Selected Papers from the 2nd International Online Conference on Nanomaterials

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (30 September 2021) | Viewed by 43259

Special Issue Editors

Facultad de Ciencias, Departamento de Química Analítica, Universidad de Alcalá, Química Física e Ingeniería Química, Ctra. Madrid-Barcelona Km. 33.6, 28805 Alcalá de Henares, Madrid, Spain
Interests: nanomaterials; polymers; nanocomposites; inorganic nanoparticles; antibacterial agents; surfactants; interphases
Special Issues, Collections and Topics in MDPI journals
Department of Physics “E.R. Caianiello”, University of Salerno, 84084 Fisciano, Italy
Interests: optical and electrical properties of nanostructured materials such as carbon nanotubes, graphene, and 2D materials; van der Waals heterostructures and Schottky junctions; field-effect transistors; non-volatile memories; solar cells; photodetectors; field emission devices
Special Issues, Collections and Topics in MDPI journals
School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China
Interests: lanthanide; crystals and nanocrystals; nonlinear; biophotonics; solar cells
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue includes selected papers from the 2nd International Online Conference on Nanomaterials, held 15–30 November 2020 on sciforum.net, an online platform for hosting scholarly e-conferences and discussion groups. The scope of this 2nd edition of the electronic conference is to cover the whole breadth of nanomaterials research and provide a forum for presenting and discussing new results. Contributors are requested to submit papers and presentations from the field of nanomaterials, such as nanomaterials synthesis and characterization, modeling and simulation of nanostructures, graphene and 2D nanomaterials, polymeric nanomaterials, devices and energy, and bio- and medicine. Papers will be subjected to peer review and published with the aim of a rapid and wide dissemination of research results, developments, and applications. We hope this Conference Series will turn out to be recognized as a novel means to (electronically) present the most recent advances in the area of nanomaterials.


Prof. Dr. Ana María Díez-Pascual
Prof. Dr. Antonio Di Bartolomeo
Prof. Dr. Guanying Chen
Guest Editors

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Keywords

  • nanomaterials
  • nanomedicine
  • nanophotonics
  • nanodevices
  • nanoplasmonics
  • nanoelectronics
  • nanostructures
  • graphene
  • 2D materials
  • magnetic nanomaterials

Published Papers (16 papers)

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Editorial

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3 pages, 213 KiB  
Editorial
Selected Papers from the Second International Online Conference on Nanomaterials
by Ana M. Díez-Pascual, Antonio Di Bartolomeo and Guanying Chen
Nanomaterials 2022, 12(3), 302; https://doi.org/10.3390/nano12030302 - 18 Jan 2022
Cited by 1 | Viewed by 1186
Abstract
Nanomaterials have gained eminence in technological developments due to their tunable physical, chemical, and biological properties, such as wettability, electrical and thermal conductivity, magnetism, light absorption and emission, catalytic activity, and so forth, leading to devices with improved performance compared to their microscopic [...] Read more.
Nanomaterials have gained eminence in technological developments due to their tunable physical, chemical, and biological properties, such as wettability, electrical and thermal conductivity, magnetism, light absorption and emission, catalytic activity, and so forth, leading to devices with improved performance compared to their microscopic counterparts [...] Full article

Research

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18 pages, 3252 KiB  
Article
Microwave-Assisted Synthesis of Zn2SnO4 Nanostructures for Photodegradation of Rhodamine B under UV and Sunlight
by Ana Rovisco, Maria Morais, Rita Branquinho, Elvira Fortunato, Rodrigo Martins and Pedro Barquinha
Nanomaterials 2022, 12(12), 2119; https://doi.org/10.3390/nano12122119 - 20 Jun 2022
Cited by 5 | Viewed by 2037
Abstract
The contamination of water resources by pollutants resulting from human activities represents a major concern nowadays. One promising alternative to solve this problem is the photocatalytic process, which has demonstrated very promising and efficient results. Oxide nanostructures are interesting alternatives for these applications [...] Read more.
