Microwave Technology and Nanomaterials: Synthesis and Application

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Synthesis, Interfaces and Nanostructures".

Deadline for manuscript submissions: closed (5 November 2021) | Viewed by 24188

Special Issue Editor

Special Issue Information

Dear Colleagues,

The development and use of nanomaterials is one of the most active research area. This class of materials has demonstrated a wide variety of applications ranging from biomedicine, to sensors or energy. Nanomaterial preparation procedures are generally based on conventional heating methods with long synthetic times and reagents consumption. In addition, conventional synthesis methods sometimes lead to the formation of heterogeneous materials. By contrast, the use of microwaves as an energy source appears as a strategy that allows some or all of these inconveniences to be overcome.

This Special Issue will offer an overview of new advances present trends and future perspectives in the use of this kind of energy as heat source. It is open to any nanomaterial prepared using microwave in any of the synthetic steps. Materials can be 2D nanomaterials, nanoparticles, etc. Also to the reports of applications of nanomaterials prepared following microwave assisted are welcome.

Dr. Jose Vicente Ros-Lis
Guest Editor

Manuscript Submission Information

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Keywords

  • microwave
  • nanomaterial
  • fast synthesis
  • solvothermal synthesis
  • graphene
  • metallic nanoparticles

Published Papers (7 papers)

