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Nanomaterials, Volume 11, Issue 8 (August 2021) – 285 articles

Cover Story (view full-size image): Nanocarbon materials have the advantages of biocompatibility, thermal stability, and chemical stability and have shown excellent electrical properties in electronic devices. In this study, Al/MWCNT:GQD/ITO memristors with rewritable nonvolatile properties were prepared based on composites consisting of multiwalled carbon nanotubes (MWCNTs) and graphene quantum dots (GQDs). The switching current ratio of such a device can be tuned in two ways: by adjusting the ultraviolet light irradiation time and by adjusting the concentration of quantum dots. These findings lay a foundation in adjustable logic memory applications. View this paper.
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15 pages, 4101 KiB  
Article
Dynamic Mechanical and Creep Behaviour of Meltspun PVDF Nanocomposite Fibers
by Fatemeh Mokhtari, Geoffrey M. Spinks, Sepidar Sayyar and Javad Foroughi
Nanomaterials 2021, 11(8), 2153; https://doi.org/10.3390/nano11082153 - 23 Aug 2021
Cited by 13 | Viewed by 4087
Abstract
Piezoelectric fibers have an important role in wearable technology as energy generators and sensors. A series of hybrid nanocomposite piezoelectric fibers of polyinylidene fluoride (PVDF) loaded with barium–titanium oxide (BT) and reduced graphene oxide (rGO) were prepared via the melt spinning method. Our [...] Read more.
Piezoelectric fibers have an important role in wearable technology as energy generators and sensors. A series of hybrid nanocomposite piezoelectric fibers of polyinylidene fluoride (PVDF) loaded with barium–titanium oxide (BT) and reduced graphene oxide (rGO) were prepared via the melt spinning method. Our previous studies show that high-performance fibers with 84% of the electroactive β-phase in the PVDF generated a peak output voltage up to 1.3 V and a power density of 3 W kg−1. Herein, the dynamic mechanical and creep behavior of these fibers were investigated to evaluate their durability and piezoelectric performance. Dynamic mechanical analysis (DMA) was used to provide phenomenological information regarding the viscoelastic properties of the fibers in the longitudinal direction. DSC and SEM were employed to characterize the crystalline structure of the samples. The storage modulus and the loss tangent increased by increasing the frequency over the temperature range (−50 to 150 °C) for all of the fibers. The storage modulus of the PVDF/rGO nanocomposite fibers had a higher value (7.5 GPa) in comparison with other fibers. The creep and creep recovery behavior of the PVDF/nanofillers in the nanocomposite fibers have been explored in the linear viscoelastic region at three different temperatures (10–130 °C). In the PVDF/rGO nanocomposite fibers, strong sheet/matrix interfacial interaction restricted the mobility of the polymer chains, which led to a higher modulus at temperatures 60 and 130 °C. Full article
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30 pages, 4783 KiB  
Review
Human Body–Electrode Interfaces for Wide-Frequency Sensing and Communication: A Review
by Kurian Polachan, Baibhab Chatterjee, Scott Weigand and Shreyas Sen
Nanomaterials 2021, 11(8), 2152; https://doi.org/10.3390/nano11082152 - 23 Aug 2021
Cited by 12 | Viewed by 7041
Abstract
Several on-body sensing and communication applications use electrodes in contact with the human body. Body–electrode interfaces in these cases act as a transducer, converting ionic current in the body to electronic current in the sensing and communication circuits and vice versa. An ideal [...] Read more.
Several on-body sensing and communication applications use electrodes in contact with the human body. Body–electrode interfaces in these cases act as a transducer, converting ionic current in the body to electronic current in the sensing and communication circuits and vice versa. An ideal body–electrode interface should have the characteristics of an electrical short, i.e., the transfer of ionic currents and electronic currents across the interface should happen without any hindrance. However, practical body–electrode interfaces often have definite impedances and potentials that hinder the free flow of currents, affecting the application’s performance. Minimizing the impact of body–electrode interfaces on the application’s performance requires one to understand the physics of such interfaces, how it distorts the signals passing through it, and how the interface-induced signal degradations affect the applications. Our work deals with reviewing these elements in the context of biopotential sensing and human body communication. Full article
(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications)
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19 pages, 2839 KiB  
Review
Application of MXenes in Perovskite Solar Cells: A Short Review
by Syed Afaq Ali Shah, Muhammad Hassan Sayyad, Karim Khan, Jinghua Sun and Zhongyi Guo
Nanomaterials 2021, 11(8), 2151; https://doi.org/10.3390/nano11082151 - 23 Aug 2021
Cited by 30 | Viewed by 6075
Abstract
Application of MXene materials in perovskite solar cells (PSCs) has attracted considerable attention owing to their supreme electrical conductivity, excellent carrier mobility, adjustable surface functional groups, excellent transparency and superior mechanical properties. This article reviews the progress made so far in using Ti [...] Read more.
Application of MXene materials in perovskite solar cells (PSCs) has attracted considerable attention owing to their supreme electrical conductivity, excellent carrier mobility, adjustable surface functional groups, excellent transparency and superior mechanical properties. This article reviews the progress made so far in using Ti3C2Tx MXene materials in the building blocks of perovskite solar cells such as electrodes, hole transport layer (HTL), electron transport layer (ETL) and perovskite photoactive layer. Moreover, we provide an outlook on the exciting opportunities this recently developed field offers, and the challenges faced in effectively incorporating MXene materials in the building blocks of PSCs for better operational stability and enhanced performance. Full article
(This article belongs to the Special Issue Nanostructures for Perovskite Solar Cells and Light-Emitting Diodes)
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40 pages, 18336 KiB  
Review
Recent Progress on ZnO Nanowires Cold Cathode and Its Applications
by Yicong Chen, Shaozhi Deng, Ningsheng Xu and Jun Chen
Nanomaterials 2021, 11(8), 2150; https://doi.org/10.3390/nano11082150 - 23 Aug 2021
Cited by 6 | Viewed by 2986
Abstract
A cold cathode has many applications in high frequency and high power electronic devices, X-ray source, vacuum microelectronic devices and vacuum nanoelectronic devices. After decades of exploration on the cold cathode materials, ZnO nanowire has been regarded as one of the most promising [...] Read more.
A cold cathode has many applications in high frequency and high power electronic devices, X-ray source, vacuum microelectronic devices and vacuum nanoelectronic devices. After decades of exploration on the cold cathode materials, ZnO nanowire has been regarded as one of the most promising candidates, in particular for large area field emitter arrays (FEAs). Numerous works on the fundamental field emission properties of ZnO nanowire, as well as demonstrations of varieties of large area vacuum microelectronic applications, have been reported. Moreover, techniques such as modifying the geometrical structure, surface decoration and element doping were also proposed for optimizing the field emissions. This paper aims to provide a comprehensive review on recent progress on the ZnO nanowire cold cathode and its applications. We will begin with a brief introduction on the synthesis methods and discuss their advantages/disadvantages for cold cathode applications. After that, the field emission properties, mechanism and optimization will be introduced in detail. Then, the development for applications of large-area ZnO nanowire FEAs will also be covered. Finally, some future perspectives are provided. Full article
(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)
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19 pages, 4009 KiB  
Article
Unravelling the Role of Synthesis Conditions on the Structure of Zinc Oxide-Reduced Graphene Oxide Nanofillers
by Zélia Alves, Cláudia Nunes and Paula Ferreira
Nanomaterials 2021, 11(8), 2149; https://doi.org/10.3390/nano11082149 - 23 Aug 2021
Cited by 12 | Viewed by 2725
Abstract
The diversity of zinc oxide (ZnO) particles and derived composites applications is highly dependent on their structure, size, morphology, defect amounts, and/or presence of dopant molecules. In this work, ZnO nanostructures are grown in situ on graphene oxide (GO) sheets by an easily [...] Read more.
