Nanomaterials

12 pages, 2174 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Effect of Catalyst Crystallinity on V-Based Selective Catalytic Reduction with Ammonia

by Min Seong Lee, Sun-I Kim, Myeung-jin Lee, Bora Ye, Taehyo Kim, Hong-Dae Kim, Jung Woo Lee and Duck Hyun Lee

Nanomaterials 2021, 11(6), 1452; https://doi.org/10.3390/nano11061452 - 30 May 2021

Cited by 15 | Viewed by 4052

Abstract

In this study, we synthesized V₂O₅-WO₃/TiO₂ catalysts with different crystallinities via one-sided and isotropic heating methods. We then investigated the effects of the catalysts’ crystallinity on their acidity, surface species, and catalytic performance through various analysis [...] Read more.

In this study, we synthesized V₂O₅-WO₃/TiO₂ catalysts with different crystallinities via one-sided and isotropic heating methods. We then investigated the effects of the catalysts’ crystallinity on their acidity, surface species, and catalytic performance through various analysis techniques and a fixed-bed reactor experiment. The isotropic heating method produced crystalline V₂O₅ and WO₃, increasing the availability of both Brønsted and Lewis acid sites, while the one-sided method produced amorphous V₂O₅ and WO₃. The crystalline structure of the two species significantly enhanced NO₂ formation, causing more rapid selective catalytic reduction (SCR) reactions and greater catalyst reducibility for NO_X decomposition. This improved NO_X removal efficiency and N₂ selectivity for a wider temperature range of 200 °C–450 °C. Additionally, the synthesized, crystalline catalysts exhibited good resistance to SO₂, which is common in industrial flue gases. Through the results reported herein, this study may contribute to future studies on SCR catalysts and other catalyst systems. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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24 pages, 3673 KB

Open AccessEditor’s ChoiceArticle

Carbon-Supported Trimetallic Catalysts (PdAuNi/C) for Borohydride Oxidation Reaction

by Ahmed M. A. ElSheikh, Gordana Backović, Raisa C. P. Oliveira, César A. C. Sequeira, James McGregor, Biljana Šljukić and Diogo M. F. Santos

Nanomaterials 2021, 11(6), 1441; https://doi.org/10.3390/nano11061441 - 29 May 2021

Cited by 12 | Viewed by 3966

Abstract

The synthesis of palladium-based trimetallic catalysts via a facile and scalable synthesis procedure was shown to yield highly promising materials for borohydride-based fuel cells, which are attractive for use in compact environments. This, thereby, provides a route to more environmentally friendly energy storage [...] Read more.

The synthesis of palladium-based trimetallic catalysts via a facile and scalable synthesis procedure was shown to yield highly promising materials for borohydride-based fuel cells, which are attractive for use in compact environments. This, thereby, provides a route to more environmentally friendly energy storage and generation systems. Carbon-supported trimetallic catalysts were herein prepared by three different routes: using a NaBH₄-ethylene glycol complex (PdAuNi/C_SBEG), a NaBH₄-2-propanol complex (PdAuNi/C_SBIPA), and a three-step route (PdAuNi/C_3-step). Notably, PdAuNi/C_SBIPA yielded highly dispersed trimetallic alloy particles, as determined by XRD, EDX, ICP-OES, XPS, and TEM. The activity of the catalysts for borohydride oxidation reaction was assessed by cyclic voltammetry and RDE-based procedures, with results referenced to a Pd/C catalyst. A number of exchanged electrons close to eight was obtained for PdAuNi/C_3-step and PdAuNi/C_SBIPA (7.4 and 7.1, respectively), while the others, PdAuNi/C_SBEG and Pd/C_SBIPA, presented lower values, 2.8 and 1.2, respectively. A direct borohydride-peroxide fuel cell employing PdAuNi/C_SBIPA catalyst in the anode attained a power density of 47.5 mW cm⁻² at room temperature, while the elevation of temperature to 75 °C led to an approximately four-fold increase in power density to 175 mW cm⁻². Trimetallic catalysts prepared via this synthesis route have significant potential for future development. Full article

(This article belongs to the Special Issue Nanoalloy Electrocatalysts for Electrochemical Devices)

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8 pages, 1746 KB

Open AccessEditor’s ChoiceArticle

Funneling Spontaneous Emission into Waveguides via Epsilon-Near-Zero Metamaterials

by M. Channab, C. F. Pirri and A. Angelini

Nanomaterials 2021, 11(6), 1410; https://doi.org/10.3390/nano11061410 - 27 May 2021

Cited by 2 | Viewed by 3374

Abstract

In this work, we discuss the use of epsilon-near-zero (ENZ) metamaterials to efficiently couple light radiated by a dipolar source to an in-plane waveguide. We exploit both enhanced and directional emission provided by ENZ metamaterials to optimize the injection of light into the [...] Read more.

In this work, we discuss the use of epsilon-near-zero (ENZ) metamaterials to efficiently couple light radiated by a dipolar source to an in-plane waveguide. We exploit both enhanced and directional emission provided by ENZ metamaterials to optimize the injection of light into the waveguide by tuning the metal fill factor. We show that a net increase in intensity injected into the waveguide with respect to the total power radiated by the isolated dipole can be achieved in experimentally feasible conditions. We think the proposed system may open up new opportunities for several optical applications and integrated technologies, especially for those limited by outcoupling efficiency and emission rate. Full article

(This article belongs to the Special Issue Nanophotonic and Optical Nanomaterials)

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18 pages, 5209 KB

Open AccessEditor’s ChoiceArticle

Fabrication, Microstructure and Colloidal Stability of Humic Acids Loaded Fe₃O₄/APTES Nanosorbents for Environmental Applications

by Lyubov Bondarenko, Erzsébet Illés, Etelka Tombácz, Gulzhian Dzhardimalieva, Nina Golubeva, Olga Tushavina, Yasuhisa Adachi and Kamila Kydralieva

Nanomaterials 2021, 11(6), 1418; https://doi.org/10.3390/nano11061418 - 27 May 2021

Cited by 31 | Viewed by 5857

Abstract

Nowadays, numerous researches are being performed to formulate nontoxic multifunctional magnetic materials possessing both high colloidal stability and magnetization, but there is a demand in the prediction of chemical and colloidal stability in water solutions. Herein, a series of silica-coated magnetite nanoparticles (MNPs) [...] Read more.

Nowadays, numerous researches are being performed to formulate nontoxic multifunctional magnetic materials possessing both high colloidal stability and magnetization, but there is a demand in the prediction of chemical and colloidal stability in water solutions. Herein, a series of silica-coated magnetite nanoparticles (MNPs) has been synthesized via the sol-gel method with and without establishing an inert atmosphere, and then it was tested in terms of humic acids (HA) loading applied as a multifunctional coating agent. The influence of ambient conditions on the microstructure, colloidal stability and HA loading of different silica-coated MNPs has been established. The XRD patterns show that the content of stoichiometric Fe₃O₄ decreases from 78.8% to 42.4% at inert and ambient atmosphere synthesis, respectively. The most striking observation was the shift of the MNPs isoelectric point from pH ~7 to 3, with an increasing HA reaching up to the reversal of the zeta potential sign as it was covered completely by HA molecules. The zeta potential data of MNPs can be used to predict the loading capacity for HA polyanions. The data help to understand the way for materials’ development with the complexation ability of humic acids and with the insolubility of silica gel to pave the way to develop a novel, efficient and magnetically separable adsorbent for contaminant removal. Full article

(This article belongs to the Special Issue Iron Oxide Nanomaterials)

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15 pages, 5552 KB

Open AccessEditor’s ChoiceArticle

Investigation on Ge_0.8Si_0.2-Selective Atomic Layer Wet-Etching of Ge for Vertical Gate-All-Around Nanodevice

by Lu Xie, Huilong Zhu, Yongkui Zhang, Xuezheng Ai, Junjie Li, Guilei Wang, Anyan Du, Zhenzhen Kong, Qi Wang, Shunshun Lu, Chen Li, Yangyang Li, Weixing Huang and Henry H. Radamson

Nanomaterials 2021, 11(6), 1408; https://doi.org/10.3390/nano11061408 - 26 May 2021

Cited by 9 | Viewed by 5572

Abstract

For the formation of nano-scale Ge channels in vertical Gate-all-around field-effect transistors (vGAAFETs), the selective isotropic etching of Ge selective to Ge_0.8Si_0.2 was considered. In this work, a dual-selective atomic layer etching (ALE), including Ge_0.8Si_0.2-selective etching [...] Read more.

For the formation of nano-scale Ge channels in vertical Gate-all-around field-effect transistors (vGAAFETs), the selective isotropic etching of Ge selective to Ge_0.8Si_0.2 was considered. In this work, a dual-selective atomic layer etching (ALE), including Ge_0.8Si_0.2-selective etching of Ge and crystal-orientation selectivity of Ge oxidation, has been developed to control the etch rate and the size of the Ge nanowires. The ALE of Ge in p⁺-Ge_0.8Si_0.2/Ge stacks with 70% HNO₃ as oxidizer and deionized (DI) water as oxide-removal was investigated in detail. The saturated relative etched amount per cycle (REPC) and selectivity at different HNO₃ temperatures between Ge and p⁺-Ge_0.8Si_0.2 were obtained. In p⁺-Ge_0.8Si_0.2/Ge stacks with (110) sidewalls, the REPC of Ge was 3.1 nm and the saturated etching selectivity was 6.5 at HNO₃ temperature of 20 °C. The etch rate and the selectivity were affected by HNO₃ temperatures. As the HNO₃ temperature decreased to 10 °C, the REPC of Ge was decreased to 2 nm and the selectivity remained at about 7.4. Finally, the application of ALE in the formation of Ge nanowires in vGAAFETs was demonstrated where the preliminary I_d–V_ds output characteristic curves of Ge vGAAFET were provided. Full article

(This article belongs to the Special Issue Silicon Nanodevices)

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13 pages, 2477 KB

Open AccessEditor’s ChoiceArticle

Dielectric Imaging of Fixed HeLa Cells by In-Liquid Scanning Dielectric Force Volume Microscopy

by Martí Checa, Ruben Millan-Solsona, Adrianna Glinkowska Mares, Silvia Pujals and Gabriel Gomila

Nanomaterials 2021, 11(6), 1402; https://doi.org/10.3390/nano11061402 - 25 May 2021

Cited by 7 | Viewed by 5743

Abstract

Mapping the dielectric properties of cells with nanoscale spatial resolution can be an important tool in nanomedicine and nanotoxicity analysis, which can complement structural and mechanical nanoscale measurements. Recently we have shown that dielectric constant maps can be obtained on dried fixed cells [...] Read more.

Mapping the dielectric properties of cells with nanoscale spatial resolution can be an important tool in nanomedicine and nanotoxicity analysis, which can complement structural and mechanical nanoscale measurements. Recently we have shown that dielectric constant maps can be obtained on dried fixed cells in air environment by means of scanning dielectric force volume microscopy. Here, we demonstrate that such measurements can also be performed in the much more challenging case of fixed cells in liquid environment. Performing the measurements in liquid media contributes to preserve better the structure of the fixed cells, while also enabling accessing the local dielectric properties under fully hydrated conditions. The results shown in this work pave the way to address the nanoscale dielectric imaging of living cells, for which still further developments are required, as discussed here. Full article

(This article belongs to the Special Issue Microscopy for Nanomedicine Research)

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7 pages, 1773 KB

Open AccessEditor’s ChoiceArticle

Single-Pixel Photon-Counting Imaging Based on Dual-Comb Interferometry

by Huiqin Hu, Xinyi Ren, Zhaoyang Wen, Xingtong Li, Yan Liang, Ming Yan and E Wu

Nanomaterials 2021, 11(6), 1379; https://doi.org/10.3390/nano11061379 - 24 May 2021

Cited by 10 | Viewed by 3927

Abstract

We propose and experimentally demonstrate single-pixel photon counting imaging based on dual-comb interferometry at 1550 nm. Different from traditional dual-comb imaging, this approach enables imaging at the photon-counting regime by using single-photon detectors combined with a time-correlated single-photon counter to record the returning [...] Read more.

