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Nanomaterials, Volume 11, Issue 4 (April 2021) – 233 articles

Cover Story (view full-size image): Silver nanoparticles have become useful tools with potential applications in a wide variety of fields; however, NPs also appear on the scene as potential emerging pollutants whose effects on human health and the environment are not yet fully known. This paper shows that asymmetrical flow field-flow fractionation (AF4) provides relevant and new information for characterizing their aggregation processes in the different environmental water matrices studied. Several populations of aggregates were obtained by AF4 with different sizes between them, depending on both the mixture time for a given matrix and the type of water matrix for the same time. View this paper
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13 pages, 4462 KiB  
Article
Efficient and Rapid Photocatalytic Degradation of Methyl Orange Dye Using Al/ZnO Nanoparticles
by Piangjai Peerakiatkhajohn, Teera Butburee, Jung-Hoon Sul, Supphasin Thaweesak and Jung-Ho Yun
Nanomaterials 2021, 11(4), 1059; https://doi.org/10.3390/nano11041059 - 20 Apr 2021
Cited by 46 | Viewed by 4279
Abstract
ZnO and Aluminum doped ZnO nanoparticles (Al/ZnO NPs) were successfully synthesized by the sol-gel method. Together with the effect of calcination temperatures (200, 300 and 400 °C) and Al dosage (1%, 3%, 5% and 10%) on structural, morphological and optical properties of Al/ZnO [...] Read more.
ZnO and Aluminum doped ZnO nanoparticles (Al/ZnO NPs) were successfully synthesized by the sol-gel method. Together with the effect of calcination temperatures (200, 300 and 400 °C) and Al dosage (1%, 3%, 5% and 10%) on structural, morphological and optical properties of Al/ZnO NPs, their photocatalytic degradation of methyl orange (MO) dye was investigated. The calcination temperatures at 200, 300 and 400 °C in forming structure of ZnO NPs led to spherical nanoparticle, nanorod and nanoflake structures with a well-crystalline hexagonal wurtzite, respectively. The ZnO NPs calcined at 200 °C exhibited the highest specific surface area and light absorption property, leading to the MO removal efficiency of 80% after 4 h under the Ultraviolet (UV) light irradiation. The MO removal efficiency was approximately two times higher than the nanoparticles calcined at 400 °C. Furthermore, the 5% Al/ZnO NPs exhibited superior MO removal efficiency of 99% in only 40 min which was approximately 20 times enhancement in photocatalytic activity compared to pristine ZnO under the visible light irradiation. This high degradation performance was attributed to the extended light absorption, narrowed band gap and effective suppression of electron–hole recombination through an addition of Al metal. Full article
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17 pages, 3310 KiB  
Review
Revealing the Exciton Fine Structure in Lead Halide Perovskite Nanocrystals
by Lei Hou, Philippe Tamarat and Brahim Lounis
Nanomaterials 2021, 11(4), 1058; https://doi.org/10.3390/nano11041058 - 20 Apr 2021
Cited by 22 | Viewed by 6026
Abstract
Lead-halide perovskite nanocrystals (NCs) are attractive nano-building blocks for photovoltaics and optoelectronic devices as well as quantum light sources. Such developments require a better knowledge of the fundamental electronic and optical properties of the band-edge exciton, whose fine structure has long been debated. [...] Read more.
Lead-halide perovskite nanocrystals (NCs) are attractive nano-building blocks for photovoltaics and optoelectronic devices as well as quantum light sources. Such developments require a better knowledge of the fundamental electronic and optical properties of the band-edge exciton, whose fine structure has long been debated. In this review, we give an overview of recent magneto-optical spectroscopic studies revealing the entire excitonic fine structure and relaxation mechanisms in these materials, using a single-NC approach to get rid of their inhomogeneities in morphology and crystal structure. We highlight the prominent role of the electron-hole exchange interaction in the order and splitting of the bright triplet and dark singlet exciton sublevels and discuss the effects of size, shape anisotropy and dielectric screening on the fine structure. The spectral and temporal manifestations of thermal mixing between bright and dark excitons allows extracting the specific nature and strength of the exciton–phonon coupling, which provides an explanation for their remarkably bright photoluminescence at low temperature although the ground exciton state is optically inactive. We also decipher the spectroscopic characteristics of other charge complexes whose recombination contributes to photoluminescence. With the rich knowledge gained from these experiments, we provide some perspectives on perovskite NCs as quantum light sources. Full article
(This article belongs to the Special Issue Nanocrystals: Synthesis, Properties and Applications)
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16 pages, 2903 KiB  
Article
Magnetic Nanoparticle-Based Dianthin Targeting for Controlled Drug Release Using the Endosomal Escape Enhancer SO1861
by Ajmal Zarinwall, Mazdak Asadian-Birjand, Didem Ag Seleci, Viktor Maurer, Alexandra Trautner, Georg Garnweitner and Hendrik Fuchs
Nanomaterials 2021, 11(4), 1057; https://doi.org/10.3390/nano11041057 - 20 Apr 2021
Cited by 8 | Viewed by 3034
Abstract
Targeted tumor therapy can provide the basis for the inhibition of tumor growth. However, a number of toxin-based therapeutics lack efficacy because of insufficient endosomal escape after being internalized by endocytosis. To address this problem, the potential of glycosylated triterpenoids, such as SO1861, [...] Read more.
Targeted tumor therapy can provide the basis for the inhibition of tumor growth. However, a number of toxin-based therapeutics lack efficacy because of insufficient endosomal escape after being internalized by endocytosis. To address this problem, the potential of glycosylated triterpenoids, such as SO1861, as endosomal escape enhancers (EEE) for superparamagnetic iron oxide nanoparticle (SPION)-based toxin therapy was investigated. Herein, two different SPION-based particle systems were synthesized, each selectively functionalized with either the targeted toxin, dianthin-epidermal growth factor (DiaEGF), or the EEE, SO1861. After applying both particle systems in vitro, an almost 2000-fold enhancement in tumor cell cytotoxicity compared to the monotherapy with SPION-DiaEGF and a 6.7-fold gain in specificity was observed. Thus, the required dose of the formulation was appreciably reduced, and the therapeutic window widened. Full article
(This article belongs to the Special Issue Structure and Properties of Functional Nanomaterials)
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20 pages, 5586 KiB  
Article
Enhanced Electrochemical Behavior of Peanut-Shell Activated Carbon/Molybdenum Oxide/Molybdenum Carbide Ternary Composites
by Ndeye F. Sylla, Samba Sarr, Ndeye M. Ndiaye, Bridget K. Mutuma, Astou Seck, Balla D. Ngom, Mohamed Chaker and Ncholu Manyala
Nanomaterials 2021, 11(4), 1056; https://doi.org/10.3390/nano11041056 - 20 Apr 2021
Cited by 12 | Viewed by 3500
Abstract
Biomass-waste activated carbon/molybdenum oxide/molybdenum carbide ternary composites are prepared using a facile in-situ pyrolysis process in argon ambient with varying mass ratios of ammonium molybdate tetrahydrate to porous peanut shell activated carbon (PAC). The formation of MoO2 and Mo2C nanostructures [...] Read more.
