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17 pages, 3363 KiB

Open AccessArticle

Mono- and Bimetallic Nanoparticles Stabilized by an Aromatic Polymeric Network for a Suzuki Cross-Coupling Reaction

by Linda Zh. Nikoshvili, Kristina N. Shkerina, Alexey V. Bykov, Alexander I. Sidorov, Alexander L. Vasiliev, Mikhail G. Sulman and Lioubov Kiwi-Minsker

Nanomaterials 2022, 12(1), 94; https://doi.org/10.3390/nano12010094 - 29 Dec 2021

Cited by 2 | Viewed by 2093

Abstract

This work addresses the Suzuki cross-coupling between 4-bromoanisole (BrAn) and phenylboronic acid (PBA) in an environmentally benign ethanol–water solvent catalysed by mono- (Pd) and bimetallic (PdAu, PdCu, PdZn) nanoparticles (NPs) stabilised within hyper-cross-linked polystyrene (HPS) bearing tertiary amino groups. Small Pd NPs of [...] Read more.

This work addresses the Suzuki cross-coupling between 4-bromoanisole (BrAn) and phenylboronic acid (PBA) in an environmentally benign ethanol–water solvent catalysed by mono- (Pd) and bimetallic (PdAu, PdCu, PdZn) nanoparticles (NPs) stabilised within hyper-cross-linked polystyrene (HPS) bearing tertiary amino groups. Small Pd NPs of about 2 nm in diameters were formed and stabilized by HPS independently in the presence of other metals. High catalytic activity and complete conversion of BrAn was attained at low Pd loading. Introduction of Zn to the catalyst composition resulted in the formation of Pd/Zn/ZnO NPs, which demonstrated nearly double activity as compared to Pd/HPS. Bimetallic core-shell PdAu/HPS samples were 3-fold more active as compared to Pd/HPS. Both Pd/HPS and PdAu/HPS samples revealed promising stability confirmed by catalyst recycling in repeated reaction runs. Full article

(This article belongs to the Special Issue Metal Oxide Nanoparticles and Nanowires: Synthesis, Characterization, and Applications)

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13 pages, 2579 KiB

Open AccessArticle

Evaluation of Ni-Based Flexible Resistance Temperature Detectors Fabricated by Laser Digital Pattering

by Vu Binh Nam and Daeho Lee

Nanomaterials 2021, 11(3), 576; https://doi.org/10.3390/nano11030576 - 25 Feb 2021

Cited by 24 | Viewed by 4014

Abstract

Temperature sensors are ubiquitous in every field of engineering application since temperature control is vital in operating, testing and monitoring various equipment systems. Herein, we introduce a facile and rapid laser digital patterning (LDP) process to fabricate low-cost, Ni-based flexible resistance temperature detectors [...] Read more.

Temperature sensors are ubiquitous in every field of engineering application since temperature control is vital in operating, testing and monitoring various equipment systems. Herein, we introduce a facile and rapid laser digital patterning (LDP) process to fabricate low-cost, Ni-based flexible resistance temperature detectors (RTDs). Ni-based RTDs are directly generated on a thin flexible polyimide substrate (thickness: 50 µm) by laser-induced reductive sintering of a solution-processed nonstoichiometric nickel oxide (NiO_x) nanoparticle thin film under ambient conditions. The shape of RTDs can be easily adjusted by controlling computer-aided design (CAD) data without using the physical patterning mask while the sensitivity (temperature coefficient of resistance (α) ~ 3.52 × 10⁻³ °C⁻¹) of the sensors can be maintained regardless of shape and size of the sensor electrodes. The flexible Ni-based RTDs can operate over a wide temperature range up to 200 °C with excellent repeatability. Additionally, the Ni-based RTDs respond quickly to the temperature change and can operate in corrosive environments including water and seawater. Moreover, the Ni-based RTDs show a superior mechanical and electrical stability with a negligible resistance change up to a radius of curvature of 1.75 mm. Finally, a tape-pull test demonstrates the robust adhesion of Ni-based RTDs on the substrate. Full article

(This article belongs to the Special Issue Metal Oxide Nanoparticles and Nanowires: Synthesis, Characterization, and Applications)

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12 pages, 2244 KiB

Open AccessArticle

Border Trap Characterizations of Al₂O₃/ZrO₂ and Al₂O₃/HfO₂ Bilayer Films Based on Ambient Post Metal Annealing and Constant Voltage Stress

by Md. Mamunur Rahman, Dae-Hyun Kim and Tae-Woo Kim

Nanomaterials 2020, 10(3), 527; https://doi.org/10.3390/nano10030527 - 15 Mar 2020

Cited by 10 | Viewed by 4274

Abstract

This study represents a comparison of the border trap behavior and reliability between HfO₂ and ZrO₂ films on n-In_0.53Ga_0.47As with an Al₂O₃ interfacial layer. The effect of different post metal annealing conditions on [...] Read more.