The diversity of zinc oxide (ZnO) particles and derived composites applications is highly dependent on their structure, size, morphology, defect amounts, and/or presence of dopant molecules. In this work, ZnO nanostructures are grown in situ on graphene oxide (GO) sheets by an easily implementable solvothermal method with simultaneous reduction of GO. The effect of two zinc precursors (zinc acetate (ZA) and zinc acetate dihydrate (ZAD)), NaOH concentration (0.5, 1 or 2 M), and concentration (1 and 12.5 mg/mL) and pH (pH = 1, 4, 8, and 12) of GO suspension were evaluated. While the ZnO particle morphology shows to be precursor dependent, the average particle size length decreases with lower NaOH concentration, as well as with the addition of a higher basicity and concentration of GO suspension. A lowered band gap and a higher specific surface area are obtained from the ZnO composites with higher amounts of GO suspension. Otherwise, the low concentration and the higher pH of GO suspension induce more lattice defects on the ZnO crystal structure. The role of the different condition parameters on the ZnO nanostructures and their interaction with graphene sheets was observed to tune the ZnO–rGO nanofiller properties for photocatalytic and antimicrobial activities. Full article
(This article belongs to the Special Issue Synthesis, Characteristics, and Applications of Nanocomposites)
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10 pages, 3141 KiB  
Article
Local Structure and Redox Properties of Amorphous CeO2-TiO2 Prepared Using the H2O2-Modified Sol-Gel Method
by Myungju Kim, Gwanhee Park and Heesoo Lee
Nanomaterials 2021, 11(8), 2148; https://doi.org/10.3390/nano11082148 - 23 Aug 2021
Cited by 9 | Viewed by 2375
Abstract
Amorphous CeO2-TiO2 nanoparticles synthesized by the H2O2-modified sol-gel method were investigated in terms of the Ce-O-Ce and Ti-O-Ti linkage, local structure, and redox properties. The decrease in the crystallinity of CeO2 [...] Read more.
Amorphous CeO2-TiO2 nanoparticles synthesized by the H2O2-modified sol-gel method were investigated in terms of the Ce-O-Ce and Ti-O-Ti linkage, local structure, and redox properties. The decrease in the crystallinity of CeO2-TiO2 by H2O2 addition was confirmed. The metal–oxygen linkage analysis showed the difference in size of the metal–oxygen network between crystalline CeO2-TiO2 and amorphous CeO2-TiO2 due to the O22− formed by H2O2. The local structure of CeO2-TiO2 was analyzed with an extended X-ray absorption fine structure (EXAFS), and the oscillation changes in the k space revealed the disordering of CeO2-TiO2. The decrease in Ce-O bond length and the Ce-O peak broadening was attributed to O22− interfering with the formation of the extended metal–oxygen network. The temperature-programmed reduction of the H2 profile of amorphous CeO2-TiO2 exhibited the disappearance of the bulk oxygen reduction peak and a low-temperature shift of the surface oxygen reduction peak. The H2 consumption increased compared to crystalline CeO2-TiO2, which indicated the improvement of redox properties by amorphization. Full article
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16 pages, 1765 KiB  
Review
Recent Advances in Synthesis, Medical Applications and Challenges for Gold-Coated Iron Oxide: Comprehensive Study
by Mohammed Ali Dheyab, Azlan Abdul Aziz, Mahmood S. Jameel and Pegah Moradi Khaniabadi
Nanomaterials 2021, 11(8), 2147; https://doi.org/10.3390/nano11082147 - 23 Aug 2021
Cited by 16 | Viewed by 2842
Abstract
Combining iron oxide nanoparticles (Fe3O4 NPs) and gold nanoparticles (Au NPs) in one nanostructure is a promising technique for various applications. Fe3O4 NPs have special supermagnetic attributes that allow them to be applied in different areas, and [...] Read more.
Combining iron oxide nanoparticles (Fe3O4 NPs) and gold nanoparticles (Au NPs) in one nanostructure is a promising technique for various applications. Fe3O4 NPs have special supermagnetic attributes that allow them to be applied in different areas, and Au NPs stand out in biomaterials due to their oxidation resistance, chemical stability, and unique optical properties. Recent studies have generally defined the physicochemical properties of nanostructures without concentrating on a particular formation strategy. This detailed review provides a summary of the latest research on the formation strategy and applications of Fe3O4@Au. The diverse methods of synthesis of Fe3O4@Au NPs with different basic organic and inorganic improvements are introduced. The role and applicability of Au coating on the surface of Fe3O4 NPs schemes were explored. The 40 most relevant publications were identified and reviewed. The versatility of combining Fe3O4@Au NPs as an option for medical application is proven in catalysis, hyperthermia, biomedical imaging, drug delivery and protein separation. Full article
(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)
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21 pages, 4310 KiB  
Review
Nanoarchitectonics for Hierarchical Fullerene Nanomaterials
by Subrata Maji, Lok Kumar Shrestha and Katsuhiko Ariga
Nanomaterials 2021, 11(8), 2146; https://doi.org/10.3390/nano11082146 - 23 Aug 2021
Cited by 21 | Viewed by 4135
Abstract
Nanoarchitectonics is a universal concept to fabricate functional materials from nanoscale building units. Based on this concept, fabrications of functional materials with hierarchical structural motifs from simple nano units of fullerenes (C60 and C70 molecules) are described in this review article. [...] Read more.
Nanoarchitectonics is a universal concept to fabricate functional materials from nanoscale building units. Based on this concept, fabrications of functional materials with hierarchical structural motifs from simple nano units of fullerenes (C60 and C70 molecules) are described in this review article. Because fullerenes can be regarded as simple and fundamental building blocks with mono-elemental and zero-dimensional natures, these demonstrations for hierarchical functional structures impress the high capability of the nanoarchitectonics approaches. In fact, various hierarchical structures such as cubes with nanorods, hole-in-cube assemblies, face-selectively etched assemblies, and microstructures with mesoporous frameworks are fabricated by easy fabrication protocols. The fabricated fullerene assemblies have been used for various applications including volatile organic compound sensing, microparticle catching, supercapacitors, and photoluminescence systems. Full article
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12 pages, 2532 KiB  
Article
Dichroic Circular Polarizers Based on Plasmonics for Polarization Imaging Applications
by Junyan Zheng, Xin He, Paul Beckett, Xinjie Sun, Zixin Cai, Wenyi Zhang, Xu Liu and Xiang Hao
Nanomaterials 2021, 11(8), 2145; https://doi.org/10.3390/nano11082145 - 23 Aug 2021
Cited by 5 | Viewed by 3437
Abstract
Dichroic circular polarizers (DCP) represent an important group of optical filters that transfer only that part of the incident light with the desired polarization state and absorb the remainder. However, DCPs are usually bulky and exhibit significant optical loss. Moreover, the integration of [...] Read more.