Biomass-waste activated carbon/molybdenum oxide/molybdenum carbide ternary composites are prepared using a facile in-situ pyrolysis process in argon ambient with varying mass ratios of ammonium molybdate tetrahydrate to porous peanut shell activated carbon (PAC). The formation of MoO2 and Mo2C nanostructures embedded in the porous carbon framework is confirmed by extensive structural characterization and elemental mapping analysis. The best composite when used as electrodes in a symmetric supercapacitor (PAC/MoO2/Mo2C-1//PAC/MoO2/Mo2C-1) exhibited a good cell capacitance of 115 F g−1 with an associated high specific energy of 51.8 W h kg−1, as well as a specific power of 0.9 kW kg−1 at a cell voltage of 1.8 V at 1 A g−1. Increasing the specific current to 20 A g−1 still showcased a device capable of delivering up to 30 W h kg−1 specific energy and 18 kW kg−1 of specific power. Additionally, with a great cycling stability, a 99.8% coulombic efficiency and capacitance retention of ~83% were recorded for over 25,000 galvanostatic charge-discharge cycles at 10 A g−1. The voltage holding test after a 160 h floating time resulted in increase of the specific capacitance from 74.7 to 90 F g−1 at 10 A g−1 for this storage device. The remarkable electrochemical performance is based on the synergistic effect of metal oxide/metal carbide (MoO2/Mo2C) with the interconnected porous carbon. The PAC/MoO2/Mo2C ternary composites highlight promising Mo-based electrode materials suitable for high-performance energy storage. Explicitly, this work also demonstrates a simple and sustainable approach to enhance the electrochemical performance of porous carbon materials. Full article
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20 pages, 3772 KiB  
Article
Functional Antimicrobial Surface Coatings Deposited onto Nanostructured 316L Food-Grade Stainless Steel
by A. Silvia González, Angela Riego, Victor Vega, Javier García, Serena Galié, Ignacio Gutiérrez del Río, Maria del Valle Martínez de Yuso, Claudio Jesús Villar, Felipe Lombó and Victor Manuel De la Prida
Nanomaterials 2021, 11(4), 1055; https://doi.org/10.3390/nano11041055 - 20 Apr 2021
Cited by 10 | Viewed by 2836
Abstract
In our study, we demonstrated the performance of antimicrobial coatings on properly functionalized and nanostructured 316L food-grade stainless steel pipelines. For the fabrication of these functional coatings, we employed facile and low-cost electrochemical techniques and surface modification processes. The development of a nanoporous [...] Read more.
In our study, we demonstrated the performance of antimicrobial coatings on properly functionalized and nanostructured 316L food-grade stainless steel pipelines. For the fabrication of these functional coatings, we employed facile and low-cost electrochemical techniques and surface modification processes. The development of a nanoporous structure on the 316L stainless steel surface was performed by following an electropolishing process in an electrolytic bath, at a constant anodic voltage of 40 V for 10 min, while the temperature was maintained between 0 and 10 °C. Subsequently, we incorporated on this nanostructure additional coatings with antimicrobial and bactericide properties, such as Ag nanoparticles, Ag films, or TiO2 thin layers. These functional coatings were grown on the nanostructured substrate by following electroless process, electrochemical deposition, and atomic layer deposition (ALD) techniques. Then, we analyzed the antimicrobial efficiency of these functionalized materials against different biofilms types (Candida parapsilosis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis). The results of the present study demonstrate that the nanostructuring and surface functionalization processes constitute a promising route to fabricate novel functional materials exhibiting highly efficient antimicrobial features. In fact, we have shown that our use of an appropriated association of TiO2 layer and Ag nanoparticle coatings over the nanostructured 316L stainless steel exhibited an excellent antimicrobial behavior for all biofilms examined. Full article
(This article belongs to the Special Issue ALD Technique for Functional Coatings of Nanostructured Materials)
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10 pages, 3433 KiB  
Article
Vanadium Pentoxide Nanofibers/Carbon Nanotubes Hybrid Film for High-Performance Aqueous Zinc-Ion Batteries
by Xianyu Liu, Liwen Ma, Yehong Du, Qiongqiong Lu, Aikai Yang and Xinyu Wang
Nanomaterials 2021, 11(4), 1054; https://doi.org/10.3390/nano11041054 - 20 Apr 2021
Cited by 30 | Viewed by 3827
Abstract
Aqueous zinc-ion batteries (ZIBs) with the characteristics of low production costs and good safety have been regarded as ideal candidates for large-scale energy storage applications. However, the nonconductive and non-redox active polymer used as the binder in the traditional preparation of electrodes hinders [...] Read more.
Aqueous zinc-ion batteries (ZIBs) with the characteristics of low production costs and good safety have been regarded as ideal candidates for large-scale energy storage applications. However, the nonconductive and non-redox active polymer used as the binder in the traditional preparation of electrodes hinders the exposure of active sites and limits the diffusion of ions, compromising the energy density of the electrode in ZIBs. Herein, we fabricated vanadium pentoxide nanofibers/carbon nanotubes (V2O5/CNTs) hybrid films as binder-free cathodes for ZIBs. High ionic conductivity and electronic conductivity were enabled in the V2O5/CNTs film due to the porous structure of the film and the introduction of carbon nanotubes with high electronic conductivity. As a result, the batteries based on the V2O5/CNTs film exhibited a higher capacity of 390 mAh g−1 at 1 A g−1, as compared to batteries based on V2O5 (263 mAh g−1). Even at 5 A g−1, the battery based on the V2O5/CNTs film maintained a capacity of 250 mAh g−1 after 2000 cycles with a capacity retention of 94%. In addition, the V2O5/CNTs film electrode also showed a high energy/power density (e.g., 67 kW kg−1/267 Wh kg−1). The capacitance response and rapid diffusion coefficient of Zn2+ (~10−8 cm−2 s−1) can explain the excellent rate capability of V2O5/CNTs. The vanadium pentoxide nanofibers/carbon nanotubes hybrid film as binder-free cathodes showed a high capability and a stable cyclability, demonstrating that it is highly promising for large-scale energy storage applications. Full article
(This article belongs to the Special Issue 2D Nanostructures for Optoelectronic and Green Energy Devices)
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16 pages, 4433 KiB  
Article
Influence of Alumina Addition on the Optical Properties and the Thermal Stability of Titania Thin Films and Inverse Opals Produced by Atomic Layer Deposition
by Martin Waleczek, Jolien Dendooven, Pavel Dyachenko, Alexander Y. Petrov, Manfred Eich, Robert H. Blick, Christophe Detavernier, Kornelius Nielsch, Kaline P. Furlan and Robert Zierold
Nanomaterials 2021, 11(4), 1053; https://doi.org/10.3390/nano11041053 - 20 Apr 2021
Cited by 10 | Viewed by 3045
Abstract
TiO2 thin films deposited by atomic layer deposition (ALD) at low temperatures (<100 °C) are, in general, amorphous and exhibit a smaller refractive index in comparison to their crystalline counterparts. Nonetheless, low-temperature ALD is needed when the substrates or templates are based [...] Read more.
