Titanate Nanostructures

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (31 January 2020) | Viewed by 19857

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Department of Applied and Environmental Chemistry, Faculty of Natural Sciences and Informatics, Institute of Chemistry, University of Szeged, Szeged, Hungary
Interests: catalysis; surface chemistry; photocatalysis; carbon nanostructures; green chemistry
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Dear Colleagues,

Titanium dioxide is one of the most heavily investigated oxide materials. Poly-titanate-based materials have close structural resemblance to titanium dioxide since both are composed of TiO6 octahedra units connected by sharing corners and edges. The favorable properties of titanates are embossed by their unique crystal structure, where the negatively charged two-dimensional titanium-containing sheets are separated by a large distance by cations and molecules in the interlayer.

Research interest in the area of these polytitanate-based nanostructures has been increasing steadily in the past decades because of their unique structure- and size-dependent physicochemical properties. These materials have been widely used in adsorption, heterogeneous catalytic, photocatalytic, photovoltaic, solar energy conversion, and energy storage applications, just to mention a few.

By the same token, their size- and shape-dependent physicochemical properties allow for size- and shape-dependent biological and environmental effects as well. In the recent years, many efforts have been made to design and/or modify titanate-based nanostructures in order to use them in chemical and biological sensor devices, drug delivery systems, or even cancer therapy.

This Special Issue of Nanomaterials will attempt to cover the most recent story of the titanate-based nanostructures from the novel synthetic approaches based on their structural, compositional, and functional characterization, to their different applications (photo-, bio- and electrocatalytic applications, chemical and biological sensor devices, drug delivery systems, solar energy conversion, energy storage, etc.).

Prof. Zoltán Kónya
Guest Editor

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Keywords

  • Novel synthetic approaches
  • Structural, compositional, and functional properties
  • Photo-, bio- and electrocatalytic applications
  • Environmental and biological impact
  • Chemical and biological sensor devices
  • Nanotitanates in drug delivery systems
  • Solar energy conversion
  • Energy storage

Published Papers (5 papers)

