carried out using DFT functional B3LYP/cc-pvtz level of basis set through Gaussian 09 program.

P123 Assisted Sol- Gel Combustion Synthesis of Mesoporous Strontium Titanate Nanomaterials for Photocatalytic Degradation of Methylene Blue

We have reported the synthesis of strontium titanate (ST) nanomaterials via sol-gel combustion method in the presence and absence of pluronic P123 as a templating agent and citric acid as fuel at relatively high temperature. The presence of templating agent and fuel helps to generate mesoporosity in the materials resulting in mesoporous strontium titanate (MST). The materials are well characterized by various instrumental techniques. X-ray powder diffraction analysis has confirmed that both of the strontium titanate materials exhibited cubic perovskite structure. The FT-IR spectra has indicated that during high temperature calcination, carbonate species expelled out from the decomposition of the volatile impurities get adsorbed on the surface of titanate nanostructure, which is predominant in MST as indicated by the variation in the intensity of peak in between 1450 cm-1 –1470 cm-1. From diffuse reflectance spectra, the absorption edge of the MST is extended to visible regions and showed band gap energy of 3.14 eV compared to 3.21 eV for ST. The reduction in intensities of PL emission bands in MST compared to ST has indicated that slow electron-hole recombination takes place in this material compared to ST. The Transmission electron microscopic studies reveal the formation of spherical and cuboidal nanostructures with an average size of 55 and 38 nm for ST and MST material, respectively. From N2 sorption studies, the MST exhibit type IV adsorption isotherms with H3 type hysteresis loop indicated the formation of mesoporosity in this material whereas the ST indicated the formation of type II adsorption isotherms typical of nonporous materials. The elemental analysis of MST material is further confirmed from X-ray photoelectron spectroscopic analysis and confirm the formation of carbonate species on the surface of the materials. The photocatalytic activity of the materials is elucidated by the degradation of methylene blue under UV light irradiation and degradation followed first order kinetics with Langmuir-Hinshelwood adsorption pathways. The activity of MST material is found to be 5 times faster than ST at similar experimental conditions. The enhanced activity of the MST might be attributed to, lower band gap energy, presence of carbonate species, and lower electron-hole recombination in this material.

Synthesis and characterizations of metal ions doped barium strontium titanate (BST) nanomaterials for photocatalytic and electrical applications: A mini review

AbstractThe ferroelectric barium strontium titanate (Ba1-xSrxTiO3) is a homogeneous solid solution prepared from the mixture of barium titanate (BaTiO3), strontium titanate (SrTiO3) and titanium (IV) isopropoxide. Barium strontium titanate (BST) nanomaterials with improved permittivity and dielectric properties due to their nano-properties have attracted great interest for extensive and versatile applications as super capacitors, dielectrics, ceramics and catalysts. Introduction of metal ion dopants into the parent system of BST significantly alters its structural, morphological, electrical, optical and dielectric characteristics. This review is aimed at addressing synthesis, characterization methods, photocatalytic and electrical applications of metal ions doped BST nanomaterials. The effect of doping BST, through metal ions, on its properties and application with most probable reasons have been thoroughly discussed.

Oxygen defective titanate nanotubes induced by iron deposition for enhanced peroxymonosulfate activation and acetaminophen degradation: Mechanisms, water chemistry effects, and theoretical calculation