TiO2 thin films deposited by atomic layer deposition (ALD) at low temperatures (<100 °C) are, in general, amorphous and exhibit a smaller refractive index in comparison to their crystalline counterparts. Nonetheless, low-temperature ALD is needed when the substrates or templates are based on polymeric materials, as the deposition has to be performed below their glass transition or melting temperatures. This is the case for photonic crystals generated via ALD infiltration of self-assembled polystyrene templates. When heated up, crystal phase transformations take place in the thin films or photonic structures, and the accompanying volume reduction as well as the burn-out of residual impurities can lead to mechanical instability. The introduction of cation doping (e.g., Al or Nb) in bulk TiO2 parts is known to alter phase transitions and to stabilize crystalline phases. In this work, we have developed low-temperature ALD super-cycles to introduce Al2O3 into TiO2 thin films and photonic crystals. The aluminum oxide content was adjusted by varying the TiO2:Al2O3 internal loop ratio within the ALD super-cycle. Both thin films and inverse opal photonic crystal structures were subjected to thermal treatments ranging from 200 to 1200 °C and were characterized by in- and ex-situ X-ray diffraction, spectroscopic ellipsometry, and spectroscopic reflectance measurements. The results show that the introduction of alumina affects the crystallization and phase transition temperatures of titania as well as the optical properties of the inverse opal photonic crystals (iPhC). The thermal stability of the titania iPhCs was increased by the alumina introduction, maintaining their photonic bandgap even after heat treatment at 900 °C and outperforming the pure titania, with the best results being achieved with the super-cycles corresponding to an estimated alumina content of 26 wt.%. Full article
(This article belongs to the Special Issue ALD Technique for Functional Coatings of Nanostructured Materials)
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17 pages, 2601 KiB  
Article
Engineering Iron Oxide Nanocatalysts by a Microwave-Assisted Polyol Method for the Magnetically Induced Degradation of Organic Pollutants
by Alvaro Gallo-Cordova, Sabino Veintemillas-Verdaguer, Pedro Tartaj, Eva Mazarío, María del Puerto Morales and Jesús G. Ovejero
Nanomaterials 2021, 11(4), 1052; https://doi.org/10.3390/nano11041052 - 20 Apr 2021
Cited by 24 | Viewed by 3155
Abstract
Advanced oxidation processes constitute a promising alternative for the treatment of wastewater containing organic pollutants. Still, the lack of cost-effective processes has hampered the widespread use of these methodologies. Iron oxide magnetic nanoparticles stand as a great alternative since they can be engineered [...] Read more.
Advanced oxidation processes constitute a promising alternative for the treatment of wastewater containing organic pollutants. Still, the lack of cost-effective processes has hampered the widespread use of these methodologies. Iron oxide magnetic nanoparticles stand as a great alternative since they can be engineered by different reproducible and scalable methods. The present study consists of the synthesis of single-core and multicore magnetic iron oxide nanoparticles by the microwave-assisted polyol method and their use as self-heating catalysts for the degradation of an anionic (acid orange 8) and a cationic dye (methylene blue). Decolorization of these dyes was successfully improved by subjecting the catalyst to an alternating magnetic field (AMF, 16 kA/m, 200 kHz). The sudden temperature increase at the surface of the catalyst led to an intensification of 10% in the decolorization yields using 1 g/L of catalyst, 0.3 M H2O2 and 500 ppm of dye. Full decolorization was achieved at 90 °C, but iron leaching (40 ppm) was detected at this temperature leading to a homogeneous Fenton process. Multicore nanoparticles showed higher degradation rates and 100% efficiencies in four reusability cycles under the AMF. The improvement of this process with AMF is a step forward into more sustainable remediation techniques. Full article
(This article belongs to the Special Issue Microwave Technology and Nanomaterials: Synthesis and Application)
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10 pages, 2261 KiB  
Article
Nanoimprint Replication of Biomimetic, Multilevel Undercut Nanostructures
by Michael Muehlberger, Stephan Ruttloff, Dieter Nees, Amiya Moharana, Maria R. Belegratis, Philipp Taus, Sonja Kopp, Heinz D. Wanzenboeck, Adrian Prinz and Daniel Fechtig
Nanomaterials 2021, 11(4), 1051; https://doi.org/10.3390/nano11041051 - 20 Apr 2021
Cited by 10 | Viewed by 2768
Abstract
The nanoimprint replication of biomimetic nanostructures can be interesting for a wide range of applications. We demonstrate the process chain for Morpho-blue-inspired nanostructures, which are especially challenging for the nanoimprint process, since they consist of multilayer undercut structures, which typically cannot be replicated [...] Read more.
The nanoimprint replication of biomimetic nanostructures can be interesting for a wide range of applications. We demonstrate the process chain for Morpho-blue-inspired nanostructures, which are especially challenging for the nanoimprint process, since they consist of multilayer undercut structures, which typically cannot be replicated using nanoimprint lithography. To achieve this, we used a specially made, proprietary imprint material to firstly allow successful stamp fabrication from an undercut master structure, and secondly to enable UV-based nanoimprinting using the same material. Nanoimprinting was performed on polymer substrates with stamps on polymer backplanes to be compatible with roller-based imprinting processes. We started with single layer undercut structures to finally show that it is possible to successfully replicate a multilayer undercut stamp from a multilayer undercut master and use this stamp to obtain multilayer undercut nanoimprinted samples. Full article
(This article belongs to the Special Issue Nanoimprint Lithography Technology and Applications)
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11 pages, 34508 KiB  
Article
Mechanochemical Preparation of Magnetically Separable Fe and Cu-Based Bimetallic Nanocatalysts for Vanillin Production
by Paulette Gómez-López, Claudia Espro, Daily Rodríguez-Padrón, Alina M. Balu, Francisco Ivars-Barceló, Olvido Irrazábal Moreda, Clemente G. Alvarado-Beltrán and Rafael Luque
Nanomaterials 2021, 11(4), 1050; https://doi.org/10.3390/nano11041050 - 20 Apr 2021
Cited by 3 | Viewed by 2490
Abstract
A highly sustainable method for the preparation of supported iron oxide and copper nanoparticles (NPs) on a biomass-derived carbon by solvent-free mechanochemical process is reported. In-situ mechanochemically obtained extracts from orange peel could behave as a green reducing agent, allowing the formation of [...] Read more.