We propose and experimentally demonstrate single-pixel photon counting imaging based on dual-comb interferometry at 1550 nm. Different from traditional dual-comb imaging, this approach enables imaging at the photon-counting regime by using single-photon detectors combined with a time-correlated single-photon counter to record the returning photons. The illumination power is as low as 14 pW, corresponding to 2.2 × 10⁻³ photons/pulse. The lateral resolution is about 50 μm. This technique paves the way for applying dual-comb in remote sensing and imaging. Full article

(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)

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7 pages, 1673 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Enantioselective Self-Assembled Nanofibrillar Network with Glutamide-Based Organogelator

by Nao Nagatomo, Hisashi Oishi, Yutaka Kuwahara, Makoto Takafuji, Reiko Oda, Taisuke Hamada and Hirotaka Ihara

Nanomaterials 2021, 11(6), 1376; https://doi.org/10.3390/nano11061376 - 23 May 2021

Viewed by 2591

Abstract

A chiral molecular gelation system, as a chiral host, was used to effectively realize enantioselectivity using the simple carboxylic acid functional group. For this purpose, an L-glutamic-acid-based lipidic amphiphile (G-CA) with a carboxylic head group was selected and its responsiveness to [...] Read more.

A chiral molecular gelation system, as a chiral host, was used to effectively realize enantioselectivity using the simple carboxylic acid functional group. For this purpose, an L-glutamic-acid-based lipidic amphiphile (G-CA) with a carboxylic head group was selected and its responsiveness to cationic guest molecules was investigated. The dispersion morphology of G-CA in its solution state was examined by confocal and transmission electron microscopies, while interactions between the G-CA, as the host system, and guest molecules were evaluated by UV-visible, circular dichroism, and fluorescence spectroscopies. As a result, enantioselectivity was effectively induced when G-CA formed highly ordered aggregates that provide negatively charged surfaces in which carboxyl groups are assembled in highly ordered states, and when the two cationic groups of the guest molecule are attached to this surface through multiple interactions. Full article

(This article belongs to the Special Issue Self-Assembled Nanostructures for Molecular Recognition)

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11 pages, 12987 KB

Open AccessEditor’s ChoiceArticle

Creation of Negatively Charged Boron Vacancies in Hexagonal Boron Nitride Crystal by Electron Irradiation and Mechanism of Inhomogeneous Broadening of Boron Vacancy-Related Spin Resonance Lines

by Fadis F. Murzakhanov, Boris V. Yavkin, Georgiy V. Mamin, Sergei B. Orlinskii, Ivan E. Mumdzhi, Irina N. Gracheva, Bulat F. Gabbasov, Alexander N. Smirnov, Valery Yu. Davydov and Victor A. Soltamov

Nanomaterials 2021, 11(6), 1373; https://doi.org/10.3390/nano11061373 - 22 May 2021

Cited by 49 | Viewed by 6947

Abstract

Optically addressable high-spin states (S ≥ 1) of defects in semiconductors are the basis for the development of solid-state quantum technologies. Recently, one such defect has been found in hexagonal boron nitride (hBN) and identified as a negatively charged boron vacancy ( [...] Read more.

Optically addressable high-spin states (S ≥ 1) of defects in semiconductors are the basis for the development of solid-state quantum technologies. Recently, one such defect has been found in hexagonal boron nitride (hBN) and identified as a negatively charged boron vacancy (

V_{B}^{-}

). To explore and utilize the properties of this defect, one needs to design a robust way for its creation in an hBN crystal. We investigate the possibility of creating

V_{B}^{-}

centers in an hBN single crystal by means of irradiation with a high-energy (E = 2 MeV) electron flux. Optical excitation of the irradiated sample induces fluorescence in the near-infrared range together with the electron spin resonance (ESR) spectrum of the triplet centers with a zero-field splitting value of D = 3.6 GHz, manifesting an optically induced population inversion of the ground state spin sublevels. These observations are the signatures of the

V_{B}^{-}

centers and demonstrate that electron irradiation can be reliably used to create these centers in hBN. Exploration of the

V_{B}^{-}

spin resonance line shape allowed us to establish the source of the line broadening, which occurs due to the slight deviation in orientation of the two-dimensional B-N atomic plains being exactly parallel relative to each other. The results of the analysis of the broadening mechanism can be used for the crystalline quality control of the 2D materials, using the

V_{B}^{-}

spin embedded in the hBN as a probe. Full article

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21 pages, 4891 KB

Open AccessEditor’s ChoiceArticle

Influence of Physicochemical Characteristics and Stability of Gold and Silver Nanoparticles on Biological Effects and Translocation across an Intestinal Barrier—A Case Study from In Vitro to In Silico

by Yvonne Kohl, Michelle Hesler, Roland Drexel, Lukas Kovar, Stephan Dähnhardt-Pfeiffer, Dominik Selzer, Sylvia Wagner, Thorsten Lehr, Hagen von Briesen and Florian Meier

Nanomaterials 2021, 11(6), 1358; https://doi.org/10.3390/nano11061358 - 21 May 2021

Cited by 12 | Viewed by 3863

Abstract

A better understanding of their interaction with cell-based tissue is a fundamental prerequisite towards the safe production and application of engineered nanomaterials. Quantitative experimental data on the correlation between physicochemical characteristics and the interaction and transport of engineered nanomaterials across biological barriers, in [...] Read more.

A better understanding of their interaction with cell-based tissue is a fundamental prerequisite towards the safe production and application of engineered nanomaterials. Quantitative experimental data on the correlation between physicochemical characteristics and the interaction and transport of engineered nanomaterials across biological barriers, in particular, is still scarce, thus hampering the development of effective predictive non-testing strategies. Against this background, the presented study investigated the translocation of gold and silver nanoparticles across the gastrointestinal barrier along with related biological effects using an in vitro 3D-triple co-culture cell model. Standardized in vitro assays and quantitative polymerase chain reaction showed no significant influence of the applied nanoparticles on both cell viability and generation of reactive oxygen species. Transmission electron microscopy indicated an intact cell barrier during the translocation study. Single particle ICP-MS revealed a time-dependent increase of translocated nanoparticles independent of their size, shape, surface charge, and stability in cell culture medium. This quantitative data provided the experimental basis for the successful mathematical description of the nanoparticle transport kinetics using a non-linear mixed effects modeling approach. The results of this study may serve as a basis for the development of predictive tools for improved risk assessment of engineered nanomaterials in the future. Full article

(This article belongs to the Special Issue Safety and Biocompatibility of Metallic Nanoparticles)

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24 pages, 4445 KB

Open AccessEditor’s ChoiceArticle

Hyaluronic Acid-Based Nanocapsules as Efficient Delivery Systems of Garlic Oil Active Components with Anticancer Activity

by Małgorzata Janik-Hazuka, Kamil Kamiński, Marta Kaczor-Kamińska, Joanna Szafraniec-Szczęsny, Aleksandra Kmak, Hassan Kassassir, Cezary Watała, Maria Wróbel and Szczepan Zapotoczny

Nanomaterials 2021, 11(5), 1354; https://doi.org/10.3390/nano11051354 - 20 May 2021

Cited by 19 | Viewed by 5225

Abstract

Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are garlic oil compounds exhibiting beneficial healthy properties including anticancer action. However, these compounds are sparingly water-soluble with a limited stability that may imply damage to blood vessels or cells after administration. Thus, their encapsulation in [...] Read more.

Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are garlic oil compounds exhibiting beneficial healthy properties including anticancer action. However, these compounds are sparingly water-soluble with a limited stability that may imply damage to blood vessels or cells after administration. Thus, their encapsulation in the oil-core nanocapsules based on a derivative of hyaluronic acid was investigated here as a way of protecting against oxidation and undesired interactions with blood and digestive track components. The nuclear magnetic resonance (¹H NMR) technique was used to follow the oxidation processes. It was proved that the shell of the capsule acts as a barrier limiting the sulfur oxidation, enhancing the stability of C=C bonds in DADS and DATS. Moreover, it was shown that the encapsulation inhibited the lysis of the red blood cell membrane (mainly for DADS) and interactions with serum or digestive track components. Importantly, the biological functions and anticancer activity of DADS and DATS were preserved after encapsulation. Additionally, the nanocapsule formulations affected the migration of neoplastic cells—a desirable preliminary observation concerning the inhibition of migration. The proposed route of administration of these garlic extract components would enable reaching their higher concentrations in blood, longer circulation in a bloodstream, and thus, imply a better therapeutic effect. Full article

(This article belongs to the Special Issue Nanoparticles from Natural Polymers: Synthesis and Applications)

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15 pages, 5297 KB

Open AccessEditor’s ChoiceArticle

Hydrous Hydrazine Decomposition for Hydrogen Production Using of Ir/CeO₂: Effect of Reaction Parameters on the Activity

by Davide Motta, Ilaria Barlocco, Silvio Bellomi, Alberto Villa and Nikolaos Dimitratos

Nanomaterials 2021, 11(5), 1340; https://doi.org/10.3390/nano11051340 - 19 May 2021

Cited by 29 | Viewed by 4429

Abstract

In the present work, an Ir/CeO₂ catalyst was prepared by the deposition–precipitation method and tested in the decomposition of hydrazine hydrate to hydrogen, which is very important in the development of hydrogen storage materials for fuel cells. The catalyst was characterised using [...] Read more.

In the present work, an Ir/CeO₂ catalyst was prepared by the deposition–precipitation method and tested in the decomposition of hydrazine hydrate to hydrogen, which is very important in the development of hydrogen storage materials for fuel cells. The catalyst was characterised using different techniques, i.e., X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with X-ray detector (EDX) and inductively coupled plasma—mass spectroscopy (ICP-MS). The effect of reaction conditions on the activity and selectivity of the material was evaluated in this study, modifying parameters such as temperature, the mass of the catalyst, stirring speed and concentration of base in order to find the optimal conditions of reaction, which allow performing the test in a kinetically limited regime. Full article

(This article belongs to the Section Energy and Catalysis)

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13 pages, 2725 KB

Open AccessEditor’s ChoiceArticle

Spatiotemporal Visualization of Insecticides and Fungicides within Fruits and Vegetables Using Gold Nanoparticle-Immersed Paper Imprinting Mass Spectrometry Imaging

by Run Qin, Ping Li, Mingyi Du, Lianlian Ma, Yudi Huang, Zhibin Yin, Yue Zhang, Dong Chen, Hanhong Xu and Xinzhou Wu

Nanomaterials 2021, 11(5), 1327; https://doi.org/10.3390/nano11051327 - 18 May 2021

Cited by 28 | Viewed by 4515

Abstract

Food safety issues caused by pesticide residue have exerted far-reaching impacts on human daily life, yet the available detection methods normally focus on surface residue rather than pesticide penetration to the internal area of foods. Herein, we demonstrated gold nanoparticle (AuNP)-immersed paper imprinting [...] Read more.

