Nanomaterials

25 pages, 5458 KiB

Open AccessArticle

Photoinduced Glycerol Oxidation over Plasmonic Au and AuM (M = Pt, Pd and Bi) Nanoparticle-Decorated TiO₂ Photocatalysts

by Trin Jedsukontorn, Nagahiro Saito and Mali Hunsom

Nanomaterials 2018, 8(4), 269; https://doi.org/10.3390/nano8040269 - 23 Apr 2018

Cited by 21 | Viewed by 6117

Abstract

In this study, sol-immobilization was used to prepare gold nanoparticle (Au NP)-decorated titanium dioxide (TiO₂) photocatalysts at different Au weight % (wt. %) loading (Au_x/TiO₂, where x is the Au wt. %) and Au–M NP-decorated TiO₂ [...] Read more.

In this study, sol-immobilization was used to prepare gold nanoparticle (Au NP)-decorated titanium dioxide (TiO₂) photocatalysts at different Au weight % (wt. %) loading (Au_x/TiO₂, where x is the Au wt. %) and Au–M NP-decorated TiO₂ photocatalysts (Au₃M₃/TiO₂), where M is bismuth (Bi), platinum (Pt) or palladium (Pd) at 3 wt. %. The Au_x/TiO₂ photocatalysts exhibited a stronger visible light absorption than the parent TiO₂ due to the localized surface plasmon resonance effect. Increasing the Au content from 1 wt. % to 7 wt. % led to increased visible light absorption due to the increasing presence of defective structures that were capable of enhancing the photocatalytic activity of the as-prepared catalyst. The addition of Pt and Pd coupled with the Au₃/TiO₂ to form Au₃M₃/TiO₂ improved the photocatalytic activity of the Au₃/TiO₂ photocatalyst by maximizing their light-absorption property. The Au₃/TiO₂, Au₃Pt₃/TiO₂ and Au₃Pd₃/TiO₂ photocatalysts promoted the formation of glyceraldehyde from glycerol as the principle product, while Au₃Bi₃/TiO₂ facilitated glycolaldehyde formation as the major product. Among all the prepared photocatalysts, Au₃Pd₃/TiO₂ exhibited the highest photocatalytic activity with a 98.75% glycerol conversion at 24 h of reaction time. Full article

(This article belongs to the Special Issue Nanostructure Metal Alloys for the Transformation of Biomass)

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27 pages, 7100 KiB

Open AccessReview

ZnO Nanostructures for Drug Delivery and Theranostic Applications

by Marina Martínez-Carmona, Yurii Gun’ko and María Vallet-Regí

Nanomaterials 2018, 8(4), 268; https://doi.org/10.3390/nano8040268 - 23 Apr 2018

Cited by 193 | Viewed by 16361

Abstract

In the last two decades, zinc oxide (ZnO) semiconductor Quantum dots (QDs) have been shown to have fantastic luminescent properties, which together with their low-cost, low-toxicity and biocompatibility have turned these nanomaterials into one of the main candidates for bio-imaging. The discovery of [...] Read more.

In the last two decades, zinc oxide (ZnO) semiconductor Quantum dots (QDs) have been shown to have fantastic luminescent properties, which together with their low-cost, low-toxicity and biocompatibility have turned these nanomaterials into one of the main candidates for bio-imaging. The discovery of other desirable traits such as their ability to produce destructive reactive oxygen species (ROS), high catalytic efficiency, strong adsorption capability and high isoelectric point, also make them promising nanomaterials for therapeutic and diagnostic functions. Herein, we review the recent progress on the use of ZnO based nanoplatforms in drug delivery and theranostic in several diseases such as bacterial infection and cancer. Full article

(This article belongs to the Special Issue ZnO Nanostructures for Tissue Regeneration, Drug-Delivery and Theranostics Applications)

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13 pages, 1250 KiB

Open AccessArticle

Non-Canonical Activation of the Epidermal Growth Factor Receptor by Carbon Nanoparticles

by Daniel Stöckmann, Tim Spannbrucker, Niloofar Ale-Agha, Philipp Jakobs, Christine Goy, Nadine Dyballa-Rukes, Tamara Hornstein, Alexander Kümper, Annette Kraegeloh, Judith Haendeler and Klaus Unfried

Nanomaterials 2018, 8(4), 267; https://doi.org/10.3390/nano8040267 - 23 Apr 2018

Cited by 5 | Viewed by 4928

Abstract

The epidermal growth factor receptor (EGFR) is an abundant membrane protein, which is essential for regulating many cellular processes including cell proliferation. In our earlier studies, we observed an activation of the EGFR and subsequent signaling events after the exposure of epithelial cells [...] Read more.

The epidermal growth factor receptor (EGFR) is an abundant membrane protein, which is essential for regulating many cellular processes including cell proliferation. In our earlier studies, we observed an activation of the EGFR and subsequent signaling events after the exposure of epithelial cells to carbon nanoparticles. In the current study, we describe molecular mechanisms that allow for discriminating carbon nanoparticle-specific from ligand-dependent receptor activation. Caveolin-1 is a key player that co-localizes with the EGFR upon receptor activation by carbon nanoparticles. This specific process mediated by nanoparticle-induced reactive oxygen species and the accumulation of ceramides in the plasma membrane is not triggered when cells are exposed to non-nano carbon particles or the physiological ligand EGF. The role of caveolae formation was demonstrated by the induction of higher order structures of caveolin-1 and by the inhibition of caveolae formation. Using an in vivo model with genetically modified mice lacking caveolin-1, it was possible to demonstrate that carbon nanoparticles in vivo trigger EGFR downstream signaling cascades via caveolin-1. The identified molecular mechanisms are, therefore, of toxicological relevance for inhaled nanoparticles. However, nanoparticles that are intentionally applied to humans might cause side effects depending on this phenomenon. Full article

(This article belongs to the Special Issue Nanosafety 2017)

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15 pages, 23968 KiB

Open AccessArticle

Electrodes Based on Carbon Aerogels Partially Graphitized by Doping with Transition Metals for Oxygen Reduction Reaction

by Abdalla Abdelwahab, Jesica Castelo-Quibén, José F. Vivo-Vilches, María Pérez-Cadenas, Francisco J. Maldonado-Hódar, Francisco Carrasco-Marín and Agustín F. Pérez-Cadenas

Nanomaterials 2018, 8(4), 266; https://doi.org/10.3390/nano8040266 - 23 Apr 2018

Cited by 26 | Viewed by 6007

Abstract

A series of carbon aerogels doped with iron, cobalt and nickel have been prepared. Metal nanoparticles very well dispersed into the carbon matrix catalyze the formation of graphitic clusters around them. Samples with different Ni content are obtained to test the influence of [...] Read more.