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Research

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22 pages, 4205 KiB  
Article
Facile In Situ Synthesis of ZnO Flower-like Hierarchical Nanostructures by the Microwave Irradiation Method for Multifunctional Textile Coatings
by Maria Antonia Tănase, Andreia Cristina Soare, Petruţa Oancea, Adina Răducan, Cătălin Ionuţ Mihăescu, Elvira Alexandrescu, Cristian Petcu, Lia Mara Diţu, Marilena Ferbinteanu, Bogdan Cojocaru and Ludmila Otilia Cinteza
Nanomaterials 2021, 11(10), 2574; https://doi.org/10.3390/nano11102574 - 30 Sep 2021
Cited by 14 | Viewed by 3122
Abstract
ZnO nanoparticle-based multifunctional coatings were prepared by a simple, time-saving microwave method. Arginine and ammonia were used as precipitation agents, and zinc acetate dehydrate was used as a zinc precursor. Under the optimized conditions, flower-like morphologies of ZnO aggregates were obtained. The prepared [...] Read more.
ZnO nanoparticle-based multifunctional coatings were prepared by a simple, time-saving microwave method. Arginine and ammonia were used as precipitation agents, and zinc acetate dehydrate was used as a zinc precursor. Under the optimized conditions, flower-like morphologies of ZnO aggregates were obtained. The prepared nanopowders were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and UV/Visible spectroscopy. The developed in situ synthesis with microwave irradiation enabled significant ZnO nanoparticle deposition on cotton fabrics, without additional steps. The functionalized textiles were tested as a photocatalyst in methylene blue (MB) photodegradation and showed good self-cleaning and UV-blocking properties. The coated cotton fabrics exhibited good antibacterial properties against common microbial trains (Staphylococcus aureus, Escherichia coli, and Candida albicans), together with self-cleaning and photocatalytic efficiency in organic dye degradation. The proposed microwave-assisted in situ synthesis of ZnO nanocoatings on textiles shows high potential as a rapid, efficient, environmentally friendly, and scalable method to fabricate functional fabrics. Full article
(This article belongs to the Special Issue Microwave Technology and Nanomaterials: Synthesis and Application)
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17 pages, 2601 KiB  
Article
Engineering Iron Oxide Nanocatalysts by a Microwave-Assisted Polyol Method for the Magnetically Induced Degradation of Organic Pollutants
by Alvaro Gallo-Cordova, Sabino Veintemillas-Verdaguer, Pedro Tartaj, Eva Mazarío, María del Puerto Morales and Jesús G. Ovejero
Nanomaterials 2021, 11(4), 1052; https://doi.org/10.3390/nano11041052 - 20 Apr 2021
Cited by 24 | Viewed by 3323
Abstract
Advanced oxidation processes constitute a promising alternative for the treatment of wastewater containing organic pollutants. Still, the lack of cost-effective processes has hampered the widespread use of these methodologies. Iron oxide magnetic nanoparticles stand as a great alternative since they can be engineered [...] Read more.
Advanced oxidation processes constitute a promising alternative for the treatment of wastewater containing organic pollutants. Still, the lack of cost-effective processes has hampered the widespread use of these methodologies. Iron oxide magnetic nanoparticles stand as a great alternative since they can be engineered by different reproducible and scalable methods. The present study consists of the synthesis of single-core and multicore magnetic iron oxide nanoparticles by the microwave-assisted polyol method and their use as self-heating catalysts for the degradation of an anionic (acid orange 8) and a cationic dye (methylene blue). Decolorization of these dyes was successfully improved by subjecting the catalyst to an alternating magnetic field (AMF, 16 kA/m, 200 kHz). The sudden temperature increase at the surface of the catalyst led to an intensification of 10% in the decolorization yields using 1 g/L of catalyst, 0.3 M H2O2 and 500 ppm of dye. Full decolorization was achieved at 90 °C, but iron leaching (40 ppm) was detected at this temperature leading to a homogeneous Fenton process. Multicore nanoparticles showed higher degradation rates and 100% efficiencies in four reusability cycles under the AMF. The improvement of this process with AMF is a step forward into more sustainable remediation techniques. Full article
(This article belongs to the Special Issue Microwave Technology and Nanomaterials: Synthesis and Application)
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9 pages, 3049 KiB  
Article
Decrease in the Crystallite Diameter of Solid Crystalline Magnetite around the Curie Temperature by Microwave Magnetic Fields Irradiation
by Takayuki Tsuchida, Jun Fukushima and Hirotsugu Takizawa
Nanomaterials 2021, 11(4), 984; https://doi.org/10.3390/nano11040984 - 11 Apr 2021
Cited by 3 | Viewed by 1705
Abstract
A decrease in the crystallite diameter of ferrites irradiated with microwaves has been considered as a non-thermal effect of so-called de-crystallization; however, its mechanism has not been elucidated. We hypothesized that a decrease in the crystallite diameter is caused by interaction between the [...] Read more.
A decrease in the crystallite diameter of ferrites irradiated with microwaves has been considered as a non-thermal effect of so-called de-crystallization; however, its mechanism has not been elucidated. We hypothesized that a decrease in the crystallite diameter is caused by interaction between the ordered spins of ferrite and the magnetic field of microwaves. To verify this, we focused on magnetite with a Curie temperature of 585 °C. Temperature dependence around this temperature and time dependence of the crystallite diameter of the magnetite irradiated with microwaves at different temperatures and durations were investigated. From the X-ray diffraction data, the crystallite diameter of magnetite exhibited a minimum value at 500 °C, just below the Curie temperature of magnetite, where the energy loss of the interaction between magnetite’s spins and the microwaves takes the maximum value. The crystallite diameter exhibited a minimum value at 5 min irradiation time, during which the microwaves were excessively absorbed. Transmission electron microscopy observations showed that the microstructure of irradiated magnetite in this study was different from that reported previously, indicating that a decrease in the crystallite diameter is not caused by de-crystallization but its similar phenomenon. A decrease in coercivity and lowering temperature of Verwey transition were observed, evidencing decreased crystallite diameter. This study can thus contribute to the development of the theory of a non-thermal effect. Full article
(This article belongs to the Special Issue Microwave Technology and Nanomaterials: Synthesis and Application)
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16 pages, 3895 KiB  
Article
Crystallization Kinetics in BaTiO3 Synthesis from Hydrate Precursors via Microwave-Assisted Heat Treatment
by Han-Sol Yun, Byeong-Gyu Yun, So-Young Shin, Dae-Yong Jeong and Nam-Hee Cho
Nanomaterials 2021, 11(3), 754; https://doi.org/10.3390/nano11030754 - 17 Mar 2021
Cited by 3 | Viewed by 1736
Abstract
The crystallization kinetics in BaTiO3 synthesis from hydrate precursors via microwave-assisted heating (MWH) were investigated. The structural and chemical features of powders synthesized via MWH and conventional heating (CH) were compared. The charged radicals generated under microwave irradiation were identified by chemical [...] Read more.
The crystallization kinetics in BaTiO3 synthesis from hydrate precursors via microwave-assisted heating (MWH) were investigated. The structural and chemical features of powders synthesized via MWH and conventional heating (CH) were compared. The charged radicals generated under microwave irradiation were identified by chemical analysis and real-time charge flux measurements. Using Ba(OH)2∙H2O (BH1), Ba(OH)2 (BH0), and BaCO3 (BC) as the precursors for a Ba source, and TiO2∙4H2O (TH) for a Ti source, three different mixture samples, BH1TH (BH1 + TH), BH0TH (BH0 + TH), and BCTH (BC + TH), were heat-treated in the temperature range of 100–900 °C. BaTiO3 powders were synthesized at temperatures as low as 100 °C when sample BH1TH was subjected to MWH. Based on the growth exponent (n), the synthesis reactions were inferred to be diffusion-controlled processes (3 ≤ n ≤ 4) for MWH and interface-controlled processes (2 ≤ n ≤ 3) for CH. Current densities of approximately 0.073 and 0.022 mA/m2 were measured for samples BH1TH and BH0TH, respectively, indicating the generation of charged radicals by the interaction between the precursors and injected microwaves. The radicals were determined as OH groups by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Full article
(This article belongs to the Special Issue Microwave Technology and Nanomaterials: Synthesis and Application)
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14 pages, 2505 KiB  
Article
Metal Organic Framework Derived MnO2-Carbon Nanotubes for Efficient Oxygen Reduction Reaction and Arsenic Removal from Contaminated Water
by Vadahanambi Sridhar, Inwon Lee, Kwang Hyo Jung and Hyun Park
Nanomaterials 2020, 10(9), 1895; https://doi.org/10.3390/nano10091895 - 22 Sep 2020
Cited by 7 | Viewed by 4067
Abstract
Even though manganese oxides are attractive materials for batteries, super-capacitors and electro-catalysts for oxygen reduction reactions, in most practical applications MnO2 needs to be hybridized with conductive carbon nano-structures to overcome its inherent poor electrical conductivity. In this manuscript we report microwave-assisted [...] Read more.
Even though manganese oxides are attractive materials for batteries, super-capacitors and electro-catalysts for oxygen reduction reactions, in most practical applications MnO2 needs to be hybridized with conductive carbon nano-structures to overcome its inherent poor electrical conductivity. In this manuscript we report microwave-assisted synthesis of MnO2 embedded carbon nanotubes (MnO2@CNT) from Mn-H3BTC (benzene-1,3,5-carboxylic acid) metal organic frameworks (MOF) precursors. Using graphene oxide as microwave susceptible surface, MnO2 nano-particles embedded in three dimensional reduced graphene oxide (rGO) -CNT frameworks (MnO2@CNT-rGO) were synthesized which when applied as electro-catalysts in oxygen reduction reaction (ORR) demonstrated comparable half-wave potential to commercial Pt/C, better stability, and excellent immunity to methanol crossover effect in alkaline media. When carbon fiber (CF) was used as substrate, three-dimensional MnO2@CNT-CF were obtained whose utility as effective adsorbents for arsenic removal from contaminated waters is demonstrated. Full article
(This article belongs to the Special Issue Microwave Technology and Nanomaterials: Synthesis and Application)
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15 pages, 6090 KiB  
Article
Performance Enhancement of Electrospun IGZO-Nanofiber-Based Field-Effect Transistors with High-k Gate Dielectrics through Microwave Annealing and Postcalcination Oxygen Plasma Treatment
by Seong-Kun Cho and Won-Ju Cho
Nanomaterials 2020, 10(9), 1804; https://doi.org/10.3390/nano10091804 - 10 Sep 2020
Cited by 4 | Viewed by 3469
Abstract
We investigated the effects of various high-k gate dielectrics as well as microwave annealing (MWA) calcination and a postcalcination oxygen plasma treatment on the electrical properties and stability of electrospun indium gallium zinc oxide (IGZO)-nanofiber (NF)-based field-effect transistors (FETs). We found that [...] Read more.
We investigated the effects of various high-k gate dielectrics as well as microwave annealing (MWA) calcination and a postcalcination oxygen plasma treatment on the electrical properties and stability of electrospun indium gallium zinc oxide (IGZO)-nanofiber (NF)-based field-effect transistors (FETs). We found that the higher the dielectric constant of the gate dielectric, the better the electric field is transferred, resulting in the better performance of the IGZO NF FET. In addition, the MWA-calcined IGZO NF FET was superior to the conventional furnace annealing-calcined device in terms of the electrical properties of the device and the operation of resistor-loaded inverter, and it was proved that the oxygen plasma treatment further improved the performance. The results of the gate bias temperature stress test confirmed that the MWA calcination process and postcalcination oxygen plasma treatment greatly improved the stability of the IGZO NF FET by reducing the number of defects and charge traps. This verified that the MWA calcination process and oxygen plasma treatment effectively remove the organic solvent and impurities that act as charge traps in the chemical analysis of NF using X-ray photoelectron spectroscopy. Furthermore, it was demonstrated through scanning electron microscopy and ultraviolet-visible spectrophotometer that the MWA calcination process and postcalcination oxygen plasma treatment also improve the morphological and optical properties of IGZO NF. Full article
(This article belongs to the Special Issue Microwave Technology and Nanomaterials: Synthesis and Application)
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Review