The contamination of water resources by pollutants resulting from human activities represents a major concern nowadays. One promising alternative to solve this problem is the photocatalytic process, which has demonstrated very promising and efficient results. Oxide nanostructures are interesting alternatives for these applications since they present wide band gaps and high surface areas. Among the photocatalytic oxide nanostructures, zinc tin oxide (ZTO) presents itself as an eco-friendly alternative since its composition includes abundant and non-toxic zinc and tin, instead of critical elements. Moreover, ZTO nanostructures have a multiplicity of structures and morphologies possible to be obtained through low-cost solution-based syntheses. In this context, the current work presents an optimization of ZTO nanostructures (polyhedrons, nanoplates, and nanoparticles) obtained by microwave irradiation-assisted hydrothermal synthesis, toward photocatalytic applications. The nanostructures’ photocatalytic activity in the degradation of rhodamine B under both ultraviolet (UV) irradiation and natural sunlight was evaluated. Among the various morphologies, ZTO nanoparticles revealed the best performance, with degradation > 90% being achieved in 60 min under UV irradiation and in 90 min under natural sunlight. The eco-friendly production process and the demonstrated ability of these nanostructures to be used in various water decontamination processes reinforces their sustainability and the role they can play in a circular economy. Full article
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13 pages, 1490 KiB  
Article
Characterization of Gold Nanorods Conjugated with Synthetic Glycopolymers Using an Analytical Approach Based on spICP-SFMS and EAF4-MALS
by Milica Velimirovic, Alessia Pancaro, Robert Mildner, Panagiotis G. Georgiou, Kristof Tirez, Inge Nelissen, Christoph Johann, Matthew I. Gibson and Frank Vanhaecke
Nanomaterials 2021, 11(10), 2720; https://doi.org/10.3390/nano11102720 - 15 Oct 2021
Cited by 2 | Viewed by 2026
Abstract
A new comprehensive analytical approach based on single-particle inductively coupled plasma-sector field mass spectrometry (spICP-SFMS) and electrical asymmetric-flow field-flow-fractionation combined with multi-angle light scattering detection (EAF4-MALS) has been examined for the characterization of galactosamine-terminated poly(N-hydroxyethyl acrylamide)-coated gold nanorods (GNRs) in two different degrees [...] Read more.
A new comprehensive analytical approach based on single-particle inductively coupled plasma-sector field mass spectrometry (spICP-SFMS) and electrical asymmetric-flow field-flow-fractionation combined with multi-angle light scattering detection (EAF4-MALS) has been examined for the characterization of galactosamine-terminated poly(N-hydroxyethyl acrylamide)-coated gold nanorods (GNRs) in two different degrees of polymerization (DP) by tuning the feed ratio (short: DP 35; long: DP 60). spICP-SFMS provided information on the particle number concentration, size and size distribution of the GNRs, and was found to be useful as an orthogonal method for fast characterization of GNRs. Glycoconjugated GNRs were separated and characterized via EAF4-MALS in terms of their size and charge and compared to the bare GNRs. In contrast to spICP-SFMS, EAF4-MALS was also able of providing an estimate of the thickness of the glycopolymer coating on the GNRs surface. Full article
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13 pages, 37398 KiB  
Article
Anisotropic Optical Response of WTe2 Single Crystals Studied by Ellipsometric Analysis
by Krastyo Buchkov, Rosen Todorov, Penka Terziyska, Marin Gospodinov, Velichka Strijkova, Dimitre Dimitrov and Vera Marinova
Nanomaterials 2021, 11(9), 2262; https://doi.org/10.3390/nano11092262 - 31 Aug 2021
Cited by 9 | Viewed by 3514
Abstract
In this paper we report the crystal growth conditions and optical anisotropy properties of Tungsten ditelluride (WTe2) single crystals. The chemical vapor transport (CVT) method was used for the synthesis of large WTe2 crystals with high crystallinity and surface quality. [...] Read more.