A highly sustainable method for the preparation of supported iron oxide and copper nanoparticles (NPs) on a biomass-derived carbon by solvent-free mechanochemical process is reported. In-situ mechanochemically obtained extracts from orange peel could behave as a green reducing agent, allowing the formation of Cu metal nanoparticles as well as generating a magnetic phase (magnetite) in the systems via partial Fe3+ reduction. At the same time, orange peel residues also served as template and carbon source, adding oxygen functionalities, which were found to benefit the catalytic performance of mechanochemically synthesized nanomaterials. The series of magnetic Cu-Fe@OP were tested in the oxidation of trans-ferulic acid towards vanillin, remarkably revealing a maximum vanillin yield of 82% for the sample treated at 200 °C. Full article
(This article belongs to the Special Issue Mechanochemistry and Nanotechnology)
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13 pages, 1741 KiB  
Article
Time Optimization of Seed-Mediated Gold Nanotriangle Synthesis Based on Kinetic Studies
by Ekaterina Podlesnaia, Andrea Csáki and Wolfgang Fritzsche
Nanomaterials 2021, 11(4), 1049; https://doi.org/10.3390/nano11041049 - 20 Apr 2021
Cited by 8 | Viewed by 2856
Abstract
The synthesis of shape-anisotropic plasmonic nanoparticles such as gold nanotriangles is of increasing interest. These particles have a high potential for applications due to their notable optical properties. A key challenge of the synthesis is usually the low reproducibility. Even the optimized seed-based [...] Read more.
The synthesis of shape-anisotropic plasmonic nanoparticles such as gold nanotriangles is of increasing interest. These particles have a high potential for applications due to their notable optical properties. A key challenge of the synthesis is usually the low reproducibility. Even the optimized seed-based methods often lack in the synthesis yield or are labor- and time-consuming. In this work, a seed-mediated synthesis with high reproducibility is replicated in order to determine the necessary reaction time for each step. Online monitoring of the reaction mixtures by UV–VIS spectroscopy is used as a powerful tool to track the evolution of the synthesis. The kinetics of the individual stages is elucidated by real-time investigations. As a consequence, the complete synthesis could be optimized and can now be realized in a single day instead of three without any loss in the resulting sample quality. Full article
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38 pages, 3046 KiB  
Review
Polymeric Nanoparticle Delivery of Combination Therapy with Synergistic Effects in Ovarian Cancer
by Shani L. Levit and Christina Tang
Nanomaterials 2021, 11(4), 1048; https://doi.org/10.3390/nano11041048 - 20 Apr 2021
Cited by 20 | Viewed by 3970
Abstract
Treatment of ovarian cancer is challenging due to late stage diagnosis, acquired drug resistance mechanisms, and systemic toxicity of chemotherapeutic agents. Combination chemotherapy has the potential to enhance treatment efficacy by activation of multiple downstream pathways to overcome drug resistance and reducing required [...] Read more.
Treatment of ovarian cancer is challenging due to late stage diagnosis, acquired drug resistance mechanisms, and systemic toxicity of chemotherapeutic agents. Combination chemotherapy has the potential to enhance treatment efficacy by activation of multiple downstream pathways to overcome drug resistance and reducing required dosages. Sequence of delivery and the dosing schedule can further enhance treatment efficacy. Formulation of drug combinations into nanoparticles can further enhance treatment efficacy. Due to their versatility, polymer-based nanoparticles are an especially promising tool for clinical translation of combination therapies with tunable dosing schedules. We review polymer nanoparticle (e.g., micelles, dendrimers, and lipid nanoparticles) carriers of drug combinations formulated to treat ovarian cancer. In particular, the focus on this review is combinations of platinum and taxane agents (commonly used first line treatments for ovarian cancer) combined with other small molecule therapeutic agents. In vitro and in vivo drug potency are discussed with a focus on quantifiable synergistic effects. The effect of drug sequence and dosing schedule is examined. Computational approaches as a tool to predict synergistic drug combinations and dosing schedules as a tool for future nanoparticle design are also briefly discussed. Full article
(This article belongs to the Section Biology and Medicines)
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7 pages, 1201 KiB  
Article
Size-Dependent Alloying Ability of Immiscible W-Cu Bimetallic Nanoparticles: A Theoretical and Experimental Study
by Hongbo Zhang, Tao Liu, Siqi Zhao, Zhanyuan Xu, Yaozha Lv, Jinglian Fan and Yong Han
Nanomaterials 2021, 11(4), 1047; https://doi.org/10.3390/nano11041047 - 20 Apr 2021
Cited by 6 | Viewed by 1862
Abstract
The preparation of alloyed bimetallic nanoparticles (BNPs) between immiscible elements is always a huge challenge due to the lack of thermodynamic driving forces. W–Cu is a typical immiscible binary system, and it is difficult to alloy them under conventional circumstances. Here, we used [...] Read more.
The preparation of alloyed bimetallic nanoparticles (BNPs) between immiscible elements is always a huge challenge due to the lack of thermodynamic driving forces. W–Cu is a typical immiscible binary system, and it is difficult to alloy them under conventional circumstances. Here, we used the bond energy model (BEM) to calculate the effect of size on the alloying ability of W–Cu systems. The prediction results show that reducing the synthesis size (the original size of W and Cu) to less than 10 nm can obtain alloyed W–Cu BNPs. Moreover, we prepared alloyed W50Cu50 BNPs with a face-centered-cubic (FCC) crystalline structure via the nano in situ composite method. Energy-dispersive X-ray spectroscopy (EDS) coupled with scan transmission electron microscopy (STEM) confirmed that W and Cu are well mixed in a single-phase particle, instead of a phase segregation into a core-shell or other heterostructures. The present results suggest that the nanoscale size effect can overcome the immiscibility in immiscible binary systems. In the meantime, this work provided a high-yield and universal method for preparing alloyed BNPs between immiscible elements. Full article
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33 pages, 3160 KiB  
Review
Superhydrophobic Nanocoatings as Intervention against Biofilm-Associated Bacterial Infections
by Yinghan Chan, Xun Hui Wu, Buong Woei Chieng, Nor Azowa Ibrahim and Yoon Yee Then
Nanomaterials 2021, 11(4), 1046; https://doi.org/10.3390/nano11041046 - 19 Apr 2021
Cited by 33 | Viewed by 4765
Abstract
Biofilm formation represents a significant cause of concern as it has been associated with increased morbidity and mortality, thereby imposing a huge burden on public healthcare system throughout the world. As biofilms are usually resistant to various conventional antimicrobial interventions, they may result [...] Read more.
Biofilm formation represents a significant cause of concern as it has been associated with increased morbidity and mortality, thereby imposing a huge burden on public healthcare system throughout the world. As biofilms are usually resistant to various conventional antimicrobial interventions, they may result in severe and persistent infections, which necessitates the development of novel therapeutic strategies to combat biofilm-based infections. Physicochemical modification of the biomaterials utilized in medical devices to mitigate initial microbial attachment has been proposed as a promising strategy in combating polymicrobial infections, as the adhesion of microorganisms is typically the first step for the formation of biofilms. For instance, superhydrophobic surfaces have been shown to possess substantial anti-biofilm properties attributed to the presence of nanostructures. In this article, we provide an insight into the mechanisms underlying biofilm formation and their composition, as well as the applications of nanomaterials as superhydrophobic nanocoatings for the development of novel anti-biofilm therapies. Full article
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18 pages, 3125 KiB  
Article
Phytofabrication of Silver Nanoparticles (AgNPs) with Pharmaceutical Capabilities Using Otostegia persica (Burm.) Boiss. Leaf Extract
by Majid Sharifi-Rad, Pawel Pohl and Francesco Epifano
Nanomaterials 2021, 11(4), 1045; https://doi.org/10.3390/nano11041045 - 19 Apr 2021
Cited by 50 | Viewed by 3095
Abstract
In the last years, the plant-mediated synthesis of nanoparticles has been extensively researched as an affordable and eco-friendly method. The current study confirms for the first time the capability of the Otostegia persica (Burm.) Boiss. leaf extract for the synthesis of silver nanoparticles [...] Read more.