The large consumption of acetaminophen (APAP) worldwide and unsatisfactory treatment efficiencies by conventional wastewater treatment processes give rise to the seeking of new technology for its effective removal. Herein, we proposed a facile one-step hydrothermal method to synthesize defective iron deposited titanate nanotubes (Fe/TNTs) for peroxymonosulfate (PMS) activation and APAP degradation. The retarded first-order reaction rate of APAP degradation by Fe/TNTs was 5.1 times higher than that of neat TNTs. Characterizations indicated iron deposition effectively induced oxygen vacancies and Ti3+, facilitating the electrical conductivity and PMS binding affinity of Fe/TNTs. Besides, oxygen vacancies could act as an electron mediator through PMS activation by iron. Moreover, the formation of Fe–O–Ti bond facilitated the synergistic redox coupling between Fe and Ti, further enhancing the PMS activation. SO4•− was the major radical, causing C–N bond cleavage and decreasing the overall toxicity. In contrast, APAP degradation by neat TNTs-PMS system mainly works through nonradical reaction. The Fe/TNTs activated PMS showed desired APAP removal under mild water chemistry conditions and good reusability. This work is expected to expand the potential application of titanate nanomaterials for PMS activation, and shed light on facile synthesis of oxygen defective materials for sulfate-radical-based advanced oxidation processes.

Comparative study on photocatalytic degradation of the antidepressant trazodone using (Co, Fe and Ru) doped titanate nanowires: Kinetics, transformation products and in silico toxicity assessment

Titanate nanomaterials have been outstanding in the removal of emerging contaminants by the photocatalysis process. These photocatalysts, when modified through techniques such as doping with metals, they have advantages over TiO2, especially in the region of visible light. In this work, the photocatalytic performance of four recent reported catalysts, pristine titanate nanowires, cobalt-doped titanate nanowires, iron-doped titanate nanowires and ruthenium-doped titanate nanowires, for the removal of the antidepressant trazodone under visible light radiation was compared. The iron-doped titanate nanowires presented the best catalytic activity by the catalyst surface area. Additionally, thirteen transformation products (TPs) were identified by high-resolution mass spectrometry and, to the best of our knowledge, nine of them have never been described in the literature. It was shown that for each catalyst different TPs were formed with distinct time profiles. Finally, toxicity assessment by computational methods showed that TPs were not readily biodegradable and they presented toxicity to aquatic organisms with mutagenic potential. These findings reinforce the importance of taking into consideration the TPs formed during the removal of pollutants since many of them may be toxic and can be produced during photocatalysis.

Structural, optical and enhanced electrical properties of vanadium alloyed sodium bismuth titanate solid solution synthesized by a chemical-mechanical hybrid method

This work focuses on the effect of V2O5 addition on the structural, optical and electrical properties of Sodium Bismuth Titanate (Na0.5Bi0.5TiO3) nanomaterials, for its possible application as an electrolyte in SOFC. Pure Na0.5Bi0.5TiO3 (NBT) material has been synthesized using citrate auto-ignition method and V2O5 has been reinforced in the perovskite structure by mechanical alloying. X-ray diffraction analysis confirms the formation of the rhombohedral phase of NBT perovskite with space group R3c. Rietveld Analysis indicates the presence of insoluble minor V2O5 phase in the 20% milled composition. The values of lattice parameters, particle size, and the microstrain have been found to vary with V2O5 addition. The presence of different bonds has been confirmed from FT-IR analysis. It has been found that the vanadium incorporation can tune the optical bandgap of the material. The real part of complex ac conductivity has been found to follow universal Jonscher power law. The variation in conductivity is correlated with the structural changes due to V2O5 addition. The highest conductivity achieved was 1.0143 × 10−4 at 400 °C for the 15% doped composition. The conductivity mechanism has been explained by Mott’s variable range hopping model.

Synthesis and enhanced gas sensing properties of iron titanate and copper titanate nanomaterials

Titanate-based materials have been widely used in energy and environmental fields, but only few work was focused on the gas sensing applications, partly because of their high operating temperature and poor selectivity. Herein, amorphous iron titanate and copper titanate nanomaterials were successfully synthesized by a simple hydrothermal method followed by a cationic substitution process. They are spherical nanoparticles agglomerated from nanosheets, and the surface area is as high as 188.7 m2 g−1. It revealed that the selective gas sensing performance towards ethanol exhibited n-type behaviors. Moreover, the sensitivity can be down to 100 ppm at an operating temperature as low as 131.4 °C. The typical response and recovery times are 17s and 124 s, respectively. Life assessments indicated that the sensing performance could remain stable up to 210 days. In all, the good ethanol selectivity, the low operating temperature, the fast response time and the long life stability indicate their promising and practical applications in trace detection of ethanol.

