Special Issue "ZnO and TiO2 Based Nanostructures"

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

Deadline for manuscript submissions: closed (30 September 2017)

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Guest Editor
Dr. Andrea Lamberti

Politecnico di Torino, Torino, Italy
Website 1 | Website 2 | E-Mail
Interests: metal-oxide nanostructures; TiO2 nanotubes; graphene; supercapacitors; nanotechnology; dye-sensitized solar cells

Special Issue Information

Dear Colleagues,

Transition-metal oxide nanostructures are the focus of current research efforts in nanotechnology since they are the most common minerals on Earth, and also thanks to their special shapes, compositions, and chemical and physical properties. They have now been widely used in the design of energy saving and harvesting devices, such as lithium-ion batteries, fuel cells, solar cells, and even transistors, light emitting devices (LEDs), hydrogen production by water photolysis and its storage, water and air purification by degradation of organic/inorganic pollutants, bio-sensing devices, environmental monitoring by their applications in the fabrication of gas, humidity, and temperature sensors, and photodetectors.

In addition to the great application potentials, oxide-based nanomaterials, such as ZnO and TiO2, have recently revolutionized nanomaterial research thanks to their outstanding properties. They can be produced in different shapes (such as nanowires, nanobelts, nanorods, nanotubes, nanocombs, nanorings, nanohelixes/nanosprings, nanocages and nanosheets, and nanostars) depending on the synthesis routes, which range in techniques.

This Special Issue of Nanomaterials will attempt to cover the most recent advances in ZnO and TiO2 nanostructures, concerning, not only the synthesis and characterization, but especially reports of their functional and smart properties to be applied in working devices. Applications of nanosized ZnO and TiO2 can range widely, from biomedical and drug delivery devices to piezoelectric and chemical sensors, and energy harvesting, conversion and storage devices.

Dr. Andrea Lamberti
Guest Editor

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Keywords

  • Advanced synthesis
  • Smart properties
  • Characterizations
  • Multifunctional materials
  • Energy harvesting/storage device
  • Sensors
  • Bio-materials and bio-devices

Published Papers (28 papers)

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Editorial

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Open AccessEditorial ZnO- and TiO2-Based Nanostructures
Nanomaterials 2018, 8(5), 325; https://doi.org/10.3390/nano8050325
Received: 8 May 2018 / Revised: 8 May 2018 / Accepted: 10 May 2018 / Published: 14 May 2018
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Abstract
Transition-metal oxide (TMO) nanostructures are the focus of current research efforts in nanotechnology since they are the most common minerals on Earth, and also thanks to their special shapes, compositions, and chemical and physical properties.[...] Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Research