In this paper we report the crystal growth conditions and optical anisotropy properties of Tungsten ditelluride (WTe2) single crystals. The chemical vapor transport (CVT) method was used for the synthesis of large WTe2 crystals with high crystallinity and surface quality. These were structurally and morphologically characterized by means of X-ray diffraction, optical profilometry and Raman spectroscopy. Through spectroscopic ellipsometry analysis, based on the Tauc–Lorentz model, we identified a high refractive index value (~4) and distinct tri-axial anisotropic behavior of the optical constants, which opens prospects for surface plasmon activity, revealed by the dielectric function. The anisotropic physical nature of WTe2 shows practical potential for low-loss light modulation at the 2D nanoscale level. Full article
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32 pages, 56804 KiB  
Article
Synthesis and Characterization of Gefitinib and Paclitaxel Mono and Dual Drug-Loaded Blood Cockle Shells (Anadara granosa)-Derived Aragonite CaCO3 Nanoparticles
by S. Chemmalar, Abdul Razak Intan-Shameha, Che Azurahanim Che Abdullah, Nor Asma Ab Razak, Loqman Mohamad Yusof, Mokrish Ajat, N. S. K. Gowthaman and Md Zuki Abu Bakar
Nanomaterials 2021, 11(8), 1988; https://doi.org/10.3390/nano11081988 - 02 Aug 2021
Cited by 8 | Viewed by 3067
Abstract
Calcium carbonate has slowly paved its way into the field of nanomaterial research due to its inherent properties: biocompatibility, pH-sensitivity, and slow biodegradability. In our efforts to synthesize calcium carbonate nanoparticles (CSCaCO3NP) from blood cockle shells (Anadara granosa), we [...] Read more.
Calcium carbonate has slowly paved its way into the field of nanomaterial research due to its inherent properties: biocompatibility, pH-sensitivity, and slow biodegradability. In our efforts to synthesize calcium carbonate nanoparticles (CSCaCO3NP) from blood cockle shells (Anadara granosa), we developed a simple method to synthesize CSCaCO3NP, and loaded them with gefitinib (GEF) and paclitaxel (PTXL) to produce mono drug-loaded GEF-CSCaCO3NP, PTXL-CSCaCO3NP, and dual drug-loaded GEF-PTXL-CSCaCO3NP without usage of toxic chemicals. Fourier-transform infrared spectroscopy (FTIR) results reveal that the drugs are bound to CSCaCO3NP. Scanning electron microscopy studies reveal that the CSCaCO3NP, GEF-CSCaCO3NP, PTXL-CSCaCO3NP, and GEF-PTXL-CSCaCO3NP are almost spherical nanoparticles, with a diameter of 63.9 ± 22.3, 83.9 ± 28.2, 78.2 ± 26.4, and 87.2 ± 26.7 (nm), respectively. Dynamic light scattering (DLS) and N2 adsorption-desorption experiments revealed that the synthesized nanoparticles are negatively charged and mesoporous, with surface areas ranging from ~8 to 10 (m2/g). Powder X-ray diffraction (PXRD) confirms that the synthesized nanoparticles are aragonite. The CSCaCO3NP show excellent alkalinization property in plasma simulating conditions and greater solubility in a moderately acidic pH medium. The release of drugs from the nanoparticles showed zero order kinetics with a slow and sustained release. Therefore, the physico-chemical characteristics and in vitro findings suggest that the drug loaded CSCaCO3NP represent a promising drug delivery system to deliver GEF and PTXL against breast cancer. Full article
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10 pages, 4634 KiB  
Article
Preparation of Copper Surface for the Synthesis of Single-Layer Graphene
by Ivan Kondrashov, Maxim Komlenok, Pavel Pivovarov, Sergey Savin, Elena Obraztsova and Maxim Rybin
Nanomaterials 2021, 11(5), 1071; https://doi.org/10.3390/nano11051071 - 22 Apr 2021
Cited by 12 | Viewed by 2745
Abstract
Chemical vapor deposition synthesis of graphene on copper foil from methane is the most promising technology for industrial production. However, an important problem of the formation of the additional graphene layers during synthesis arises due to the strong roughness of the initial copper [...] Read more.