In the last years, the plant-mediated synthesis of nanoparticles has been extensively researched as an affordable and eco-friendly method. The current study confirms for the first time the capability of the Otostegia persica (Burm.) Boiss. leaf extract for the synthesis of silver nanoparticles (AgNPs). The phytofabricated AgNPs were characterized by ultraviolet–visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and zeta potential analysis. Moreover, the total phenolic and flavonoids contents, and the antioxidant, antibacterial, antifungal, and anti-inflammatory properties of the phytofabricated AgNPs and the O. persica leaf extract were assessed. The results showed that the produced AgNPs were crystalline in nature and spherical in shape with an average size of 36.5 ± 2.0 nm, and indicated a localized surface plasmon resonance (LSPR) peak at around 420 nm. The zeta potential value of −25.2 mV pointed that the AgNPs were stable. The phytofabricated AgNPs had lower total phenolic and flavonoids contents than those for the O. persica leaf extract. The abovementioned AgNPs showed a higher antioxidant activity as compared with the O. persica leaf extract. They also exhibited significant antibacterial activity against both Gram-positive (Staphylococcus aureus, Bacillus subtilis, and Streptococcus pyogenes) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhi) bacteria. In addition, appropriate antifungal effects with the minimum inhibitory concentration (MIC) values of 18.75, 37.5, and 75 µg mL−1 against Candida krusei, Candida glabrata, and Candida albicans, respectively, were noted for this new bionanomaterial. Finally, the phytofabricated AgNPs showed dose-dependent anti-inflammatory activity in the human red blood cell (RBC) membrane stabilization test, being higher than that for the O. persica leaf extract. The resulting phytofabricated AgNPs could be used as a promising antioxidant, antibacterial, antifungal, and anti-inflammatory agent in the treatments of many medical complications. Full article
(This article belongs to the Section Synthesis, Interfaces and Nanostructures)
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3 pages, 159 KiB  
Editorial
Special Issue “Wet Chemical Synthesis of Functional Nanomaterials”
by Enrico Della Gaspera
Nanomaterials 2021, 11(4), 1044; https://doi.org/10.3390/nano11041044 - 19 Apr 2021
Cited by 1 | Viewed by 2016
Abstract
“Wet chemical synthesis, also called solution processing, represents an accessible, versatile, and powerful approach for synthesizing materials with excellent control of their structural, chemical, and physical properties” [...] Full article
(This article belongs to the Special Issue Wet Chemical Synthesis of Functional Nanomaterials)
8 pages, 2908 KiB  
Article
Formation of Fractal Dendrites by Laser-Induced Melting of Aluminum Alloys
by Alexey Kucherik, Vlad Samyshkin, Evgeny Prusov, Anton Osipov, Alexey Panfilov, Dmitry Buharov, Sergey Arakelian, Igor Skryabin, Alexey Vitalievich Kavokin and Stella Kutrovskaya
Nanomaterials 2021, 11(4), 1043; https://doi.org/10.3390/nano11041043 - 19 Apr 2021
Cited by 7 | Viewed by 2061
Abstract
We report on the fabrication of fractal dendrites using laser-induced melting of aluminum alloys. We target boron carbide (B4C), which is one of the most effective radiation-absorbing materials characterized by a low coefficient of thermal expansion. Due to the high fragility [...] Read more.
We report on the fabrication of fractal dendrites using laser-induced melting of aluminum alloys. We target boron carbide (B4C), which is one of the most effective radiation-absorbing materials characterized by a low coefficient of thermal expansion. Due to the high fragility of B4C crystals, we were able to introduce its nanoparticles into a stabilization aluminum matrix of AA385.0. The high-intensity laser field action led to the formation of composite dendrite structures under the effect of local surface melting. Modelling the dendrite cluster growth confirms its fractal nature and sheds light on the pattern behavior of the resulting quasicrystal structure. Full article
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9 pages, 2077 KiB  
Article
Kinematic Viscosity ofMulticomponent FeCuNbSiB-BasedMelts
by Yuri N. Starodubtsev, Vladimir S. Tsepelev and Nadezhda P. Tsepeleva
Nanomaterials 2021, 11(4), 1042; https://doi.org/10.3390/nano11041042 - 19 Apr 2021
Cited by 4 | Viewed by 1956
Abstract
The work investigated the temperature dependences of the kinematic viscosity for multicomponent melts of nanocrystalline soft magnetic alloys. It is shown that there is a linear relationship between the reduced activation energy of viscous flow Ea·(RT)−1 and the [...] Read more.
The work investigated the temperature dependences of the kinematic viscosity for multicomponent melts of nanocrystalline soft magnetic alloys. It is shown that there is a linear relationship between the reduced activation energy of viscous flow Ea·(RT)−1 and the pre-exponential factor ν0. This ratio is universal for all quantities, the temperature dependence of which is expressed by the Arrhenius equation. It is shown that the activation energy of a viscous flow is linearly related to the cluster size on a natural logarithmic scale, and the melt viscosity increases with decreasing cluster size. The change in the Arrhenius plot in the anomalous zone on the temperature dependence of viscosity can be interpreted as a liquid–liquid structure transition, which begins with the disintegration of clusters and ends with the formation of a new cluster structure. Full article
(This article belongs to the Section Theory and Simulation of Nanostructures)
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20 pages, 2794 KiB  
Article
Magnetic Properties of Iron Oxide Nanoparticles Do Not Essentially Contribute to Ferrogel Biocompatibility
by Felix A. Blyakhman, Alexander P. Safronov, Emilia B. Makarova, Fedor A. Fadeyev, Tatyana F. Shklyar, Pavel A. Shabadrov, Sergio Fernandez Armas and Galina V. Kurlyandskaya
Nanomaterials 2021, 11(4), 1041; https://doi.org/10.3390/nano11041041 - 19 Apr 2021
Cited by 11 | Viewed by 2338
Abstract
Two series of composite polyacrylamide (PAAm) gels with embedded superparamagnetic Fe2O3 or diamagnetic Al2O3 nanoparticles were synthesized, aiming to study the direct contribution of the magnetic interactions to the ferrogel biocompatibility. The proliferative activity was estimated for [...] Read more.