Jump to: Editorial, Review

Open AccessFeature PaperArticle Lipid-Coated Zinc Oxide Nanoparticles as Innovative ROS-Generators for Photodynamic Therapy in Cancer Cells
Nanomaterials 2018, 8(3), 143; https://doi.org/10.3390/nano8030143
Received: 9 February 2018 / Revised: 28 February 2018 / Accepted: 28 February 2018 / Published: 2 March 2018
Cited by 6 | PDF Full-text (4245 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In the present paper, we use zinc oxide nanoparticles under the excitation of ultraviolet (UV) light for the generation of Reactive Oxygen Species (ROS), with the aim of further using these species for fighting cancer cells in vitro. Owing to the difficulties in
[...] Read more.
In the present paper, we use zinc oxide nanoparticles under the excitation of ultraviolet (UV) light for the generation of Reactive Oxygen Species (ROS), with the aim of further using these species for fighting cancer cells in vitro. Owing to the difficulties in obtaining highly dispersed nanoparticles (NPs) in biological media, we propose their coating with a double-lipidic layer and we evaluate their colloidal stability in comparison to the pristine zinc oxide NPs. Then, using Electron Paramagnetic Resonance (EPR) coupled with the spin-trapping technique, we demonstrate and characterize the ability of bare and lipid-coated ZnO NPs to generate ROS in water only when remotely actuated via UV light irradiation. Interestingly, our results reveal that the surface chemistry of the NPs greatly influences the type of photo-generated ROS. Finally, we show that lipid-coated ZnO NPs are effectively internalized inside human epithelial carcinoma cells (HeLa) via a lysosomal pathway and that they can generate ROS inside cancer cells, leading to enhanced cell death. The results are promising for the development of ZnO-based therapeutic systems. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle The Critical Role of Thioacetamide Concentration in the Formation of ZnO/ZnS Heterostructures by Sol-Gel Process
Nanomaterials 2018, 8(2), 55; https://doi.org/10.3390/nano8020055
Received: 30 September 2017 / Revised: 3 November 2017 / Accepted: 6 November 2017 / Published: 23 January 2018
Cited by 1 | PDF Full-text (2457 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
ZnO/ZnS heterostructures have emerged as an attractive approach for tailoring the properties of particles comprising these semiconductors. They can be synthesized using low temperature sol-gel routes. The present work yields insight into the mechanisms involved in the formation of ZnO/ZnS nanostructures. ZnO colloidal
[...] Read more.
ZnO/ZnS heterostructures have emerged as an attractive approach for tailoring the properties of particles comprising these semiconductors. They can be synthesized using low temperature sol-gel routes. The present work yields insight into the mechanisms involved in the formation of ZnO/ZnS nanostructures. ZnO colloidal suspensions, prepared by hydrolysis and condensation of a Zn acetate precursor solution, were allowed to react with an ethanolic thioacetamide solution (TAA) as sulfur source. The reactions were monitored in situ by Small Angle X-ray Scattering (SAXS) and UV-vis spectroscopy, and the final colloidal suspensions were characterized by High Resolution Transmission Electron Microscopy (HRTEM). The powders extracted at the end of the reactions were analyzed by X-ray Absorption spectroscopy (XAS) and X-ray diffraction (XRD). Depending on TAA concentration, different nanostructures were revealed. ZnO and ZnS phases were mainly obtained at low and high TAA concentrations, respectively. At intermediate TAA concentrations, we evidenced the formation of ZnO/ZnS heterostructures. ZnS formation could take place via direct crystal growth involving Zn ions remaining in solution and S ions provided by TAA and/or chemical conversion of ZnO to ZnS. The combination of all the characterization techniques was crucial to elucidate the reaction steps and the nature of the final products. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Crystallization of TiO2 Nanotubes by In Situ Heating TEM
Nanomaterials 2018, 8(1), 40; https://doi.org/10.3390/nano8010040
Received: 27 September 2017 / Revised: 12 December 2017 / Accepted: 11 January 2018 / Published: 14 January 2018
Cited by 1 | PDF Full-text (8422 KB) | HTML Full-text | XML Full-text
Abstract
The thermally-induced crystallization of anodically grown TiO2 amorphous nanotubes has been studied so far under ambient pressure conditions by techniques such as differential scanning calorimetry and in situ X-ray diffraction, then looking at the overall response of several thousands of nanotubes in
[...] Read more.
The thermally-induced crystallization of anodically grown TiO2 amorphous nanotubes has been studied so far under ambient pressure conditions by techniques such as differential scanning calorimetry and in situ X-ray diffraction, then looking at the overall response of several thousands of nanotubes in a carpet arrangement. Here we report a study of this phenomenon based on an in situ transmission electron microscopy approach that uses a twofold strategy. First, a group of some tens of TiO2 amorphous nanotubes was heated looking at their electron diffraction pattern change versus temperature, in order to determine both the initial temperature of crystallization and the corresponding crystalline phases. Second, the experiment was repeated on groups of few nanotubes, imaging their structural evolution in the direct space by spherical aberration-corrected high resolution transmission electron microscopy. These studies showed that, differently from what happens under ambient pressure conditions, under the microscope’s high vacuum (p < 10−5 Pa) the crystallization of TiO2 amorphous nanotubes starts from local small seeds of rutile and brookite, which then grow up with the increasing temperature. Besides, the crystallization started at different temperatures, namely 450 and 380 °C, when the in situ heating was performed irradiating the sample with electron beam energy of 120 or 300 keV, respectively. This difference is due to atomic knock-on effects induced by the electron beam with diverse energy. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Thermally Stimulated Currents in Nanocrystalline Titania
Nanomaterials 2018, 8(1), 13; https://doi.org/10.3390/nano8010013
Received: 31 October 2017 / Revised: 12 December 2017 / Accepted: 12 December 2017 / Published: 5 January 2018
Cited by 1 | PDF Full-text (4232 KB) | HTML Full-text | XML Full-text
Abstract
A thorough study on the distribution of defect-related active energy levels has been performed on nanocrystalline TiO2. Films have been deposited on thick-alumina printed circuit boards equipped with electrical contacts, heater and temperature sensors, to carry out a detailed thermally stimulated
[...] Read more.