This study represents a comparison of the border trap behavior and reliability between HfO₂ and ZrO₂ films on n-In_0.53Ga_0.47As with an Al₂O₃ interfacial layer. The effect of different post metal annealing conditions on the trap response was analyzed and it was found that the N₂:H₂ mixed FGA passivates the border trap quite well, whereas N₂-based RTA performs better on interface traps. Al₂O₃/HfO₂ showed more degradation in terms of the threshold voltage shift while Al₂O₃/ZrO₂ showed higher leakage current behavior. Moreover, Al₂O₃/ZrO₂ showed a higher permittivity, hysteresis, and breakdown field than Al₂O₃/HfO₂. Full article

(This article belongs to the Special Issue Metal Oxide Nanoparticles and Nanowires: Synthesis, Characterization, and Applications)

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13 pages, 3047 KiB

Open AccessArticle

Highly Rectifying Heterojunctions Formed by Annealed ZnO Nanorods on GaN Substrates

by Stanislav Tiagulskyi, Roman Yatskiv, Hana Faitová, Šárka Kučerová, David Roesel, Jan Vaniš, Jan Grym and Jozef Veselý

Nanomaterials 2020, 10(3), 508; https://doi.org/10.3390/nano10030508 - 11 Mar 2020

Cited by 11 | Viewed by 3826

Abstract

We study the effect of thermal annealing on the electrical properties of the nanoscale p-n heterojunctions based on single n-type ZnO nanorods on p-type GaN substrates. The ZnO nanorods are prepared by chemical bath deposition on both plain GaN [...] Read more.

We study the effect of thermal annealing on the electrical properties of the nanoscale p-n heterojunctions based on single n-type ZnO nanorods on p-type GaN substrates. The ZnO nanorods are prepared by chemical bath deposition on both plain GaN substrates and on the substrates locally patterned by focused ion beam lithography. Electrical properties of single nanorod heterojunctions are measured with a nanoprobe in the vacuum chamber of a scanning electron microscope. The focused ion beam lithography provides a uniform nucleation of ZnO, which results in a uniform growth of ZnO nanorods. The specific configuration of the interface between the ZnO nanorods and GaN substrate created by the focused ion beam suppresses the surface leakage current and improves the current-voltage characteristics. Further improvement of the electrical characteristics is achieved by annealing of the structures in nitrogen, which limits the defect-mediated leakage current and increases the carrier injection efficiency. Full article

(This article belongs to the Special Issue Metal Oxide Nanoparticles and Nanowires: Synthesis, Characterization, and Applications)

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16 pages, 5701 KiB

Open AccessArticle

High-Performance Ultraviolet Photodetector Based on a Zinc Oxide Nanoparticle@Single-Walled Carbon Nanotube Heterojunction Hybrid Film

by Myung-Soo Choi, Taehyun Park, Woo-Jae Kim and Jaehyun Hur

Nanomaterials 2020, 10(2), 395; https://doi.org/10.3390/nano10020395 - 24 Feb 2020

Cited by 40 | Viewed by 5303

Abstract

A hybrid film consisting of zinc oxide nanoparticles (ZnO NPs) and carbon nanotubes (CNTs) is formed on a glass substrate using a simple and swift spin coating process for the use in ultraviolet photodetectors (UV PDs). The incorporation of various types of CNTs [...] Read more.