Two series of composite polyacrylamide (PAAm) gels with embedded superparamagnetic Fe2O3 or diamagnetic Al2O3 nanoparticles were synthesized, aiming to study the direct contribution of the magnetic interactions to the ferrogel biocompatibility. The proliferative activity was estimated for the case of human dermal fibroblast culture grown onto the surfaces of these types of substrates. Spherical non-agglomerated nanoparticles (NPs) of 20–40 nm in diameter were prepared by laser target evaporation (LTE) electrophysical technique. The concentration of the NPs in gel was fixed at 0.0, 0.3, 0.6, or 1.2 wt.%. Mechanical, electrical, and magnetic properties of composite gels were characterized by the dependence of Young’s modulus, electrical potential, magnetization measurements on the content of embedded NPs. The fibroblast monolayer density grown onto the surface of composite substrates was considered as an indicator of the material biocompatibility after 96 h of incubation. Regardless of the superparamagnetic or diamagnetic nature of nanoparticles, the increase in their concentration in the PAAm composite provided a parallel increase in the cell culture proliferation when grown onto the surface of composite substrates. The effects of cell interaction with the nanostructured surface of composites are discussed in order to explain the results. Full article
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10 pages, 2413 KiB  
Article
Ultrahigh-Pressure Preparation and Catalytic Activity of MOF-Derived Cu Nanoparticles
by Ichiro Yamane, Kota Sato, Ryoichi Otomo, Takashi Yanase, Akira Miura, Taro Nagahama, Yuichi Kamiya and Toshihiro Shimada
Nanomaterials 2021, 11(4), 1040; https://doi.org/10.3390/nano11041040 - 19 Apr 2021
Cited by 10 | Viewed by 2746
Abstract
A metal–organic framework (MOF) consisting of Cu-benzenetricarboxylic acid was processed under ultrahigh pressure (5 GPa) and at temperature of up to 500 °C. The products were characterized with TEM, FTIR, and XAFS. The decomposition of the MOF started at 200 °C at 5 [...] Read more.
A metal–organic framework (MOF) consisting of Cu-benzenetricarboxylic acid was processed under ultrahigh pressure (5 GPa) and at temperature of up to 500 °C. The products were characterized with TEM, FTIR, and XAFS. The decomposition of the MOF started at 200 °C at 5 GPa. This temperature was much lower than that in the vacuum. Single-nanometer Cu nanoparticles were obtained in carbon matrix, which was significantly smaller than the Cu particles prepared at ambient pressure. The catalytic activity for Huisgen cycloaddition was examined, and the sample processed at 5 GPa showed a much improved performance compared with that of the MOF-derived Cu nanoparticles prepared without high pressure. Full article
(This article belongs to the Special Issue Carbon-Doped Nanocomposites for Catalytical Application)
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23 pages, 2468 KiB  
Review
Ionic Liquids-Based Nanocolloids—A Review of Progress and Prospects in Convective Heat Transfer Applications
by Alina Adriana Minea and S. M. Sohel Murshed
Nanomaterials 2021, 11(4), 1039; https://doi.org/10.3390/nano11041039 - 19 Apr 2021
Cited by 29 | Viewed by 2554
Abstract
Ionic liquids are a new and challenging class of fluids with great and tunable properties, having the capability of an extensive area of real-life applications, from chemistry, biology, medicine to heat transfer. These fluids are often considered as green solvents. Several properties of [...] Read more.
Ionic liquids are a new and challenging class of fluids with great and tunable properties, having the capability of an extensive area of real-life applications, from chemistry, biology, medicine to heat transfer. These fluids are often considered as green solvents. Several properties of these fluids can be enhanced by adding nanoparticles following the idea of nanofluids. These ionic liquids-based nanocolloids are also termed in the literature as ionanofluids or nanoparticles-enhanced ionic liquids. This review summarizes the findings in both areas of ionic liquids and ionic liquids nanocolloids (i.e., ionic liquids with nanoparticles in suspension) with direct applicability in convective heat transfer applications. The review presents in a unified manner the progress and prospects of ionic liquids and their nanocolloids from preparation, thermophysical properties and equally experimental and numerical works. As the heat transfer enhancement requires innovative fluids, this new class of ionic liquids-based nanocolloids is certainly a viable option, despite the noticed drawbacks. Nevertheless, experimental studies are very limited, and thus, extensive experiments are needed to elucidate ionic liquids interaction with nanoparticles, as well as their behavior in convective heat transfer. Full article
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32 pages, 14945 KiB  
Review
High-Performance Photodetectors Based on Nanostructured Perovskites
by Chunlong Li, Jie Li, Zhengping Li, Huayong Zhang, Yangyang Dang and Fangong Kong
Nanomaterials 2021, 11(4), 1038; https://doi.org/10.3390/nano11041038 - 19 Apr 2021
Cited by 29 | Viewed by 6605
Abstract
In recent years, high-performance photodetectors have attracted wide attention because of their important applications including imaging, spectroscopy, fiber-optic communications, remote control, chemical/biological sensing and so on. Nanostructured perovskites are extremely suitable for detective applications with their long carrier lifetime, high carrier mobility, facile [...] Read more.
In recent years, high-performance photodetectors have attracted wide attention because of their important applications including imaging, spectroscopy, fiber-optic communications, remote control, chemical/biological sensing and so on. Nanostructured perovskites are extremely suitable for detective applications with their long carrier lifetime, high carrier mobility, facile synthesis, and beneficial to device miniaturization. Because the structure of the device and the dimension of nanostructured perovskite have a profound impact on the performance of photodetector, we divide nanostructured perovskite into 2D, 1D, and 0D, and review their applications in photodetector (including photoconductor, phototransistor, and photodiode), respectively. The devices exhibit high performance with high photoresponsivity, large external quantum efficiency (EQE), large gain, high detectivity, and fast response time. The intriguing properties suggest that nanostructured perovskites have a great potential in photodetection. Full article
(This article belongs to the Special Issue Nano Fabrications of Solid-State Sensors and Sensor Systems)
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23 pages, 3428 KiB  
Review
Modulated Luminescence of Lanthanide Materials by Local Surface Plasmon Resonance Effect
by Jinhua Liu, Qingru Wang, Xu Sang, Huimin Hu, Shuhong Li, Dong Zhang, Cailong Liu, Qinglin Wang, Bingyuan Zhang, Wenjun Wang and Feng Song
Nanomaterials 2021, 11(4), 1037; https://doi.org/10.3390/nano11041037 - 19 Apr 2021
Cited by 19 | Viewed by 3934
Abstract
Lanthanide materials have great applications in optical communication, biological fluorescence imaging, laser, and so on, due to their narrow emission bandwidths, large Stokes’ shifts, long emission lifetimes, and excellent photo-stability. However, the photon absorption cross-section of lanthanide ions is generally small, and the [...] Read more.