Food safety issues caused by pesticide residue have exerted far-reaching impacts on human daily life, yet the available detection methods normally focus on surface residue rather than pesticide penetration to the internal area of foods. Herein, we demonstrated gold nanoparticle (AuNP)-immersed paper imprinting mass spectrometry imaging (MSI) for monitoring pesticide migration behaviors in various fruits and vegetables (i.e., apple, cucumber, pepper, plum, carrot, and strawberry). By manually stamping food tissues onto AuNP-immersed paper, this method affords the spatiotemporal visualization of insecticides and fungicides within fruits and vegetables, avoiding tedious and time-consuming sample preparation. Using the established MSI platform, we can track the migration of insecticides and fungicides into the inner region of foods. The results revealed that both the octanol-water partition coefficient of pesticides and water content of garden stuffs could influence the discrepancy in the migration speed of pesticides into food kernels. Taken together, this nanopaper imprinting MSI is poised to be a powerful tool because of its simplicity, rapidity, and easy operation, offering the potential to facilitate further applications in food analysis. Moreover, new perspectives are given to provide guidelines for the rational design of novel pesticide candidates, reducing the risk of food safety issues caused by pesticide residue. Full article

(This article belongs to the Special Issue Advances in Food Nanotechnology)

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10 pages, 4283 KB

Open AccessEditor’s ChoiceArticle

Lattice-Match Stabilization and Magnetic Properties of Metastable Epitaxial Permalloy-Disilicide Nanostructures on a Vicinal Si(111) Substrate

by Anjan Bhukta, Dror Horvitz, Amit Kohn and Ilan Goldfarb

Nanomaterials 2021, 11(5), 1310; https://doi.org/10.3390/nano11051310 - 16 May 2021

Cited by 1 | Viewed by 3027

Abstract

We report the epitaxial formation of metastable γ-(Fe_xNi_1−x)Si₂ nanostructure arrays resulting from the reaction of Ni₈₀Fe₂₀ permalloy with vicinal Si(111) surface atoms. We then explore the effect of structure and composition on the nanostructure’s magnetic [...] Read more.

We report the epitaxial formation of metastable γ-(Fe_xNi_1−x)Si₂ nanostructure arrays resulting from the reaction of Ni₈₀Fe₂₀ permalloy with vicinal Si(111) surface atoms. We then explore the effect of structure and composition on the nanostructure’s magnetic properties. The low-temperature annealing (T < 600 °C) of a pre-deposited permalloy film led to solid-phase epitaxial nucleation of compact disk-shaped island nanostructures decorating <110> ledges of the stepped surface, with either (2

\times

2) or (

\sqrt{3} \times \sqrt{3}

) R30° reconstructed flat top faces. High resolution scanning transmission electron microscopy analysis demonstrated fully coherent epitaxy of the islands with respect to the substrate, consistent with a well-matched CaF₂-prototype structure associated with γ-FeSi₂, along perfect atomically sharp interfaces. Energy dispersive spectroscopy detected ternary composition of the islands, with Fe and Ni atoms confined to the islands, and no trace of segregation. Our magnetometry measurements revealed the superparamagnetic behavior of the silicide islands, with a blocking temperature around 30 K, reflecting the size, shape, and dilute arrangement of the islands in the assembly. Full article

(This article belongs to the Special Issue Epitaxial Self-Assembly of Magnetic Nanostructures)

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15 pages, 2050 KB

Open AccessEditor’s ChoiceArticle

Quantifying the Charge Carrier Interaction in Metallic Twisted Bilayer Graphene Superlattices

by Evgueni F. Talantsev

Nanomaterials 2021, 11(5), 1306; https://doi.org/10.3390/nano11051306 - 15 May 2021

Cited by 9 | Viewed by 3070

Abstract

The mechanism of charge carrier interaction in twisted bilayer graphene (TBG) remains an unresolved problem, where some researchers proposed the dominance of the electron–phonon interaction, while the others showed evidence for electron–electron or electron–magnon interactions. Here we propose to resolve this problem by [...] Read more.

The mechanism of charge carrier interaction in twisted bilayer graphene (TBG) remains an unresolved problem, where some researchers proposed the dominance of the electron–phonon interaction, while the others showed evidence for electron–electron or electron–magnon interactions. Here we propose to resolve this problem by generalizing the Bloch–Grüneisen equation and using it for the analysis of the temperature dependent resistivity in TBG. It is a well-established theoretical result that the Bloch–Grüneisen equation power-law exponent, p, exhibits exact integer values for certain mechanisms. For instance, p = 5 implies the electron–phonon interaction, p = 3 is associated with the electron–magnon interaction and p = 2 applies to the electron–electron interaction. Here we interpret the linear temperature-dependent resistance, widely observed in TBG, as

p \to 1

, which implies the quasielastic charge interaction with acoustic phonons. Thus, we fitted TBG resistance curves to the Bloch–Grüneisen equation, where we propose that p is a free-fitting parameter. We found that TBGs have a smoothly varied p-value (ranging from 1.4 to 4.4) depending on the Moiré superlattice constant, λ, or the charge carrier concentration, n. This implies that different mechanisms of the charge carrier interaction in TBG superlattices smoothly transition from one mechanism to another depending on, at least, λ and n. The proposed generalized Bloch–Grüneisen equation is applicable to a wide range of disciplines, including superconductivity and geology. Full article

(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)

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11 pages, 3413 KB

Open AccessEditor’s ChoiceArticle

Studies of Defect Structure in Epitaxial AlN/GaN Films Grown on (111) 3C-SiC

by Andreea Bianca Serban, Vladimir Lucian Ene, Doru Dinescu, Iulia Zai, Nikolay Djourelov, Bogdan Stefan Vasile and Victor Leca

Nanomaterials 2021, 11(5), 1299; https://doi.org/10.3390/nano11051299 - 14 May 2021

Cited by 3 | Viewed by 3580

Abstract

Several aspects such as the growth relation between the layers of the GaN/AlN/SiC heterostructure, the consistency of the interfaces, and elemental diffusion are achieved by High Resolution Transmission Electron Microscopy (HR-TEM). In addition, the dislocation densities together with the defect correlation lengths are [...] Read more.

Several aspects such as the growth relation between the layers of the GaN/AlN/SiC heterostructure, the consistency of the interfaces, and elemental diffusion are achieved by High Resolution Transmission Electron Microscopy (HR-TEM). In addition, the dislocation densities together with the defect correlation lengths are investigated via High-Resolution X-ray Diffraction (HR-XRD) and the characteristic positron diffusion length is achieved by Doppler Broadening Spectroscopy (DBS). Moreover, a comparative analysis with our previous work (i.e., GaN/AlN/Si and GaN/AlN/Al₂O₃) has been carried out. Within the epitaxial GaN layer defined by the relationship

F \bar{4} 3 m

(111) 3C-SiC ||

P 63 m c

(0002) AlN ||

P 63 m c

(0002) GaN, the total dislocation density has been assessed as being 1.47 × 10¹⁰ cm⁻². Compared with previously investigated heterostructures (on Si and Al₂O₃ substrates), the obtained dislocation correlation lengths (L^e = 171 nm and L^s =288 nm) and the mean distance between two dislocations (r_d = 82 nm) are higher. This reveals an improved crystal quality of the GaN with SiC as a growth template. In addition, the DBS measurements upheld the aforementioned results with a higher effective positron diffusion length

L_{eff}^{GaN 2}

= 75 ± 20 nm for the GaN layer. Full article

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17 pages, 8325 KB

Open AccessEditor’s ChoiceArticle

Li₄(OH)₃Br-Based Shape Stabilized Composites for High-Temperature TES Applications: Selection of the Most Convenient Supporting Material

by Imane Mahroug, Stefania Doppiu, Jean-Luc Dauvergne, Angel Serrano and Elena Palomo del Barrio

Nanomaterials 2021, 11(5), 1279; https://doi.org/10.3390/nano11051279 - 13 May 2021

Cited by 4 | Viewed by 2649

Abstract

Peritectic compound Li₄(OH)₃Br has been recently proposed as phase change material (PCM) for thermal energy storage (TES) applications at approx. 300 °C Compared to competitor PCM materials (e.g., sodium nitrate), the main assets of this compound are high volumetric [...] Read more.

Peritectic compound Li₄(OH)₃Br has been recently proposed as phase change material (PCM) for thermal energy storage (TES) applications at approx. 300 °C Compared to competitor PCM materials (e.g., sodium nitrate), the main assets of this compound are high volumetric latent heat storage capacity (>140 kWh/m³) and very low volume changes (<3%) during peritectic reaction and melting. The objective of the present work was to find proper supporting materials able to shape stabilize Li₄(OH)₃Br during the formation of the melt and after its complete melting, avoiding any leakage and thus obtaining a composite apparently always in the solid state during the charge and discharge of the TES material. Micro-nanoparticles of MgO, Fe₂O₃, CuO, SiO₂ and Al₂O₃ have been considered as candidate supporting materials combined with the cold-compression route for shape-stabilized composites preparation. The work carried out allowed for the identification of the most promising composite based on MgO nanoparticles through a deep experimental analysis and characterization, including chemical compatibility tests, anti-leakage performance evaluation, structural and thermodynamic properties analysis and preliminary cycling stability study. Full article

(This article belongs to the Special Issue Multifunctional Nanomaterials for Energy Applications)

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16 pages, 4800 KB

Open AccessEditor’s ChoiceArticle

Remotely Self-Healable, Shapeable and pH-Sensitive Dual Cross-Linked Polysaccharide Hydrogels with Fast Response to Magnetic Field

by Andrey V. Shibaev, Maria E. Smirnova, Darya E. Kessel, Sergey A. Bedin, Irina V. Razumovskaya and Olga E. Philippova

Nanomaterials 2021, 11(5), 1271; https://doi.org/10.3390/nano11051271 - 12 May 2021

Cited by 21 | Viewed by 4151

Abstract

The development of actuators with remote control is important for the construction of devices for soft robotics. The present paper describes a responsive hydrogel of nontoxic, biocompatible, and biodegradable polymer carboxymethyl hydroxypropyl guar with dynamic covalent cross-links and embedded cobalt ferrite nanoparticles. The [...] Read more.

The development of actuators with remote control is important for the construction of devices for soft robotics. The present paper describes a responsive hydrogel of nontoxic, biocompatible, and biodegradable polymer carboxymethyl hydroxypropyl guar with dynamic covalent cross-links and embedded cobalt ferrite nanoparticles. The nanoparticles significantly enhance the mechanical properties of the gel, acting as additional multifunctional non-covalent linkages between the polymer chains. High magnetization of the cobalt ferrite nanoparticles provides to the gel a strong responsiveness to the magnetic field, even at rather small content of nanoparticles. It is demonstrated that labile cross-links in the polymer matrix impart to the hydrogel the ability of self-healing and reshaping as well as a fast response to the magnetic field. In addition, the gel shows pronounced pH sensitivity due to pH-cleavable cross-links. The possibility to use the multiresponsive gel as a magnetic-field-triggered actuator is demonstrated. Full article

(This article belongs to the Special Issue Advanced Magnetic Nanocomposites: Structural, Physical Properties and Application)

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11 pages, 2750 KB

Open AccessEditor’s ChoiceArticle

Fabrication of Porous Lead Bromide Films by Introducing Indium Tribromide for Efficient Inorganic CsPbBr₃ Perovskite Solar Cells

by Xianwei Meng, Kailin Chi, Qian Li, Bingtao Feng, Haodi Wang, Tianjiao Gao, Pengyu Zhou, Haibin Yang and Wuyou Fu

Nanomaterials 2021, 11(5), 1253; https://doi.org/10.3390/nano11051253 - 11 May 2021

Cited by 12 | Viewed by 3804

Abstract

In the process of preparing CsPbBr₃ films by two-step or multi-step methods, due to the low solubility of CsBr in organic solvents, the prepared perovskite films often have a large number of holes, which is definitely not conducive to the performance of [...] Read more.