A thorough study on the distribution of defect-related active energy levels has been performed on nanocrystalline TiO2. Films have been deposited on thick-alumina printed circuit boards equipped with electrical contacts, heater and temperature sensors, to carry out a detailed thermally stimulated currents analysis on a wide temperature range (5–630 K), in view to evidence contributions from shallow to deep energy levels within the gap. Data have been processed by numerically modelling electrical transport. The model considers both free and hopping contribution to conduction, a density of states characterized by an exponential tail of localized states below the conduction band and the convolution of standard Thermally Stimulated Currents (TSC) emissions with gaussian distributions to take into account the variability in energy due to local perturbations in the highly disordered network. Results show that in the low temperature range, up to 200 K, hopping within the exponential band tail represents the main contribution to electrical conduction. Above room temperature, electrical conduction is dominated by free carriers contribution and by emissions from deep energy levels, with a defect density ranging within 1014–1018 cm−3, associated with physio- and chemi-sorbed water vapour, OH groups and to oxygen vacancies. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Organozinc Precursor-Derived Crystalline ZnO Nanoparticles: Synthesis, Characterization and Their Spectroscopic Properties
Nanomaterials 2018, 8(1), 22; https://doi.org/10.3390/nano8010022
Received: 5 November 2017 / Revised: 20 December 2017 / Accepted: 21 December 2017 / Published: 4 January 2018
Cited by 1 | PDF Full-text (12185 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Crystalline ZnO-ROH and ZnO-OR (R = Me, Et, iPr, nBu) nanoparticles (NPs) have been successfully synthesized by the thermal decomposition of in-situ-formed organozinc complexes Zn(OR)2 deriving from the reaction of Zn[N(SiMe3)2]2 with ROH
[...] Read more.
Crystalline ZnO-ROH and ZnO-OR (R = Me, Et, iPr, nBu) nanoparticles (NPs) have been successfully synthesized by the thermal decomposition of in-situ-formed organozinc complexes Zn(OR)2 deriving from the reaction of Zn[N(SiMe3)2]2 with ROH and of the freshly prepared Zn(OR)2 under an identical condition, respectively. With increasing carbon chain length of alkyl alcohol, the thermal decomposition temperature and dispersibility of in-situ-formed intermediate zinc alkoxides in oleylamine markedly influenced the particle sizes of ZnO-ROH and its shape (sphere, plate-like aggregations), while a strong diffraction peak-broadening effect is observed with decreasing particle size. For ZnO-OR NPs, different particle sizes and various morphologies (hollow sphere or cuboid-like rod, solid sphere) are also observed. As a comparison, the calcination of the fresh-prepared Zn(OR)2 generated ZnO-R NPs possessing the particle sizes of 5.4~34.1 nm. All crystalline ZnO nanoparticles are characterized using X-ray diffraction analysis, electron microscopy and solid-state 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The size effect caused by confinement of electrons’ movement and the defect centres caused by unpaired electrons on oxygen vacancies or ionized impurity heteroatoms in the crystal lattices are monitored by UV-visible spectroscopy, electron paramagnetic resonance (EPR) and photoluminescent (PL) spectroscopy, respectively. Based on the types of defects determined by EPR signals and correspondingly defect-induced probably appeared PL peak position compared to actual obtained PL spectra, we find that it is difficult to establish a direct relationship between defect types and PL peak position, revealing the complication of the formation of defect types and photoluminescence properties. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Piezoelectric Potential in Single-Crystalline ZnO Nanohelices Based on Finite Element Analysis
Nanomaterials 2017, 7(12), 430; https://doi.org/10.3390/nano7120430
Received: 7 October 2017 / Revised: 8 November 2017 / Accepted: 1 December 2017 / Published: 7 December 2017
Cited by 4 | PDF Full-text (1155 KB) | HTML Full-text | XML Full-text
Abstract
Electric potential produced in deformed piezoelectric nanostructures is of significance for both fundamental study and practical applications. To reveal the piezoelectric property of ZnO nanohelices, the piezoelectric potential in single-crystal nanohelices was simulated by finite element method calculations. For a nanohelix with a
[...] Read more.
Electric potential produced in deformed piezoelectric nanostructures is of significance for both fundamental study and practical applications. To reveal the piezoelectric property of ZnO nanohelices, the piezoelectric potential in single-crystal nanohelices was simulated by finite element method calculations. For a nanohelix with a length of 1200 nm, a mean coil radius of 150 nm, five active coils, and a hexagonal coiled wire with a side length 100 nm, a compressing force of 100 nN results in a potential of 1.85 V. This potential is significantly higher than the potential produced in a straight nanowire with the same length and applied force. Maintaining the length and increasing the number of coils or mean coil radius leads to higher piezoelectric potential in the nanohelix. Appling a force along the axial direction produces higher piezoelectric potential than in other directions. Adding lateral forces to an existing axial force can change the piezoelectric potential distribution in the nanohelix, while the maximum piezoelectric potential remains largely unchanged in some cases. This research demonstrates the promising potential of ZnO nanohelices for applications in sensors, micro-electromechanical systems (MEMS) devices, nanorobotics, and energy sciences. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle ZnO Nanoparticles Protect RNA from Degradation Better than DNA
Nanomaterials 2017, 7(11), 378; https://doi.org/10.3390/nano7110378
Received: 22 September 2017 / Revised: 23 October 2017 / Accepted: 31 October 2017 / Published: 8 November 2017
Cited by 2 | PDF Full-text (1624 KB) | HTML Full-text | XML Full-text
Abstract
Gene therapy and RNA delivery require a nanoparticle (NP) to stabilize these nucleic acids when administered in vivo. The presence of degradative hydrolytic enzymes within these environments limits the nucleic acids’ pharmacologic activity. This study compared the effects of nanoscale ZnO and MgO
[...] Read more.
Gene therapy and RNA delivery require a nanoparticle (NP) to stabilize these nucleic acids when administered in vivo. The presence of degradative hydrolytic enzymes within these environments limits the nucleic acids’ pharmacologic activity. This study compared the effects of nanoscale ZnO and MgO in the protection afforded to DNA and RNA from degradation by DNase, serum or tumor homogenate. For double-stranded plasmid DNA degradation by DNase, our results suggest that the presence of MgO NP can protect DNA from DNase digestion at an elevated temperature (65 °C), a biochemical activity not present in ZnO NP-containing samples at any temperature. In this case, intact DNA was remarkably present for MgO NP after ethidium bromide staining and agarose gel electrophoresis where these same stained DNA bands were notably absent for ZnO NP. Anticancer RNA, polyinosinic-polycytidylic acid (poly I:C) is now considered an anti-metastatic RNA targeting agent and as such there is great interest in its delivery by NP. For it to function, the NP must protect it from degradation in serum and the tumor environment. Surprisingly, ZnO NP protected the RNA from degradation in either serum-containing media or melanoma tumor homogenate after gel electrophoretic analysis, whereas the band was much more diminished in the presence of MgO. For both MgO and ZnO NP, buffer-dependent rescue from degradation occurred. These data suggest a fundamental difference in the ability of MgO and ZnO NP to stabilize nucleic acids with implications for DNA and RNA delivery and therapy. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle ZnO Interactions with Biomatrices: Effect of Particle Size on ZnO-Protein Corona