Efficient adsorption of europium (III) and uranium (VI) by titanate nanorings: Insights into radioactive metal species

Radioactive wastewater containing high concentration of radionuclides poses severe threats to ecosystem and human health, so efficient removal of these toxic heavy metals is urgently needed. Titanate nanomaterials have been demonstrated good adsorbents for heavy metals due to ion exchange property. In this study, titanate nanorings (TNRs) were synthesized using the facile hydrothermal-cooling method. The TNRs were composed of sodium trititanate, with a chemical formula of Na0.66H1.34Ti3O7•0.27H2O and a Na content of 2.38 mmol/g. The TNRs demonstrated sufficient adsorption performance to radionuclides europium (Eu) and uranium (U) ions. Specifically, even at a high initial concentration of 50 mg/L, 86.5% and 92.6% of the two metal ions can be rapidly adsorbed by the TNRs within 5 min, and equilibrium was reached within 60 min at pH 5. The maximum adsorption capacity (Qmax) obtained by the Langmuir isotherm model was 115.3 mg/g for Eu(III) and 282.5 mg/g for uranium U(VI) at pH 5, respectively. The adsorption capacities of the two metals under various water chemical conditions were highly related to their species. Ion exchange between metal cations and Na+ in the TNR interlayers was the dominant adsorption mechanism, and adsorption of U(VI) was more complicated because of the co-existence of various uranyl (UO22+) and uranyl-hydroxyl species. The spent TNRs were effectively regenerated through an acid-base or ethylenediamine tetraacetic acid (EDTA) treatment and reused. Considering the large adsorption capacity and quick kinetic, TNRs are promising materials to remove radionuclides in environmental purification applications, especially emergent treatment of leaked radionuclides.

Hydrothermal synthesis and characterisation of titanate nanomaterial thin films in mixed aqueous NaOH/KOH

Titanate nanomaterial thin films were prepared using an alkaline hydrothermal method in various molar ratios of NaOH/KOH mixed aqueous solution at a total concentration of 10 M. The as-prepared nanomaterials were characterised by X-ray diffractometer, scanning electron microscopy and transmission electron microscopy. The effects of the molar ratio of Na+/K+ on the morphologies and microstructures of titanate nanomaterials were studied. With the molar ratio of Na+/K+ decreases, the mean diameter of nanomaterials increases. The phase and structure transformation of nanomaterials were from sodium titanate nanotubes to potassium titanate nanowires and the formation mechanism was discussed.

APPLICATION OF SODIUM TITANATE BASED NANOMATERIALS FOR DYE ADSORPTION

The application of sodium titanium-based nanomaterials for the adsorption of dyes deserves to be invested by an innovative and low-cost technique. Also, contamination of effluents by used dyes can cause damage and public health due to their toxicity and recalcitrance. So, an end of environmental impact impacted by these effluents, it is necessary or the development of new technologies of removal. An alternative to remedy this problem is found in the application of the adsorption technique through the use of sodium titanium nanomaterials. These factors do not have surface areas, spaces between and charge transfer rates of efficient interfaces, or what significantly increases the adsorbents. Thus, the present work aimed to synthesize sodium titanium nanomaterials and to investigate their use for the removal of dyes or gum from the aqueous medium. The materials were synthesized using the hydrothermal method, without the use of a structured guide, using titanium dioxide as the starting material in the alkaline medium (10M NaOH). These materials were studied, using their use in the removal of organic pollutants in aqueous medium, where it verified the formation of fibrillar morphology for all the materials used. Through the X-ray diffraction technique, it was confirmed the establishment of four crystallographic phases of lamellar titanates, predominantly, of disodium titanate, with monoclinic symmetry. In short, the results proved that there was a formation of titanate nanomaterials. Tests to remove methylene blue are promising for the adsorptive activity of the captured materials concerning the starting oxide, removing up to 81% of the dye in 30 min. Titanium nanomaterials are efficient to remedy aquatic ecosystems contaminated by this organic pollutant; in addition, the collected data become a reference for future studies.