In the process of preparing CsPbBr₃ films by two-step or multi-step methods, due to the low solubility of CsBr in organic solvents, the prepared perovskite films often have a large number of holes, which is definitely not conducive to the performance of CsPbBr₃ perovskite solar cells (PSCs). In response to this problem, this article proposed a method of introducing InBr₃ into the PbBr₂ precursor to prepare a porous PbBr₂ film to increase the reaction efficiency between CsBr and PbBr₂ and achieve the purpose of In (Ⅲ) incorporation, which not only optimized the morphology of the produced CsPbBr₃ film but also enhanced the charge extraction and transport capabilities, which was ascribed to the reduction of the trap state density and impurity phases in the perovskite films, improving the performance of CsPbBr₃ PSCs. At the optimal InBr₃ concentration of 0.21 M, the InBr₃:CsPbBr₃ perovskite solar cell exhibited a power conversion efficiency of 6.48%, which was significantly higher than that of the pristine device. Full article

(This article belongs to the Special Issue Nanostructures for Perovskite Solar Cells and Light-Emitting Diodes)

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11 pages, 7623 KB

Open AccessEditor’s ChoiceArticle

Fabrication of Flexible Electrode with Sub-Tenth Micron Thickness Using Heat-Induced Peelable Pressure-Sensitive Adhesive Containing Amide Groups

by Hyebeom Shin, Eunseong Yang, Yong-Hoon Kim, Min-Gi Kwak and Youngmin Kim

Nanomaterials 2021, 11(5), 1250; https://doi.org/10.3390/nano11051250 - 10 May 2021

Cited by 3 | Viewed by 3123

Abstract

In response to the increasing demand for flexible devices, there is increasing effort to manufacture flexible electrodes. However, the difficulty of handling a thin film is an obstacle to the production of flexible electrodes. In this study, a heat-induced peelable pressure-sensitive adhesive (h-PSA) [...] Read more.

In response to the increasing demand for flexible devices, there is increasing effort to manufacture flexible electrodes. However, the difficulty of handling a thin film is an obstacle to the production of flexible electrodes. In this study, a heat-induced peelable pressure-sensitive adhesive (h-PSA) was fabricated and used to manufacture a flexible electrode with sub-tenth micron thickness. Unlike the control PSA, the incorporation of amide groups made the h-PSA fail through adhesive failure at temperatures ranging from 20 to 80 °C. Compared to the peeling adhesion (1719 gf/in) of h-PSA measured at 20 °C, the value (171 gf/in) measured at 80 °C was decreased by one order of magnitude. Next, the 8 μm thick polyethylene terephthalate (PET) film was attached on a thick substrate (50 μm) via h-PSA, and Mo/Al/Mol patterns were fabricated on the PET film through sputtering, photolithography, and wet-etching processes. The thick substrate alleviated the difficulty of handling the thin PET film during the electrode fabrication process. Thanks to the low peel force and clean separation of the h-PSA at 80 °C, the flexible electrode of metal patterns on the PET (8 μm) film was isolated from the substrate with little change (<1%) in electrical conductivity. Finally, the mechanical durability of the flexible electrode was evaluated by a U-shape folding test, and no cracking or delamination was observed after 10,000 test cycles. Full article

(This article belongs to the Special Issue Nanomaterial Electrodes)

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30 pages, 12212 KB

Open AccessEditor’s ChoiceReview

Graphene/Reduced Graphene Oxide-Carbon Nanotubes Composite Electrodes: From Capacitive to Battery-Type Behaviour

by Olena Okhay and Alexander Tkach

Nanomaterials 2021, 11(5), 1240; https://doi.org/10.3390/nano11051240 - 8 May 2021

Cited by 103 | Viewed by 10294

Abstract

Thanks to the advanced technologies for energy generation such as solar cells and thermo- or piezo-generators the amount of electricity transformed from light, heat or mechanical pressure sources can be significantly enhanced. However, there is still a demand for effective storage devices to [...] Read more.

Thanks to the advanced technologies for energy generation such as solar cells and thermo- or piezo-generators the amount of electricity transformed from light, heat or mechanical pressure sources can be significantly enhanced. However, there is still a demand for effective storage devices to conserve electrical energy which addresses the wide range of large stationary applications from electric vehicles to small portable devices. Among the large variety of energy-storage systems available today, electrochemical energy sources and, in particular, supercapacitors (SC), are rather promising in terms of cost, scaling, power management, life cycle and safety. Therefore, this review surveys recent achievements in the development of SC based on composites of such carbon-derived materials as graphene (G) and reduced graphene oxide (rGO) with carbon nanotubes (CNT). Various factors influencing the specific capacitance are discussed, while specific energy and power as well as cycling stability of SC with G/rGO-CNT composite electrode materials are overviewed. Full article

(This article belongs to the Special Issue Ceramics and Nanostructures for Energy Harvesting and Storage)

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11 pages, 5197 KB

Open AccessEditor’s ChoiceArticle

Enhanced Light Absorption by Facile Patterning of Nano-Grating on Mesoporous TiO₂ Photoelectrode for Cesium Lead Halide Perovskite Solar Cells

by Kang-Pil Kim, Wook Hyun Kim, Soo Min Kwon, Jun Yong Kim, Yun Seon Do and Sungho Woo

Nanomaterials 2021, 11(5), 1233; https://doi.org/10.3390/nano11051233 - 7 May 2021

Cited by 10 | Viewed by 3730

Abstract

CsPbIBr₂, a cesium-based all-inorganic halide perovskite (CsPe), is a very promising alternative material to mainstream organic–inorganic hybrid halide perovskite (HPe) materials owing to its exceptional moisture stability, thermal stability, and light stability. However, because of the wide band gap (2.05 eV) [...] Read more.

CsPbIBr₂, a cesium-based all-inorganic halide perovskite (CsPe), is a very promising alternative material to mainstream organic–inorganic hybrid halide perovskite (HPe) materials owing to its exceptional moisture stability, thermal stability, and light stability. However, because of the wide band gap (2.05 eV) of CsPbIBr₂, it has a low power conversion efficiency (PCE), which hinders its application in highly efficient solar cells. In this study, a facile nanoimprinted one-dimensional grating nanopattern (1D GNP) formation on mesoporous TiO₂ (mp-TiO₂) photoelectrodes was introduced to improve the effective light utilization and enhance the performance of CsPbIBr₂ perovskite solar cells (PSCs). The 1D GNP structure on the mp-TiO₂ layer increases the light absorption efficiency by diffracting the unabsorbed light into the active mp-TiO₂ and CsPbIBr₂ layers as well as increasing the charge separation and collection due to the extended interfacial contact area between the mp-TiO₂ and CsPbIBr₂ layers. Consequently, both the current density (J_SC) and the fill factor (FF) of the fabricated cells improved, leading to over a 20% enhancement in the solar cell’s PCE. Thus, this periodic grating structure, fabricated by simple nanoimprinting, could play an important role in the large-scale production of highly efficient and cost-effective Cs-based PSCs. Full article

(This article belongs to the Special Issue Mesoporous Materials and Nanoscale Phenomena in Hybrid Photovoltaics)

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11 pages, 5243 KB

Open AccessEditor’s ChoiceArticle

Bimetallic ZIF-Derived Co/N-Codoped Porous Carbon Supported Ruthenium Catalysts for Highly Efficient Hydrogen Evolution Reaction

by Hui Qi, Xinglong Guan, Guangyu Lei, Mengyao Zhao, Hongwei He, Kai Li, Guoliang Zhang, Fengbao Zhang, Xiaobin Fan, Wenchao Peng and Yang Li

Nanomaterials 2021, 11(5), 1228; https://doi.org/10.3390/nano11051228 - 6 May 2021

Cited by 19 | Viewed by 4934

Abstract

Exploring the economical, powerful, and durable electrocatalysts for hydrogen evolution reaction (HER) is highly required for practical application. Herein, nanoclusters-decorated ruthenium, cobalt nanoparticles, and nitrogen codoped porous carbon (Ru-pCo@NC) are prepared with bimetallic zeolite imidazole frameworks (ZnCo-ZIF) as the precursor. Thus, the prepared [...] Read more.

Exploring the economical, powerful, and durable electrocatalysts for hydrogen evolution reaction (HER) is highly required for practical application. Herein, nanoclusters-decorated ruthenium, cobalt nanoparticles, and nitrogen codoped porous carbon (Ru-pCo@NC) are prepared with bimetallic zeolite imidazole frameworks (ZnCo-ZIF) as the precursor. Thus, the prepared Ru-pCo@NC catalyst with a low Ru loading of 3.13 wt% exhibits impressive HER catalytic behavior in 1 M KOH, with an overpotential of only 30 mV at the current density of 10 mA cm⁻², Tafel slope as low as 32.1 mV dec⁻¹, and superior stability for long-time running with a commercial 20 wt% Pt/C. The excellent electrocatalytic properties are primarily by virtue of the highly specific surface area and porosity of carbon support, uniformly dispersed Ru active species, and rapid reaction kinetics of the interaction between Ru and O. Full article

(This article belongs to the Special Issue Inorganic Materials in Nanotechnology: Fabrication, Characterization and Application)

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31 pages, 22082 KB

Open AccessEditor’s ChoiceReview

Materials, Electrical Performance, Mechanisms, Applications, and Manufacturing Approaches for Flexible Strain Sensors

by Fei Han, Min Li, Huaiyu Ye and Guoqi Zhang

Nanomaterials 2021, 11(5), 1220; https://doi.org/10.3390/nano11051220 - 5 May 2021

Cited by 60 | Viewed by 9583

Abstract

With the recent great progress made in flexible and wearable electronic materials, the upcoming next generation of skin-mountable and implantable smart devices holds extensive potential applications for the lifestyle modifying, including personalized health monitoring, human-machine interfaces, soft robots, and implantable biomedical devices. As [...] Read more.

With the recent great progress made in flexible and wearable electronic materials, the upcoming next generation of skin-mountable and implantable smart devices holds extensive potential applications for the lifestyle modifying, including personalized health monitoring, human-machine interfaces, soft robots, and implantable biomedical devices. As a core member within the wearable electronics family, flexible strain sensors play an essential role in the structure design and functional optimization. To further enhance the stretchability, flexibility, sensitivity, and electricity performances of the flexible strain sensors, enormous efforts have been done covering the materials design, manufacturing approaches and various applications. Thus, this review summarizes the latest advances in flexible strain sensors over recent years from the material, application, and manufacturing strategies. Firstly, the critical parameters measuring the performances of flexible strain sensors and materials development contains different flexible substrates, new nano- and hybrid- materials are introduced. Then, the developed working mechanisms, theoretical analysis, and computational simulation are presented. Next, based on different material design, diverse applications including human motion detection and health monitoring, soft robotics and human-machine interface, implantable devices, and biomedical applications are highlighted. Finally, synthesis consideration of the massive production industry of flexible strain sensors in the future; different fabrication approaches that are fully expected are classified and discussed. Full article

(This article belongs to the Special Issue 10th Anniversary of Nanomaterials—Recent Advances in Nanofabrication and Nanomanufacturing)

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12 pages, 2166 KB

Open AccessEditor’s ChoiceArticle

An Inverted Honeycomb Plasmonic Lattice as an Efficient Refractive Index Sensor

by Javier Rodríguez-Álvarez, Lorenzo Gnoatto, Marc Martínez-Castells, Albert Guerrero, Xavier Borrisé, Arantxa Fraile Rodríguez, Xavier Batlle and Amílcar Labarta

Nanomaterials 2021, 11(5), 1217; https://doi.org/10.3390/nano11051217 - 4 May 2021

Cited by 2 | Viewed by 3445

Abstract

We present an efficient refractive index sensor consisting of a heterostructure that contains an Au inverted honeycomb lattice as a main sensing element. Our design aims at maximizing the out-of-plane near-field distributions of the collective modes of the lattice mapping the sensor surroundings. [...] Read more.