Nanomaterials 2017, 7(11), 377; https://doi.org/10.3390/nano7110377
Received: 27 September 2017 / Revised: 28 October 2017 / Accepted: 2 November 2017 / Published: 6 November 2017
Cited by 6 | PDF Full-text (2467 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Zinc oxide (ZnO) nanoparticles (NPs) have been widely used for food fortification, because zinc is essential for many enzyme and hormone activities and cellular functions, but public concern about their potential toxicity is increasing. Interactions between ZnO and biomatrices might affect the oral
[...] Read more.
Zinc oxide (ZnO) nanoparticles (NPs) have been widely used for food fortification, because zinc is essential for many enzyme and hormone activities and cellular functions, but public concern about their potential toxicity is increasing. Interactions between ZnO and biomatrices might affect the oral absorption, distribution, and toxicity of ZnO, which may be influenced by particle size. In this study, ZnO interactions with biomatrices were investigated by examining the physicochemical properties, solubility, protein fluorescence quenching, particle–protein corona, and intestinal transport with respect to the particle size (bulk vs. nano) in simulated gastrointestinal (GI) and plasma fluids and in rat-extracted fluids. The results demonstrate that the hydrodynamic radii and zeta potentials of bulk ZnO and nano ZnO in biofluids changed in different ways, and that nano ZnO induced higher protein fluorescence quenching than bulk ZnO. However, ZnO solubility and its intestinal transport mechanism were unaffected by particle size. Proteomic analysis revealed that albumin, fibrinogen, and fibronectin play roles in particle–plasma protein corona, regardless of particle size. Furthermore, nano ZnO was found to interact more strongly with plasma proteins. These observations show that bulk ZnO and nano ZnO interact with biomatrices in different ways and highlight the need for further study of their long-term toxicity. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Resistive Switching of Sub-10 nm TiO2 Nanoparticle Self-Assembled Monolayers
Nanomaterials 2017, 7(11), 370; https://doi.org/10.3390/nano7110370
Received: 28 September 2017 / Revised: 27 October 2017 / Accepted: 31 October 2017 / Published: 4 November 2017
Cited by 5 | PDF Full-text (5796 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Resistively switching devices are promising candidates for the next generation of non-volatile data memories. Such devices are up to now fabricated mainly by means of top-down approaches that apply thin films sandwiched between electrodes. Recent works have demonstrated that resistive switching (RS) is
[...] Read more.
Resistively switching devices are promising candidates for the next generation of non-volatile data memories. Such devices are up to now fabricated mainly by means of top-down approaches that apply thin films sandwiched between electrodes. Recent works have demonstrated that resistive switching (RS) is also feasible on chemically synthesized nanoparticles (NPs) in the 50 nm range. Following this concept, we developed this approach further to the sub-10 nm range. In this work, we report RS of sub-10 nm TiO2 NPs that were self-assembled into monolayers and transferred onto metallic substrates. We electrically characterized these monolayers in regard to their RS properties by means of a nanorobotics system in a scanning electron microscope, and found features typical of bipolar resistive switching. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Preparation of Nano-TiO2-Coated SiO2 Microsphere Composite Material and Evaluation of Its Self-Cleaning Property
Nanomaterials 2017, 7(11), 367; https://doi.org/10.3390/nano7110367
Received: 28 September 2017 / Revised: 26 October 2017 / Accepted: 30 October 2017 / Published: 3 November 2017
Cited by 1 | PDF Full-text (7019 KB) | HTML Full-text | XML Full-text
Abstract
In order to improve the dispersion of nano-TiO2 particles and enhance its self-cleaning properties, including photocatalytic degradation of pollutants and surface hydrophilicity, we prepared nano-TiO2-coated SiO2 microsphere composite self-cleaning materials (SiO2–TiO2) by co-grinding SiO2
[...] Read more.
In order to improve the dispersion of nano-TiO2 particles and enhance its self-cleaning properties, including photocatalytic degradation of pollutants and surface hydrophilicity, we prepared nano-TiO2-coated SiO2 microsphere composite self-cleaning materials (SiO2–TiO2) by co-grinding SiO2 microspheres and TiO2 soliquid and calcining the ground product. The structure, morphology, and self-cleaning properties of the SiO2–TiO2 were characterized. The characterization results showed that the degradation efficiency of methyl orange by SiO2–TiO2 was 97%, which was significantly higher than that obtained by pure nano-TiO2. The minimum water contact angle of SiO2–TiO2 was 8°, indicating strong hydrophilicity and the good self-cleaning effect. The as-prepared SiO2–TiO2 was characterized by the nano-TiO2 particles uniformly coated on the SiO2 microspheres and distributed in the gap among the microspheres. The nano-TiO2 particles were in an anatase phase with the particle size of 15–20 nm. The nano-TiO2 particles were combined with SiO2 microspheres via the dehydroxylation of hydroxyl groups on their surfaces. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Photoelectrochemical Water Splitting Properties of Ti-Ni-Si-O Nanostructures on Ti-Ni-Si Alloy
Nanomaterials 2017, 7(11), 359; https://doi.org/10.3390/nano7110359
Received: 31 August 2017 / Revised: 18 September 2017 / Accepted: 25 September 2017 / Published: 31 October 2017
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Abstract
Ti-Ni-Si-O nanostructures were successfully prepared on Ti-1Ni-5Si alloy foils via electrochemical anodization in ethylene glycol/glycerol solutions containing a small amount of water. The Ti-Ni-Si-O nanostructures were characterized by field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and diffuse reflectance
[...] Read more.