Dichroic circular polarizers (DCP) represent an important group of optical filters that transfer only that part of the incident light with the desired polarization state and absorb the remainder. However, DCPs are usually bulky and exhibit significant optical loss. Moreover, the integration of these kinds of DCP devices can be difficult and costly as different compositions of chemicals are needed to achieve the desired polarization status. Circular polarizers based on metasurfaces require only thin films in the order of hundreds of nanometers but are limited by their sensitivity to angle of incidence. Furthermore, few existing solutions offer broadband operation in the visible range. By using computational simulations, this paper proposes and analyses a plasmonic DCP structure operating in the visible, from 400 nm to 700 nm which overcomes these drawbacks. The resulting circular dichroism transmission (CDT) is more than 0.9, and the maximum transmission efficiency is greater than 78% at visible wavelengths. These CDT characteristics are largely independent of angle of incidence up to angles of 80 degrees. Full article
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15 pages, 2811 KiB  
Article
Adsorption of Recombinant Human β-Defensin 2 and Two Mutants on Mesoporous Silica Nanoparticles and Its Effect against Clavibacter michiganensis subsp. michiganensis
by Gabriel Marcelino-Pérez, Roberto Ruiz-Medrano, Salvador Gallardo-Hernández and Beatriz Xoconostle-Cázares
Nanomaterials 2021, 11(8), 2144; https://doi.org/10.3390/nano11082144 - 23 Aug 2021
Cited by 3 | Viewed by 2982
Abstract
Solanum lycopersicum L. is affected among other pests and diseases, by the actinomycete Clavibacter michiganensis subsp. michiganensis (Cmm), causing important economic losses worldwide. Antimicrobial peptides (AMPs) are amphipathic cationic oligopeptides with which the development of pathogenic microorganisms has been inhibited. Therefore, [...] Read more.
Solanum lycopersicum L. is affected among other pests and diseases, by the actinomycete Clavibacter michiganensis subsp. michiganensis (Cmm), causing important economic losses worldwide. Antimicrobial peptides (AMPs) are amphipathic cationic oligopeptides with which the development of pathogenic microorganisms has been inhibited. Therefore, in this study, we evaluate antimicrobial activity of mesoporous silica nanoparticles (MSN5.4) loaded with human β-defensin-2 (hβD2) and two mutants (TRX-hβD2-M and hβD2-M) against Cmm. hβD2, TRX-hβD2-M and hβD2-M presented a half-maximum inhibitory concentration (IC50) of 3.64, 1.56 and 6.17 μg/mL, respectively. MSNs had average particle sizes of 140 nm (SEM) and a tunable pore diameter of 4.8 up to 5.4 nm (BJH). AMPs were adsorbed more than 99% into MSN and a first release after 24 h was observed. The MSN loaded with the AMPs inhibited the growth of Cmm in solid and liquid media. It was also determined that MSNs protect AMPs from enzymatic degradation when the MSN/AMPs complexes were exposed to a pepsin treatment. An improved AMP performance was registered when it was adsorbed in the mesoporous matrix. The present study could expand the applications of MSNs loaded with AMPs as a biological control and provide new tools for the management of phytopathogenic microorganisms. Full article
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14 pages, 3810 KiB  
Article
The Effect of Precursor Concentration on the Particle Size, Crystal Size, and Optical Energy Gap of CexSn1−xO2 Nanofabrication
by Naif Mohammed Al-Hada, Rafiziana Md. Kasmani, Hairoladenan Kasim, Abbas M. Al-Ghaili, Muneer Aziz Saleh, Essam M. Banoqitah, Abdulsalam M. Alhawsawi, Anwar Ali Baqer, Jian Liu, Shicai Xu, Qiang Li, Azlan Muhammad Noorazlan, Abdullah A. A. Ahmed, Moayad Husein Flaifel, Suriati Paiman, Nazirul Nazrin, Bandar Ali Al-Asbahi and Jihua Wang
Nanomaterials 2021, 11(8), 2143; https://doi.org/10.3390/nano11082143 - 22 Aug 2021
Cited by 10 | Viewed by 3466
Abstract
In the present work, a thermal treatment technique is applied for the synthesis of CexSn1−xO2 nanoparticles. Using this method has developed understanding of how lower and higher precursor values affect the morphology, structure, and optical properties of Ce [...] Read more.
In the present work, a thermal treatment technique is applied for the synthesis of CexSn1−xO2 nanoparticles. Using this method has developed understanding of how lower and higher precursor values affect the morphology, structure, and optical properties of CexSn1−xO2 nanoparticles. CexSn1−xO2 nanoparticle synthesis involves a reaction between cerium and tin sources, namely, cerium nitrate hexahydrate and tin (II) chloride dihydrate, respectively, and the capping agent, polyvinylpyrrolidone (PVP). The findings indicate that lower x values yield smaller particle size with a higher energy band gap, while higher x values yield a larger particle size with a smaller energy band gap. Thus, products with lower x values may be suitable for antibacterial activity applications as smaller particles can diffuse through the cell wall faster, while products with higher x values may be suitable for solar cell energy applications as more electrons can be generated at larger particle sizes. The synthesized samples were profiled via a number of methods, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). As revealed by the XRD pattern analysis, the CexSn1−xO2 nanoparticles formed after calcination reflect the cubic fluorite structure and cassiterite-type tetragonal structure of CexSn1−xO2 nanoparticles. Meanwhile, using FT-IR analysis, Ce-O and Sn-O were confirmed as the primary bonds of ready CexSn1−xO2 nanoparticle samples, whilst TEM analysis highlighted that the average particle size was in the range 6−21 nm as the precursor concentration (Ce(NO3)3·6H2O) increased from 0.00 to 1.00. Moreover, the diffuse UV-visible reflectance spectra used to determine the optical band gap based on the Kubelka–Munk equation showed that an increase in x value has caused a decrease in the energy band gap and vice versa. Full article
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18 pages, 4909 KiB  
Article
Synthesis of Ag Nanoparticles-Decorated CNTs via Laser Ablation Method for the Enhancement the Photocatalytic Removal of Naphthalene from Water
by Fowzia S. Alamro, Ayman M. Mostafa, Khulood A. Abu Al-Ola, Hoda A. Ahmed and Arafat Toghan
Nanomaterials 2021, 11(8), 2142; https://doi.org/10.3390/nano11082142 - 22 Aug 2021
Cited by 50 | Viewed by 2966
Abstract
Silver nanoparticles (Ag NPs) were decorated with different amounts on the exterior walls of carbon nanotubes (CNTs) by a laser ablation assisted method, especially in liquid media to be applied as a good adsorption material against naphthalene. The laser ablation time was controlled [...] Read more.