We present an efficient refractive index sensor consisting of a heterostructure that contains an Au inverted honeycomb lattice as a main sensing element. Our design aims at maximizing the out-of-plane near-field distributions of the collective modes of the lattice mapping the sensor surroundings. These modes are further enhanced by a patterned SiO₂ layer with the same inverted honeycomb lattice, an SiO₂ spacer, and an Au mirror underneath the Au sensing layer that contribute to achieving a high performance. The optical response of the heterostructure was studied by numerical simulation. The results corresponding to one of the collective modes showed high sensitivity values ranging from 99 to 395 nm/RIU for relatively thin layers of test materials within 50 and 200 nm. In addition, the figure of merit of the sensor detecting slight changes of the refractive index of a water medium at a fixed wavelength was as high as 199 RIU⁻¹. As an experimental proof of concept, the heterostructure was manufactured by a simple method based on electron beam lithography and the measured optical response reproduces the simulations. This work paves the way for improving both the sensitivity of plasmonic sensors and the signal of some enhanced surface spectroscopies. Full article

(This article belongs to the Special Issue Plasmonic Nanostructures and Their Applications)

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11 pages, 1198 KB

Open AccessEditor’s ChoiceArticle

Beyond Nitrogen in the Oxygen Reduction Reaction on Nitrogen-Doped Carbons: A NEXAFS Investigation

by Eugenia Tanasa, Florentina Iuliana Maxim, Tugce Erniyazov, Matei-Tom Iacob, Tomáš Skála, Liviu Cristian Tanase, Cătălin Ianăși, Cristina Moisescu, Cristina Miron, Ioan Ardelean, Vlad-Andrei Antohe, Eugenia Fagadar-Cosma and Serban N. Stamatin

Nanomaterials 2021, 11(5), 1198; https://doi.org/10.3390/nano11051198 - 1 May 2021

Cited by 8 | Viewed by 3316

Abstract

Polymer electrolyte membrane fuel cells require cheap and active electrocatalysts to drive the oxygen reduction reaction. Nitrogen-doped carbons have been extensively studied regarding their oxygen reduction reaction. The work at hand looks beyond the nitrogen chemistry and brings to light the role of [...] Read more.

Polymer electrolyte membrane fuel cells require cheap and active electrocatalysts to drive the oxygen reduction reaction. Nitrogen-doped carbons have been extensively studied regarding their oxygen reduction reaction. The work at hand looks beyond the nitrogen chemistry and brings to light the role of oxygen. Nitrogen-doped nanocarbons were obtained by a radio-frequency plasma route at 0, 100, 250, and 350 W. The lateral size of the graphitic domain, determined from Raman spectroscopy, showed that the nitrogen plasma treatment decreased the crystallite size. Synchrotron radiation photoelectron spectroscopy showed a similar nitrogen chemistry, albeit the nitrogen concentration increased with the plasma power. Lateral crystallite size and several nitrogen moieties were plotted against the onset potential determined from oxygen reduction reaction curves. There was no correlation between the electrochemical activity and the sample structure, as determine from Raman and synchrotron radiation photoelectron spectroscopy. Near-edge X-ray absorption fine structure (NEXAFS) was performed to unravel the carbon and nitrogen local structure. A difference analysis of the NEXAFS spectra showed that the oxygen surrounding the pyridinic nitrogen was critical in achieving high onset potentials. The work shows that there were more factors at play, other than carbon organization and nitrogen chemistry. Full article

(This article belongs to the Special Issue Nanoparticles for Electrocatalysts)

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22 pages, 5251 KB

Open AccessEditor’s ChoiceArticle

Accessible Silver-Iron Oxide Nanoparticles as a Nanomaterial for Supported Liquid Membranes

by Ioana Alina Dimulescu (Nica), Aurelia Cristina Nechifor, Cristina Bǎrdacǎ (Urducea), Ovidiu Oprea, Dumitru Paşcu, Eugenia Eftimie Totu, Paul Constantin Albu, Gheorghe Nechifor and Simona Gabriela Bungău

Nanomaterials 2021, 11(5), 1204; https://doi.org/10.3390/nano11051204 - 1 May 2021

Cited by 31 | Viewed by 3602

Abstract

The present study introduces the process performances of nitrophenols pertraction using new liquid supported membranes under the action of a magnetic field. The membrane system is based on the dispersion of silver–iron oxide nanoparticles in n-alcohols supported on hollow microporous polypropylene fibers. The [...] Read more.

The present study introduces the process performances of nitrophenols pertraction using new liquid supported membranes under the action of a magnetic field. The membrane system is based on the dispersion of silver–iron oxide nanoparticles in n-alcohols supported on hollow microporous polypropylene fibers. The iron oxide–silver nanoparticles are obtained directly through cyclic voltammetry electrolysis run in the presence of soluble silver complexes ([AgCl₂]⁻; [Ag(S₂O₃)₂]³⁻; [Ag(NH₃)₂]⁺) and using pure iron electrodes. The nanostructured particles are characterized morphologically and structurally by scanning electron microscopy (SEM and HFSEM), EDAX, XRD, and thermal analysis (TG, DSC). The performances of the nitrophenols permeation process are investigated in a variable magnetic field. These studies show that the flux and extraction efficiency have the highest values for the membrane system embedding iron oxide–silver nanoparticles obtained electrochemically in the presence of [Ag(NH₃)₂]⁺ electrolyte. It is demonstrated that the total flow of nitrophenols through the new membrane system depends on diffusion, convection, and silver-assisted transport. Full article

(This article belongs to the Special Issue Nanomaterials for Membranes, Membrane Reactors and Catalyst Systems)

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14 pages, 3467 KB

Open AccessEditor’s ChoiceArticle

Highly Conductive Al/Al Interfaces in Ultrafine Grained Al Compact Prepared by Low Oxygen Powder Metallurgy Technique

by Dasom Kim, Yusuke Hirayama, Zheng Liu, Hansang Kwon, Makoto Kobashi and Kenta Takagi

Nanomaterials 2021, 11(5), 1182; https://doi.org/10.3390/nano11051182 - 30 Apr 2021

Cited by 5 | Viewed by 2686

Abstract

The low oxygen powder metallurgy technique makes it possible to prepare full-dense ultrafine-grained (UFG) Al compacts with an average grain size of 160 nm by local surface bonding at a substantially lower temperature of 423 K from an Al nanopowder prepared by a [...] Read more.

The low oxygen powder metallurgy technique makes it possible to prepare full-dense ultrafine-grained (UFG) Al compacts with an average grain size of 160 nm by local surface bonding at a substantially lower temperature of 423 K from an Al nanopowder prepared by a low oxygen induction thermal plasma process. By atomic level analysis using transmission electron microscopy, it was found that there was almost no oxide layer at the Al/Al interfaces (grain boundaries) in UFG Al compact. The electrical conductivity of the UFG Al compact reached 3.5 × 10⁷ S/m, which is the same level as that of the cast Al bulk. The Vickers hardness of the UFG Al compact of 1078 MPa, which is 8 times that of the cast Al bulk, could be explained by the Hall–Petch law. In addition, fracture behavior was analyzed by conducting a small punch test. The as-sintered UFG Al compact initially fractured before reaching its ultimate strength due to its large number of grain boundaries with a high misorientation angle. Ultimate strength and elongation were enhanced to 175 MPa and 24%, respectively, by reduction of grain boundaries after annealing, indicating that high compatibility of strength and elongation can be realized by appropriate microstructure control. Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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13 pages, 3937 KB

Open AccessEditor’s ChoiceCommunication

Functionalizable Glyconanoparticles for a Versatile Redox Platform

by Marie Carrière, Paulo Henrique M. Buzzetti, Karine Gorgy, Muhammad Mumtaz, Christophe Travelet, Redouane Borsali and Serge Cosnier

Nanomaterials 2021, 11(5), 1162; https://doi.org/10.3390/nano11051162 - 29 Apr 2021

Cited by 8 | Viewed by 3525

Abstract

A series of new glyconanoparticles (GNPs) was obtained by self-assembly by direct nanoprecipitation of a mixture of two carbohydrate amphiphilic copolymers consisting of polystyrene-block-β-cyclodextrin and polystyrene-block-maltoheptaose with different mass ratios, respectively 0–100, 10–90, 50–50 and 0–100%. Characterizations for all these GNPs were achieved [...] Read more.

A series of new glyconanoparticles (GNPs) was obtained by self-assembly by direct nanoprecipitation of a mixture of two carbohydrate amphiphilic copolymers consisting of polystyrene-block-β-cyclodextrin and polystyrene-block-maltoheptaose with different mass ratios, respectively 0–100, 10–90, 50–50 and 0–100%. Characterizations for all these GNPs were achieved using dynamic light scattering, scanning and transmission electron microscopy techniques, highlighting their spherical morphology and their nanometric size (diameter range 20–40 nm). In addition, by using the inclusion properties of cyclodextrin, these glyconanoparticles were successfully post-functionalized using a water-soluble redox compound, such as anthraquinone sulfonate (AQS) and characterized by cyclic voltammetry. The resulting glyconanoparticles exhibit the classical electroactivity of free AQS in solution. The amount of AQS immobilized by host–guest interactions is proportional to the percentage of polystyrene-block-β-cyclodextrin entering into the composition of GNPs. The modulation of the surface density of the β-cyclodextrin at the shell of the GNPs may constitute an attractive way for the elaboration of different electroactive GNPs and even GNPs modified by biotinylated proteins. Full article

(This article belongs to the Section Nanocomposite Materials)

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8 pages, 4088 KB

Open AccessEditor’s ChoiceArticle

Facile Organometallic Synthesis of Fe-Based Nanomaterials by Hot Injection Reaction

by Georgia Basina, Hafsa Khurshid, Nikolaos Tzitzios, George Hadjipanayis and Vasileios Tzitzios

Nanomaterials 2021, 11(5), 1141; https://doi.org/10.3390/nano11051141 - 28 Apr 2021

Cited by 4 | Viewed by 3193

Abstract

Fe-based colloids with a core/shell structure consisting of metallic iron and iron oxide were synthesized by a facile hot injection reaction of iron pentacarbonyl in a multi-surfactant mixture. The size of the colloidal particles was affected by the reaction temperature and the results [...] Read more.

Fe-based colloids with a core/shell structure consisting of metallic iron and iron oxide were synthesized by a facile hot injection reaction of iron pentacarbonyl in a multi-surfactant mixture. The size of the colloidal particles was affected by the reaction temperature and the results demonstrated that their stability against complete oxidation related to their size. The crystal structure and the morphology were identified by powder X-ray diffraction and transmission electron microscopy, while the magnetic properties were studied at room temperature with a vibrating sample magnetometer. The injection temperature plays a very crucial role and higher temperatures enhance the stability and the resistance against oxidation. For the case of injection at 315 °C, the nanoparticles had around a 10 nm mean diameter and revealed 132 emu/g. Remarkably, a stable dispersion was created due to the colloids’ surface functionalization in a nonpolar solvent. Full article

(This article belongs to the Special Issue Synthesis, Development and Characterization of Magnetic Nanomaterials)

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13 pages, 3803 KB

Open AccessEditor’s ChoiceArticle

Straightforward Patterning of Functional Polymers by Sequential Nanosecond Pulsed Laser Irradiation

by Edgar Gutiérrez-Fernández, Tiberio A. Ezquerra, Aurora Nogales and Esther Rebollar

Nanomaterials 2021, 11(5), 1123; https://doi.org/10.3390/nano11051123 - 27 Apr 2021

Cited by 8 | Viewed by 3385

Abstract

Laser-based methods have demonstrated to be effective in the fabrication of surface micro- and nanostructures, which have a wide range of applications, such as cell culture, sensors or controlled wettability. One laser-based technique used for micro- and nanostructuring of surfaces is the formation [...] Read more.