Chemical vapor deposition synthesis of graphene on copper foil from methane is the most promising technology for industrial production. However, an important problem of the formation of the additional graphene layers during synthesis arises due to the strong roughness of the initial copper foil. In this paper, various approaches are demonstrated to form a smooth copper surface before graphene synthesis to reduce the amount of few layer graphene islands. Six methods of surface processing of copper foils are studied and the decrease of the roughness from 250 to as low as 80 nm is achieved. The correlation between foil roughness and the formation of the additional layer is demonstrated. Under optimized conditions of surface treatment, the content of the additional graphene layer drops from 9 to 2.1%. The quality and the number of layers of synthesized graphene are analyzed by Raman spectroscopy, scanning electron microscopy and measurements of charge mobility. Full article
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12 pages, 3071 KiB  
Article
Simultaneous Removal of Arsenic and Manganese from Synthetic Aqueous Solutions Using Polymer Gel Composites
by Syed Ragib Safi and Takehiko Gotoh
Nanomaterials 2021, 11(4), 1032; https://doi.org/10.3390/nano11041032 - 18 Apr 2021
Cited by 6 | Viewed by 2387
Abstract
The groundwater in approximately 50% of the Bangladesh landmass contains Mn concentrations greater than the limit prescribed by the WHO drinking water guidelines. Although studies have suggested that γ-FeOOH can effectively remove Mn from water, its practicability has not been investigated, considering that [...] Read more.
The groundwater in approximately 50% of the Bangladesh landmass contains Mn concentrations greater than the limit prescribed by the WHO drinking water guidelines. Although studies have suggested that γ-FeOOH can effectively remove Mn from water, its practicability has not been investigated, considering that the additional processes required to separate the adsorbents and precipitates are not environment-friendly. To improve the efficiency of adsorptive Mn-removal under natural conditions, we employed a cationic polymer gel composite, N,N’-Dimethylaminopropyl acrylamide, methyl chloride quaternary (DMAPAAQ) loaded with iron hydroxide (DMAPAAQ + FeOOH), and a non-ionic polymer gel composite, N,N’-Dimethylacrylamide (DMAA) loaded with iron hydroxide (DMAA + FeOOH). DMAPAAQ + FeOOH exhibited a higher As removal efficiency under natural conditions while being environment-friendly. Our results suggest that the higher efficiency of the cationic gel composite is owed to the higher γ-FeOOH content in its gel structure. The maximum adsorption of Mn by DMAPAAQ + FeOOH was 39.02 mg/g. Furthermore, the presence of As did not influence the adsorption of Mn on the DMAPAAQ + FeOOH gel composite and vice versa. DMAPAAQ adsorbed As and the γ-FeOOH particles simultaneously adsorbed Mn. Our findings can serve as a basis for the simultaneous removal of contaminants such as As, Mn, Cr, and Cd. Full article
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11 pages, 4048 KiB  
Article
ALD Deposited ZnO:Al Films on Mica for Flexible PDLC Devices
by Dimitre Z. Dimitrov, Zih Fan Chen, Vera Marinova, Dimitrina Petrova, Chih Yao Ho, Blagovest Napoleonov, Blagoy Blagoev, Velichka Strijkova, Ken Yuh Hsu, Shiuan Huei Lin and Jenh-Yih Juang
Nanomaterials 2021, 11(4), 1011; https://doi.org/10.3390/nano11041011 - 15 Apr 2021
Cited by 14 | Viewed by 3092
Abstract
In this work, highly conductive Al-doped ZnO (AZO) films are deposited on transparent and flexible muscovite mica substrates by using the atomic layer deposition (ALD) technique. AZO-mica structures possess high optical transmittance at visible and near-infrared spectral range and retain low electric resistivity, [...] Read more.