Ti-Ni-Si-O nanostructures were successfully prepared on Ti-1Ni-5Si alloy foils via electrochemical anodization in ethylene glycol/glycerol solutions containing a small amount of water. The Ti-Ni-Si-O nanostructures were characterized by field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and diffuse reflectance absorption spectra. Furthermore, the photoelectrochemical water splitting properties of the Ti-Ni-Si-O nanostructure films were investigated. It was found that, after anodization, three different kinds of Ti-Ni-Si-O nanostructures formed in the α-Ti phase region, Ti2Ni phase region, and Ti5Si3 phase region of the alloy surface. Both the anatase and rutile phases of Ti-Ni-Si-O oxide appeared after annealing at 500 °C for 2 h. The photocurrent density obtained from the Ti-Ni-Si-O nanostructure photoanodes was 0.45 mA/cm2 at 0 V (vs. Ag/AgCl) in 1 M KOH solution. The above findings make it feasible to further explore excellent photoelectrochemical properties of the nanostructure-modified surface of Ti-Ni-Si ternary alloys. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Ti-Based Biomedical Material Modified with TiOx/TiNx Duplex Bioactivity Film via Micro-Arc Oxidation and Nitrogen Ion Implantation
Nanomaterials 2017, 7(10), 343; https://doi.org/10.3390/nano7100343
Received: 29 September 2017 / Revised: 16 October 2017 / Accepted: 18 October 2017 / Published: 23 October 2017
Cited by 2 | PDF Full-text (7125 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Titanium (Ti) and Ti-based alloy are widely used in the biomedical field owing to their excellent mechanical compatibility and biocompatibility. However, the bioinert bioactivity and biotribological properties of titanium limit its clinical application in implants. In order to improve the biocompatibility of titanium,
[...] Read more.
Titanium (Ti) and Ti-based alloy are widely used in the biomedical field owing to their excellent mechanical compatibility and biocompatibility. However, the bioinert bioactivity and biotribological properties of titanium limit its clinical application in implants. In order to improve the biocompatibility of titanium, we modified its surface with TiOx/TiNx duplex composite films using a new method via micro-arc oxidation (MAO) and nitrogen ion implantation (NII) treatment. The structural characterization results revealed that the modified film was constructed by nanoarrays composed of TiOx/TiNx composite nanostitches with a size of 20~40 nm. Meanwhile, comparing this with pure Ti, the friction property, wear resistance, and bioactivity were significantly improved based on biotribological results and in vitro bioactivity tests. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Study of the Photodynamic Activity of N-Doped TiO2 Nanoparticles Conjugated with Aluminum Phthalocyanine
Nanomaterials 2017, 7(10), 338; https://doi.org/10.3390/nano7100338
Received: 29 September 2017 / Revised: 14 October 2017 / Accepted: 17 October 2017 / Published: 20 October 2017
Cited by 1 | PDF Full-text (1376 KB) | HTML Full-text | XML Full-text
Abstract
TiO2 nanoparticles modified with phthalocyanines (Pc) have been proven to be a potential photosensitizer in the application of photodynamic therapy (PDT). However, the generation of reactive oxygen species (ROS) by TiO2 nanoparticles modified with Pc has not been demonstrated clearly. In
[...] Read more.
TiO2 nanoparticles modified with phthalocyanines (Pc) have been proven to be a potential photosensitizer in the application of photodynamic therapy (PDT). However, the generation of reactive oxygen species (ROS) by TiO2 nanoparticles modified with Pc has not been demonstrated clearly. In this study, nitrogen-doped TiO2 conjugated with Pc (N-TiO2-Pc) were studied by means of monitoring the generation of ROS. The absorbance and photokilling effect on HeLa cells upon visible light of different regions were also studied and compared with non-doped TiO2-Pc and Pc. Both N-TiO2-Pc and TiO2-Pc can be activated by visible light and exhibited much higher photokilling effect on HeLa cells than Pc. In addition, nitrogen-doping can greatly enhance the formation of 1O2 and •O2, while it suppresses the generation of OH•. This resulted in significant photodynamic activity. Therefore, N-TiO2-Pc can be an excellent candidate for a photosensitizer in PDT with wide-spectrum visible irradiation. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Enhanced UV-Visible Light Photocatalytic Activity by Constructing Appropriate Heterostructures between Mesopore TiO2 Nanospheres and Sn3O4 Nanoparticles
Nanomaterials 2017, 7(10), 336; https://doi.org/10.3390/nano7100336
Received: 25 September 2017 / Revised: 12 October 2017 / Accepted: 13 October 2017 / Published: 19 October 2017
Cited by 2 | PDF Full-text (6809 KB) | HTML Full-text | XML Full-text
Abstract
Novel TiO2/Sn3O4 heterostructure photocatalysts were ingeniously synthesized via a scalable two-step method. The impressive photocatalytic abilities of the TiO2/Sn3O4 sphere nanocomposites were validated by the degradation test of methyl orange and •OH trapping
[...] Read more.
Novel TiO2/Sn3O4 heterostructure photocatalysts were ingeniously synthesized via a scalable two-step method. The impressive photocatalytic abilities of the TiO2/Sn3O4 sphere nanocomposites were validated by the degradation test of methyl orange and •OH trapping photoluminescence experiments under ultraviolet (UV) and visible light irradiation, respectively. Especially under the visible light, the TiO2/Sn3O4 nanocomposites demonstrated a superb photocatalytic activity, with 81.2% of methyl orange (MO) decomposed at 30 min after irradiation, which greatly exceeded that of the P25 (13.4%), TiO2 (0.5%) and pure Sn3O4 (59.1%) nanostructures. This enhanced photocatalytic performance could be attributed to the mesopore induced by the monodispersed TiO2 cores that supply sufficient surface areas and accessibility to reactant molecules. This exquisite hetero-architecture facilitates extended UV-visible absorption and efficient photoexcited charge carrier separation. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Microstructuring of Mesoporous Titania Films Loaded with Silver Salts to Enhance the Photocatalytic Degradation of Methyl Blue under Visible Light
Nanomaterials 2017, 7(10), 334; https://doi.org/10.3390/nano7100334
Received: 22 September 2017 / Revised: 29 September 2017 / Accepted: 5 October 2017 / Published: 17 October 2017
Cited by 2 | PDF Full-text (2298 KB) | HTML Full-text | XML Full-text
Abstract
The microstructuring of the distribution of silver nanoparticles (NPs) in mesoporous titania films loaded with silver salts, using two-beam interference lithography leading to 1 Dimension (1D) grating, induces variations in the photocatalytic efficiency. The influence of the structuration was tested on the degradation
[...] Read more.
The microstructuring of the distribution of silver nanoparticles (NPs) in mesoporous titania films loaded with silver salts, using two-beam interference lithography leading to 1 Dimension (1D) grating, induces variations in the photocatalytic efficiency. The influence of the structuration was tested on the degradation of methyl blue (MB) under ultraviolet (UV) and visible illumination, giving rise to a significant improvement of the photocatalytic efficiency. The periodic distribution of the NPs was characterized by transmission electron microscopy (TEM), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and scanning electron microscopy (SEM). Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Periodic TiO2 Nanostructures with Improved Aspect and Line/Space Ratio Realized by Colloidal Photolithography Technique