Silver nanoparticles (Ag NPs) were decorated with different amounts on the exterior walls of carbon nanotubes (CNTs) by a laser ablation assisted method, especially in liquid media to be applied as a good adsorption material against naphthalene. The laser ablation time was controlled the amount of decoration Ag NPs on CNTs. The prepared nanocomposite was analyzed via different analytical techniques. Ag NPs with a small size distribution of 29 nm are uniformly decorated with spherical shape on CNTs walls. The disorder degree of tubular structure and shifting of the vibrational characteristic peaks increase with the increase in the decoration of Ag NPs. After that, the prepared samples were investigated for the removal of naphthalene. These studies of loading Ag NPs with different amounts on the surface of CNTs act as a promising material for water treatment. Full article
(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)
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10 pages, 1860 KiB  
Article
Enhancement of Energy-Storage Density in PZT/PZO-Based Multilayer Ferroelectric Thin Films
by Jie Zhang, Yuanyuan Zhang, Qianqian Chen, Xuefeng Chen, Genshui Wang, Xianlin Dong, Jing Yang, Wei Bai and Xiaodong Tang
Nanomaterials 2021, 11(8), 2141; https://doi.org/10.3390/nano11082141 - 22 Aug 2021
Cited by 20 | Viewed by 3298
Abstract
PbZr0.35Ti0.65O3 (PZT), PbZrO3 (PZO), and PZT/PZO ferroelectric/antiferroelectric multilayer films were prepared on a Pt/Ti/SiO2/Si substrate using the sol–gel method. Microstructures and physical properties such as the polarization behaviors, leakage current, dielectric features, and energy-storage characteristics [...] Read more.
PbZr0.35Ti0.65O3 (PZT), PbZrO3 (PZO), and PZT/PZO ferroelectric/antiferroelectric multilayer films were prepared on a Pt/Ti/SiO2/Si substrate using the sol–gel method. Microstructures and physical properties such as the polarization behaviors, leakage current, dielectric features, and energy-storage characteristics of the three films were systematically explored. All electric field-dependent phase transitions, from sharp to diffused, can be tuned by layer structure, indicated by the polarization, shift current, and dielectric properties. The leakage current behaviors suggested that the layer structure could modulate the current mechanism, including space-charge-limited bulk conduction for single layer films and Schottky emission for multilayer thin films. The electric breakdown strength of a PZT/PZO multilayer structure can be further enhanced to 1760 kV/cm, which is higher than PZT (1162 kV/cm) and PZO (1373 kV/cm) films. A recoverable energy-storage density of 21.1 J/cm3 was received in PZT/PZO multilayers due to its high electric breakdown strength. Our results demonstrate that a multilayer structure is an effective method for enhancing energy-storage capacitors. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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13 pages, 5837 KiB  
Article
Skin Sensitization Potential and Cellular ROS-Induced Cytotoxicity of Silica Nanoparticles
by Sung-Hyun Kim, Dong Han Lee, SeoYoon Choi, Jun-Young Yang, Kikyung Jung, Jayoung Jeong, Jae Ho Oh and Jin Hee Lee
Nanomaterials 2021, 11(8), 2140; https://doi.org/10.3390/nano11082140 - 22 Aug 2021
Cited by 11 | Viewed by 2660
Abstract
Nowadays, various industries using nanomaterials are growing rapidly, and in particular, as the commercialization and use of nanomaterials increase in the cosmetic field, the possibility of exposure of nanomaterials to the skin of product producers and consumers is increasing. Due to the unique [...] Read more.
Nowadays, various industries using nanomaterials are growing rapidly, and in particular, as the commercialization and use of nanomaterials increase in the cosmetic field, the possibility of exposure of nanomaterials to the skin of product producers and consumers is increasing. Due to the unique properties of nanomaterials with a very small size, they can act as hapten and induce immune responses and skin sensitization, so accurate identification of toxicity is required. Therefore, we selected silica nanomaterials used in various fields such as cosmetics and biomaterials and evaluated the skin sensitization potential step-by-step according to in-vitro and in-vivo alternative test methods. KeratinoSensTM cells of modified keratinocyte and THP-1 cells mimicking dendritic-cells were treated with silica nanoparticles, and their potential for skin sensitization and cytotoxicity were evaluated, respectively. We also confirmed the sensitizing ability of silica nanoparticles in the auricle-lymph nodes of BALB/C mice by in-vivo analysis. As a result, silica nanoparticles showed high protein binding and reactive oxygen species (ROS) mediated cytotoxicity, but no significant observation of skin sensitization indicators was observed. Although more studies are needed to elucidate the mechanism of skin sensitization by nanomaterials, the results of this study showed that silica nanoparticles did not induce skin sensitization. Full article
(This article belongs to the Special Issue Biological and Toxicological Studies of Nanoparticles)
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17 pages, 3672 KiB  
Article
Lysozyme–AuNPs Interactions: Determination of Binding Free Energy
by Axel Gomes, Jose M. Carnerero, Aila Jimenez-Ruiz, Elia Grueso, Rosa M. Giráldez-Pérez and Rafael Prado-Gotor
Nanomaterials 2021, 11(8), 2139; https://doi.org/10.3390/nano11082139 - 22 Aug 2021
Cited by 5 | Viewed by 1888
Abstract
Investigation and optimization of lysozyme (Lys) adsorption onto gold nanoparticles, AuNPs, were carried out. The purpose of this study is to determine the magnitude of the AuNPs–lysozyme interaction in aqueous media by simple spectrophotometric means, and to obtain the free energy of binding [...] Read more.
Investigation and optimization of lysozyme (Lys) adsorption onto gold nanoparticles, AuNPs, were carried out. The purpose of this study is to determine the magnitude of the AuNPs–lysozyme interaction in aqueous media by simple spectrophotometric means, and to obtain the free energy of binding of the system for the first time. In order to explore the possibilities of gold nanoparticles for sensing lysozyme in aqueous media, the stability of the samples and the influence of the gold and nanoparticle concentrations in the detection limit were studied. ζ potential measurements and the shift of the surface plasmon band showed a state of saturation with an average number of 55 Lys per gold nanoparticle. Lysozyme–AuNPs interactions induce aggregation of citrate-stabilized AuNPs at low concentrations by neutering the negative charges of citrate anions; from those aggregation data, the magnitude of the interactions has been measured by using Benesi–Hildebrand plots. However, at higher protein concentrations aggregation has been found to decrease. Although the nanocluster morphology remains unchanged in the presence of Lys, slight conformational changes of the protein occur. The influence of the size of the nanoclusters was also investigated for 5, 10, and 20 nm AuNPs, and 10 nm AuNPs was found the most appropriate. Full article
(This article belongs to the Special Issue New Avenues of Research for Nanoparticle Drug Delivery Systems)
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27 pages, 11236 KiB  
Article
Pool Boiling Amelioration by Aqueous Dispersion of Silica Nanoparticles
by Sayantan Mukherjee, Naser Ali, Nawaf F. Aljuwayhel, Purna C. Mishra, Swarnendu Sen and Paritosh Chaudhuri
Nanomaterials 2021, 11(8), 2138; https://doi.org/10.3390/nano11082138 - 22 Aug 2021
Cited by 10 | Viewed by 2248
Abstract
Non-metallic oxide nanofluids have recently attracted interest in pool boiling heat transfer (PBHT) studies. Research work on carbon and silica-based nanofluids is now being reported frequently by scholars. The majority of these research studies showed improvement in PBHT performance. The present study reports [...] Read more.