In this work, highly conductive Al-doped ZnO (AZO) films are deposited on transparent and flexible muscovite mica substrates by using the atomic layer deposition (ALD) technique. AZO-mica structures possess high optical transmittance at visible and near-infrared spectral range and retain low electric resistivity, even after continuous bending of up to 800 cycles. Structure performances after bending tests have been supported by atomic force microscopy (AFM) analysis. Based on performed optical and electrical characterizations AZO films on mica are implemented as transparent conductive electrodes in flexible polymer dispersed liquid crystal (PDLC) devices. The measured electro-optical characteristics and response time of the proposed devices reveal the higher potential of AZO-mica for future ITO-free flexible optoelectronic applications. Full article
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11 pages, 3225 KiB  
Article
Fabrication and Characterization of an Efficient Inverted Perovskite Solar Cells with POSS Passivating Hole Transport Layer
by Bo-Tau Liu, Hong-Ru Lin, Rong-Ho Lee, Nima E. Gorji and Jung-Chuan Chou
Nanomaterials 2021, 11(4), 974; https://doi.org/10.3390/nano11040974 - 10 Apr 2021
Cited by 10 | Viewed by 2842
Abstract
Polyhedral oligomeric silsesquioxane (POSS), featuring a hollow-cage or semi-cage structure is a new type of organic–inorganic hybrid nanoparticles. POSS combines the advantages of inorganic components and organic components with a great potential for optoelectronic applications such as in emerging perovskite solar cells. When [...] Read more.
Polyhedral oligomeric silsesquioxane (POSS), featuring a hollow-cage or semi-cage structure is a new type of organic–inorganic hybrid nanoparticles. POSS combines the advantages of inorganic components and organic components with a great potential for optoelectronic applications such as in emerging perovskite solar cells. When POSS is well dispersed in the polymer matrix, it can effectively improve the thermal, mechanical, magnetic, acoustic, and surface properties of the polymer. In this study, POSS was spin-coated as an ultra-thin passivation layer over the hole transporting layer of nickel-oxide (NOx) in the structure of a perovskite solar cell. The POSS incorporation led to a more hydrophobic and smoother surface for further perovskite deposition, resulting in the increase in the grain size of perovskite. An appropriate POSS passivation layer could effectively reduce the recombination of the electron and hole at grain boundaries and increase the short-circuit current from 18.0 to 20.5 mA·cm−2. Moreover, the open-circuit voltage of the cell could slightly increase over 1 V. Full article
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9 pages, 2451 KiB  
Article
Asymmetric Hysteresis Loops in Structured Ferromagnetic Nanoparticles with Hard/Soft Areas
by Joscha Detzmeier, Kevin Königer, Tomasz Blachowicz and Andrea Ehrmann
Nanomaterials 2021, 11(3), 800; https://doi.org/10.3390/nano11030800 - 21 Mar 2021
Cited by 10 | Viewed by 2947
Abstract
Horizontally shifted and asymmetric hysteresis loops are often associated with exchange-biased samples, consisting of a ferromagnet exchange coupled with an antiferromagnet. In purely ferromagnetic samples, such effects can occur due to undetected minor loops or thermal effects. Simulations of ferromagnetic nanostructures at zero [...] Read more.