Nanomaterials 2017, 7(10), 316; https://doi.org/10.3390/nano7100316
Received: 11 September 2017 / Revised: 29 September 2017 / Accepted: 5 October 2017 / Published: 12 October 2017
Cited by 1 | PDF Full-text (4988 KB) | HTML Full-text | XML Full-text
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This paper presents substantial improvements of the colloidal photolithography technique (also called microsphere lithography) with the goal of better controlling the geometry of the fabricated nano-scale structures—in this case, hexagonally arranged nanopillars—printed in a layer of directly photopatternable sol-gel TiO2. Firstly,
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This paper presents substantial improvements of the colloidal photolithography technique (also called microsphere lithography) with the goal of better controlling the geometry of the fabricated nano-scale structures—in this case, hexagonally arranged nanopillars—printed in a layer of directly photopatternable sol-gel TiO2. Firstly, to increase the achievable structure height the photosensitive layer underneath the microspheres is deposited on a reflective layer instead of the usual transparent substrate. Secondly, an increased width of the pillars is achieved by tilting the incident wave and using multiple exposures or substrate rotation, additionally allowing to better control the shape of the pillar’s cross section. The theoretical analysis is carried out by rigorous modelling of the photonics nanojet underneath the microspheres and by optimizing the experimental conditions. Aspect ratios (structure height/lateral structure size) greater than 2 are predicted and demonstrated experimentally for structure dimensions in the sub micrometer range, as well as line/space ratios (lateral pillar size/distance between pillars) greater than 1. These nanostructures could lead for example to materials exhibiting efficient light trapping in the visible and near-infrared range, as well as improved hydrophobic or photocatalytic properties for numerous applications in environmental and photovoltaic systems. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle TiO2 Nanowire Networks Prepared by Titanium Corrosion and Their Application to Bendable Dye-Sensitized Solar Cells
Nanomaterials 2017, 7(10), 315; https://doi.org/10.3390/nano7100315
Received: 10 August 2017 / Revised: 20 September 2017 / Accepted: 25 September 2017 / Published: 12 October 2017
Cited by 2 | PDF Full-text (3746 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
TiO2 nanowire networks were prepared, using the corrosion of Ti foils in alkaline (potassium hydroxide, KOH) solution at different temperatures, and then a further ion-exchange process. The prepared nanostructures were characterized by field emission scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron
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TiO2 nanowire networks were prepared, using the corrosion of Ti foils in alkaline (potassium hydroxide, KOH) solution at different temperatures, and then a further ion-exchange process. The prepared nanostructures were characterized by field emission scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The wet corroded foils were utilized as the photoanodes of bendable dye-sensitized solar cells (DSSCs), which exhibited a power conversion efficiency of 1.11% under back illumination. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Tuning the Electronic Conductivity in Hydrothermally Grown Rutile TiO2 Nanowires: Effect of Heat Treatment in Different Environments
Nanomaterials 2017, 7(10), 289; https://doi.org/10.3390/nano7100289
Received: 28 August 2017 / Revised: 13 September 2017 / Accepted: 19 September 2017 / Published: 23 September 2017
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Abstract
Hydrothermally grown rutile TiO2 nanowires are intrinsically full of lattice defects, especially oxygen vacancies. These vacancies have a significant influence on the structural and electronic properties of the nanowires. In this study, we report a post-growth heat treatment in different environments that
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Hydrothermally grown rutile TiO2 nanowires are intrinsically full of lattice defects, especially oxygen vacancies. These vacancies have a significant influence on the structural and electronic properties of the nanowires. In this study, we report a post-growth heat treatment in different environments that allows control of the distribution of these defects inside the nanowire, and thus gives direct access to tuning of the properties of rutile TiO2 nanowires. A detailed transmission electron microscopy study is used to analyze the structural changes inside the nanowires which are correlated to the measured optical and electrical properties. The highly defective as-grown nanowire arrays have a white appearance and show typical semiconducting properties with n-type conductivity, which is related to the high density of oxygen vacancies. Heat treatment in air atmosphere leads to a vacancy condensation and results in nanowires which possess insulating properties, whereas heat treatment in N2 atmosphere leads to nanowire arrays that appear black and show almost metal-like conductivity. We link this high conductivity to a TiO2−x shell which forms during the annealing process due to the slightly reducing N2 environment. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle In Vitro Sonodynamic Therapeutic Effect of Polyion Complex Micelles Incorporating Titanium Dioxide Nanoparticles
Nanomaterials 2017, 7(9), 268; https://doi.org/10.3390/nano7090268
Received: 1 August 2017 / Revised: 28 August 2017 / Accepted: 6 September 2017 / Published: 11 September 2017
Cited by 2 | PDF Full-text (1967 KB) | HTML Full-text | XML Full-text
Abstract
Titanium dioxide nanoparticles (TiO2 NPs) can act as sonosensitizers, generating reactive oxygen species under ultrasound irradiation, for use in sonodynamic therapy. For TiO2 NPs delivery, we prepared polyion complex micelles incorporating TiO2 NPs (TiO2 NPs-PIC micelles) by mixing TiO
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Titanium dioxide nanoparticles (TiO2 NPs) can act as sonosensitizers, generating reactive oxygen species under ultrasound irradiation, for use in sonodynamic therapy. For TiO2 NPs delivery, we prepared polyion complex micelles incorporating TiO2 NPs (TiO2 NPs-PIC micelles) by mixing TiO2 NPs with polyallylamine bearing poly(ethylene glycol) grafts. In this study, the effects of polymer composition and ultrasound irradiation conditions on the sonodynamic therapeutic effect toward HeLa cells were evaluated experimentally using cell viability evaluation, intracellular distribution observation, and a cell staining assay. TiO2 NPs-PIC micelles with widely distributed features induced a significant decrease in cell viability under ultrasound irradiation. Furthermore, prolonging the irradiation time killed cells more effectively than did increasing the ultrasound power. The combination of TiO2 NP-PIC micelles and ultrasound irradiation was confirmed to induce apoptotic cell death. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Growth Method-Dependent and Defect Density-Oriented Structural, Optical, Conductive, and Physical Properties of Solution-Grown ZnO Nanostructures