Non-metallic oxide nanofluids have recently attracted interest in pool boiling heat transfer (PBHT) studies. Research work on carbon and silica-based nanofluids is now being reported frequently by scholars. The majority of these research studies showed improvement in PBHT performance. The present study reports an investigation on the PBHT characteristics and performance of water-based silica nanofluids in the nucleate boiling region. Sonication-aided stable silica nanofluids with 0.0001, 0.001, 0.01, and 0.1 particle concentrations were prepared. The stability of nanofluids was detected and confirmed via visible light absorbance and zeta potential analyses. The PBHT performance of nanofluids was examined in a customized boiling pool with a flat heating surface. The boiling characteristics, pool boiling heat transfer coefficient (PBHTC), and critical heat flux (CHF) were analyzed. The effects of surface wettability, contact angle, and surface roughness on heat transfer performance were investigated. Bubble diameter and bubble departure frequency were estimated using experimental results. PBHTC and CHF of water have shown an increase due to the nanoparticle inclusion, where they have reached a maximum improvement of ≈1.33 times over that of the base fluid. The surface wettability of nanofluids was also enhanced due to a decrease in boiling surface contact angle from 74.1° to 48.5°. The roughness of the boiling surface was reduced up to 1.5 times compared to the base fluid, which was due to the nanoparticle deposition on the boiling surface. Such deposition reduces the active nucleation sites and increases the thermal resistance between the boiling surface and bulk fluid layer. The presence of the dispersed nanoparticles caused a lower bubble departure frequency by 2.17% and an increase in bubble diameter by 4.48%, which vigorously affects the pool boiling performance. Full article
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12 pages, 3036 KiB  
Article
Double-Antibody Sandwich Immunoassay and Plasmonic Coupling Synergistically Improved Long-Range SPR Biosensor with Low Detection Limit
by Jianying Jing, Kun Liu, Junfeng Jiang, Tianhua Xu, Shuang Wang, Jinying Ma, Zhao Zhang, Wenlin Zhang and Tiegen Liu
Nanomaterials 2021, 11(8), 2137; https://doi.org/10.3390/nano11082137 - 22 Aug 2021
Cited by 6 | Viewed by 2339
Abstract
A long-range surface plasmonic resonance (LR-SPR) biosensor modified with double-antibody sandwich immunoassay and plasmonic coupling is demonstrated for human-immunoglobulin G detection with a low limit of detection (LOD). The double-antibody sandwich immunoassay dramatically changes the average refractive index of the medium layer on [...] Read more.
A long-range surface plasmonic resonance (LR-SPR) biosensor modified with double-antibody sandwich immunoassay and plasmonic coupling is demonstrated for human-immunoglobulin G detection with a low limit of detection (LOD). The double-antibody sandwich immunoassay dramatically changes the average refractive index of the medium layer on the sensor surface. The near-field electron coupling between the localized surface plasmon and the long-range surface plasmon leads to a significant perturbation of the evanescent field. The large penetration depth and the long propagation distance of the long-range surface plasmonic waves facilitate the LR-SPR sensor in the detection of biological macromolecules. The unique light absorption characteristic of the nanocomposite material in the sensor provides the in situ self-compensation for the disturbance. Therefore, besides the inherent advantages of optical fiber sensors, the developed biosensor can realize the detection of biomolecules with high sensitivity, low LOD and high accuracy and reliability. Experimental results demonstrate that the LOD of the biosensor is as low as 0.11 μg/mL in the detection of the phosphate-buffered saline sample, and the spike-and-repetition rate is 105.56% in the detection of the real serum sample, which partly shows the practicability of the biosensor. This indicates that the LR-SPR biosensor provides better response compared with existing similar sensors and can be regarded as a valuable method for biochemical analysis and disease detection. Full article
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26 pages, 9995 KiB  
Review
A Review on the Properties and Applications of WO3 Nanostructure−Based Optical and Electronic Devices
by Yu Yao, Dandan Sang, Liangrui Zou, Qinglin Wang and Cailong Liu
Nanomaterials 2021, 11(8), 2136; https://doi.org/10.3390/nano11082136 - 22 Aug 2021
Cited by 71 | Viewed by 6995
Abstract
Tungsten oxide (WO3) is a wide band gap semiconductor with unintentionally n−doping performance, excellent conductivity, and high electron hall mobility, which is considered as a candidate material for application in optoelectronics. Several reviews on WO3 and its derivatives for various [...] Read more.
Tungsten oxide (WO3) is a wide band gap semiconductor with unintentionally n−doping performance, excellent conductivity, and high electron hall mobility, which is considered as a candidate material for application in optoelectronics. Several reviews on WO3 and its derivatives for various applications dealing with electrochemical, photoelectrochemical, hybrid photocatalysts, electrochemical energy storage, and gas sensors have appeared recently. Moreover, the nanostructured transition metal oxides have attracted considerable attention in the past decade because of their unique chemical, photochromic, and physical properties leading to numerous other potential applications. Owing to their distinctive photoluminescence (PL), electrochromic and electrical properties, WO3 nanostructure−based optical and electronic devices application have attracted a wide range of research interests. This review mainly focuses on the up−to−date progress in different advanced strategies from fundamental analysis to improve WO3 optoelectric, electrochromic, and photochromic properties in the development of tungsten oxide−based advanced devices for optical and electronic applications including photodetectors, light−emitting diodes (LED), PL properties, electrical properties, and optical information storage. This review on the prior findings of WO3−related optical and electrical devices, as well as concluding remarks and forecasts will help researchers to advance the field of optoelectric applications of nanostructured transition metal oxides. Full article
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13 pages, 11109 KiB  
Article
Effect of Cu Ion Concentration on Microstructures and Mechanical Properties of Nanotwinned Cu Foils Fabricated by Rotary Electroplating
by Yu-Wen Hung, Dinh-Phuc Tran and Chih Chen
Nanomaterials 2021, 11(8), 2135; https://doi.org/10.3390/nano11082135 - 22 Aug 2021
Cited by 22 | Viewed by 3529
Abstract
Rotary electroplating was employed to fabricate high-strength nanotwinned copper (nt-Cu) foils serving as a current collector for high energy-density lithium ion batteries (LIBs). The effect of Cu ion concentration on the microstructural and mechanical properties of the nt-Cu foils was then investigated. Formation [...] Read more.