Horizontally shifted and asymmetric hysteresis loops are often associated with exchange-biased samples, consisting of a ferromagnet exchange coupled with an antiferromagnet. In purely ferromagnetic samples, such effects can occur due to undetected minor loops or thermal effects. Simulations of ferromagnetic nanostructures at zero temperature with sufficiently large saturation fields should not lead to such asymmetries. Here we report on micromagnetic simulations at zero temperature, performed on sputtered nanoparticles with different structures. The small deviations of the systems due to random anisotropy orientations in the different grains can not only result in strong deviations of magnetization reversal processes and hysteresis loops, but also lead to distinctly asymmetric, horizontally shifted hysteresis loops in purely ferromagnetic nanoparticles. Full article
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14 pages, 17678 KiB  
Article
Molybdenum–Tungsten Blue Nanoparticles as a Precursor for Ultrafine Binary Carbides
by Maria Myachina, Natalia Gavrilova, Ksenia Poluboyarinova and Victor Nazarov
Nanomaterials 2021, 11(3), 761; https://doi.org/10.3390/nano11030761 - 17 Mar 2021
Cited by 3 | Viewed by 2648
Abstract
Herein, we demonstrate a promising method for the synthesis of ultrafine carbide particles using dispersions of molybdenum–tungsten nanoparticles. Dispersions of molybdenum–tungsten blue nanoparticles with different initial molar ratios of molybdenum/tungsten were synthesized through the reduction of molybdate and tungstate ions by ascorbic acid [...] Read more.
Herein, we demonstrate a promising method for the synthesis of ultrafine carbide particles using dispersions of molybdenum–tungsten nanoparticles. Dispersions of molybdenum–tungsten blue nanoparticles with different initial molar ratios of molybdenum/tungsten were synthesized through the reduction of molybdate and tungstate ions by ascorbic acid in an acidic medium (pH = 1.0–2.5). Molybdenum–tungsten blue nanoparticles were characterized by ultraviolet–visual (UV–VIS), infrared (FTIR), and X-ray photoelectron (XPS) spectroscopies; transmission electronic microscopy (TEM); and dynamic light scattering (DLS). We demonstrated that molybdenum–tungsten blue nanoparticles belong to toroidal polyoxometalate clusters (λmax = 680–750 nm) with a predominant particle size of 4.0 nm. Molybdenum–tungsten blue dispersions were shown to be monodispersed systems with a small particle size and long-term stability (>30 days) and are suitable for further catalytic applications. Full article
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21 pages, 28998 KiB  
Article
Evaluation of a Model Photo-Caged Dehydropeptide as a Stimuli-Responsive Supramolecular Hydrogel
by Peter J. Jervis, Loic Hilliou, Renato B. Pereira, David M. Pereira, José A. Martins and Paula M. T. Ferreira
Nanomaterials 2021, 11(3), 704; https://doi.org/10.3390/nano11030704 - 11 Mar 2021
Cited by 13 | Viewed by 2806
Abstract
Short peptides capped on the N-terminus with aromatic groups are often able to form supramolecular hydrogels, via self-assembly, in aqueous media. The rheological properties of these readily tunable hydrogels resemble those of the extracellular matrix (ECM) and therefore have potential for various [...] Read more.
Short peptides capped on the N-terminus with aromatic groups are often able to form supramolecular hydrogels, via self-assembly, in aqueous media. The rheological properties of these readily tunable hydrogels resemble those of the extracellular matrix (ECM) and therefore have potential for various biological applications, such as tissue engineering, biosensors, 3D bioprinting, drug delivery systems and wound dressings. We herein report a new photo-responsive supramolecular hydrogel based on a “caged” dehydropeptide (CNB-Phe-ΔPhe-OH 2), containing a photo-cleavable carboxy-2-nitrobenzyl (CNB) group. We have characterized this hydrogel using a range of techniques. Irradiation with UV light cleaves the pendant aromatic capping group, to liberate the corresponding uncaged model dehydropeptide (H-Phe-ΔPhe-OH 3), a process which was investigated by 1H NMR and HPLC