A series of carbon aerogels doped with iron, cobalt and nickel have been prepared. Metal nanoparticles very well dispersed into the carbon matrix catalyze the formation of graphitic clusters around them. Samples with different Ni content are obtained to test the influence of the metal loading. All aerogels have been characterized to analyze their textural properties, surface chemistry and crystal structures. These metal-doped aerogels have a very well-developed porosity, making their mesoporosity remarkable. Ni-doped aerogels are the ones with the largest surface area and the smallest graphitization. They also present larger mesopore volumes than Co- and Fe-doped aerogels. These materials are tested as electro-catalysts for the oxygen reduction reaction. Results show a clear and strong influence of the carbonaceous structure on the whole electro-catalytic behavior of the aerogels. Regarding the type of metal doping, aerogel doped with Co is the most active one, followed by Ni- and Fe-doped aerogels, respectively. As the Ni content is larger, the kinetic current densities increase. Comparatively, among the different doping metals, the results obtained with Ni are especially remarkable. Full article

(This article belongs to the Special Issue Electrochemically Engineering of Nanoporous Materials)

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12 pages, 4541 KiB

Open AccessArticle

Galvanic-Cell-Reaction-Driven Deposition of Large-Area Au Nanourchin Arrays for Surface-Enhanced Raman Scattering

by Zhongbo Li, Kexi Sun, Zhaofang Du, Bensong Chen and Xuan He

Nanomaterials 2018, 8(4), 265; https://doi.org/10.3390/nano8040265 - 23 Apr 2018

Cited by 8 | Viewed by 5359

Abstract

Here we report a low-cost synthetic approach for the direct fabrication of large-area Au nanourchin arrays on indium tin oxide (ITO) via a facile galvanic-cell-reaction-driven deposition in an aqueous solution of chloroauric acid and poly(vinyl pyrrolidone) (PVP). The homogeneous Au nanourchins are composed [...] Read more.

Here we report a low-cost synthetic approach for the direct fabrication of large-area Au nanourchin arrays on indium tin oxide (ITO) via a facile galvanic-cell-reaction-driven deposition in an aqueous solution of chloroauric acid and poly(vinyl pyrrolidone) (PVP). The homogeneous Au nanourchins are composed of abundant sharp nanotips, which can served as nanoantennas and increase the local electromagnetic field enhancement dramatically. Finite element theoretical calculations confirm the strong electromagnetic field can be created around the sharp nanotips and located in the nanogaps between adjacent tips of the Au nanourchins. In addition, the interparticle nanogaps between the neighboring Au nanourchins may create additional hotspots, which can induce the higher electromagnetic field intensity. By using rhodamine 6G as a test molecule, the large-area Au nanourchin arrays on ITO exhibit active, uniform, and reproducible surface-enhanced Raman scattering (SERS) effect. To trial their practical application, the Au nanourchin arrays are utilized as SERS substrates to detect 3,3’,4,4’-tetrachlorobiphenyl (PCB-77) one congener of polychlorinated biphenyls (PCBs) as a notorious class of persistent organic pollutants. The characteristic Raman peaks can be still identified when the concentration of PCB-77 is down to 5 × 10⁻⁶ M. Full article

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18 pages, 7605 KiB

Open AccessArticle

Electrically and Thermally Conductive Low Density Polyethylene-Based Nanocomposites Reinforced by MWCNT or Hybrid MWCNT/Graphene Nanoplatelets with Improved Thermo-Oxidative Stability

by Sandra Paszkiewicz, Anna Szymczyk, Daria Pawlikowska, Jan Subocz, Marek Zenker and Roman Masztak

Nanomaterials 2018, 8(4), 264; https://doi.org/10.3390/nano8040264 - 22 Apr 2018

Cited by 52 | Viewed by 5969

Abstract

In this paper, the electrical and thermal conductivity and morphological behavior of low density polyethylene (LDPE)/multi-walled carbon nanotubes (MWCNTs) + graphene nanoplatelets (GNPs) hybrid nanocomposites (HNCs) have been studied. The distribution of MWCNTs and the hybrid of MWCNTs/GNPs within the polymer matrix has [...] Read more.

In this paper, the electrical and thermal conductivity and morphological behavior of low density polyethylene (LDPE)/multi-walled carbon nanotubes (MWCNTs) + graphene nanoplatelets (GNPs) hybrid nanocomposites (HNCs) have been studied. The distribution of MWCNTs and the hybrid of MWCNTs/GNPs within the polymer matrix has been investigated with scanning electron microscopy (SEM). The results showed that the thermal and electrical conductivity of the LDPE-based nanocomposites increased along with the increasing content of carbon nanofillers. However, one could observe greater improvement in the thermal and electrical conductivity when only MWCNTs have been incorporated. Moreover, the improvement in tensile properties and thermal stability has been observed when carbon nanofillers have been mixed with LDPE. At the same time, the increasing content of MWCNTs and MWCNTs/GNPs caused an increase in the melt viscosity with only little effect on phase transition temperatures. Full article

(This article belongs to the Special Issue Thermoplastic Nanocomposites)

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11 pages, 5436 KiB

Open AccessArticle

Effect of Organic Substrates on the Photocatalytic Reduction of Cr(VI) by Porous Hollow Ga₂O₃ Nanoparticles

by Jin Liu, Huihui Gan, Hongzhang Wu, Xinlei Zhang, Jun Zhang, Lili Li and Zhenling Wang

Nanomaterials 2018, 8(4), 263; https://doi.org/10.3390/nano8040263 - 22 Apr 2018

Cited by 4 | Viewed by 4670

Abstract

Porous hollow Ga₂O₃ nanoparticles were successfully synthesized by a hydrolysis method followed by calcination. The prepared samples were characterized by field emission scanning electron microscope, transmission electron microscope, thermogravimetry and differential scanning calorimetry, UV-vis diffuse reflectance spectra and Raman spectrum. [...] Read more.

Porous hollow Ga₂O₃ nanoparticles were successfully synthesized by a hydrolysis method followed by calcination. The prepared samples were characterized by field emission scanning electron microscope, transmission electron microscope, thermogravimetry and differential scanning calorimetry, UV-vis diffuse reflectance spectra and Raman spectrum. The porous structure of Ga₂O₃ nanoparticles can enhance the light harvesting efficiency, and provide lots of channels for the diffusion of Cr(VI) and Cr(III). Photocatalytic reduction of Cr(VI), with different initial pH and degradation of several organic substrates by porous hollow Ga₂O₃ nanoparticles in single system and binary system, were investigated in detail. The reduction rate of Cr(VI) in the binary pollutant system is markedly faster than that in the single Cr(VI) system, because Cr(VI) mainly acts as photogenerated electron acceptor. In addition, the type and concentration of organic substrates have an important role in the photocatalytic reduction of Cr(VI). Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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16 pages, 4826 KiB

Open AccessReview

Thermocatalytic Behavior of Manganese (IV) Oxide as Nanoporous Material on the Dissociation of a Gas Mixture Containing Hydrogen Peroxide

by Zaid B. Jildeh, Jan Oberländer, Patrick Kirchner, Patrick H. Wagner and Michael J. Schöning

Nanomaterials 2018, 8(4), 262; https://doi.org/10.3390/nano8040262 - 21 Apr 2018

Cited by 28 | Viewed by 7369

Abstract

In this article, we present an overview on the thermocatalytic reaction of hydrogen peroxide (H

_{2}

O

_{2}

) gas on a manganese (IV) oxide (MnO

_{2}

) catalytic structure. The principle of operation and manufacturing techniques are introduced for a calorimetric H [...] Read more.