Laser-based methods have demonstrated to be effective in the fabrication of surface micro- and nanostructures, which have a wide range of applications, such as cell culture, sensors or controlled wettability. One laser-based technique used for micro- and nanostructuring of surfaces is the formation of laser-induced periodic surface structures (LIPSS). LIPSS are formed upon repetitive irradiation at fluences well below the ablation threshold and in particular, linear structures are formed in the case of irradiation with linearly polarized laser beams. In this work, we report on the simple fabrication of a library of ordered nanostructures in a polymer surface by repeated irradiation using a nanosecond pulsed laser operating in the UV and visible region in order to obtain nanoscale-controlled functionality. By using a combination of pulses at different wavelengths and sequential irradiation with different polarization orientations, it is possible to obtain different geometries of nanostructures, in particular linear gratings, grids and arrays of nanodots. We use this experimental approach to nanostructure the semiconductor polymer poly(3-hexylthiophene) (P3HT) and the ferroelectric copolymer poly[(vinylidenefluoride-co-trifluoroethylene] (P(VDF-TrFE)) since nanogratings in semiconductor polymers, such as P3HT and nanodots, in ferroelectric systems are viewed as systems with potential applications in organic photovoltaics or non-volatile memories. Full article

(This article belongs to the Special Issue Laser-Generated Periodic Nanostructures)

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16 pages, 14648 KB

Open AccessEditor’s ChoiceArticle

Modulation of Macrophage Polarization by Carbon Nanodots and Elucidation of Carbon Nanodot Uptake Routes in Macrophages

by Andrew Dunphy, Kamal Patel, Sarah Belperain, Aubrey Pennington, Norman H. L. Chiu, Ziyu Yin, Xuewei Zhu, Brandon Priebe, Shaomin Tian, Jianjun Wei, Xianwen Yi and Zhenquan Jia

Nanomaterials 2021, 11(5), 1116; https://doi.org/10.3390/nano11051116 - 26 Apr 2021

Cited by 13 | Viewed by 3676

Abstract

Atherosclerosis represents an ever-present global concern, as it is a leading cause of cardiovascular disease and an immense public welfare issue. Macrophages play a key role in the onset of the disease state and are popular targets in vascular research and therapeutic treatment. [...] Read more.

Atherosclerosis represents an ever-present global concern, as it is a leading cause of cardiovascular disease and an immense public welfare issue. Macrophages play a key role in the onset of the disease state and are popular targets in vascular research and therapeutic treatment. Carbon nanodots (CNDs) represent a type of carbon-based nanomaterial and have garnered attention in recent years for potential in biomedical applications. This investigation serves as a foremost attempt at characterizing the interplay between macrophages and CNDs. We have employed THP-1 monocyte-derived macrophages as our target cell line representing primary macrophages in the human body. Our results showcase that CNDs are non-toxic at a variety of doses. THP-1 monocytes were differentiated into macrophages by treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) and co-treatment with 0.1 mg/mL CNDs. This co-treatment significantly increased the expression of CD 206 and CD 68 (key receptors involved in phagocytosis) and increased the expression of CCL2 (a monocyte chemoattractant and pro-inflammatory cytokine). The phagocytic activity of THP-1 monocyte-derived macrophages co-treated with 0.1 mg/mL CNDs also showed a significant increase. Furthermore, this study also examined potential entrance routes of CNDs into macrophages. We have demonstrated an inhibition in the uptake of CNDs in macrophages treated with nocodazole (microtubule disruptor), N-phenylanthranilic acid (chloride channel blocker), and mercury chloride (aquaporin channel inhibitor). Collectively, this research provides evidence that CNDs cause functional changes in macrophages and indicates a variety of potential entrance routes. Full article

(This article belongs to the Special Issue Nanomaterials for Drug Delivery and Cancer Therapy)

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25 pages, 10341 KB

Open AccessEditor’s ChoiceArticle

Superparamagnetic ZnFe₂O₄ Nanoparticles-Reduced Graphene Oxide-Polyurethane Resin Based Nanocomposites for Electromagnetic Interference Shielding Application

by Raghvendra Singh Yadav, Anju, Thaiskang Jamatia, Ivo Kuřitka, Jarmila Vilčáková, David Škoda, Pavel Urbánek, Michal Machovský, Milan Masař, Michal Urbánek, Lukas Kalina and Jaromir Havlica

Nanomaterials 2021, 11(5), 1112; https://doi.org/10.3390/nano11051112 - 25 Apr 2021

Cited by 33 | Viewed by 5873

Abstract

Superparamagnetic ZnFe₂O₄ spinel ferrite nanoparticles were prepared by the sonochemical synthesis method at different ultra-sonication times of 25 min (ZS25), 50 min (ZS50), and 100 min (ZS100). The structural properties of ZnFe₂O₄ spinel ferrite nanoparticles were controlled [...] Read more.

Superparamagnetic ZnFe₂O₄ spinel ferrite nanoparticles were prepared by the sonochemical synthesis method at different ultra-sonication times of 25 min (ZS25), 50 min (ZS50), and 100 min (ZS100). The structural properties of ZnFe₂O₄ spinel ferrite nanoparticles were controlled via sonochemical synthesis time. The average crystallite size increases from 3.0 nm to 4.0 nm with a rise of sonication time from 25 min to 100 min. The change of physical properties of ZnFe₂O₄ nanoparticles with the increase of sonication time was observed. The prepared ZnFe₂O₄ nanoparticles show superparamagnetic behavior. The prepared ZnFe₂O₄ nanoparticles (ZS25, ZS50, and ZS100) and reduced graphene oxide (RGO) were embedded in a polyurethane resin (PUR) matrix as a shield against electromagnetic pollution. The ultra-sonication method has been used for the preparation of nanocomposites. The total shielding effectiveness (SE_T) value for the prepared nanocomposites was studied at a thickness of 1 mm in the range of 8.2–12.4 GHz. The high attenuation constant (α) value of the prepared ZS100-RGO-PUR nanocomposite as compared with other samples recommended high absorption of electromagnetic waves. The existence of electric-magnetic nanofillers in the resin matrix delivered the inclusive acts of magnetic loss, dielectric loss, appropriate attenuation constant, and effective impedance matching. The synergistic effect of ZnFe₂O₄ and RGO in the PUR matrix led to high interfacial polarization and, consequently, significant absorption of the electromagnetic waves. The outcomes and methods also assure an inventive and competent approach to develop lightweight and flexible polyurethane resin matrix-based nanocomposites, consisting of superparamagnetic zinc ferrite nanoparticles and reduced graphene oxide as a shield against electromagnetic pollution. Full article

(This article belongs to the Special Issue Advanced Magnetic Nanocomposites: Structural, Physical Properties and Application)

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10 pages, 2247 KB

Open AccessEditor’s ChoiceArticle

High-Performance Non-Volatile InGaZnO Based Flash Memory Device Embedded with a Monolayer Au Nanoparticles

by Muhammad Naqi, Nayoung Kwon, Sung Hyeon Jung, Pavan Pujar, Hae Won Cho, Yong In Cho, Hyung Koun Cho, Byungkwon Lim and Sunkook Kim

Nanomaterials 2021, 11(5), 1101; https://doi.org/10.3390/nano11051101 - 24 Apr 2021

Cited by 13 | Viewed by 5201

Abstract

Non-volatile memory (NVM) devices based on three-terminal thin-film transistors (TFTs) have gained extensive interest in memory applications due to their high retained characteristics, good scalability, and high charge storage capacity. Herein, we report a low-temperature (<100 °C) processed top-gate TFT-type NVM device using [...] Read more.

Non-volatile memory (NVM) devices based on three-terminal thin-film transistors (TFTs) have gained extensive interest in memory applications due to their high retained characteristics, good scalability, and high charge storage capacity. Herein, we report a low-temperature (<100 °C) processed top-gate TFT-type NVM device using indium gallium zinc oxide (IGZO) semiconductor with monolayer gold nanoparticles (AuNPs) as a floating gate layer to obtain reliable memory operations. The proposed NVM device exhibits a high memory window (ΔV_th) of 13.7 V when it sweeps from −20 V to +20 V back and forth. Additionally, the material characteristics of the monolayer AuNPs (floating gate layer) and IGZO film (semiconductor layer) are confirmed using transmission electronic microscopy (TEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS) techniques. The memory operations in terms of endurance and retention are obtained, revealing highly stable endurance properties of the device up to 100 P/E cycles by applying pulses (±20 V, duration of 100 ms) and reliable retention time up to 10⁴ s. The proposed NVM device, owing to the properties of large memory window, stable endurance, and high retention time, enables an excellent approach in futuristic non-volatile memory technology. Full article

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15 pages, 7353 KB

Open AccessEditor’s ChoiceArticle

Thermoelectric Energy Harvesting from Single-Walled Carbon Nanotube Alkali-Activated Nanocomposites Produced from Industrial Waste Materials

by Maliheh Davoodabadi, Ioanna Vareli, Marco Liebscher, Lazaros Tzounis, Massimo Sgarzi, Alkiviadis S. Paipetis, Jian Yang, Gianaurelio Cuniberti and Viktor Mechtcherine

Nanomaterials 2021, 11(5), 1095; https://doi.org/10.3390/nano11051095 - 23 Apr 2021

Cited by 25 | Viewed by 5113

Abstract

A waste-originated one-part alkali-activated nanocomposite is introduced herein as a novel thermoelectric material. For this purpose, single-walled carbon nanotubes (SWCNTs) were utilized as nanoinclusions to create an electrically conductive network within the investigated alkali-activated construction material. Thermoelectric and microstructure characteristics of SWCNT-alkali-activated nanocomposites [...] Read more.

A waste-originated one-part alkali-activated nanocomposite is introduced herein as a novel thermoelectric material. For this purpose, single-walled carbon nanotubes (SWCNTs) were utilized as nanoinclusions to create an electrically conductive network within the investigated alkali-activated construction material. Thermoelectric and microstructure characteristics of SWCNT-alkali-activated nanocomposites were assessed after 28 days. Nanocomposites with 1.0 wt.% SWCNTs exhibited a multifunctional behavior, a combination of structural load-bearing, electrical conductivity, and thermoelectric response. These nanocomposites (1.0 wt.%) achieved the highest thermoelectric performance in terms of power factor (PF), compared to the lower SWCNTs’ incorporations, namely 0.1 and 0.5 wt.%. The measured electrical conductivity (σ) and Seebeck coefficient (S) were 1660 S·m⁻¹ and 15.8 µV·K⁻¹, respectively, which led to a power factor of 0.414 μW·m⁻¹·K⁻². Consequently, they have been utilized as the building block of a thermoelectric generator (TEG) device, which demonstrated a maximum power output (P_out) of 0.695 µW, with a power density (PD) of 372 nW·m⁻², upon exposure to a temperature gradient of 60 K. The presented SWCNT-alkali-activated nanocomposites could establish the pathway towards waste thermal energy harvesting and future sustainable civil engineering structures. Full article

(This article belongs to the Special Issue Novel Thermoelectric Nanomaterials, Nanocomposites and Advanced Fabrication Techniques for Thermoelectric Generator (TEG) Devices)

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10 pages, 3700 KB

Open AccessEditor’s ChoiceArticle

On the Insignificant Role of the Oxidation Process on Ultrafast High-Spatial-Frequency LIPSS Formation on Tungsten

by Priya Dominic, Florent Bourquard, Stéphanie Reynaud, Arnaud Weck, Jean-Philippe Colombier and Florence Garrelie

Nanomaterials 2021, 11(5), 1069; https://doi.org/10.3390/nano11051069 - 22 Apr 2021

Cited by 22 | Viewed by 3758

Abstract

The presence of surface oxides on the formation of laser-induced periodic surface structures (LIPSS) is regularly advocated to favor or even trigger the formation of high-spatial-frequency LIPSS (HSFL) during ultrafast laser-induced nano-structuring. This paper reports the effect of the laser texturing environment on [...] Read more.