Nanomaterials 2017, 7(9), 266; https://doi.org/10.3390/nano7090266
Received: 1 August 2017 / Revised: 28 August 2017 / Accepted: 7 September 2017 / Published: 10 September 2017
Cited by 6 | PDF Full-text (3362 KB) | HTML Full-text | XML Full-text
Abstract
It is time for industry to pay a serious heed to the application and quality-dependent research on the most important solution growth methods for ZnO, namely, aqueous chemical growth (ACG) and microwave-assisted growth (MAG) methods. This study proffers a critical analysis on how
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It is time for industry to pay a serious heed to the application and quality-dependent research on the most important solution growth methods for ZnO, namely, aqueous chemical growth (ACG) and microwave-assisted growth (MAG) methods. This study proffers a critical analysis on how the defect density and formation behavior of ZnO nanostructures (ZNSs) are growth method-dependent. Both antithetical and facile methods are exploited to control the ZnO defect density and the growth mechanism. In this context, the growth of ZnO nanorods (ZNRs), nanoflowers, and nanotubes (ZNTs) are considered. The aforementioned growth methods directly stimulate the nanostructure crystal growth and, depending upon the defect density, ZNSs show different trends in structural, optical, etching, and conductive properties. The defect density of MAG ZNRs is the least because of an ample amount of thermal energy catered by high-power microwaves to the atoms to grow on appropriate crystallographic planes, which is not the case in faulty convective ACG ZNSs. Defect-centric etching of ZNRs into ZNTs is also probed and methodological constraints are proposed. ZNS optical properties are different in the visible region, which are quite peculiar, but outstanding for ZNRs. Hall effect measurements illustrate incongruent conductive trends in both samples. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Preparation and Characterization of ZnO Nanoparticles Supported on Amorphous SiO2
Nanomaterials 2017, 7(8), 217; https://doi.org/10.3390/nano7080217
Received: 30 June 2017 / Revised: 21 July 2017 / Accepted: 24 July 2017 / Published: 10 August 2017
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Abstract
In order to reduce the primary particle size of zinc oxide (ZnO) and eliminate the agglomeration phenomenon to form a monodisperse state, Zn2+ was loaded on the surface of amorphous silica (SiO2) by the hydrogen bond association between hydroxyl groups
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In order to reduce the primary particle size of zinc oxide (ZnO) and eliminate the agglomeration phenomenon to form a monodisperse state, Zn2+ was loaded on the surface of amorphous silica (SiO2) by the hydrogen bond association between hydroxyl groups in the hydrothermal process. After calcining the precursors, dehydration condensation among hydroxyl groups occurred and ZnO nanoparticles supported on amorphous SiO2 (ZnO–SiO2) were prepared. Furthermore, the SEM and TEM observations showed that ZnO nanoparticles with a particle size of 3–8 nm were uniformly and dispersedly loaded on the surface of amorphous SiO2. Compared with pure ZnO, ZnO–SiO2 showed a much better antibacterial performance in the minimum inhibitory concentration (MIC) test and the antibacterial properties of the paint adding ZnO–SiO2 composite. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Growth Mechanism Studies of ZnO Nanowires: Experimental Observations and Short-Circuit Diffusion Analysis
Nanomaterials 2017, 7(7), 188; https://doi.org/10.3390/nano7070188
Received: 3 July 2017 / Revised: 18 July 2017 / Accepted: 18 July 2017 / Published: 21 July 2017
Cited by 5 | PDF Full-text (4041 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Plenty of studies have been performed to probe the diverse properties of ZnO nanowires, but only a few have focused on the physical properties of a single nanowire since analyzing the growth mechanism along a single nanowire is difficult. In this study, a
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Plenty of studies have been performed to probe the diverse properties of ZnO nanowires, but only a few have focused on the physical properties of a single nanowire since analyzing the growth mechanism along a single nanowire is difficult. In this study, a single ZnO nanowire was synthesized using a Ti-assisted chemical vapor deposition (CVD) method to avoid the appearance of catalytic contamination. Two-dimensional energy dispersive spectroscopy (EDS) mapping with a diffusion model was used to obtain the diffusion length and the activation energy ratio. The ratio value is close to 0.3, revealing that the growth of ZnO nanowires was attributed to the short-circuit diffusion. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessArticle Oxygen Partial Pressure Impact on Characteristics of Indium Titanium Zinc Oxide Thin Film Transistor Fabricated via RF Sputtering
Nanomaterials 2017, 7(7), 156; https://doi.org/10.3390/nano7070156
Received: 21 April 2017 / Revised: 23 June 2017 / Accepted: 23 June 2017 / Published: 26 June 2017
Cited by 3 | PDF Full-text (2185 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Indium titanium zinc oxide (InTiZnO) as the channel layer in thin film transistor (TFT) grown by RF sputtering system is proposed in this work. Optical and electrical properties were investigated. By changing the oxygen flow ratio, we can suppress excess and undesirable oxygen-related
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Indium titanium zinc oxide (InTiZnO) as the channel layer in thin film transistor (TFT) grown by RF sputtering system is proposed in this work. Optical and electrical properties were investigated. By changing the oxygen flow ratio, we can suppress excess and undesirable oxygen-related defects to some extent, making it possible to fabricate the optimized device. XPS patterns for O 1s of InTiZnO thin films indicated that the amount of oxygen vacancy was apparently declined with the increasing oxygen flow ratio. The fabricated TFTs showed a threshold voltage of −0.9 V, mobility of 0.884 cm2/Vs, on-off ratio of 5.5 × 105, and subthreshold swing of 0.41 V/dec. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessReview Fabrication of Semiconductor ZnO Nanostructures for Versatile SERS Application
Nanomaterials 2017, 7(11), 398; https://doi.org/10.3390/nano7110398
Received: 1 October 2017 / Revised: 3 November 2017 / Accepted: 6 November 2017 / Published: 19 November 2017
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Abstract
Since the initial discovery of surface-enhanced Raman scattering (SERS) in the 1970s, it has exhibited a huge potential application in many fields due to its outstanding advantages. Since the ultra-sensitive noble metallic nanostructures have increasingly exposed themselves as having some problems during application,