In this article, we present an overview on the thermocatalytic reaction of hydrogen peroxide (H

_{2}

O

_{2}

) gas on a manganese (IV) oxide (MnO

_{2}

) catalytic structure. The principle of operation and manufacturing techniques are introduced for a calorimetric H

_{2}

O

_{2}

gas sensor based on porous MnO

_{2}

. Results from surface analyses by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) of the catalytic material provide indication of the H

_{2}

O

_{2}

dissociation reaction schemes. The correlation between theory and the experiments is documented in numerical models of the catalytic reaction. The aim of the numerical models is to provide further information on the reaction kinetics and performance enhancement of the porous MnO

_{2}

catalyst. Full article

(This article belongs to the Special Issue Oxide Nanomaterials for Chemical Sensors)

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21 pages, 34606 KiB

Open AccessArticle

A Facile Method for the Preparation of Colored Bi₄Ti₃O_12−x Nanosheets with Enhanced Visible-Light Photocatalytic Hydrogen Evolution Activity

by Yizeng Zhang, Zhiwu Chen and Zhenya Lu

Nanomaterials 2018, 8(4), 261; https://doi.org/10.3390/nano8040261 - 21 Apr 2018

Cited by 31 | Viewed by 5363

Abstract

Bi₄Ti₃O_12−x nanosheet photocatalysts with abundant oxygen vacancies are fabricated by a facile solid-state chemical reduction method for the first time. This method is simple in operation, has short reaction time, and can be conducted at mild temperatures [...] Read more.

Bi₄Ti₃O_12−x nanosheet photocatalysts with abundant oxygen vacancies are fabricated by a facile solid-state chemical reduction method for the first time. This method is simple in operation, has short reaction time, and can be conducted at mild temperatures (300~400 °C). The electron paramagnetic resonance, thermogravimetric analysis, X-ray photoelectron spectrometer, and positron annihilation lifetime spectra results indicate that oxygen vacancies are produced in Bi₄Ti₃O_12−x, and they can be adjusted by tuning the reduction reaction conditions. Control experiments show that the reduction time and temperature have great influences on the photocatalytic activities of Bi₄Ti₃O_12−x. The optimal Bi₄Ti₃O_12−x is the sample undergoing the reduction treatment at 350 °C for 60 min and it affords a hydrogen evolution rate of 129 μmol·g⁻¹·h⁻¹ under visible-light irradiation, which is about 3.4 times that of the pristine Bi₄Ti₃O₁₂. The Bi₄Ti₃O_12−x photocatalysts have good reusability and storage stability and can be used to decompose formaldehyde and formic acid for hydrogen production. The surface oxygen vacancies states result in the broadening of the valence band and the narrowing of the band gap. Such energy level structure variation helps promote the separation of photo-generated electron-hole pairs thus leading to enhancement in the visible-light photocatalytic hydrogen evolution. Meanwhile, the narrowing of the band gap leads to a broader visible light absorption of Bi₄Ti₃O_12−x. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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11 pages, 1697 KiB

Open AccessArticle

Efficient Blue to Red Afterglow Tuning in a Binary Nanocomposite Plastic Film

by Yan Xia, Huase Ou, Wanbin Li, Gang Han and Zhanjun Li

Nanomaterials 2018, 8(4), 260; https://doi.org/10.3390/nano8040260 - 20 Apr 2018

Cited by 12 | Viewed by 4896

Abstract

Colorful spectra are important for the diverse applications of persistent phosphors. A color conversion concept is developed to obtain abundant persistent luminescence color by mining capacities of known persistent phosphors with the most efficient persistent properties. Here, SiO₂/Sr₂MgSi₂ [...] Read more.

Colorful spectra are important for the diverse applications of persistent phosphors. A color conversion concept is developed to obtain abundant persistent luminescence color by mining capacities of known persistent phosphors with the most efficient persistent properties. Here, SiO₂/Sr₂MgSi₂O₇:Eu,Dy nanoparticles are chosen as a blue persistent luminescence donor nanophosphor, while ultrafine CaAlSiN₃:Eu is utilized as a red conversion phosphor to tune the persistent luminescence spectra from blue to red. The red afterglow emission can persist for more than 5 h. The decay of the red afterglow follows nearly the same kinetics as that of the blue one. Continuous color tuning can be successfully obtained by simply changing the mass ratio of the donor/conversion phosphor pair. This color conversion strategy may be significant in indicating numerous persistent/conversion nanocomposites or nanostructures and advance the development of persistent phosphors in diverse fields which need colorful spectral properties. Full article

(This article belongs to the Special Issue Nanosized Luminescent Materials: Advances and Applications)

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22 pages, 34747 KiB

Open AccessReview

Polymer-Based Electrospun Nanofibers for Biomedical Applications

by Abdullah M. Al-Enizi, Moustafa M. Zagho and Ahmed A. Elzatahry

Nanomaterials 2018, 8(4), 259; https://doi.org/10.3390/nano8040259 - 20 Apr 2018

Cited by 188 | Viewed by 12763

Abstract

Electrospinning has been considered a promising and novel procedure to fabricate polymer nanofibers due to its simplicity, cost effectiveness, and high production rate, making this technique highly relevant for both industry and academia. It is used to fabricate non-woven fibers with unique characteristics [...] Read more.

Electrospinning has been considered a promising and novel procedure to fabricate polymer nanofibers due to its simplicity, cost effectiveness, and high production rate, making this technique highly relevant for both industry and academia. It is used to fabricate non-woven fibers with unique characteristics such as high permeability, stability, porosity, surface area to volume ratio, ease of functionalization, and excellent mechanical performance. Nanofibers can be synthesized and tailored to suit a wide range of applications including energy, biotechnology, healthcare, and environmental engineering. A comprehensive outlook on the recent developments, and the influence of electrospinning on biomedical uses such as wound dressing, drug release, and tissue engineering, has been presented. Concerns regarding the procedural restrictions and research contests are addressed, in addition to providing insights about the future of this fabrication technique in the biomedical field. Full article

(This article belongs to the Special Issue The Fabrication and Application of Nanofibers)

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13 pages, 4777 KiB

Open AccessArticle

Label-Free Biosensor Using a Silver Specific RNA-Cleaving DNAzyme Functionalized Single-Walled Carbon Nanotube for Silver Ion Determination

by Hui Wang, Yang Liu and Gang Liu

Nanomaterials 2018, 8(4), 258; https://doi.org/10.3390/nano8040258 - 20 Apr 2018

Cited by 19 | Viewed by 4814

Abstract

Silver, a very common heavy metal, has been employed in electronics, medicine, jewelry, and catalysis due to its excellent chemical and physical characteristics. Silver-containing wastes can cause environmental pollution, so it is vital to monitor the Ag(I) concentration. Here, a label-free biosensor was [...] Read more.