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Research

13 pages, 4735 KiB  
Article
Impact of Oxalate Ligand in Co-Precipitation Route on Morphological Properties and Phase Constitution of Undoped and Rh-Doped BaTiO3 Nanoparticles
by Roussin Lontio Fomekong, Shujie You, Francesco Enrichi, Alberto Vomiero and Bilge Saruhan
Nanomaterials 2019, 9(12), 1697; https://doi.org/10.3390/nano9121697 - 28 Nov 2019
Cited by 8 | Viewed by 3967
Abstract
In order to design and tailor materials for a specific application like gas sensors, the synthesis route is of great importance. Undoped and rhodium-doped barium titanate powders were successfully synthesized by two routes; oxalate route and classic route (a modified conventional route where [...] Read more.
In order to design and tailor materials for a specific application like gas sensors, the synthesis route is of great importance. Undoped and rhodium-doped barium titanate powders were successfully synthesized by two routes; oxalate route and classic route (a modified conventional route where solid-state reactions and thermal evaporation induced precipitation takes place). Both powders were calcined at different temperatures. X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX) and Brunauer-Emmet-Teller (BET) analyses are employed to identify the phases and polymorphs, to determine the morphology, the chemical composition and the specific surface area of the synthesized materials, respectively. The so-called oxalate route yields pure BaTiO3 phase for undoped samples at 700 °C and 900 °C (containing both cubic and tetragonal structures), while the classic route-synthesized powder contains additional phases such as BaCO3, TiO2 and BaTi2O5. Samples of both synthesis routes prepared by the addition of Rh contain no metallic or oxide phase of rhodium. Instead, it was observed that Ti was substituted by Rh at temperatures 700 °C and 900 °C and there was some change in the composition of BaTiO3 polymorph (increase of tetragonal structure). Heat-treatments above these temperatures show that rhodium saturates out of the perovskite lattice at 1000 °C, yielding other secondary phases such as Ba3RhTi2O9 behind. Well-defined and less agglomerated spherical nanoparticles are obtained by the oxalic route, while the classic route yields particles with an undefined morphology forming very large block-like agglomerates. The surface area of the synthesized materials is higher with the oxalate route than with the classic route (4 times at 900 °C). The presence of the oxalate ligand with its steric hindrance that promotes the uniform distribution and the homogeneity of reactants could be responsible for the great difference observed between the powders prepared by two preparation routes. Full article
(This article belongs to the Special Issue Titanate Nanostructures)
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16 pages, 34646 KiB  
Article
Optimization of the Production Process and Product Quality of Titanate Nanotube–Drug Composites
by Yasmin Ranjous, Géza Regdon, Jr., Klára Pintye-Hódi, Tamás Varga, Imre Szenti, Zoltán Kónya and Tamás Sovány
Nanomaterials 2019, 9(10), 1406; https://doi.org/10.3390/nano9101406 - 2 Oct 2019
Cited by 4 | Viewed by 3621
Abstract
Recently, there has been an increasing interest in the application of nanotubular structures for drug delivery. There are several promising results with carbon nanotubes; however, in light of some toxicity issues, the search for alternative materials has come into focus. The objective of [...] Read more.
Recently, there has been an increasing interest in the application of nanotubular structures for drug delivery. There are several promising results with carbon nanotubes; however, in light of some toxicity issues, the search for alternative materials has come into focus. The objective of the present study was to investigate the influence of the applied solvent on the composite formation of titanate nanotubes (TNTs) with various drugs in order to improve their pharmacokinetics, such as solubility, stability, and bioavailability. Composites were formed by the dissolution of atenolol (ATN) and hydrochlorothiazide (HCT) in ethanol, methanol, 0.01 M hydrochloric acid or in ethanol, 1M sodium hydroxide, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), respectively, and then they were mixed with a suspension of TNTs under sonication for 30 min and vacuum-dried for 24 h. The structural properties of composites were characterized by SEM, TEM, FT-IR, differential scanning calorimetry (DSC), thermogravimetric (TG) analysis, and optical contact angle (OCA) measurements. Drug release was determined from the fast disintegrating tablets using a dissolution tester coupled with a UV–Vis spectrometer. The results revealed that not only the good solubility of the drug in the applied solvent, but also the high volatility of the solvent, is necessary for an optimal composite-formation process. Full article
(This article belongs to the Special Issue Titanate Nanostructures)
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12 pages, 2030 KiB  
Article
Titanate Nanowires as One-Dimensional Hot Spot Generators for Broadband Au–TiO2 Photocatalysis
by Yoel Negrín-Montecelo, Martín Testa-Anta, Laura Marín-Caba, Moisés Pérez-Lorenzo, Verónica Salgueiriño, Miguel A. Correa-Duarte and Miguel Comesaña-Hermo
Nanomaterials 2019, 9(7), 990; https://doi.org/10.3390/nano9070990 - 9 Jul 2019
Cited by 11 | Viewed by 3557
Abstract
Metal–semiconductor nanocomposites have become interesting materials for the development of new photocatalytic hybrids. Along these lines, plasmonic nanoparticles have proven to be particularly efficient photosensitizers due to their ability to transfer plasmonic hot electrons onto large bandgap semiconductors such as TiO2, [...] Read more.