Lanthanide materials have great applications in optical communication, biological fluorescence imaging, laser, and so on, due to their narrow emission bandwidths, large Stokes’ shifts, long emission lifetimes, and excellent photo-stability. However, the photon absorption cross-section of lanthanide ions is generally small, and the luminescence efficiency is relatively low. The effective improvement of the lanthanide-doped materials has been a challenge in the implementation of many applications. The local surface plasmon resonance (LSPR) effect of plasmonic nanoparticles (NPs) can improve the luminescence in different aspects: excitation enhancement induced by enhanced local field, emission enhancement induced by increased radiative decay, and quenching induced by increased non-radiative decay. In addition, plasmonic NPs can also regulate the energy transfer between two close lanthanide ions. In this review, the properties of the nanocomposite systems of lanthanide material and plasmonic NPs are presented, respectively. The mechanism of lanthanide materials regulated by plasmonic NPs and the scientific and technological discoveries of the luminescence technology are elaborated. Due to the large gap between the reported enhancement and the theoretical enhancement, some new strategies applied in lanthanide materials and related development in the plasmonic enhancing luminescence are presented. Full article
(This article belongs to the Special Issue Hybrid Plasmonic Nanostructures and Their Applications)
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17 pages, 2531 KiB  
Article
Synthesis, Characterization and Visible-Light Photocatalytic Activity of Solid and TiO2-Supported Uranium Oxycompounds
by Mikhail Lyulyukin, Tikhon Filippov, Svetlana Cherepanova, Maria Solovyeva, Igor Prosvirin, Andrey Bukhtiyarov, Denis Kozlov and Dmitry Selishchev
Nanomaterials 2021, 11(4), 1036; https://doi.org/10.3390/nano11041036 - 19 Apr 2021
Cited by 8 | Viewed by 2278
Abstract
In this study, various solid uranium oxycompounds and TiO2-supported materials based on nanocrystalline anatase TiO2 are synthesized using uranyl nitrate hexahydrate as a precursor. All uranium-contained samples are characterized using N2 adsorption, XRD, UV–vis, Raman, TEM, XPS and tested [...] Read more.
In this study, various solid uranium oxycompounds and TiO2-supported materials based on nanocrystalline anatase TiO2 are synthesized using uranyl nitrate hexahydrate as a precursor. All uranium-contained samples are characterized using N2 adsorption, XRD, UV–vis, Raman, TEM, XPS and tested in the oxidation of a volatile organic compound under visible light of the blue region to find correlations between their physicochemical characteristics and photocatalytic activity. Both uranium oxycompounds and TiO2-supported materials are photocatalytically active and are able to completely oxidize gaseous organic compounds under visible light. If compared to the commercial visible-light TiO2 KRONOS® vlp 7000 photocatalyst used as a benchmark, solid uranium oxycompounds exhibit lower or comparable photocatalytic activity under blue light. At the same time, uranium compounds contained uranyl ion with a uranium charge state of 6+, exhibiting much higher activity than other compounds with a lower charge state of uranium. Immobilization of uranyl ions on the surface of nanocrystalline anatase TiO2 allows for substantial increase in visible-light activity. The photonic efficiency of reaction over uranyl-grafted TiO2, 12.2%, is 17 times higher than the efficiency for commercial vlp 7000 photocatalyst. Uranyl-grafted TiO2 has the potential as a visible-light photocatalyst for special areas of application where there is no strict control for use of uranium compounds (e.g., in spaceships or submarines). Full article
(This article belongs to the Special Issue Latest Developments in Photocatalytic Materials and Processes)
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14 pages, 4857 KiB  
Communication
Drying-Time Study in Graphene Oxide
by Talia Tene, Marco Guevara, Andrea Valarezo, Orlando Salguero, Fabian Arias Arias, Melvin Arias, Andrea Scarcello, Lorenzo S. Caputi and Cristian Vacacela Gomez
Nanomaterials 2021, 11(4), 1035; https://doi.org/10.3390/nano11041035 - 19 Apr 2021
Cited by 22 | Viewed by 2996
Abstract
Graphene oxide (GO) exhibits different properties from those found in free-standing graphene, which mainly depend on the type of defects induced by the preparation method and post-processing. Although defects in graphene oxide are widely studied, we report the effect of drying time in [...] Read more.
Graphene oxide (GO) exhibits different properties from those found in free-standing graphene, which mainly depend on the type of defects induced by the preparation method and post-processing. Although defects in graphene oxide are widely studied, we report the effect of drying time in GO and how this modifies the presence or absence of edge-, basal-, and sp3-type defects. The effect of drying time is evaluated by Raman spectroscopy, UV-visible spectroscopy, and transmission electron microscopy (TEM). The traditional D, G, and 2D peaks are observed together with other less intense peaks called the D’, D*, D**, D+G, and G+D. Remarkably, the D* peak is activated/deactivated as a direct consequence of drying time. Furthermore, the broad region of the 2D peak is discussed as a function of its deconvoluted 2D1A, 2D2A, and D+G bands. The main peak in UV-visible absorption spectra undergoes a redshift as drying time increases. Finally, TEM measurements demonstrate the stacking of exfoliated GO sheets as the intercalated (water) molecules are removed. Full article
(This article belongs to the Special Issue Properties and Applications of Graphene and Its Derivatives)
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8 pages, 1699 KiB  
Article
Design of Multifunctional Janus Metasurface Based on Subwavelength Grating
by Ruonan Ji, Chuan Jin, Kun Song, Shao-Wei Wang and Xiaopeng Zhao
Nanomaterials 2021, 11(4), 1034; https://doi.org/10.3390/nano11041034 - 19 Apr 2021
Cited by 16 | Viewed by 2826
Abstract
In this paper, a Janus metasurface is designed by breaking the structural symmetry based on the polarization selection property of subwavelength grating. The structure comprises three layers: a top layer having a metallic nanostructure, a dielectric spacer, and a bottom layer having subwavelength [...] Read more.
In this paper, a Janus metasurface is designed by breaking the structural symmetry based on the polarization selection property of subwavelength grating. The structure comprises three layers: a top layer having a metallic nanostructure, a dielectric spacer, and a bottom layer having subwavelength grating. For a forward incidence, the metal-insulator-metal (MIM) structure operates as a gap plasmonic cavity if the linearly polarized (LP) component is parallel to the grating wires. It also acts as a high-efficiency dual-layer grating polarizer for the orthogonal LP component. For the backward incidence, the high reflectance of the grating blocks the function of the gap plasmonic cavity, leading to its pure functioning as a polarizer. A bifunctional Janus metasurface for 45 degrees beam deflector and polarizer, with a transmission of 0.87 and extinction ratio of 3840, is designed at 1.55 μm and is investigated to prove the validity of the proposed strategy. Moreover, the proposed metasurface can be cascaded to achieve more flexible functions since these functions are independent in terms of operational mechanism and structural parameters. A trifunctional Janus metasurface that acts as a focusing lens, as a reflector, and as a polarizer is designed based on this strategy. The proposed metasurface and the design strategy provide convenience and flexibility in the design of multifunctional, miniaturized, and integrated optical components for polarization-related analysis and for detection systems. Full article
(This article belongs to the Special Issue State-of-the-Art Nanophotonics Materials and Devices in China)
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10 pages, 2814 KiB  
Article
Nano-Crystallization of Ln-Fluoride Crystals in Glass-Ceramics via Inducing of Yb3+ for Efficient Near-Infrared Upconversion Luminescence of Tm3+
by Jianfeng Li, Yi Long, Qichao Zhao, Shupei Zheng, Zaijin Fang and Bai-Ou Guan
Nanomaterials 2021, 11(4), 1033; https://doi.org/10.3390/nano11041033 - 18 Apr 2021
Cited by 3 | Viewed by 1894
Abstract
Transparent glass-ceramic composites embedded with Ln-fluoride nanocrystals are prepared in this work to enhance the upconversion luminescence of Tm3+. The crystalline phases, microstructures, and photoluminescence properties of samples are carefully investigated. KYb3F10 nanocrystals are proved to controllably precipitate [...] Read more.