Silver, a very common heavy metal, has been employed in electronics, medicine, jewelry, and catalysis due to its excellent chemical and physical characteristics. Silver-containing wastes can cause environmental pollution, so it is vital to monitor the Ag(I) concentration. Here, a label-free biosensor was developed for the Ag(I) detection, which used single-walled carbon nanotubes/field effect transistor (SWNTs/FET) to functionalize with a specific DNAzyme, containing an Agzyme and a complementary strand DNA (CS-DNA) embedded an RNA-base. The CS-DNA was covalently immobilized on the SWNTs’ surface through peptide bonds, and then combined with the Agzyme. When Ag(I) was bound with the Agzyme, the CS-DNA can be cleaved at the RNA site efficiently. The cleaved DNAzyme induced a remarkable change in the electrical conductivity of SWNTs. The performances of DNAzyme/SWNTs/FET were investigated using different spectroscopy and electrochemical methods. Under the optimized parameters, DNAzyme/SWNTs/FET presented a high sensitivity and selectivity towards Ag(I), in which the linear response range is 10 pM to 10⁶ pM and the limit of detection is 5 pM(S/N = 3). Additionally, the prepared biosensor was applied to measure the Ag(I) concentration in the water sample with good results. Full article

(This article belongs to the Special Issue Applications of Carbon Nanotubes)

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27 pages, 7196 KiB

Open AccessFeature PaperReview

Imprinted Oxide and MIP/Oxide Hybrid Nanomaterials for Chemical Sensors ^†

by Adeel Afzal and Franz L. Dickert

Nanomaterials 2018, 8(4), 257; https://doi.org/10.3390/nano8040257 - 20 Apr 2018

Cited by 17 | Viewed by 7824

Abstract

The oxides of transition, post-transition and rare-earth metals have a long history of robust and fast responsive recognition elements for electronic, optical, and gravimetric devices. A wide range of applications successfully utilized pristine or doped metal oxides and polymer-oxide hybrids as nanostructured recognition [...] Read more.

The oxides of transition, post-transition and rare-earth metals have a long history of robust and fast responsive recognition elements for electronic, optical, and gravimetric devices. A wide range of applications successfully utilized pristine or doped metal oxides and polymer-oxide hybrids as nanostructured recognition elements for the detection of biologically relevant molecules, harmful organic substances, and drugs as well as for the investigative process control applications. An overview of the selected recognition applications of molecularly imprinted sol-gel phases, metal oxides and hybrid nanomaterials composed of molecularly imprinted polymers (MIP) and metal oxides is presented herein. The formation and fabrication processes for imprinted sol-gel layers, metal oxides, MIP-coated oxide nanoparticles and other MIP/oxide nanohybrids are discussed along with their applications in monitoring bioorganic analytes and processes. The sensor characteristics such as dynamic detection range and limit of detection are compared as the performance criterion and the miniaturization and commercialization possibilities are critically discussed. Full article

(This article belongs to the Special Issue Oxide Nanomaterials for Chemical Sensors)

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28 pages, 27593 KiB

Open AccessReview

Recent Advances in Metal Chalcogenides (MX; X = S, Se) Nanostructures for Electrochemical Supercapacitor Applications: A Brief Review

by Jayaraman Theerthagiri, K. Karuppasamy, Govindarajan Durai, Abu Ul Hassan Sarwar Rana, Prabhakarn Arunachalam, Kirubanandam Sangeetha, Parasuraman Kuppusami and Hyun-Seok Kim

Nanomaterials 2018, 8(4), 256; https://doi.org/10.3390/nano8040256 - 19 Apr 2018

Cited by 239 | Viewed by 14221

Abstract

Supercapacitors (SCs) have received a great deal of attention and play an important role for future self-powered devices, mainly owing to their higher power density. Among all types of electrical energy storage devices, electrochemical supercapacitors are considered to be the most promising because [...] Read more.

Supercapacitors (SCs) have received a great deal of attention and play an important role for future self-powered devices, mainly owing to their higher power density. Among all types of electrical energy storage devices, electrochemical supercapacitors are considered to be the most promising because of their superior performance characteristics, including short charging time, high power density, safety, easy fabrication procedures, and long operational life. An SC consists of two foremost components, namely electrode materials, and electrolyte. The selection of appropriate electrode materials with rational nanostructured designs has resulted in improved electrochemical properties for high performance and has reduced the cost of SCs. In this review, we mainly spotlight the non-metallic oxide, especially metal chalcogenides (MX; X = S, Se) based nanostructured electrode materials for electrochemical SCs. Different non-metallic oxide materials are highlighted in various categories, such as transition metal sulfides and selenides materials. Finally, the designing strategy and future improvements on metal chalcogenide materials for the application of electrochemical SCs are also discussed. Full article

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11 pages, 16871 KiB

Open AccessArticle

Self-Sacrificial Salt Templating: Simple Auxiliary Control over the Nanoporous Structure of Porous Carbon Monoliths Prepared through the Solvothermal Route

by Zhen Zhang, Junzong Feng, Yonggang Jiang, Ping Liu, Qiuhua Zhang, Ronghui Wei, Xiang Chen and Jian Feng

Nanomaterials 2018, 8(4), 255; https://doi.org/10.3390/nano8040255 - 19 Apr 2018

Cited by 9 | Viewed by 4148

Abstract

The conventional sol-gel method for preparing porous carbons is tedious and high-cost to prepare porous carbons and the control over the nanoporous architecture by solvents and carbonization is restricted. A simple and novel self-sacrificial salt templating method was first presented to adjust the [...] Read more.

The conventional sol-gel method for preparing porous carbons is tedious and high-cost to prepare porous carbons and the control over the nanoporous architecture by solvents and carbonization is restricted. A simple and novel self-sacrificial salt templating method was first presented to adjust the microporous structure of porous carbon monoliths synthesized via the solvothermal method. Apart from good monolithic appearance, the solvothermal route allowed for ambient drying because it made sure that the polymerization reaction was completed quickly and thoroughly. The intact and crack-free porous carbon monoliths were investigated by scanning electron microscopy (SEM), thermogravimetric differential scanning calorimetry (TG-DSC), Fourier transform infrared (FT-IR), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and nitrogen sorption measurements. It was proven that the self-sacrificial salts NH₄SCN had been removed during pyrolyzing and so, porous carbon monoliths could be directly obtained after carbonization without the need of washing removal of salts. Most importantly, the microporous specific surface area of the resultant porous carbon monoliths was dramatically increased up to 770 m²/g and the Brunauer–Emmett–Teller (BET) specific surface area was up to 1131 m²/g. That was because the salts NH₄SCN as self-sacrificial templating helped to form more around 0.6 nm, 0.72 nm and 1.1 nm micropores. The self-sacrificial salt templating is also a suitable and feasible method for controlling the nanoporous structure of other porous materials. Full article

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20 pages, 28765 KiB

Open AccessArticle

Preparation of Water Suspensions of Nanocalcite for Cultural Heritage Applications

by Maria-Beatrice Coltelli, Dario Paolucci, Valter Castelvetro, Sabrina Bianchi, Elisabeth Mascha, Luca Panariello, Cecilia Pesce, Johannes Weber and Andrea Lazzeri

Nanomaterials 2018, 8(4), 254; https://doi.org/10.3390/nano8040254 - 19 Apr 2018

Cited by 14 | Viewed by 5440

Abstract

The consolidation of degraded carbonate stone used in ancient monuments is an important topic for European cultural heritage conservation. The products most frequently used as consolidants are based on tetraalkoxy- or alkylalkoxy-silanes (in particular tetraethyl-orthosilicate, TEOS), resulting in the formation of relatively stable [...] Read more.