The presence of surface oxides on the formation of laser-induced periodic surface structures (LIPSS) is regularly advocated to favor or even trigger the formation of high-spatial-frequency LIPSS (HSFL) during ultrafast laser-induced nano-structuring. This paper reports the effect of the laser texturing environment on the resulting surface oxides and its consequence for HSFLs formation. Nanoripples are produced on tungsten samples using a Ti:sapphire femtosecond laser under atmospheres with varying oxygen contents. Specifically, ambient, 10 mbar pressure of air, nitrogen and argon, and 10⁻⁷ mbar vacuum pressure are used. In addition, removal of any native oxide layer is achieved using plasma sputtering prior to laser irradiation. The resulting HSFLs have a sub-100 nm periodicity and sub 20 nm amplitude. The experiments reveal the negligible role of oxygen during the HSFL formation and clarifies the significant role of ambient pressure in the resulting HSFLs period. Full article

(This article belongs to the Special Issue Laser-Generated Periodic Nanostructures)

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37 pages, 2397 KB

Open AccessEditor’s ChoiceReview

Gold Nanoparticles Synthesis and Antimicrobial Effect on Fibrous Materials

by Behnaz Mehravani, Ana Isabel Ribeiro and Andrea Zille

Nanomaterials 2021, 11(5), 1067; https://doi.org/10.3390/nano11051067 - 21 Apr 2021

Cited by 66 | Viewed by 7237

Abstract

Depositing nanoparticles in textiles have been a promising strategy to achieve multifunctional materials. Particularly, antimicrobial properties are highly valuable due to the emergence of new pathogens and the spread of existing ones. Several methods have been used to functionalize textile materials with gold [...] Read more.

Depositing nanoparticles in textiles have been a promising strategy to achieve multifunctional materials. Particularly, antimicrobial properties are highly valuable due to the emergence of new pathogens and the spread of existing ones. Several methods have been used to functionalize textile materials with gold nanoparticles (AuNPs). Therefore, this review highlighted the most used methods for AuNPs preparation and the current studies on the topic in order to obtain AuNPs with suitable properties for antimicrobial applications and minimize the environmental concerns in their production. Reporting the detailed information on the functionalization of fabrics, yarns, and fibers with AuNPs by different methods to improve the antimicrobial properties was the central objective. The studies combining AuNPs and textile materials have opened valuable opportunities to develop antimicrobial materials for health and hygiene products, as infection control and barrier material, with improved properties. Future studies are needed to amplify the antimicrobial effect of AuNPs onto textiles and minimize the concerns related to the synthesis. Full article

(This article belongs to the Special Issue Inorganic Nanoparticles: Synthesis, Characterization and Nanoscopic Properties)

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17 pages, 3310 KB

Open AccessEditor’s ChoiceReview

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 26 | Viewed by 8645

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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8 pages, 1699 KB

Open AccessEditor’s ChoiceArticle

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 19 | Viewed by 4320

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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18 pages, 3114 KB

Open AccessEditor’s ChoiceArticle

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 18 | Viewed by 4647

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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12 pages, 2560 KB

Open AccessEditor’s ChoiceArticle

Carbon-Nanotube-Coated Surface Electrodes for Cortical Recordings In Vivo

by Katharina Foremny, Wiebke S. Konerding, Ailke Behrens, Peter Baumhoff, Ulrich P. Froriep, Andrej Kral and Theodor Doll

Nanomaterials 2021, 11(4), 1029; https://doi.org/10.3390/nano11041029 - 17 Apr 2021

Cited by 9 | Viewed by 3485

Abstract

Current developments of electrodes for neural recordings address the need of biomedical research and applications for high spatial acuity in electrophysiological recordings. One approach is the usage of novel materials to overcome electrochemical constraints of state-of-the-art metal contacts. Promising materials are carbon nanotubes [...] Read more.

Current developments of electrodes for neural recordings address the need of biomedical research and applications for high spatial acuity in electrophysiological recordings. One approach is the usage of novel materials to overcome electrochemical constraints of state-of-the-art metal contacts. Promising materials are carbon nanotubes (CNTs), as they are well suited for neural interfacing. The CNTs increase the effective contact surface area to decrease high impedances while keeping minimal contact diameters. However, to prevent toxic dissolving of CNTs, an appropriate surface coating is required. In this study, we tested flexible surface electrocorticographic (ECoG) electrodes, coated with a CNT-silicone rubber composite. First, we describe the outcome of surface etching, which exposes the contact nanostructure while anchoring the CNTs. Subsequently, the ECoG electrodes were used for acute in vivo recordings of auditory evoked potentials from the guinea pig auditory cortex. Both the impedances and the signal-to-noise ratios of coated contacts were similar to uncoated gold contacts. This novel approach for a safe application of CNTs, embedded in a surface etched silicone rubber, showed promising results but did not lead to improvements during acute recordings. Full article

(This article belongs to the Special Issue Biomedical Applications of Graphene-Based Nanomaterials)

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12 pages, 6533 KB

Open AccessEditor’s ChoiceArticle

Self-Organization Regimes Induced by Ultrafast Laser on Surfaces in the Tens of Nanometer Scales

by Anthony Nakhoul, Claire Maurice, Marion Agoyan, Anton Rudenko, Florence Garrelie, Florent Pigeon and Jean-Philippe Colombier

Nanomaterials 2021, 11(4), 1020; https://doi.org/10.3390/nano11041020 - 16 Apr 2021

Cited by 31 | Viewed by 4444

Abstract

A laser-irradiated surface is the paradigm of a self-organizing system, as coherent, aligned, chaotic, and complex patterns emerge at the microscale and even the nanoscale. A spectacular manifestation of dissipative structures consists of different types of randomly and periodically distributed nanostructures that arise [...] Read more.

A laser-irradiated surface is the paradigm of a self-organizing system, as coherent, aligned, chaotic, and complex patterns emerge at the microscale and even the nanoscale. A spectacular manifestation of dissipative structures consists of different types of randomly and periodically distributed nanostructures that arise from a homogeneous metal surface. The noninstantaneous response of the material reorganizes local surface topography down to tens of nanometers scale modifying long-range surface morphology on the impact scale. Under ultrafast laser irradiation with a regulated energy dose, the formation of nanopeaks, nanobumps, nanohumps and nanocavities patterns with 20–80 nm transverse size unit and up to 100 nm height are reported. We show that the use of crossed-polarized double laser pulse adds an extra dimension to the nanostructuring process as laser energy dose and multi-pulse feedback tune the energy gradient distribution, crossing critical values for surface self-organization regimes. The tiny dimensions of complex patterns are defined by the competition between the evolution of transient liquid structures generated in a cavitation process and the rapid resolidification of the surface region. Strongly influencing the light coupling, we reveal that initial surface roughness and type of roughness both play a crucial role in controlling the transient emergence of nanostructures during laser irradiation. Full article

(This article belongs to the Special Issue Laser-Generated Periodic Nanostructures)

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17 pages, 30041 KB

Open AccessEditor’s ChoiceArticle

Characterization of Plasmonic Scattering, Luminescent Down-Shifting, and Metal-Enhanced Fluorescence and Applications on Silicon Solar Cells

by Wen-Jeng Ho, Jheng-Jie Liu and Jhih-Ciang Chen

Nanomaterials 2021, 11(4), 1013; https://doi.org/10.3390/nano11041013 - 15 Apr 2021

Cited by 5 | Viewed by 2798

Abstract

This paper studied characterized the plasmonic effects of silver nanoparticles (Ag-NPs), the luminescent down-shifting of Eu-doped phosphor particles, and the metal-enhanced fluorescence (MEF) achieved by combining the two processes to enhance the conversion efficiency of silicon solar cells. We obtained measurements of photoluminescence [...] Read more.

This paper studied characterized the plasmonic effects of silver nanoparticles (Ag-NPs), the luminescent down-shifting of Eu-doped phosphor particles, and the metal-enhanced fluorescence (MEF) achieved by combining the two processes to enhance the conversion efficiency of silicon solar cells. We obtained measurements of photoluminescence (PL) and external quantum efficiency (EQE) at room temperature to determine whether the fluorescence emissions intensity of Eu-doped phosphor was enhanced or quenched by excitation induced via surface plasmon resonance (SPR). Overall, fluorescence intensity was enhanced when the fluorescence emission band was strongly coupled to the SPR band of Ag-NPs and the two particles were separated by a suitable distance. We observed a 1.125× increase in PL fluorescence intensity at a wavelength of 514 nm and a 7.05% improvement in EQE (from 57.96% to 62.05%) attributable to MEF effects. The combined effects led to a 26.02% increase in conversion efficiency (from 10.23% to 12.89%) in the cell with spacer/NPs/SOG-phosphors and a 22.09% increase (from 10.23% to 12.48%) in the cell with spacer/SOG-phosphors, compared to the bare solar cell. This corresponds to an impressive 0.85% increase in absolute efficiency (from 12.04% to 12.89%), compared to the cell with only spacer/SOG. Full article

(This article belongs to the Special Issue Luminescent Nanomaterials and Their Applications)

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12 pages, 1949 KB

Open AccessEditor’s ChoiceArticle

Probing the Surface Chemistry of Nanoporous Gold via Electrochemical Characterization and Atom Probe Tomography

by AmirHossein Foroozan-Ebrahimy, Brian Langelier and Roger Charles Newman

Nanomaterials 2021, 11(4), 1002; https://doi.org/10.3390/nano11041002 - 14 Apr 2021

Cited by 2 | Viewed by 3491

Abstract

Surface chemistry information is crucial in understanding catalytic and sensing mechanisms. However, resolving the outermost monolayer composition of metallic nanoporous materials is challenging due to the high tortuosity of their morphology. In this study, we first elaborate on the capabilities and limitations of [...] Read more.