Rotary electroplating was employed to fabricate high-strength nanotwinned copper (nt-Cu) foils serving as a current collector for high energy-density lithium ion batteries (LIBs). The effect of Cu ion concentration on the microstructural and mechanical properties of the nt-Cu foils was then investigated. Formation of nano-scaled grains was found at the bottom. Its size gradually increases toward the top surface to form a microstructural mixture of gradient nano-scaled and columnar grains in the upper region. Experimental results show that the grains and elongation of the nt-Cu foils increase with increasing concentration of Cu ions. However, a trade-off between tensile strength and elongation is present. The elongation of nt-Cu foils has been enhanced by 22% (from 3.1% to 3.8%) while 8.3% and 3.9% reductions in ultimate tensile strength (UTS) and yield stress (YS) are seen. The current study shows a promising method to tune and optimize the microstructure and mechanical properties of such nt-Cu foils for various applications. Full article
(This article belongs to the Special Issue Gradient Nanograined Materials)
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11 pages, 1647 KiB  
Article
Phototransformation of Graphene Oxide on the Removal of Sulfamethazine in a Water Environment
by Fei-Fei Liu, Meng-Ru Li, Su-Chun Wang, Yu-Xue Zhang, Guang-Zhou Liu and Jin-Lin Fan
Nanomaterials 2021, 11(8), 2134; https://doi.org/10.3390/nano11082134 - 22 Aug 2021
Cited by 4 | Viewed by 2402
Abstract
Graphene oxide (GO) is widely used in various fields and has raised concerns regarding its potential environmental fate and effect. However, there are few studies on its influence on coexisting pollutants. In this study, the phototransformation of GO and coexisting sulfamethazine (SMZ) under [...] Read more.
Graphene oxide (GO) is widely used in various fields and has raised concerns regarding its potential environmental fate and effect. However, there are few studies on its influence on coexisting pollutants. In this study, the phototransformation of GO and coexisting sulfamethazine (SMZ) under UV irradiation was investigated, with a focus on the role of reactive oxygen species. The results demonstrated that GO promoted the degradation of SMZ under UV irradiation. The higher the concentration of GO, the higher the degradation rate of SMZ, and the faster the first-order reaction rate. Two main radicals, ∙OH and 1O2, both contributed greatly in terms of regulating the removal of SMZ. Cl, SO42−, and pH mainly promoted SMZ degradation by increasing the generation of ∙OH, while humic acid inhibited SMZ degradation due to the reduction of ∙OH. Moreover, after UV illumination, the GO suspension changed from light yellow to dark brown with increasing absorbance at a wavelength of 225 nm. Raman spectra revealed that the ID/IG ratio slightly decreased, indicating that some of the functional groups on the surface of GO were removed under low-intensity UV illumination. This study revealed that GO plays important roles in the photochemical transformation of environmental pollutants, which is helpful for understanding the environmental behaviors and risks of nanoparticles in aquatic environments. Full article
(This article belongs to the Special Issue Nanoparticles in the Environment and Nanotoxicology)
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18 pages, 2733 KiB  
Article
NOx Storage on BaTi0.8Cu0.2O3 Perovskite Catalysts: Addressing a Feasible Mechanism
by Vicente Albaladejo-Fuentes, María-Salvadora Sánchez-Adsuar, James A. Anderson and María-José Illán-Gómez
Nanomaterials 2021, 11(8), 2133; https://doi.org/10.3390/nano11082133 - 21 Aug 2021
Cited by 5 | Viewed by 2036
Abstract
The NOx storage mechanism on BaTi0.8Cu0.2O3 catalyst were studied using different techniques. The results obtained by XRD, ATR, TGA and XPS under NOx storage–regeneration conditions revealed that BaO generated on the catalyst by decomposition of Ba2TiO [...] Read more.
The NOx storage mechanism on BaTi0.8Cu0.2O3 catalyst were studied using different techniques. The results obtained by XRD, ATR, TGA and XPS under NOx storage–regeneration conditions revealed that BaO generated on the catalyst by decomposition of Ba2TiO4 plays a key role in the NOx storage process. In situ DRIFTS experiments under NO/O2 and NO/N2 show that nitrites and nitrates are formed on the perovskite during the NOx storage process. Thus, it seems that, as for model NSR catalysts, the NOx storage on BaTi0.8Cu0.2O3 catalyst takes place by both “nitrite” and “nitrate” routes, with the main pathway being highly dependent on the temperature and the time on stream: (i) at T < 350 °C, NO adsorption leads to nitrites formation on the catalyst and (ii) at T > 350 °C, the catalyst activity for NO oxidation promotes NO2 generation and the nitrate formation. Full article
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13 pages, 2444 KiB  
Article
Chlorosulfonic Acid Stretched Carbon Nanotube Sheet for Flexible and Low-Voltage Heating Applications
by Daniel Rui Chen, Megha Chitranshi, Paa Kwasi Adusei, Mark Schulz, Vesselin Shanov and Marc M. Cahay
Nanomaterials 2021, 11(8), 2132; https://doi.org/10.3390/nano11082132 - 21 Aug 2021
Cited by 6 | Viewed by 2428
Abstract
The carbon nanotube (CNT) is celebrated for its electrothermal property, which indicates the capability of a material to transform electrical energy into heat due to the Joule effect. The CNT nanostructure itself, as a one-dimensional material, limits the electron conduction path, thereby creating [...] Read more.
The carbon nanotube (CNT) is celebrated for its electrothermal property, which indicates the capability of a material to transform electrical energy into heat due to the Joule effect. The CNT nanostructure itself, as a one-dimensional material, limits the electron conduction path, thereby creating a unique heating phenomenon. In this work, we explore the possible correlation between CNT alignment in sheets and heating performance. The alignment of carbon nanotubes is induced by immersion and stretching in chlorosulfonic acid (CSA) solution. The developed CSA-stretched CNT sheet demonstrated excellent heating performance with a fast response rate of 6.5 °C/s and reached 180 °C in less than 30 s under a low voltage of 2.5 V. The heating profile of the stretched CNT sheet remained stable after bending and twisting movements, making it a suitable heating material for wearable devices, heatable smart windows, and in de-icing or defogging applications. The specific strength and specific conductance of the CSA-stretched CNT sheet also increased five- and two-fold, respectively, in comparison to the pristine CNT sheet. Full article
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17 pages, 9502 KiB  
Article
Al2O3 Particle Erosion Induced Phase Transformation: Structure, Mechanical Property, and Impact Toughness of an SLM Al-10Si-Mg Alloy
by Bo-Chin Huang and Fei-Yi Hung
Nanomaterials 2021, 11(8), 2131; https://doi.org/10.3390/nano11082131 - 21 Aug 2021
Cited by 5 | Viewed by 2471
Abstract
This study investigated the microstructure, mechanical properties, impact toughness, and erosion characteristics of Al-10Si-Mg alloy specimens manufactured using the selective laser melting (SLM) method with or without subsequent T6 heat treatment. Furthermore, the erosion phase transformation behavior of the test specimens was analyzed, [...] Read more.