The consolidation of degraded carbonate stone used in ancient monuments is an important topic for European cultural heritage conservation. The products most frequently used as consolidants are based on tetraalkoxy- or alkylalkoxy-silanes (in particular tetraethyl-orthosilicate, TEOS), resulting in the formation of relatively stable amorphous silica or alkylated (hydrophobic) silica inside the stone pores. However, silica is not chemically compatible with carbonate stones; in this respect, nanocalcite may be a suitable alternative. The present work concerns the preparation of water suspensions of calcite nanoparticles (CCNPs) by controlled carbonation of slaked lime using a pilot-scale reactor. A simplified design of experiment was adopted for product optimization. Calcite nanoparticles of narrow size distribution averaging about 30 nm were successfully obtained, the concentration of the interfacial agent and the size of CaO being the most critical parameters. Primary nanoparticle aggregation causing flocculation could be substantially prevented by the addition of polymeric dispersants. Copolymer-based dispersants were produced in situ by controlled heterophase polymerisation mediated by an amphiphilic macro-RAFT (reversible addition-fragmentation transfer) agent. The stabilized CCNP aqueous dispersions were then applied on carbonate and silicate substrates; Scanning Electron Microscopy (SEM)analysis of cross-sections allowed the evaluation of pore penetration, interfacial binding, and bridging (gap-filling) properties of these novel consolidants. Full article

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14 pages, 2136 KiB

Open AccessArticle

Increased Level of α2,6-Sialylated Glycans on HaCaT Cells Induced by Titanium Dioxide Nanoparticles under UV Radiation

by Yuanyuan Ren, Xin Liu, Runqing Geng, Qunwei Lu, Rong Rao, Xi Tan, Xiangliang Yang and Wei Liu

Nanomaterials 2018, 8(4), 253; https://doi.org/10.3390/nano8040253 - 19 Apr 2018

Cited by 18 | Viewed by 4406

Abstract

As one of the most widely used nanomaterials, the safety of nano-TiO₂ for human beings has raised concern in recent years. Sialylation is an important glycosylation modification that plays a critical role in signal transduction, apoptosis, and tumor metastasis. The aim of [...] Read more.

As one of the most widely used nanomaterials, the safety of nano-TiO₂ for human beings has raised concern in recent years. Sialylation is an important glycosylation modification that plays a critical role in signal transduction, apoptosis, and tumor metastasis. The aim of this work was to investigate the cytotoxicity and phototoxicity of nano-TiO₂ with different crystalline phases for human skin keratinocytes (HaCaT cells) under ultraviolet (UV) irradiation and detect sialic acid alterations. The results showed that the mixture of crystalline P25 had the highest cytotoxicity and phototoxicity, followed by pure anatase A25, whereas pure rutile R25 had the lowest cytotoxicity and phototoxicity. A25 and R25 had no effects on the expression of sialic acids on HaCaT cells. However, HaCaT cells treated with P25 and UV showed an increased level of alterations in α2,6-linked sialic acids, which was related to the level of reactive oxygen species (ROS) generated by nano-TiO₂ and UV. The abundance of α2,6-linked sialic acids increased as ROS production increased, and vice versa. Antioxidant vitamin C (VC) reversed the abnormal expression of α2,6-linked sialic acids caused by nano-TiO₂ and protected cells by eliminating ROS. These findings indicate that nano-TiO₂ can alter the sialylation status of HaCaT cells under UV irradiation in a process mediated by ROS. Full article

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11 pages, 11238 KiB

Open AccessArticle

Shape-Controlled Synthesis of Au Nanostructures Using EDTA Tetrasodium Salt and Their Photothermal Therapy Applications

by Youngjin Jang, Nohyun Lee, Jeong Hyun Kim, Yong Il Park and Yuanzhe Piao

Nanomaterials 2018, 8(4), 252; https://doi.org/10.3390/nano8040252 - 18 Apr 2018

Cited by 15 | Viewed by 6337

Abstract

Tuning the optical properties of Au nanostructures is of paramount importance for scientific interest and has a wide variety of applications. Since the surface plasmon resonance properties of Au nanostructures can be readily adjusted by changing their shape, many approaches for preparing Au [...] Read more.

Tuning the optical properties of Au nanostructures is of paramount importance for scientific interest and has a wide variety of applications. Since the surface plasmon resonance properties of Au nanostructures can be readily adjusted by changing their shape, many approaches for preparing Au nanostructures with various shapes have been reported to date. However, complicated steps or the addition of several reagents would be required to achieve shape control of Au nanostructures. The present work describes a facile and effective shape-controlled synthesis of Au nanostructures and their photothermal therapy applications. The preparation procedure involved the reaction of HAuCl₄ and ethylenediaminetetraacetic acid (EDTA) tetrasodium salt, which acted as a reducing agent and ligand, at room temperature without the need for any toxic reagent or additives. The morphology control from spheres to branched forms and nanowire networks was easily achieved by varying the EDTA concentration. Detailed investigations revealed that the four carboxylic groups of the EDTA tetrasodium salt are essential for effective growth and stabilization. The produced Au nanowire networks exhibited a broad absorption band in the near-infrared (NIR) region, thereby showing efficient cancer therapeutic performance by inducing the selective photothermal destruction of cancerous glioblastoma cells (U87MG) under NIR irradiation. Full article

(This article belongs to the Special Issue Nanostructured Materials based on Noble Metals for Advanced Biological Applications)

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12 pages, 25810 KiB

Open AccessArticle

Ti Porous Film-Supported NiCo₂S₄ Nanotubes Counter Electrode for Quantum-Dot-Sensitized Solar Cells

by Jianping Deng, Minqiang Wang, Xiaohui Song, Zhi Yang and Zhaolin Yuan

Nanomaterials 2018, 8(4), 251; https://doi.org/10.3390/nano8040251 - 17 Apr 2018

Cited by 17 | Viewed by 4780

Abstract

In this paper, a novel Ti porous film-supported NiCo₂S₄ nanotube was fabricated by the acid etching and two-step hydrothermal method and then used as a counter electrode in a CdS/CdSe quantum-dot-sensitized solar cell. Measurements of the cyclic voltammetry, Tafel polarization [...] Read more.