Removal of thallium(I) from aqueous solutions using titanate nanomaterials: The performance and the influence of morphology

Thallium (Tl) pollution has attracted environmental attention due to its high toxicity, thus the cleanup of Tl from the environment is of significance. Titanate nanomaterials (TNMs) with different morphologies can be synthesized via a hydrothermal reaction under different conditions but the knowledge of the Tl(I) removal by them is limited. Our results indicated that TNM prepared at 130 °C exhibited a nanotubular appearance and a longer reaction time resulted in the formation of perfect nanotube, while that prepared at 180 °C exhibited a nanowire-like arrangement. The nanotubular and nanowire-like TNMs possessed approximately excellent Tl(I) adsorption capacities, wide pH, and temperature application ranges but different adsorption kinetics. Inorganic ions influenced the Tl(I) removal and the inhibiting effect of heavy metal ions followed the sequence Pb(II) > Cu(II) > Cd(II) > Zn(II). The anti-interference ability and selectivity of wire-like TNMs for Tl(I) removal were higher than those of tubular TNMs. High Tl(I) uptakes of tubular and wire-like TNMs were driven by the electrostatic attraction, ion exchange with Na+/H+, and complexation with –ONa functional groups in the interlayers and Ti–OH on the surfaces of TNMs as well as microprecipitation; while their adsorption configurations were different. TNMs are promising for potential applications in Tl(I) elimination from wastewater due to the high adsorption capacity and regenerability. This work indicates that TNMs synthesized under different conditions have the similar Tl(I) adsorption performances and the preparation of TNMs used for Tl(I) removal has an undemanding synthesis condition.

Sol-Gel-Based Electrospray Synthesis of Barium Titanate Nanoparticles.

Barium titanate nanoparticles are desirable for a wide range of applications, spanning electronics to biomedicine. Here, we present an electrospray-based method for the synthesis of barium titanate nanomaterials, where their morphology can be altered, forming either particles or rods. As-electrosprayed particles are amorphous and spherical, but upon calcination in the presence of sodium chloride their morphology can vary from particles to rods as the calcination time is increased. The processing-structure-property relationships in these materials are discussed.

Zinc titanate nanomaterials—photocatalytic studies and sensitization of hydantoin derivatized porphyrin dye

ZnTiO3 cubic nanomaterials were synthesized hydrothermally under surfactant free conditions, in presence of the inexpensive material urea. Calcination at 6000C yields highly crystalline hexagonal stoichiometric ZnTiO3 phase (as confirmed from powder X-ray diffraction, X-ray photoelectron spectra and Raman studies). This is in contrast to earlier reports, which said that ZnTiO3 can be synthesized at much higher temperature i.e. 9450C. Distinct signatures of Zn-O and Ti-O vibrations were manifested in the IR spectra with concomitant decrease in intensity of -NH and -CO stretching frequencies of urea. Thus urea plays a critical role in formation and stabilization of the ZnTiO3phase. The ZnTiO3 nanomaterials showed much superior photo catalytic efficiency than TiO2 nanomaterials due to enhanced electron–hole separation in the former because electrons can easily get transferred from the conduction band (CB) of Ti to CB of Zn. Surface studies indicate larger pore volume and pore diameter of the ZnTiO3 nanomaterials. The ZnTiO3 nanomaterials also get effectively sensitized by a porphyrin dye (PHy) synthesized with hydantoin anchoring groups. Electron injection rate from PHy to ZnTiO3 is much higher than from PHy to TiO2 implying the prospect of using the titanate nanomaterials as photoanode materials in dye sensitized solar cells (DSCs).