This study investigated the microstructure, mechanical properties, impact toughness, and erosion characteristics of Al-10Si-Mg alloy specimens manufactured using the selective laser melting (SLM) method with or without subsequent T6 heat treatment. Furthermore, the erosion phase transformation behavior of the test specimens was analyzed, and the effect of the degradation mechanism on the tensile mechanical properties and impact toughness of the SLM Al-10Si-Mg alloy specimens before and after particle erosion was compared. The experimental results indicated that the Al-10Si-Mg alloy subjected to T6 heat treatment has better erosion resistance than the as-fabricated material. The tensile strength and fracture toughness of both specimen groups decreased due to the formation of microcracks on the surface caused by particle erosion. Nevertheless, the erosion-induced silicon nanoparticle solid solution softens the Al matrix and improves the elongation of the SLM Al-10Si-Mg alloy. Full article
(This article belongs to the Special Issue 2D Semiconducting Materials for Device Applications)
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30 pages, 2362 KiB  
Review
Green Synthesis of Nanomaterials
by Matthew Huston, Melissa DeBella, Maria DiBella and Anisha Gupta
Nanomaterials 2021, 11(8), 2130; https://doi.org/10.3390/nano11082130 - 21 Aug 2021
Cited by 103 | Viewed by 16717
Abstract
Nanotechnology is considered one of the paramount forefronts in science over the last decade. Its versatile implementations and fast-growing demand have paved the way for innovative measures for the synthesis of higher quality nanomaterials. In the early stages, traditional synthesis methods were utilized, [...] Read more.
Nanotechnology is considered one of the paramount forefronts in science over the last decade. Its versatile implementations and fast-growing demand have paved the way for innovative measures for the synthesis of higher quality nanomaterials. In the early stages, traditional synthesis methods were utilized, and they relied on both carcinogenic chemicals and high energy input for production of nano-sized material. The pollution produced as a result of traditional synthesis methods induces a need for environmentally safer synthesis methods. As the downfalls of climate change become more abundant, the scientific community is persistently seeking solutions to combat the devastation caused by toxic production methods. Green methods for nanomaterial synthesis apply natural biological systems to nanomaterial production. The present review highlights the history of nanoparticle synthesis, starting with traditional methods and progressing towards green methods. Green synthesis is a method just as effective, if not more so, than traditional synthesis; it provides a sustainable approach to nanomaterial manufacturing by using naturally sourced starting materials and relying on low energy processes. The recent use of active molecules in natural biological systems such as bacteria, yeast, algae and fungi report successful results in the synthesis of various nanoparticle systems. Thus, the integration of green synthesis in scientific research and mass production provides a potential solution to the limitations of traditional synthesis methods. Full article
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20 pages, 3215 KiB  
Review
Metal-Based Nanomaterials: Work as Drugs and Carriers against Viral Infections
by Junlei Yang, Lihuan Yue, Zhu Yang, Yuqing Miao, Ruizhuo Ouyang and Yihong Hu
Nanomaterials 2021, 11(8), 2129; https://doi.org/10.3390/nano11082129 - 20 Aug 2021
Cited by 10 | Viewed by 2746
Abstract
Virus infection is one of the threats to the health of organisms, and finding suitable antiviral agents is one of the main tasks of current researchers. Metal ions participate in multiple key reaction stages of organisms and maintain the important homeostasis of organisms. [...] Read more.
Virus infection is one of the threats to the health of organisms, and finding suitable antiviral agents is one of the main tasks of current researchers. Metal ions participate in multiple key reaction stages of organisms and maintain the important homeostasis of organisms. The application of synthetic metal-based nanomaterials as an antiviral therapy is a promising new research direction. Based on the application of synthetic metal-based nanomaterials in antiviral therapy, we summarize the research progress of metal-based nanomaterials in recent years. This review analyzes the three inhibition pathways of metal nanomaterials as antiviral therapeutic materials against viral infections, including direct inactivation, inhibition of virus adsorption and entry, and intracellular virus suppression; it further classifies and summarizes them according to their inhibition mechanisms. In addition, the use of metal nanomaterials as antiviral drug carriers and vaccine adjuvants is summarized. The analysis clarifies the antiviral mechanism of metal nanomaterials and broadens the application in the field of antiviral therapy. Full article
(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)
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20 pages, 4375 KiB  
Article
Nanosilicates in Compatibilized Mixed Recycled Polyolefins: Rheological Behavior and Film Production in a Circular Approach
by Emilia Garofalo, Luciano Di Maio, Paola Scarfato, Annalisa Apicella, Antonio Protopapa and Loredana Incarnato
Nanomaterials 2021, 11(8), 2128; https://doi.org/10.3390/nano11082128 - 20 Aug 2021
Cited by 2 | Viewed by 1876
Abstract
Currently, plastic packaging represents a global challenge and has become a key point of attention for governments, media and consumers due to the visibility of the waste it generates. Despite their high resource efficiency, the perceived non-recyclability of polymeric films risks precluding them [...] Read more.
Currently, plastic packaging represents a global challenge and has become a key point of attention for governments, media and consumers due to the visibility of the waste it generates. Despite their high resource efficiency, the perceived non-recyclability of polymeric films risks precluding them from being a relevant packaging solution in a circular economy approach. In this regard, the aim of this study was to implement a strategy to try closing the loop, via the mechanical recycling of post-consumer flexible packaging of small size (denoted as Fil-s) to obtain new films. In particular, two lots of Fil-s were used, which are PE/PP blends differing for the PP content and the presence of polar contaminants. The suitability for film blowing extrusion of these recycled materials, as such and after the addition of a compatibilizer and/or a lamellar nanosilicate, was evaluated. It was first evidenced that the difficulty of producing blown films with the pristine recycled materials, due to the frequent bubble breakages, occurring even at low draw ratios. Moreover, the shear and extensional rheological behavior of all Fil-s based systems was usefully correlated with their processability features, evidencing the key roles of the nanofiller to stabilize the bubble and of the compatibilizer to ensure a uniform film deformation, avoiding its premature breakage. Even if the adopted upgrading strategies allowed the production of blown films with both types of Fil-s, the different components of the recycled matrices were proven to significantly affect their processability and final film performances. Full article
(This article belongs to the Special Issue The Potential of Nanocomposites in the Packaging Field)
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17 pages, 4735 KiB  
Article
Strong Polyamide-6 Nanocomposites with Cellulose Nanofibers Mediated by Green Solvent Mixtures
by Pruthvi K. Sridhara, Ferran Masso, Peter Olsén and Fabiola Vilaseca
Nanomaterials 2021, 11(8), 2127; https://doi.org/10.3390/nano11082127 - 20 Aug 2021
Cited by 12 | Viewed by 2791
Abstract
Cellulose nanofiber (CNF) as a bio-based reinforcement has attracted tremendous interests in engineering polymer composites. This study developed a sustainable approach to reinforce polyamide-6 or nylon-6 (PA6) with CNFs through solvent casting in formic acid/water mixtures. The methodology provides an energy-efficient pathway towards [...] Read more.