In this paper, a novel Ti porous film-supported NiCo₂S₄ nanotube was fabricated by the acid etching and two-step hydrothermal method and then used as a counter electrode in a CdS/CdSe quantum-dot-sensitized solar cell. Measurements of the cyclic voltammetry, Tafel polarization curves, and electrochemical impedance spectroscopy of the symmetric cells revealed that compared with the conventional FTO (fluorine doped tin oxide)/Pt counter electrode, Ti porous film-supported NiCo₂S₄ nanotubes counter electrode exhibited greater electrocatalytic activity toward polysulfide electrolyte and lower charge-transfer resistance at the interface between electrolyte and counter electrode, which remarkably improved the fill factor, short-circuit current density, and power conversion efficiency of the quantum-dot-sensitized solar cell. Under illumination of one sun (100 mW/cm²), the quantum-dot-sensitized solar cell based on Ti porous film-supported NiCo₂S₄ nanotubes counter electrode achieved a power conversion efficiency of 3.14%, which is superior to the cell based on FTO/Pt counter electrode (1.3%). Full article

(This article belongs to the Special Issue Optoelectronic Nanodevices)

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18 pages, 23533 KiB

Open AccessArticle

Thermal Calcination-Based Production of SnO₂ Nanopowder: An Analysis of SnO₂ Nanoparticle Characteristics and Antibacterial Activities

by Naif Mohammed Al-Hada, Halimah Mohamed Kamari, Anwar Ali Baqer, Abdul H. Shaari and Elias Saion

Nanomaterials 2018, 8(4), 250; https://doi.org/10.3390/nano8040250 - 17 Apr 2018

Cited by 50 | Viewed by 7742

Abstract

SnO₂ nanoparticle production using thermal treatment with tin(II) chloride dihydrate and polyvinylpyrrolidone capping agent precursor materials for calcination was investigated. Samples were analyzed using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), Fourier Transform Infrared [...] Read more.

SnO₂ nanoparticle production using thermal treatment with tin(II) chloride dihydrate and polyvinylpyrrolidone capping agent precursor materials for calcination was investigated. Samples were analyzed using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), diffuse UV-vis reflectance spectra, photoluminescence (PL) spectra and the electron spin resonance (ESR). XRD analysis found tetragonal crystalline structures in the SnO₂ nanoparticles generated through calcination. EDX and FT-IR spectroscopy phase analysis verified the derivation of the Sn and O in the SnO₂ nanoparticle samples from the precursor materials. An average nanoparticle size of 4–15.5 nm was achieved by increasing calcination temperature from 500 °C to 800 °C, as confirmed through TEM. The valence state and surface composition of the resulting nanoparticle were analyzed using XPS. Diffuse UV-vis reflectance spectra were used to evaluate the optical energy gap using the Kubelka-Munk equation. Greater calcination temperature resulted in the energy band gap falling from 3.90 eV to 3.64 eV. PL spectra indicated a positive relationship between particle size and photoluminescence. Magnetic features were investigated through ESR, which revealed the presence of unpaired electrons. The magnetic field resonance decreases along with an increase of the g-factor value as the calcination temperature increased from 500 °C to 800 °C. Finally, Escherichia coli ATCC 25922 Gram (–ve) and Bacillus subtilis UPMC 1175 Gram (+ve) were used for in vitro evaluation of the tin oxide nanoparticle’s antibacterial activity. This work indicated that the zone of inhibition of 22 mm has good antibacterial activity toward the Gram-positive B. subtilis UPMC 1175. Full article

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9 pages, 2809 KiB

Open AccessArticle

Cobalt-Assisted Morphology and Assembly Control of Co-Doped ZnO Nanoparticles

by Xianying Han, Sebastian Wahl, Patrícia A. Russo and Nicola Pinna

Nanomaterials 2018, 8(4), 249; https://doi.org/10.3390/nano8040249 - 17 Apr 2018

Cited by 30 | Viewed by 6042

Abstract

The morphology of metal oxide nanostructures influences the response of the materials in a given application. In addition to changing the composition, doping can also modify the morphology of a host nanomaterial. Herein, we determine the effect of dopant concentration, reaction temperature, and [...] Read more.

The morphology of metal oxide nanostructures influences the response of the materials in a given application. In addition to changing the composition, doping can also modify the morphology of a host nanomaterial. Herein, we determine the effect of dopant concentration, reaction temperature, and reaction time on the morphology and assembly of Co_xZn_1−xO nanoparticles synthesized through non-aqueous sol-gel in benzyl alcohol. With the increase of the atom % of cobalt incorporated from 0 to 15, the shape of the nanoparticles changes from near spherical, to irregular, and finally to triangular. The tendency of the particles to assemble increases in the same direction, with Co_0.05Zn_0.95O consisting of non-assembled particles, whereas Co_0.15Zn_0.85O consists of triangular nanoparticles forming spherical structures. The morphology and assembly process are also sensitive to the reaction temperature. The assembly process is found to occur during the nucleation or the early stages of particle growth. The cobalt ions promote the change in the shape during the growth stage of the nanoparticles. Full article

(This article belongs to the Special Issue Sol-Gel Preparation of Nanomaterials)

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11 pages, 16430 KiB

Open AccessArticle

Comparison Study on the Adsorption Capacity of Rhodamine B, Congo Red, and Orange II on Fe-MOFs

by Fuhua Wei, Ding Chen, Zhao Liang and Shuaiqi Zhao

Nanomaterials 2018, 8(4), 248; https://doi.org/10.3390/nano8040248 - 17 Apr 2018

Cited by 51 | Viewed by 6329

Abstract

Using a microwave-assisted ball-milling approach, Fe-based metal-organic frameworks (Fe-MOFs) were prepared from FeSO₄·7H₂O and trimesic acid. Scanning electron microscopy, Fourier-transform infrared spectrometry, X-ray, and thermogravimetric analysis were utilized to characterize the thermal stability and structure of the prepared Fe-MOFs. [...] Read more.

Using a microwave-assisted ball-milling approach, Fe-based metal-organic frameworks (Fe-MOFs) were prepared from FeSO₄·7H₂O and trimesic acid. Scanning electron microscopy, Fourier-transform infrared spectrometry, X-ray, and thermogravimetric analysis were utilized to characterize the thermal stability and structure of the prepared Fe-MOFs. These Fe-MOFs were used to remove organic dyes from aqueous solutions. Specifically, they removed 96.97% of 23.3592 mg/L of Congo red in a 200 mL solution within 300 min of treatment with natural light at 15 °C. Likewise, 88.21 and 70.90% of 22.7527 mg/L of Orange II and 17.8326 mg/L of Rhodamine B, respectively, were removed from 200 mL solutions within 300 min of treatment at 15 °C. At 35 °C, 99.57, 95.98, and 99.38% of 23.3855 mg/L of Congo Red, 22.7365 mg/L of Orange II, and 17.9973 mg/L of Rhodamine B, respectively, were removed from 200 mL solutions within 300 min of treatment. The adsorption kinetics were investigated and the pseudo-first-order kinetic model was found to be superior to the pseudo-second-order kinetic model. Overall, using metal-organic frameworks to treat dye wastewater was found to be inexpensive, feasible, and efficient. Therefore, this material has future prospects in research and applications in the purification of wastewater. Full article

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12 pages, 1578 KiB

Open AccessArticle

Nanoscale Zinc Oxide Particles for Improving the Physiological and Sanitary Quality of a Mexican Landrace of Red Maize

by Juan Estrada-Urbina, Alejandro Cruz-Alonso, Martha Santander-González, Abraham Méndez-Albores and Alma Vázquez-Durán

Nanomaterials 2018, 8(4), 247; https://doi.org/10.3390/nano8040247 - 17 Apr 2018

Cited by 102 | Viewed by 7524

Abstract

In this research, quasi-spherical-shaped zinc oxide nanoparticles (ZnO NPs) were synthesized by a simple cost-competitive aqueous precipitation method. The engineered NPs were characterized using several validation methodologies: UV–Vis spectroscopy, diffuse reflection UV–Vis, spectrofluorometry, transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Fourier [...] Read more.