Metal–semiconductor nanocomposites have become interesting materials for the development of new photocatalytic hybrids. Along these lines, plasmonic nanoparticles have proven to be particularly efficient photosensitizers due to their ability to transfer plasmonic hot electrons onto large bandgap semiconductors such as TiO2, thus extending the activity of the latter into a broader range of the electromagnetic spectrum. The extent of this photosensitization process can be substantially enhanced in those geometries in which high electromagnetic fields are created at the metal–semiconductor interface. In this manner, the formation of plasmonic hot spots can be used as a versatile tool to engineer the photosensitization process in this family of hybrid materials. Herein, we introduce the use of titanate nanowires as ideal substrates for the assembly of Au nanorods and TiO2 nanoparticles, leading to the formation of robust hybrids with improved photocatalytic properties. Our approach shows that the correct choice of the individual units together with their rational assembly are of paramount importance in the development of complex nanostructures with advanced functionalities. Full article
(This article belongs to the Special Issue Titanate Nanostructures)
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13 pages, 4796 KiB  
Article
The Impact of TiO2 Nanoparticle Concentration Levels on Impulse Breakdown Performance of Mineral Oil-Based Nanofluids
by Ziyi Wang, You Zhou, Wu Lu, Neng Peng and Weijie Chen
Nanomaterials 2019, 9(4), 627; https://doi.org/10.3390/nano9040627 - 17 Apr 2019
Cited by 22 | Viewed by 3855
Abstract
The insulation of mineral oil-based nanofluids was found to vary with different concentration level of nanoparticles. However, the mechanisms behind this research finding are not well studied. In this paper, mineral oil-based nanofluids were prepared by suspending TiO2 nanoparticles with weight percentages [...] Read more.
The insulation of mineral oil-based nanofluids was found to vary with different concentration level of nanoparticles. However, the mechanisms behind this research finding are not well studied. In this paper, mineral oil-based nanofluids were prepared by suspending TiO2 nanoparticles with weight percentages ranging from 0.0057% to 0.0681%. The breakdown voltage and chop time of nanofluids were observed under standard lightning impulse waveform. The experimental results show that the presence of TiO2 nanoparticles increases the breakdown voltage of mineral oil under positive polarity. The enhancement of breakdown strength tends to saturate when the concentration of nanoparticle exceeds 0.0227 wt%. Electronic traps formed at the interfacial region of nanoparticles, which could capture fast electrons in bulk oil and reduce the net density of space charge in front of prebreakdown streamers, are responsible for the breakdown strength enhancement. When the particle concentration level is higher, the overlap of Gouy–Chapman diffusion layers results in the saturation of trap density in nanofluids. Consequently, the breakdown strength of nanofluids is saturated. Under negative polarity, the electrons are likely to be scattered by the nanoparticles on the way towards the anode, resulting in enhanced electric fields near the streamer tip and the decrement of breakdown voltage. Full article
(This article belongs to the Special Issue Titanate Nanostructures)
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17 pages, 4604 KiB  
Article
One-Step Acidic Hydrothermal Preparation of Dendritic Rutile TiO2 Nanorods for Photocatalytic Performance
by Cheng Gong, Jun Du, Xiuyun Li, Zhenjie Yu, Jiansong Ma, Wenqian Qi, Kai Zhang, Jin Yang, Mei Luo and Hailong Peng
Nanomaterials 2018, 8(9), 683; https://doi.org/10.3390/nano8090683 - 1 Sep 2018
Cited by 17 | Viewed by 4189
Abstract
Three-dimensional and dendritic rutile TiO2 nanorods were successfully fabricated on a Ti foil surface using a one-step acidic hydrothermal method. The TiO2 nanorods were characterized using X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), scanning electron microscopy [...] Read more.
Three-dimensional and dendritic rutile TiO2 nanorods were successfully fabricated on a Ti foil surface using a one-step acidic hydrothermal method. The TiO2 nanorods were characterized using X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and optical contact angle testing. The results showed that the nanorods with diameters of 100–500 nm and lengths of 100 nm to 1 μm were obtained on the Ti foil surface. The length and density of the TiO2 nanorods were perfect at the conditions of HCl concentration 0.5 mol/L, temperature 220 °C, and reaction time 12 h. The TiO2 nanorods formed parallel to the consumption of Ti and grew along the (110) direction having a tetragonal rutile crystal. The morphology of the nanorods possessed a three-dimensional structure. The contact angle of the nanorods was only 13 ± 3.1°. Meanwhile, the photocatalytic activities of the TiO2 nanorods were carried out using ultraviolet fluorescence spectrophotometry for the methyl orange detection, and the degradation was found to be about 71.00% ± 2.43%. Thus, TiO2 nanorods can be developed by a one-step acidic hydrothermal method using Ti foil simultaneously as the substrate with a TiO2 source; the TiO2 nanorods exhibited photocatalytic performance while being environment-friendly. Full article
(This article belongs to the Special Issue Titanate Nanostructures)
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