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21 pages, 1953 KiB  
Review
Recent Progress of Microwave-Assisted Synthesis of Silica Materials
by Borja Díaz de Greñu, Ruth de los Reyes, Ana M. Costero, Pedro Amorós and Jose Vicente Ros-Lis
Nanomaterials 2020, 10(6), 1092; https://doi.org/10.3390/nano10061092 - 1 Jun 2020
Cited by 50 | Viewed by 5595
Abstract
Microwaves are a source of energy of great interest for chemical synthesis. Among nanomaterials, few are as versatile as silica—it forms mesoporous materials and nanoparticles, it can be incorporated as shells or loaded in composites, it can also be functionalized. Despite the relevant [...] Read more.
Microwaves are a source of energy of great interest for chemical synthesis. Among nanomaterials, few are as versatile as silica—it forms mesoporous materials and nanoparticles, it can be incorporated as shells or loaded in composites, it can also be functionalized. Despite the relevant properties of silica, and the advantages of the use of microwave as energy source, its use in silica-based materials is not frequent. We report herein a compilation of the research results published in the last 10 years of microwave assisted synthesis of silica based materials. This review includes examples of mesoporous materials for waste removal, catalysis, drug release, and gas adsorption applications, together with examples based in the optimization of the synthesis conditions. In the case of non-porous materials, examples of analytical applications, coating of metallic nanoparticles, and SiOx-C materials have been collected. Full article
(This article belongs to the Special Issue Microwave Technology and Nanomaterials: Synthesis and Application)
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