A hybrid film consisting of zinc oxide nanoparticles (ZnO NPs) and carbon nanotubes (CNTs) is formed on a glass substrate using a simple and swift spin coating process for the use in ultraviolet photodetectors (UV PDs). The incorporation of various types of CNTs into ZnO NPs (ZnO@CNT) enhances the performance of UV PDs with respect to sensitivity, photoresponse, and long-term operation stability when compared with pristine ZnO NP films. In particular, the introduction of single-walled CNTs (SWNTs) exhibits a superior performance when compared with the multiwalled CNTs (MWNTs) because SWNTs can not only facilitate the stability of free electrons generated by the O₂ desorption on ZnO under UV irradiation owing to the built-in potential between ZnO and SWNT heterojunctions, but also allow facile and efficient transport pathways for electrons through SWNTs with high aspect ratio and low defect density. Furthermore, among the various SWNTs (arc-discharged (A-SWNT), Hipco (H-SWNT), and CoMoCat (C-SWNT) SWNTs), we demonstrate the ZnO@A-SWNT hybrid film exhibits the best performance because of higher conductivity and aspect ratio in A-SWNTs when compared with those of other types of SWNTs. At the optimized conditions for the ZnO@A-SWNT film (ratio of A-SWNTs and ZnO NPs and electrode distance), ZnO@A-SWNT displays a sensitivity of 4.9 × 10³ % with an on/off current ratio of ~10⁴ at the bias of 2 V under the UV wavelength of 365 nm (0.47 mW/cm²). In addition, the stability in long-term operation and photoresponse time are significantly improved by the introduction of A-SWNTs into the ZnO NP film when compared with the bare ZnO NPs film. Full article

(This article belongs to the Special Issue Metal Oxide Nanoparticles and Nanowires: Synthesis, Characterization, and Applications)

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8 pages, 2124 KiB

Open AccessArticle

Flexible Free-Standing Cu_xO/Ag₂O (x = 1, 2) Nanowires Integrated with Nanoporous Cu-Ag Network Composite for Glucose Sensing

by Qian Zhang, Man Li, Chunling Qin, Zhifeng Wang, Weimin Zhao and Yongyan Li

Nanomaterials 2020, 10(2), 357; https://doi.org/10.3390/nano10020357 - 19 Feb 2020

Cited by 5 | Viewed by 2932

Abstract

To improve glucose electrocatalytic performance, one efficient manner is to develop a novel Cu-Ag bimetallic composite with fertile porosity and unique architecture. Herein, the self-supported electrode with Cu_xO/Ag₂O (x = 1, 2) nanowires grown in-situ on a nanoporous [...] Read more.

To improve glucose electrocatalytic performance, one efficient manner is to develop a novel Cu-Ag bimetallic composite with fertile porosity and unique architecture. Herein, the self-supported electrode with Cu_xO/Ag₂O (x = 1, 2) nanowires grown in-situ on a nanoporous Cu-Ag network (Cu_xO/Ag₂O@NP-CuAg) has been successfully designed by a facile two-step approach. The integrated hierarchical porous structure, the tip-converged Cu_xO/Ag₂O nanowires combined with the interconnected porous conductive substrate, are favorable to provide more reactive sites and improve ions or electrons transportation. Compared with monometallic Cu₂O nanowires integrated with nanoporous Cu matrix (Cu₂O@NP-Cu), the bimetallic Cu_xO/Ag₂O@NP-CuAg composites exhibit the enhanced electrocatalytic performance for glucose. Moreover, the higher sensitivity of ~1.49 mA mM⁻¹ cm⁻² in conjunction with a wider linear range of 17 mM for the Cu_xO/Ag₂O@NP-CuAg electrode anodized for 10 min are attributed to the synergistic effect of porous structure and bimetallic Cu_xO/Ag₂O nanowires. Particularly, the integrated Cu_xO/Ag₂O@NP-CuAg composites possess good flexibility, which has been reported for the first time. Accordingly, the Cu_xO/Ag₂O@NP-CuAg with excellent glucose electrocatalytic performance and good flexibility is promising to further develop as a candidate electrode material of glucose sensors. Full article

(This article belongs to the Special Issue Metal Oxide Nanoparticles and Nanowires: Synthesis, Characterization, and Applications)

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27 pages, 8605 KiB

Open AccessArticle

Green Synthesized Copper Oxide Nanoparticles Ameliorate Defence and Antioxidant Enzymes in Lens culinaris

by Joy Sarkar, Nilanjan Chakraborty, Arindam Chatterjee, Avisek Bhattacharjee, Disha Dasgupta and Krishnendu Acharya

Nanomaterials 2020, 10(2), 312; https://doi.org/10.3390/nano10020312 - 12 Feb 2020

Cited by 156 | Viewed by 10782

Abstract

Biosynthesis of copper oxide nanoparticles (CuONPs) in a cost-effective and eco-friendly way has gained its importance. CuONPs has been prepared from copper sulfate by using Adiantum lunulatum whole plant extract. CuONPs have been characterized by X-ray diffraction, Fourier transform infrared spectroscopic, transmission electron [...] Read more.