Transparent glass-ceramic composites embedded with Ln-fluoride nanocrystals are prepared in this work to enhance the upconversion luminescence of Tm3+. The crystalline phases, microstructures, and photoluminescence properties of samples are carefully investigated. KYb3F10 nanocrystals are proved to controllably precipitate in the glass-ceramics via the inducing of Yb3+ when the doping concentration varies from 0.5 to 1.5 mol%. Pure near-infrared upconversion emissions are observed and the emission intensities are enhanced in the glass-ceramics as compared to in the precursor glass due to the incorporation of Tm3+ into the KYb3F10 crystal structures via substitutions for Yb3+. Furthermore, KYb2F7 crystals are also nano-crystallized in the glass-ceramics when the Yb3+ concentration exceeds 2.0 mol%. The upconversion emission intensity of Tm3+ is further enhanced by seven times as Tm3+ enters the lattice sites of pure KYb2F7 nanocrystals. The designed glass ceramics provide efficient gain materials for optical applications in the biological transmission window. Moreover, the controllable nano-crystallization strategy induced by Yb3+ opens a new way for engineering a wide range of functional nanomaterials with effective incorporation of Ln3+ ions into fluoride crystal structures. Full article
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12 pages, 3071 KiB  
Article
Simultaneous Removal of Arsenic and Manganese from Synthetic Aqueous Solutions Using Polymer Gel Composites
by Syed Ragib Safi and Takehiko Gotoh
Nanomaterials 2021, 11(4), 1032; https://doi.org/10.3390/nano11041032 - 18 Apr 2021
Cited by 6 | Viewed by 2541
Abstract
The groundwater in approximately 50% of the Bangladesh landmass contains Mn concentrations greater than the limit prescribed by the WHO drinking water guidelines. Although studies have suggested that γ-FeOOH can effectively remove Mn from water, its practicability has not been investigated, considering that [...] Read more.
The groundwater in approximately 50% of the Bangladesh landmass contains Mn concentrations greater than the limit prescribed by the WHO drinking water guidelines. Although studies have suggested that γ-FeOOH can effectively remove Mn from water, its practicability has not been investigated, considering that the additional processes required to separate the adsorbents and precipitates are not environment-friendly. To improve the efficiency of adsorptive Mn-removal under natural conditions, we employed a cationic polymer gel composite, N,N’-Dimethylaminopropyl acrylamide, methyl chloride quaternary (DMAPAAQ) loaded with iron hydroxide (DMAPAAQ + FeOOH), and a non-ionic polymer gel composite, N,N’-Dimethylacrylamide (DMAA) loaded with iron hydroxide (DMAA + FeOOH). DMAPAAQ + FeOOH exhibited a higher As removal efficiency under natural conditions while being environment-friendly. Our results suggest that the higher efficiency of the cationic gel composite is owed to the higher γ-FeOOH content in its gel structure. The maximum adsorption of Mn by DMAPAAQ + FeOOH was 39.02 mg/g. Furthermore, the presence of As did not influence the adsorption of Mn on the DMAPAAQ + FeOOH gel composite and vice versa. DMAPAAQ adsorbed As and the γ-FeOOH particles simultaneously adsorbed Mn. Our findings can serve as a basis for the simultaneous removal of contaminants such as As, Mn, Cr, and Cd. Full article
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18 pages, 3114 KiB  
Article
Multifunctional Magnetic Nanocolloids for Hybrid Solar-Thermoelectric Energy Harvesting
by Elisa Sani, Maria Raffaella Martina, Thomas J. Salez, Sawako Nakamae, Emmanuelle Dubois and Véronique Peyre
Nanomaterials 2021, 11(4), 1031; https://doi.org/10.3390/nano11041031 - 18 Apr 2021
Cited by 13 | Viewed by 3551
Abstract
Present environmental issues force the research to explore radically new concepts in sustainable and renewable energy production. In the present work, a functional fluid consisting of a stable colloidal suspension of maghemite magnetic nanoparticles in water was characterized from the points of view [...] Read more.
Present environmental issues force the research to explore radically new concepts in sustainable and renewable energy production. In the present work, a functional fluid consisting of a stable colloidal suspension of maghemite magnetic nanoparticles in water was characterized from the points of view of thermoelectrical and optical properties, to evaluate its potential for direct electricity generation from thermoelectric effect enabled by the absorption of sunlight. These nanoparticles were found to be an excellent solar radiation absorber and simultaneously a thermoelectric power-output enhancer with only a very small volume fraction when the fluid was heated from the top. These findings demonstrate the investigated nanofluid’s high promise as a heat transfer fluid for co-generating heat and power in brand new hybrid flat-plate solar thermal collectors where top-heating geometry is imposed. Full article
(This article belongs to the Special Issue Future and Prospects in Nanofluids Research)
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14 pages, 17416 KiB  
Article
Self-Assembly Magnetic Micro- and Nanospheres and the Effect of Applied Magnetic Fields
by Angelos Mourkas, Angeliki Zarlaha, Nikolaos Kourkoumelis and Ioannis Panagiotopoulos
Nanomaterials 2021, 11(4), 1030; https://doi.org/10.3390/nano11041030 - 17 Apr 2021
Cited by 7 | Viewed by 2139
Abstract
The impact of in-plane and perpendicular magnetic fields on the spatial arrangement of superparamagnetic nanospheres is explored. We utilize nanosphere self-organization methods like Spin Coating and Drop-Casting in the presence of magnetic fields. In this way, the additional parameter of the long range [...] Read more.
The impact of in-plane and perpendicular magnetic fields on the spatial arrangement of superparamagnetic nanospheres is explored. We utilize nanosphere self-organization methods like Spin Coating and Drop-Casting in the presence of magnetic fields. In this way, the additional parameter of the long range magnetic dipolar interactions is introduced to the competing nanosphere–surface and nanosphere–nanosphere interactions, which control order and agglomeration. We present a comparative analysis of the self-assembly characteristics with respect to the different methods and the effect of the applied field in different directions. Under zero field perfect hexagonal arrays can be obtained by spin coating. Parallel applied fields tend to create directional patterns, while perpendicular favor 3D-accumulation. Full article
(This article belongs to the Special Issue Synthesis, Development and Characterization of Magnetic Nanomaterials)
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