studies. Crucially, this cleavage of the capping group is accompanied by dissolution of the hydrogel (studied visually and by fluorescence spectroscopy), as the delicate balance of intramolecular interactions within the hydrogel structure is disrupted. Hydrogels which can be disassembled non-invasively with temporal and spatial control have great potential for specialized on-demand drug release systems, wound dressing materials and various topical treatments. Both 2 and 3 were found to be non-cytotoxic to the human keratinocyte cell line, HaCaT. The UV-responsive hydrogel system reported here is complementary to previously reported related UV-responsive systems, which are generally composed of peptides formed from canonical amino acids, which are susceptible to enzymatic proteolysis in vivo. This system is based on a dehydrodipeptide structure which is known to confer proteolytic resistance. We have investigated the ability of the photo-activated system to accelerate the release of the antibiotic, ciprofloxacin, as well as some other small model drug compounds. We have also conducted some initial studies towards skin-related applications. Moreover, this model system could potentially be adapted for on-demand “self-delivery”, through the uncaging of known biologically active dehydrodipeptides. Full article
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18 pages, 6901 KiB  
Article
Hierarchical Nanocauliflower Chemical Assembly Composed of Copper Oxide and Single-Walled Carbon Nanotubes for Enhanced Photocatalytic Dye Degradation
by Kamal Prasad Sapkota, Md. Akherul Islam, Md. Abu Hanif, Jeasmin Akter, Insup Lee and Jae Ryang Hahn
Nanomaterials 2021, 11(3), 696; https://doi.org/10.3390/nano11030696 - 10 Mar 2021
Cited by 15 | Viewed by 2210
Abstract
We present the fabrication and proficient photocatalytic performance of a series of heterojunction nanocomposites with cauliflower-like architecture synthesized from copper(II) oxide (CuO) nanocrystals and carbon nanotubes with single walls (SWCNTs). These unique photocatalysts were constructed via simplistic recrystallization succeeded by calcination and were [...] Read more.
We present the fabrication and proficient photocatalytic performance of a series of heterojunction nanocomposites with cauliflower-like architecture synthesized from copper(II) oxide (CuO) nanocrystals and carbon nanotubes with single walls (SWCNTs). These unique photocatalysts were constructed via simplistic recrystallization succeeded by calcination and were labeled as CuOSC-1, CuOSC-2, and CuOSC-3 (representing the components; CuO and SC for SWCNTs, and the calcination time in hours). The photocatalytic potency of the fabricated nanocomposites was investigated on the basis of their capability to decompose methylene blue (MB) dye under visible-light irradiation. Every as-synthesized nanocomposite was effective photocatalyst for the photodecomposition of an MB solution. Moreover, CuOSC-3 exhibited the best photocatalytic activity, with 96% degradation of the visible-light irradiated MB solution in 2 h. Pure CuO nanocrystals generated through the same route and pure SWCNTs were used as controls, where the photocatalytic actions of the nanocomposite samples were found to be remarkably better than that of either the pure CuO or the pure SWCNTs. The recycling proficiency of the photocatalysts was also explored; the results disclosed that the samples could be applied for five cycles without exhibiting a notable change in photocatalytic performance or morphology. Full article
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10 pages, 4549 KiB  
Article
Micromagnetic Simulations of Fe and Ni Nanodot Arrays Surrounded by Magnetic or Non-Magnetic Matrices
by Devika Sudsom and Andrea Ehrmann
Nanomaterials 2021, 11(2), 349; https://doi.org/10.3390/nano11020349 - 01 Feb 2021
Cited by 8 | Viewed by 3042
Abstract
Combining clusters of magnetic materials with a matrix of other magnetic materials is very interesting for basic research because new, possibly technologically applicable magnetic properties or magnetization reversal processes may be found. Here we report on different arrays combining iron and nickel, for [...] Read more.