Cellulose nanofiber (CNF) as a bio-based reinforcement has attracted tremendous interests in engineering polymer composites. This study developed a sustainable approach to reinforce polyamide-6 or nylon-6 (PA6) with CNFs through solvent casting in formic acid/water mixtures. The methodology provides an energy-efficient pathway towards well-dispersed high-CNF content PA6 biocomposites. Nanocomposite formulations up to 50 wt.% of CNFs were prepared, and excellent improvements in the tensile properties were observed, with an increase in the elastic modulus from 1.5 to 4.2 GPa, and in the tensile strength from 46.3 to 124 MPa. The experimental tensile values were compared with the analytical values obtained by micromechanical models. Fractured surfaces were observed using scanning electron microscopy to examine the interface morphology. FTIR revealed strong hydrogen bonding at the interface, and the thermal parameters were determined using TGA and DSC, where the nanocomposites’ crystallinity tended to reduce with the increase in the CNF content. In addition, nanocomposites showed good thermomechanical stability for all formulations. Overall, this work provides a facile fabrication pathway for high-CNF content nanocomposites of PA6 for high-performance and advanced material applications. Full article
(This article belongs to the Special Issue Synthesis, Properties and Applications of Polymeric Nanomaterials)
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19 pages, 7897 KiB  
Article
Characterization and Tribological Performances of Graphene and Fluorinated Graphene Particles in PAO
by Yanjie Chen, Enzhu Hu, Hua Zhong, Jianping Wang, Ayush Subedi, Kunhong Hu and Xianguo Hu
Nanomaterials 2021, 11(8), 2126; https://doi.org/10.3390/nano11082126 - 20 Aug 2021
Cited by 13 | Viewed by 2616
Abstract
Graphene has been widely used as a lubricating additive to reduce the energy consumption of engines and improve fuel economy because of its unique crystal structure. Herein, graphene (GR) and fluorinated graphene (F-GR) nanoparticles were prepared by ball milling and liquid-phase exfoliation. The [...] Read more.
Graphene has been widely used as a lubricating additive to reduce the energy consumption of engines and improve fuel economy because of its unique crystal structure. Herein, graphene (GR) and fluorinated graphene (F-GR) nanoparticles were prepared by ball milling and liquid-phase exfoliation. The SEM/EDS, HRTEM, XPS, Raman spectrometer, X-ray spectrometer, FTIR were used to investigate the morphologies, surface groups, and crystal structure of two kinds of graphene materials. The influence of loads on the tribological properties of two kinds of particles was investigated in Poly Alpha Olefin (PAO6) using a UMT-2 reciprocating tribometer. Results showed that the crystal structure of GR is better than F-GR. F-GR can improve the lubrication performance of PAO6. For PAO6 containing 1 wt% F-GR at 10 N, the average friction coefficient and average wear rate decreased by 12.3% and 87% relative to pure PAO6, respectively. However, the high load resulted in an inconspicuous anti-wear and anti-friction effect. The influence of F-GR on the tribological behavior of PAO6 was more substantial than that of GR. The friction and wear mechanisms attributed to F-GR quickly entered the interface between the friction pairs. Friction-induced F-GR nanosheets mainly took the tribo-chemical reactions to participate in the lubrication film formation and helped achieve a low friction coefficient and wear rate. Full article
(This article belongs to the Section 2D and Carbon Nanomaterials)
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14 pages, 3503 KiB  
Article
Controlled Photoanode Properties for Large-Area Efficient and Stable Dye-Sensitized Photovoltaic Modules
by Wei-Hao Chiu, Kun-Mu Lee, Vembu Suryanarayanan, Jen-Fu Hsu and Ming-Chung Wu
Nanomaterials 2021, 11(8), 2125; https://doi.org/10.3390/nano11082125 - 20 Aug 2021
Cited by 5 | Viewed by 2307
Abstract
Nowadays, a dye-sensitized solar cell (DSSC) attracts attention to its development widely due to its several advantages, such as simple processes, low costs, and flexibility. In this work, we demonstrate the difference in device structures between small size and large size cells (5 [...] Read more.
Nowadays, a dye-sensitized solar cell (DSSC) attracts attention to its development widely due to its several advantages, such as simple processes, low costs, and flexibility. In this work, we demonstrate the difference in device structures between small size and large size cells (5 cm × 5 cm, 10 cm × 10 cm and 10 cm × 15 cm). The design of the photoanode and dye-sensitized process plays important roles in affecting the cell efficiency and stability. The effects of the TiO2 electrode, using TiCl4(aq) pretreatment and post-treatment processes, are also discussed, whereas, the open-circuit voltage (Voc), short-circuit current density (Jsc), and module efficiency are successfully improved. Furthermore, the effects on module performances by some factors, such as dye solution concentration, dye soaking temperature, and electrolyte injection method are also investigated. We have demonstrated that the output power of a 5 cm × 5 cm DSSC module increases from 86.2 mW to 93.7 mW, and the module efficiency achieves an outstanding performance of 9.79%. Furthermore, enlarging the DSSC modules to two sizes (10 cm × 10 cm and 10 cm × 15 cm) and comparing the performance with different module designs (C-DSSC and S-DSSC) also provides the specific application of polymer sealing and preparing high-efficiency large-area DSSC modules. Full article
(This article belongs to the Section Solar Energy and Solar Cells)
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19 pages, 7556 KiB  
Article
Homogeneous versus Inhomogeneous Polarization Switching in PZT Thin Films: Impact of the Structural Quality and Correlation to the Negative Capacitance Effect
by Lucian Pintilie, Georgia Andra Boni, Cristina Florentina Chirila, Viorica Stancu, Lucian Trupina, Cosmin Marian Istrate, Cristian Radu and Ioana Pintilie
Nanomaterials 2021, 11(8), 2124; https://doi.org/10.3390/nano11082124 - 20 Aug 2021
Cited by 3 | Viewed by 2459
Abstract
Polarization switching in ferroelectric films is exploited in many applications, such as non-volatile memories and negative capacitance field affect transistors. This can be inhomogeneous or homogeneous, depending on if ferroelectric domains are forming or not during the switching process. The relation between the [...] Read more.
Polarization switching in ferroelectric films is exploited in many applications, such as non-volatile memories and negative capacitance field affect transistors. This can be inhomogeneous or homogeneous, depending on if ferroelectric domains are forming or not during the switching process. The relation between the polarization switching, the structural quality of the films and the negative capacitance was not studied in depth. Here, Pb(Zr0.2Ti0.8)O3 (PZT) layers were deposited by pulse laser deposition (PLD) and sol-gel (SG) on single crystal SrTiO3 (STO) and Si substrates, respectively. The structural quality was analyzed by X-ray diffraction and transmission electron microscopy, while the electric properties were investigated by performing hysteresis, dynamic dielectric measurements, and piezo-electric force microscopy analysis. It was found that the PZT layers grown by PLD on SRO/STO substrates are epitaxial while the layers deposited by SG on Pt/Si are polycrystalline. The polarization value decreases as the structure changes from epitaxial to polycrystalline, as well as the magnitude of the leakage current and of the differential negative capacitance, while the switching changes from homogeneous to inhomogeneous. The results are explained by the compensation rate of the depolarization field during the switching process, which is much faster in epitaxial films than in polycrystalline ones. Full article
(This article belongs to the Special Issue Ferroic Nanomaterials: From Synthesis to Applications)
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