Synthesis and Applications of Nanostructured Metals and Metal Oxides

Topic Information

Dear Colleagues,

Nanomaterials have been the frontrunners of the numerous technological advancements in this era of cutting-edge technology. Specifically, nanostructured metals and metal oxides exhibit unique size-tunable properties (e.g., optical, electronic, magnetic, catalytic, and mechanical properties). In addition, the pendant surface functionalities of metals and metal oxides-based nanomaterials also contribute to their interaction and effect on biological systems (e.g., nanotoxicity and drug delivery). As such, the aforementioned properties of metals and metal oxides account for their diverse applications such as environmental remediation (e.g., catalysis, gas sensing, energy storage, and energy harvesting), sensing of diverse targets (e.g., explosives, environmental pollutants, and pathogens), therapeutics (e.g., drug delivery and toxicity) and relevant applications in many other fields (e.g., cosmetics, textile, and food industries). In consideration of the diverse properties and applications of metals and metal oxides-based nanomaterials, we cordially invite you to contribute to this Topic entitled, “Synthesis and applications of nanostructured metals and metal oxides”. The major aim of this Topic is to collect very recent original and innovative reports (original research, communications, or review articles) and developments on the synthesis and applications of metals and metal oxides-based nanomaterials (e.g., noble metal nanoparticles, transition metals and metal oxides, and semiconductor inorganic nanocrystals). Prospective authors may consider the diverse applications of the above-mentioned categories of nanomaterials such as catalysis, sensing of diverse targets (e.g., environmental pollutants, microbes, pathogens, explosives, and many more), energy storage and harvesting, opto-electronics, therapeutics (e.g., drug delivery, diagnosis, and toxicity), and food preservation and food packaging.

Prof. Dr. Ki-Hyun Kim
Dr. Deepak Kukkar
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Applied Sciences applsci	2.5	5.3	2011	18.4 Days	CHF 2400
Nanomaterials nanomaterials	4.4	8.5	2010	14.1 Days	CHF 2400
Solids solids	2.4	3.4	2020	27.5 Days	CHF 1000
Sensors sensors	3.4	7.3	2001	18.6 Days	CHF 2600
Chemosensors chemosensors	3.7	5.0	2013	20.1 Days	CHF 2000

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Published Papers (46 papers)

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9 pages, 2141 KiB  

Open AccessArticle

Neutron Irradiation to Transmute Zinc into Gallium

by M. M. Zeidan and S. Abedrabbo

Nanomaterials 2023, 13(9), 1487; https://doi.org/10.3390/nano13091487 - 27 Apr 2023

Cited by 3 | Viewed by 1480

Abstract

Modified ²⁴¹Am-Be neutron beams showed an ability to change the optical properties of zinc oxide (ZnO) photoluminescence (PL) spectra by transmuting zinc (Zn) into gallium (Ga) after irradiation. This study investigates the time required by slow neutron irradiation to register the transmutation [...] Read more.

Modified ²⁴¹Am-Be neutron beams showed an ability to change the optical properties of zinc oxide (ZnO) photoluminescence (PL) spectra by transmuting zinc (Zn) into gallium (Ga) after irradiation. This study investigates the time required by slow neutron irradiation to register the transmutation of the Zn into Ga. Two series of samples from different suppliers hydrothermally (HT) grown by TEW Tokyo Denpa Co. Ltd., Tokyo, Japan, and MTI corporation, China, are irradiated for 6, 12, 18, and 24 days on the Zn-polar face of each sample to specify the relationship between the irradiation intensity and transmutation. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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15 pages, 4508 KiB  

Open AccessArticle

Numerical and Experimental Study of Gas Phase Nanoparticle Synthesis Using NanoDOME

by Giorgio La Civita, Edoardo Ugolini, Nicola Patelli, Alberto Piccioni, Andrea Migliori, Luca Pasquini and Emanuele Ghedini

Nanomaterials 2023, 13(8), 1317; https://doi.org/10.3390/nano13081317 - 8 Apr 2023

Viewed by 1708

Abstract

Nowadays, with the rocketing of computational power, advanced numerical tools, and parallel computing, multi-scale simulations are becoming applied more and more to complex multi-physics industrial processes. One of the several challenging processes to be numerically modelled is gas phase nanoparticle synthesis. In an [...] Read more.

Nowadays, with the rocketing of computational power, advanced numerical tools, and parallel computing, multi-scale simulations are becoming applied more and more to complex multi-physics industrial processes. One of the several challenging processes to be numerically modelled is gas phase nanoparticle synthesis. In an applied industrial scenario, the possibility to correctly estimate the geometric properties of the mesoscopic entities population (e.g., their size distribution) and to more precisely control the results is a crucial step to improve the quality and efficiency of the production. The “NanoDOME” project (2015–2018) aims to be an efficient and functional computational service to be applied in such processes. NanoDOME has also been refactored and upscaled during the H2020 Project “SimDOME”. To prove its reliability, we present here an integrated study between experimental data and NanoDOME’s predictions. The main goal is to finely investigate the effect of a reactor’s thermodynamic conditions on the thermophysical history of mesoscopic entities along the computational domain. To achieve this goal, the production of silver nanoparticles has been assessed for five cases with different experimental operative conditions of the reactor. The time evolution and final size distribution of nanoparticles have been simulated with NanoDOME by exploiting the method of moments and population balance model. The validation is performed by comparing NanoDOME’s calculations with the experimental data. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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20 pages, 4809 KiB  

Open AccessArticle

Insights into the Fe³⁺ Doping Effects on the Structure and Electron Distribution of Cr₂O₃ Nanoparticles

by Cledson Santos, John M. Attah-Baah, Romualdo S. Silva Junior, Marcelo A. Mâcedo, Marcos V. S. Rezende, Robert S. Matos, Ştefan Ţălu, Dung Nguyen Trong, Simone P. A. da Paz, Rômulo S. Angélica and Nilson S. Ferreira

Nanomaterials 2023, 13(6), 980; https://doi.org/10.3390/nano13060980 - 8 Mar 2023

Cited by 18 | Viewed by 2844

Abstract

Herein, we carefully investigated the Fe³⁺ doping effects on the structure and electron distribution of Cr₂O₃ nanoparticles using X-ray diffraction analysis (XRD), maximum entropy method (MEM), and density functional theory (DFT) calculations. We showed that increasing the Fe doping [...] Read more.