Surface chemistry information is crucial in understanding catalytic and sensing mechanisms. However, resolving the outermost monolayer composition of metallic nanoporous materials is challenging due to the high tortuosity of their morphology. In this study, we first elaborate on the capabilities and limitations of atom probe tomography (APT) in resolving interfaces. Subsequently, an electrochemical approach is designed to characterize the surface composition of nanoporous gold (NPG), developed from dealloying an inexpensive precursor (95 at. % Ag, 5 at. % Au), by the means of aqueous electrochemical measurements of the selective electrosorption of sulfide ions, which react strongly with Ag, but to a significantly lesser extent with Au. Accordingly, cyclic voltammetry was performed at various scan rates on NPG in alkaline aqueous solutions (0.2 M NaOH; pH 13) in the presence and absence of 1 mM Na₂S. Calibrations via similar voltammetric measurements on pure polycrystalline Ag and Au surfaces allowed for a quantitative estimation for the Ag surface coverage of NPG. The sensitivity threshold for the detection of the adsorbate–Ag interaction was assessed to be approximately 2% Ag surface coverage. As curves measured on NPG only showed featureless capacitive currents, no faradaic charge density associated with sulfide electrosorption could be detected. This study opens a new avenue to gain further insight into the monolayer surface coverage of metallic nanoporous materials and assists in enhancement of the interpretation of APT reconstructions. Full article

(This article belongs to the Special Issue Growth, Characterization, and Modelling of Nanostructures for Applications in Sensing)

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10 pages, 14327 KB

Open AccessEditor’s ChoiceArticle

Study on Performance Improvements in Perovskite-Based Ultraviolet Sensors Prepared Using Toluene Antisolvent and CH₃NH₃Cl

by Seong Gwan Shin, Chung Wung Bark and Hyung Wook Choi

Nanomaterials 2021, 11(4), 1000; https://doi.org/10.3390/nano11041000 - 13 Apr 2021

Cited by 14 | Viewed by 3298

Abstract

In this study, a simply structured perovskite-based ultraviolet C (UVC) sensor was prepared using a one-step, low-temperature solution-processing coating method. The UVC sensor utilized CH₃NH₃PbBr₃ perovskite as the light-absorbing layer. To improve the characteristics of CH₃NH [...] Read more.

In this study, a simply structured perovskite-based ultraviolet C (UVC) sensor was prepared using a one-step, low-temperature solution-processing coating method. The UVC sensor utilized CH₃NH₃PbBr₃ perovskite as the light-absorbing layer. To improve the characteristics of CH₃NH₃PbBr₃, an antisolvent process using toluene and the addition of CH₃NH₃Cl were introduced. The device with these modifications exhibited a response rise/fall time of 15.8/16.2 ms, mobility of 158.7 cm²/V·s, responsivity of 4.57 mA/W, detectivity of 1.02 × 10¹³ Jones, and external quantum efficiency of 22.32% under the 254-nm UV illumination. Therefore, this methodology could be a good approach in facilitating UVC detection. Full article

(This article belongs to the Section Nanophotonics Materials and Devices)

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24 pages, 9498 KB

Open AccessEditor’s ChoiceArticle

Numerical Study of Natural Convection Heat Transfer in a Porous Annulus Filled with a Cu-Nanofluid

by Lingyun Zhang, Yupeng Hu and Minghai Li

Nanomaterials 2021, 11(4), 990; https://doi.org/10.3390/nano11040990 - 12 Apr 2021

Cited by 19 | Viewed by 3765

Abstract

Natural convection heat transfer in a porous annulus filled with a Cu nanofluid has been investigated numerically. The Darcy–Brinkman and the energy transport equations are employed to describe the nanofluid motion and the heat transfer in the porous medium. Numerical results including the [...] Read more.

Natural convection heat transfer in a porous annulus filled with a Cu nanofluid has been investigated numerically. The Darcy–Brinkman and the energy transport equations are employed to describe the nanofluid motion and the heat transfer in the porous medium. Numerical results including the isotherms, streamlines, and heat transfer rate are obtained under the following parameters: Brownian motion, Rayleigh number (10³–10⁵), Darcy number (10⁻⁴–10⁻²), nanoparticle volume fraction (0.01–0.09), nanoparticle diameter (10–90 nm), porosity (0.1–0.9), and radius ratio (1.1–10). Results show that Brownian motion should be considered. The nanoparticle volume fraction has a positive effect on the heat transfer rate, especially with high Rayleigh number and Darcy number, while the nanoparticle diameter has an inverse influence. The heat transfer rate is enhanced with the increase of porosity. The radius ratio has a significant influence on the isotherms, streamlines, and heat transfer rate, and the rate is greatly enhanced with the increase of radius ratio. Full article

(This article belongs to the Special Issue Heat Transfer and Fluids Properties of Nanofluids)

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10 pages, 5234 KB

Open AccessEditor’s ChoiceArticle

Enhanced Heat-Electric Conversion via Photonic-Assisted Radiative Cooling

by Jeng-Yi Lee, Chih-Ming Wang, Chieh-Lun Chi, Sheng-Rui Wu, Ya-Xun Lin, Mao-Kuo Wei and Chu-Hsuan Lin

Nanomaterials 2021, 11(4), 983; https://doi.org/10.3390/nano11040983 - 11 Apr 2021

Cited by 9 | Viewed by 3239

Abstract

In this paper, an inorganic polymer composite film is proposed as an effective radiative cooling device. The inherent absorption is enhanced by choosing an appropriately sized SiO₂ microsphere with a diameter of 6 μm. The overall absorption at the transparent window of [...] Read more.

In this paper, an inorganic polymer composite film is proposed as an effective radiative cooling device. The inherent absorption is enhanced by choosing an appropriately sized SiO₂ microsphere with a diameter of 6 μm. The overall absorption at the transparent window of the atmosphere is higher than 90%, as the concentration of SiO₂–PMMA composite is 35 wt%. As a result, an effective radiative device is made by a spin coating process. Moreover, the device is stacked on the cold side of a thermoelectric generator chip. It is found that the temperature gradient can be increased via the effective radiative cooling process. An enhanced Seebeck effect is observed, and the corresponding output current can be enhanced 1.67-fold via the photonic-assisted radiative cooling. Full article

(This article belongs to the Special Issue State-of-the-Art Optical Properties and Applications of Metallic Nanostructures in Asia)

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23 pages, 4527 KB

Open AccessEditor’s ChoiceArticle

Synthesis of Polystyrene-Based Cationic Nanomaterials with Pro-Oxidant Cytotoxic Activity on Etoposide-Resistant Neuroblastoma Cells

by Silvana Alfei, Barbara Marengo, Giulia Elda Valenti and Cinzia Domenicotti

Nanomaterials 2021, 11(4), 977; https://doi.org/10.3390/nano11040977 - 10 Apr 2021

Cited by 21 | Viewed by 2874

Abstract

Drug resistance is a multifactorial phenomenon that limits the action of antibiotics and chemotherapeutics. Therefore, it is essential to develop new therapeutic strategies capable of inducing cytotoxic effects circumventing chemoresistance. In this regard, the employment of natural and synthetic cationic peptides and polymers [...] Read more.

Drug resistance is a multifactorial phenomenon that limits the action of antibiotics and chemotherapeutics. Therefore, it is essential to develop new therapeutic strategies capable of inducing cytotoxic effects circumventing chemoresistance. In this regard, the employment of natural and synthetic cationic peptides and polymers has given satisfactory results both in microbiology, as antibacterial agents, but also in the oncological field, resulting in effective treatment against several tumors, including neuroblastoma (NB). To this end, two polystyrene-based copolymers (P5, P7), containing primary ammonium groups, were herein synthetized and tested on etoposide-sensitive (HTLA-230) and etoposide-resistant (HTLA-ER) NB cells. Both copolymers were water-soluble and showed a positive surface charge due to nitrogen atoms, which resulted in protonation in the whole physiological pH range. Furthermore, P5 and P7 exhibited stability in solution, excellent buffer capacity, and nanosized particles, and they were able to reduce NB cell viability in a concentration-dependent way. Interestingly, a significant increase in reactive oxygen species (ROS) production was observed in both NB cell populations treated with P5 or P7, establishing for both copolymers an unequivocal correlation between cytotoxicity and ROS generation. Therefore, P5 and P7 could be promising template macromolecules for the development of new chemotherapeutic agents able to fight NB chemoresistance. Full article

(This article belongs to the Special Issue Nanoparticles for Bio-Medical Applications)

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21 pages, 4907 KB

Open AccessEditor’s ChoiceArticle

Synthesis of Poly(Malic Acid) Derivatives End-Functionalized with Peptides and Preparation of Biocompatible Nanoparticles to Target Hepatoma Cells

by Clarisse Brossard, Manuel Vlach, Elise Vène, Catherine Ribault, Vincent Dorcet, Nicolas Noiret, Pascal Loyer, Nicolas Lepareur and Sandrine Cammas-Marion

Nanomaterials 2021, 11(4), 958; https://doi.org/10.3390/nano11040958 - 9 Apr 2021

Cited by 15 | Viewed by 3484

Abstract

Recently, short synthetic peptides have gained interest as targeting agents in the design of site-specific nanomedicines. In this context, our work aimed at developing new tools for the diagnosis and/or therapy of hepatocellular carcinoma (HCC) by grafting the hepatotropic George Baker (GB) virus [...] Read more.

Recently, short synthetic peptides have gained interest as targeting agents in the design of site-specific nanomedicines. In this context, our work aimed at developing new tools for the diagnosis and/or therapy of hepatocellular carcinoma (HCC) by grafting the hepatotropic George Baker (GB) virus A (GBVA10-9) and Plasmodium circumsporozoite protein (CPB)-derived peptides to the biocompatible poly(benzyl malate), PMLABe. We successfully synthesized PMLABe derivatives end-functionalized with peptides GBVA10-9, CPB, and their corresponding scrambled peptides through a thiol/maleimide reaction. The corresponding nanoparticles (NPs), varying by the nature of the peptide (GBVA10-9, CPB, and their scrambled peptides) and the absence or presence of poly(ethylene glycol) were also successfully formulated using nanoprecipitation technique. NPs were further characterized by dynamic light scattering (DLS), electrophoretic light scattering (ELS) and transmission electron microscopy (TEM), highlighting a diameter lower than 150 nm, a negative surface charge, and a more or less spherical shape. Moreover, a fluorescent probe (DiD Oil) has been encapsulated during the nanoprecipitation process. Finally, preliminary in vitro internalisation assays using HepaRG hepatoma cells demonstrated that CPB peptide-functionalized PMLABe NPs were efficiently internalized by endocytosis, and that such nanoobjects may be promising drug delivery systems for the theranostics of HCC. Full article

(This article belongs to the Special Issue Development of Multifunctional Nanoparticles for Therapy and/or Diagnosis)

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10 pages, 2541 KB

Open AccessEditor’s ChoiceArticle

Li₂(BH₄)(NH₂) Nanoconfined in SBA-15 as Solid-State Electrolyte for Lithium Batteries

by Qianyi Yang, Fuqiang Lu, Yulin Liu, Yijie Zhang, Xiujuan Wang, Yuepeng Pang and Shiyou Zheng

Nanomaterials 2021, 11(4), 946; https://doi.org/10.3390/nano11040946 - 8 Apr 2021

Cited by 9 | Viewed by 3647

Abstract

Solid electrolytes with high Li-ion conductivity and electrochemical stability are very important for developing high-performance all-solid-state batteries. In this work, Li₂(BH₄)(NH₂) is nanoconfined in the mesoporous silica molecule sieve (SBA-15) using a melting–infiltration approach. This electrolyte exhibits [...] Read more.

Solid electrolytes with high Li-ion conductivity and electrochemical stability are very important for developing high-performance all-solid-state batteries. In this work, Li₂(BH₄)(NH₂) is nanoconfined in the mesoporous silica molecule sieve (SBA-15) using a melting–infiltration approach. This electrolyte exhibits excellent Li-ion conduction properties, achieving a Li-ion conductivity of 5.0 × 10⁻³ S cm⁻¹ at 55 °C, an electrochemical stability window of 0 to 3.2 V and a Li-ion transference number of 0.97. In addition, this electrolyte can enable the stable cycling of Li|Li₂(BH₄)(NH₂)@SBA-15|TiS₂ cells, which exhibit a reversible specific capacity of 150 mAh g⁻¹ with a Coulombic efficiency of 96% after 55 cycles. Full article

(This article belongs to the Special Issue Advances in Nanomaterials for Lithium-Ion/Post-Lithium-Ion Batteries and Supercapacitors)

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