In this research, quasi-spherical-shaped zinc oxide nanoparticles (ZnO NPs) were synthesized by a simple cost-competitive aqueous precipitation method. The engineered NPs were characterized using several validation methodologies: UV–Vis spectroscopy, diffuse reflection UV–Vis, spectrofluorometry, transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Fourier transform infrared (FTIR) spectroscopy with attenuated total reflection (ATR). A procedure was established to coat a landrace of red maize using gelatinized maize starch. Each maize seed was treated with 0.16 mg ZnO NPs (~7.7 × 10⁹ particles). The standard germination (SG) and accelerated aging (AA) tests indicated that ZnO NP-treated maize seeds presented better physiological quality (higher percentage of normal seedlings) and sanitary quality (lower percentage of seeds contaminated by microorganisms) as compared to controls. The application of ZnO NPs also improved seedling vigor, correlated to shoot length, shoot diameter, root length, and number of secondary roots. Furthermore, shoots and roots of the ZnO NP-treated maize seeds showed a marked increment in the main active FTIR band areas, most notably for the vibrations associated with peptide-protein, lipid, lignin, polysaccharide, hemicellulose, cellulose, and carbohydrate. From these results, it is concluded that ZnO NPs have potential for applications in peasant agriculture to improve the quality of small-scale farmers’ seeds and, as a result, preserve germplasm resources. Full article

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13 pages, 17243 KiB

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Iron Oxide-Cobalt Nanocatalyst for O-tert-Boc Protection and O-Arylation of Phenols

by Vilas B. Gade, Anandarup Goswami, Rajender S. Varma, Sharad N. Shelke and Manoj B. Gawande

Nanomaterials 2018, 8(4), 246; https://doi.org/10.3390/nano8040246 - 17 Apr 2018

Cited by 12 | Viewed by 4905

Abstract

Efficient and general protocols for the O-tert-boc protection and O-arylation of phenols were developed in this paper using a recyclable magnetic Fe₃O₄-Co₃O₄ nanocatalyst (Nano-Fe-Co), which is easily accessible via simple wet impregnation [...] Read more.

Efficient and general protocols for the O-tert-boc protection and O-arylation of phenols were developed in this paper using a recyclable magnetic Fe₃O₄-Co₃O₄ nanocatalyst (Nano-Fe-Co), which is easily accessible via simple wet impregnation techniques in aqueous mediums from inexpensive precursors. The results showed the catalysts were well characterized by XRD (X-ray Diffraction), ICP-AES (Inductive Coupled Plasma Atomic Emission Spectroscopy), TEM (Transmission Electron Microscopy), TOF-SIMS (Time-Of-Flight Secondary Ion Mass Spectrometry) and XPS (X-ray Photoelectron Spectroscopy). The O-tert-boc protection and O-arylation of phenols was accomplished in good to excellent yields (85–95%) and the catalyst was reusable and recyclable with no loss of catalytic activity for at least six repetitions. Full article

(This article belongs to the Special Issue Sustainable Nanoparticles - Their Synthesis and Catalytic Applications)

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16 pages, 32722 KiB

Open AccessArticle

A Facile Approach to Prepare Black TiO₂ with Oxygen Vacancy for Enhancing Photocatalytic Activity

by Shihao Chen, Yang Xiao, Yinhai Wang, Zhengfa Hu, Hui Zhao and Wei Xie

Nanomaterials 2018, 8(4), 245; https://doi.org/10.3390/nano8040245 - 16 Apr 2018

Cited by 146 | Viewed by 13197

Abstract

Black TiO₂ has triggered worldwide research interest due to its excellent photocatalytic properties. However, the understanding of its structure–property relationships and a more effective, facile and versatile method to produce it remain great challenges. We have developed a facile approach to synthesize [...] Read more.

Black TiO₂ has triggered worldwide research interest due to its excellent photocatalytic properties. However, the understanding of its structure–property relationships and a more effective, facile and versatile method to produce it remain great challenges. We have developed a facile approach to synthesize black TiO₂ nanoparticles with significantly improved light absorption in the visible and infrared regions. The experimental results show that oxygen vacancies are the major factors responsible for black coloration. More importantly, our black TiO₂ nanoparticles have no Ti³⁺ ions. These oxygen vacancies could introduce localized states in the bandgap and act as trap centers, significantly decreasing the electron–hole recombination. The photocatalytic decomposition of both rhodamine B and methylene blue demonstrated that, under ultraviolet light irradiation, better photocatalytic performance is achieved with our black TiO₂ nanoparticles than with commercial TiO₂ nanoparticles. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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11 pages, 7593 KiB

Open AccessArticle

Study on the Coupling Mechanism of the Orthogonal Dipoles with Surface Plasmon in Green LED by Cathodoluminescence

by Yulong Feng, Zhizhong Chen, Shuang Jiang, Chengcheng Li, Yifan Chen, Jinglin Zhan, Yiyong Chen, Jingxin Nie, Fei Jiao, Xiangning Kang, Shunfeng Li, Tongjun Yu, Guoyi Zhang and Bo Shen

Nanomaterials 2018, 8(4), 244; https://doi.org/10.3390/nano8040244 - 16 Apr 2018

Cited by 5 | Viewed by 4133

Abstract

We analyzed the coupling behavior between the localized surface plasmon (LSP) and quantum wells (QWs) using cathodoluminescence (CL) in a green light-emitting diodes (LED) with Ag nanoparticles (NPs) filled in photonic crystal (PhC) holes. Photoluminescence (PL) suppression and CL enhancement were obtained for [...] Read more.

We analyzed the coupling behavior between the localized surface plasmon (LSP) and quantum wells (QWs) using cathodoluminescence (CL) in a green light-emitting diodes (LED) with Ag nanoparticles (NPs) filled in photonic crystal (PhC) holes. Photoluminescence (PL) suppression and CL enhancement were obtained for the same green LED sample with the Ag NP array. Time-resolved PL (TRPL) results indicate strong coupling between the LSP and the QWs. Three-dimensional (3D) finite difference time domain (FDTD) simulation was performed using a three-body model consisting of two orthogonal dipoles and a single Ag NP. The LSP–QWs coupling effect was separated from the electron-beam (e-beam)–LSP–QW system by linear approximation. The energy dissipation was significantly reduced by the z-dipole introduction under the e-beam excitation. In this paper, the coupling mechanism is discussed and a novel emission structure is proposed. Full article

(This article belongs to the Special Issue Optoelectronic Nanodevices)

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14 pages, 3833 KiB

Open AccessArticle

Towards the Development of Global Nano-Quantitative Structure–Property Relationship Models: Zeta Potentials of Metal Oxide Nanoparticles

by Andrey A. Toropov, Natalia Sizochenko, Alla P. Toropova and Jerzy Leszczynski

Nanomaterials 2018, 8(4), 243; https://doi.org/10.3390/nano8040243 - 15 Apr 2018

Cited by 35 | Viewed by 4681

Abstract

Zeta potential indirectly reflects a charge of the surface of nanoparticles in solutions and could be used to represent the stability of the colloidal solution. As processes of synthesis, testing and evaluation of new nanomaterials are expensive and time-consuming, so it would be [...] Read more.