Combining clusters of magnetic materials with a matrix of other magnetic materials is very interesting for basic research because new, possibly technologically applicable magnetic properties or magnetization reversal processes may be found. Here we report on different arrays combining iron and nickel, for example, by surrounding circular nanodots of one material with a matrix of the other or by combining iron and nickel nanodots in air. Micromagnetic simulations were performed using the OOMMF (Object Oriented MicroMagnetic Framework). Our results show that magnetization reversal processes are strongly influenced by neighboring nanodots and the magnetic matrix by which the nanodots are surrounded, respectively, which becomes macroscopically visible by several steps along the slopes of the hysteresis loops. Such material combinations allow for preparing quaternary memory systems, and are thus highly relevant for applications in data storage and processing. Full article
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18 pages, 2788 KiB  
Article
Graphene Oxides Derivatives Prepared by an Electrochemical Approach: Correlation between Structure and Properties
by Carlos Sainz-Urruela, Soledad Vera-López, María Paz San Andrés and Ana M. Díez-Pascual
Nanomaterials 2020, 10(12), 2532; https://doi.org/10.3390/nano10122532 - 17 Dec 2020
Cited by 11 | Viewed by 1798
Abstract
Graphene oxide (GO) can be defined as a single monolayer of graphite with oxygen-containing functionalities such as epoxides, alcohols, and carboxylic acids. It is an interesting alternative to graphene for many applications due to its exceptional properties and feasibility of functionalization. In this [...] Read more.
Graphene oxide (GO) can be defined as a single monolayer of graphite with oxygen-containing functionalities such as epoxides, alcohols, and carboxylic acids. It is an interesting alternative to graphene for many applications due to its exceptional properties and feasibility of functionalization. In this study, electrochemically exfoliated graphene oxides (EGOs) with different amounts of surface groups, hence level of oxidation, were prepared by an electrochemical two-stage approach using graphite as raw material. A complete characterization of the EGOs was carried out in order to correlate their surface topography, interlayer spacing, defect content, and specific surface area (SSA) with their electrical, thermal, and mechanical properties. It has been found that the SSA has a direct relationship with the d-spacing. The EGOs electrical resistance decreases with increasing SSA while rises with increasing the D/G band intensity ratio in the Raman spectra, hence the defect content. Their thermal stability under both nitrogen and dry air atmospheres depends on both their oxidation level and defect content. Their macroscopic mechanical properties, namely the Young’s modulus and tensile strength, are influenced by the defect content, while no correlation was found with their SSA or interlayer spacing. Young moduli values as high as 54 GPa have been measured, which corroborates that the developed method preserves the integrity of the graphene flakes. Understanding the structure-property relationships in these materials is useful for the design of modified GOs with controllable morphologies and properties for a wide range of applications in electrical/electronic devices. Full article
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12 pages, 5758 KiB  
Article
Annealing Effect on the Properties of Electrochromic V2O5 Thin Films Grown by Spray Deposition Technique
by Kyriakos Mouratis, Ioan Valentin Tudose, Andrianna Bouranta, Cristina Pachiu, Cosmin Romanitan, Oana Tutunaru, Stelios Couris, Emmanouel Koudoumas and Mirela Suchea
Nanomaterials 2020, 10(12), 2397; https://doi.org/10.3390/nano10122397 - 30 Nov 2020
Cited by 12 | Viewed by 2696
Abstract
Nanostructured electrochromic V2O5 thin films were prepared using spray pyrolysis technique growth at a temperature of 250 °C using air-carrier spray deposition, starting from ammonium metavanadate precursor in water, followed by annealing at 400 °C in O2 atmosphere for [...] Read more.
Nanostructured electrochromic V2O5 thin films were prepared using spray pyrolysis technique growth at a temperature of 250 °C using air-carrier spray deposition, starting from ammonium metavanadate precursor in water, followed by annealing at 400 °C in O2 atmosphere for 2 h. The V2O5 films were characterized by X-ray diffraction, scanning electron microscopy, and Raman spectroscopy, and their electrochromic behavior was studied using optical spectroscopy and cyclic voltammetry in both the as-deposited and postannealing case. The studies showed that the simple, cost -effective, suitable for large area deposition method used can lead to an interesting surface structuring with large active surface properties suitable for electrochromic applications. Further studies for growth optimization and improvements of films properties and stability are to be performed. Full article
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