Biosynthesis of copper oxide nanoparticles (CuONPs) in a cost-effective and eco-friendly way has gained its importance. CuONPs has been prepared from copper sulfate by using Adiantum lunulatum whole plant extract. CuONPs have been characterized by X-ray diffraction, Fourier transform infrared spectroscopic, transmission electron microscope, etc. Mono-disperse, spherical, pure, and highly stable CuONPs have formed with an average diameter of 6.5 ± 1.5 nm. Biosynthesized CuONPs at different concentrations were applied to seeds of Lens culinaris. Physiological characteristics were investigated in the germinated seeds. Roots obtained from the seeds treated with 0.025 mgmL⁻¹ concentration of CuONPs showed highest activity of different defence enzymes and total phenolics. However, at higher concentration it becomes close to control. It showed gradual increase of antioxidative enzymes, in accordance with the increasing dose of CuONPs. Likewise, lipid peroxidation and proline content gradually increased with the increasing concentration. Reactive oxygen species and nitric oxide generation was also altered due to CuONPs treatment indicating stress signal transduction. Finally, this study provides a new approach of the production of valuable CuONPs, is a unique, economical, and handy tool for large scale saleable production which can also be used as a potent plant defence booster instead of other commercial uses. Full article

(This article belongs to the Special Issue Metal Oxide Nanoparticles and Nanowires: Synthesis, Characterization, and Applications)

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11 pages, 3774 KiB

Open AccessArticle

A Convenient Colorimetric Bacteria Detection Method Utilizing Chitosan-Coated Magnetic Nanoparticles

by Thao Nguyen Le, Tai Duc Tran and Moon Il Kim

Nanomaterials 2020, 10(1), 92; https://doi.org/10.3390/nano10010092 - 2 Jan 2020

Cited by 47 | Viewed by 6415

Abstract

An effective novel strategy to detect bacteria is promising because it may improve human health by allowing early diagnosis and timely treatment of bacterial infections. Here, we report a simple, reliable, and economical colorimetric assay using the peroxidase-like activity of chitosan-coated iron oxide [...] Read more.

An effective novel strategy to detect bacteria is promising because it may improve human health by allowing early diagnosis and timely treatment of bacterial infections. Here, we report a simple, reliable, and economical colorimetric assay using the peroxidase-like activity of chitosan-coated iron oxide magnetic nanoparticles (CS-MNPs). When CS-MNPs are incubated with a sample containing bacterial cells such as the gram-negative Escherichia coli or the gram-positive Staphylococcus aureus, the negatively-charged bacterial membrane interacts with positively-charged chitosan on the surface of CS-MNPs, thus resulting in significant reduction of their peroxidase-like activity presumably by a hindrance in the accessibility of the negatively charged substrate, 2-2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) to the positively-charged CS-MNPs. This simple colorimetric strategy allowed the rapid detection of bacterial cells down to 10⁴ CFU mL⁻¹ by the naked eye and 10² CFU mL⁻¹ by spectrophotometry within 10 min. Based on the results, we anticipate that the CS-MNPs-based assay has great potential for the on-site diagnosis of bacterial infections in facility-limited or point-of-care testing (POCT) environments. Full article

(This article belongs to the Special Issue Metal Oxide Nanoparticles and Nanowires: Synthesis, Characterization, and Applications)

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7 pages, 250 KiB

Open AccessPerspective

A Pragmatic Perspective of the Antibacterial Properties of Metal-Based Nanoparticles

by Edward Sacher and Arthur Yelon

Nanomaterials 2021, 11(12), 3214; https://doi.org/10.3390/nano11123214 - 26 Nov 2021

Cited by 3 | Viewed by 1770

Abstract

A consideration of the antibacterial efficacy of metal-based nanoparticles, from the point of view of their physicochemical properties, suggests that such efficacy arises from the protein coronas that form around them, and that the contents of the coronas depend on the chemical groups [...] Read more.

A consideration of the antibacterial efficacy of metal-based nanoparticles, from the point of view of their physicochemical properties, suggests that such efficacy arises from the protein coronas that form around them, and that the contents of the coronas depend on the chemical groups found on the nanoparticle surfaces. We offer a new perspective and new insights, making use of our earlier observations of the physicochemical properties of nanoparticle surfaces, to propose that the nanoparticle serves as a mediator for the formation and activation of the protein corona, which attacks the bacterium. That is, the nanoparticle enhances the body’s natural defenses, using proteins present in body fluids. Full article

(This article belongs to the Special Issue Metal Oxide Nanoparticles and Nanowires: Synthesis, Characterization, and Applications)

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