Zeta potential indirectly reflects a charge of the surface of nanoparticles in solutions and could be used to represent the stability of the colloidal solution. As processes of synthesis, testing and evaluation of new nanomaterials are expensive and time-consuming, so it would be helpful to estimate an approximate range of properties for untested nanomaterials using computational modeling. We collected the largest dataset of zeta potential measurements of bare metal oxide nanoparticles in water (87 data points). The dataset was used to develop quantitative structure–property relationship (QSPR) models. Essential features of nanoparticles were represented using a modified simplified molecular input line entry system (SMILES). SMILES strings reflected the size-dependent behavior of zeta potentials, as the considered quasi-SMILES modification included information about both chemical composition and the size of the nanoparticles. Three mathematical models were generated using the Monte Carlo method, and their statistical quality was evaluated (R² for the training set varied from 0.71 to 0.87; for the validation set, from 0.67 to 0.82; root mean square errors for both training and validation sets ranged from 11.3 to 17.2 mV). The developed models were analyzed and linked to aggregation effects in aqueous solutions. Full article

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14 pages, 21648 KiB

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Alignment of Boron Nitride Nanofibers in Epoxy Composite Films for Thermal Conductivity and Dielectric Breakdown Strength Improvement

by Zhengdong Wang, Jingya Liu, Yonghong Cheng, Siyu Chen, Mengmeng Yang, Jialiang Huang, Hongkang Wang, Guanglei Wu and Hongjing Wu

Nanomaterials 2018, 8(4), 242; https://doi.org/10.3390/nano8040242 - 15 Apr 2018

Cited by 61 | Viewed by 8106

Abstract

Development of polymer-based composites with simultaneously high thermal conductivity and breakdown strength has attracted considerable attention owing to their important applications in both electronic and electric industries. In this work, boron nitride (BN) nanofibers (BNNF) are successfully prepared as fillers, which are used [...] Read more.

Development of polymer-based composites with simultaneously high thermal conductivity and breakdown strength has attracted considerable attention owing to their important applications in both electronic and electric industries. In this work, boron nitride (BN) nanofibers (BNNF) are successfully prepared as fillers, which are used for epoxy composites. In addition, the BNNF in epoxy composites are aligned by using a film casting method. The composites show enhanced thermal conductivity and dielectric breakdown strength. For instance, after doping with BNNF of 2 wt%, the thermal conductivity of composites increased by 36.4% in comparison with that of the epoxy matrix. Meanwhile, the breakdown strength of the composite with 1 wt% BNNF is 122.9 kV/mm, which increased by 6.8% more than that of neat epoxy (115.1 kV/mm). Moreover, the composites have maintained a low dielectric constant and alternating current conductivity among the range of full frequency, and show a higher thermal decomposition temperature and glass-transition temperature. The composites with aligning BNNF have wide application prospects in electronic packaging material and printed circuit boards. Full article

(This article belongs to the Special Issue Boron Nitride Nanostructures)

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10 pages, 13625 KiB

Open AccessArticle

Structure and Magnetism of Mn₅Ge₃ Nanoparticles

by Onur Tosun, Mohammed Salehi-Fashami, Balamurugan Balasubramanian, Ralph Skomski, David J. Sellmyer and George C. Hadjipanayis

Nanomaterials 2018, 8(4), 241; https://doi.org/10.3390/nano8040241 - 15 Apr 2018

Cited by 6 | Viewed by 5751

Abstract

In this work, we investigated the magnetic and structural properties of isolated Mn₅Ge₃ nanoparticles prepared by the cluster-beam deposition technique. Particles with sizes between 7.2 and 12.6 nm were produced by varying the argon pressure and power in the cluster [...] Read more.

In this work, we investigated the magnetic and structural properties of isolated Mn₅Ge₃ nanoparticles prepared by the cluster-beam deposition technique. Particles with sizes between 7.2 and 12.6 nm were produced by varying the argon pressure and power in the cluster gun. X-ray diffraction (XRD)and selected area diffraction (SAD) measurements show that the nanoparticles crystallize in the hexagonal Mn₅Si₃-type crystal structure, which is also the structure of bulk Mn₅Ge₃. The temperature dependence of the magnetization shows that the as-made particles are ferromagnetic at room temperature and have slightly different Curie temperatures. Hysteresis-loop measurements show that the saturation magnetization of the nanoparticles increases significantly with particle size, varying from 31 kA/m to 172 kA/m when the particle size increases from 7.2 to 12.6 nm. The magnetocrystalline anisotropy constant K at 50 K, determined by fitting the high-field magnetization data to the law of approach to saturation, also increases with particle size, from 0.4 × 10⁵ J/m³ to 2.9 × 10⁵ J/m³ for the respective sizes. This trend is mirrored by the coercivity at 50 K, which increases from 0.04 T to 0.13 T. A possible explanation for the magnetization trend is a radial Ge concentration gradient. Full article

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16 pages, 29226 KiB

Open AccessArticle

UV Light-Assisted Synthesis of Highly Efficient Pd-Based Catalyst over NiO for Hydrogenation of o-Chloronitrobenzene

by Weidong Jiang, Bin Xu, Guangyin Fan, Kaiming Zhang, Zhen Xiang and Xiaoqiang Liu

Nanomaterials 2018, 8(4), 240; https://doi.org/10.3390/nano8040240 - 14 Apr 2018

Cited by 8 | Viewed by 5342

Abstract

Supported Pd-based catalyst over active nickel oxide (NiO) was repared using the impregnation method companying with UV-light irradiation. Moreover, the catalytic performance of the obtained Pd-based catalysts was evaluated towards the hydrogenation of o-chloronitrobenzene (o-CNB). Observations indicate that the as-prepared [...] Read more.

Supported Pd-based catalyst over active nickel oxide (NiO) was repared using the impregnation method companying with UV-light irradiation. Moreover, the catalytic performance of the obtained Pd-based catalysts was evaluated towards the hydrogenation of o-chloronitrobenzene (o-CNB). Observations indicate that the as-prepared UV-irradiated Pd/NiO catalyst with a mole fraction 0.2% (0.2%Pd/NiO) has higher activity and selectivity in the o-CNB hydrogenation. Especially, UV-light irradiation played a positive role in the improvement of catalytic activity of 0.2%Pd/NiO catalyst, exhibiting an excess 11-fold activity superiority in contrast with non-UV-irradiated 0.2%Pd/NiO catalyst. In addition, it was investigated that effects of varied factors (i.e., reaction time, temperature, o-CNB/Pd ratio, Pd loading, hydrogen pressure) on the selective hydrogenation of ο-CNB catalyzed by UV-irradiated 0.2%Pd/NiO catalyst. Under the reaction conditions of 60 °C, 0.5 h, 1 MPa H₂ pressure, 100% conversion of o-CNB, and 81.1% o-CAN selectivity were obtained, even at high molar ratio (8000:1) of o-CNB to Pd. Full article

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