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Since the initial discovery of surface-enhanced Raman scattering (SERS) in the 1970s, it has exhibited a huge potential application in many fields due to its outstanding advantages. Since the ultra-sensitive noble metallic nanostructures have increasingly exposed themselves as having some problems during application, semiconductors have been gradually exploited as one of the critical SERS substrate materials due to their distinctive advantages when compared with noble metals. ZnO is one of the most representative metallic oxide semiconductors with an abundant reserve, various and cost-effective fabrication techniques, as well as special physical and chemical properties. Thanks to the varied morphologies, size-dependent exciton, good chemical stability, a tunable band gap, carrier concentration, and stoichiometry, ZnO nanostructures have the potential to be exploited as SERS substrates. Moreover, other distinctive properties possessed by ZnO such as biocompatibility, photocatcalysis and self-cleaning, and gas- and chemo-sensitivity can be synergistically integrated and exerted with SERS activity to realize the multifunctional potential of ZnO substrates. In this review, we discuss the inevitable development trend of exploiting the potential semiconductor ZnO as a SERS substrate. After clarifying the root cause of the great disparity between the enhancement factor (EF) of noble metals and that of ZnO nanostructures, two specific methods are put forward to improve the SERS activity of ZnO, namely: elemental doping and combination of ZnO with noble metals. Then, we introduce a distinctive advantage of ZnO as SERS substrate and illustrate the necessity of reporting a meaningful average EF. We also summarize some fabrication methods for ZnO nanostructures with varied dimensions (0–3 dimensions). Finally, we present an overview of ZnO nanostructures for the versatile SERS application. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessReview Engineering the Surface/Interface Structures of Titanium Dioxide Micro and Nano Architectures towards Environmental and Electrochemical Applications
Nanomaterials 2017, 7(11), 382; https://doi.org/10.3390/nano7110382
Received: 30 September 2017 / Revised: 5 November 2017 / Accepted: 6 November 2017 / Published: 9 November 2017
Cited by 4 | PDF Full-text (7306 KB) | HTML Full-text | XML Full-text
Abstract
Titanium dioxide (TiO2) materials have been intensively studied in the past years because of many varied applications. This mini review article focuses on TiO2 micro and nano architectures with the prevalent crystal structures (anatase, rutile, brookite, and TiO2(B)),
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Titanium dioxide (TiO2) materials have been intensively studied in the past years because of many varied applications. This mini review article focuses on TiO2 micro and nano architectures with the prevalent crystal structures (anatase, rutile, brookite, and TiO2(B)), and summarizes the major advances in the surface and interface engineering and applications in environmental and electrochemical applications. We analyze the advantages of surface/interface engineered TiO2 micro and nano structures, and present the principles and growth mechanisms of TiO2 nanostructures via different strategies, with an emphasis on rational control of the surface and interface structures. We further discuss the applications of TiO2 micro and nano architectures in photocatalysis, lithium/sodium ion batteries, and Li–S batteries. Throughout the discussion, the relationship between the device performance and the surface/interface structures of TiO2 micro and nano structures will be highlighted. Then, we discuss the phase transitions of TiO2 nanostructures and possible strategies of improving the phase stability. The review concludes with a perspective on the current challenges and future research directions. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessReview ZnO Nanowire Application in Chemoresistive Sensing: A Review
Nanomaterials 2017, 7(11), 381; https://doi.org/10.3390/nano7110381
Received: 30 September 2017 / Revised: 31 October 2017 / Accepted: 6 November 2017 / Published: 9 November 2017
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Abstract
This article provides an overview of the recent development of ZnO nanowires (NWs) for chemoresistive sensing. Working mechanisms of chemoresistive sensors are unified for gas, ultraviolet (UV) and bio sensor types: single nanowire and nanowire junction sensors are described, giving the overview for
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This article provides an overview of the recent development of ZnO nanowires (NWs) for chemoresistive sensing. Working mechanisms of chemoresistive sensors are unified for gas, ultraviolet (UV) and bio sensor types: single nanowire and nanowire junction sensors are described, giving the overview for a simple sensor manufacture by multiple nanowire junctions. ZnO NW surface functionalization is discussed, and how this effects the sensing is explained. Further, novel approaches for sensing, using ZnO NW functionalization with other materials such as metal nanoparticles or heterojunctions, are explained, and limiting factors and possible improvements are discussed. The review concludes with the insights and recommendations for the future improvement of the ZnO NW chemoresistive sensing. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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Open AccessReview Wet-Chemical Preparation of TiO2-Based Composites with Different Morphologies and Photocatalytic Properties
Nanomaterials 2017, 7(10), 310; https://doi.org/10.3390/nano7100310
Received: 7 September 2017 / Revised: 30 September 2017 / Accepted: 2 October 2017 / Published: 9 October 2017
Cited by 11 | PDF Full-text (13874 KB) | HTML Full-text | XML Full-text
Abstract
TiO2-based composites have been paid significant attention in the photocatalysis field. The size, crystallinity and nanomorphology of TiO2 materials have an important effect on the photocatalytic efficiency. The synthesis and photocatalytic activity of TiO2-based materials have been widely
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TiO2-based composites have been paid significant attention in the photocatalysis field. The size, crystallinity and nanomorphology of TiO2 materials have an important effect on the photocatalytic efficiency. The synthesis and photocatalytic activity of TiO2-based materials have been widely investigated in past decades. Based on our group’s research works on TiO2 materials, this review introduces several methods for the fabrication of TiO2, rare-earth-doped TiO2 and noble-metal-decorated TiO2 particles with different morphologies. We focused on the preparation and the formation mechanism of TiO2-based materials with unique structures including spheres, hollow spheres, porous spheres, hollow porous spheres and urchin-like spheres. The photocatalytical activity of urchin-like TiO2, noble metal nanoparticle-decorated 3D (three-dimensional) urchin-like TiO2 and bimetallic core/shell nanoparticle-decorated urchin-like hierarchical TiO2 are briefly discussed. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures) Printed Edition available
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