Herein, we carefully investigated the Fe³⁺ doping effects on the structure and electron distribution of Cr₂O₃ nanoparticles using X-ray diffraction analysis (XRD), maximum entropy method (MEM), and density functional theory (DFT) calculations. We showed that increasing the Fe doping induces an enlargement in the axial ratio of c/a, which is associated with an anisotropic expansion of the unit cell. We found that as Fe³⁺ replaces Cr in the Cr₂O₃ lattice, it caused a higher interaction between the metal 3d states and the oxygen 2p states, which led to a slight increase in the Cr/Fe–O1 bond length followed by an opposite effect for the Cr/Fe–O2 bonds. Our results also suggest that the excitations characterize a well-localized bandgap region from occupied Cr d to unoccupied Fe d states. The Cr₂O₃ and Fe-doped Cr₂O₃ nanoparticles behave as Mott–Hubbard insulators due to their band gap being in the d−d gap, and Cr 3d orbitals dominate the conduction band. These findings suggest that the magnitude and the character of the electronic density near the O atom bonds in Cr₂O₃ nanoparticles are modulated by the Cr–Cr distances until its stabilization at the induced quasi-equilibrium of the Cr₂O₃ lattice when the Fe³⁺ doping values reaches the saturation level range. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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14 pages, 4545 KiB  

Open AccessArticle

Reproducibility and Repeatability Tests on (SnTiNb)O₂ Sensors in Detecting ppm-Concentrations of CO and Up to 40% of Humidity: A Statistical Approach

by Michele Astolfi, Giorgio Rispoli, Sandro Gherardi, Giulia Zonta and Cesare Malagù

Sensors 2023, 23(4), 1983; https://doi.org/10.3390/s23041983 - 10 Feb 2023

Cited by 8 | Viewed by 2496

Abstract

Nowadays, most medical-diagnostic, environmental monitoring, etc. devices employ sensors whose fabrication reproducibility and response repeatability assessment are crucial. The former consists of large-scale sensor manufacture through a standardized process with almost identical morphology and behavior, while the latter consists of giving the same [...] Read more.

Nowadays, most medical-diagnostic, environmental monitoring, etc. devices employ sensors whose fabrication reproducibility and response repeatability assessment are crucial. The former consists of large-scale sensor manufacture through a standardized process with almost identical morphology and behavior, while the latter consists of giving the same response upon repeating the same stimulus. The thermo-activated chemoresistive sensors, which change their conductance by interacting with the molecules composing the surrounding gas, are currently employed in many devices: in particular, thick-film (SnTiNb)O₂ nanosensors were demonstrated to be particularly suitable in the medical and biological fields. Therefore, a set of thirteen of them, randomly selected from the same screen-printing deposition, were laboratory tested, and the outcomes were statistically analyzed in order to assess their consistency. At first, the working temperature that maximized both the sensor sensitivity and response repeatability was identified. Then, the sensors were subjected to different gas concentrations and humidities at this optimal working temperature. It resulted in the (SnTiNb)O₂ nanosensors detecting and discriminating CO concentrations as low as 1 ppm and at high humidity degrees (up to 40%) with high repeatability since the response relative standard error ranged from 0.8 to 3.3% for CO and from 3.6 to 5.4% for water vapor. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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20 pages, 5491 KiB  

Open AccessFeature PaperArticle

Synergistic Effect of Pt and Dual Ni/Co Cations in Hydrotalcite-Derived Pt/Ni_1.5Co_0.5AlO Catalysts for Promoting Soot Combustion

by Yilin Zhang, Peng Zhang, Jing Xiong, Yuanfeng Li, Yaxiao Ma, Sicheng Zhang, Zhen Zhao, Jian Liu and Yuechang Wei

Nanomaterials 2023, 13(4), 623; https://doi.org/10.3390/nano13040623 - 4 Feb 2023

Cited by 4 | Viewed by 1930

Abstract

In this article, the catalysts of hydrotalcite-derived Ni_1.5Co_0.5AlO nanosheet-supported highly dispersed Pt nanoparticles (Pt_n/Ni_1.5Co_0.5AlO, where n% is the weigh percentage of the Pt element in the catalysts) were elaborately fabricated by the gas-bubble-assisted [...] Read more.

In this article, the catalysts of hydrotalcite-derived Ni_1.5Co_0.5AlO nanosheet-supported highly dispersed Pt nanoparticles (Pt_n/Ni_1.5Co_0.5AlO, where n% is the weigh percentage of the Pt element in the catalysts) were elaborately fabricated by the gas-bubble-assisted membrane--reduction method. The specific porous structure formed by the stack of hydrotalcite-derived Ni_1.5Co_0.5AlO nanosheets can increase the transfer mass efficiency of the reactants (O₂, NO, and soot) and the strong Pt–Ni_1.5Co_0.5AlO interaction can weaken the Ni/Co-O bond for promoting the mobility of lattice oxygen and the formation of surface-oxygen vacancies. The Pt_n/Ni_1.5Co_0.5AlO catalysts exhibited excellent catalytic activity and stability during diesel soot combustion under the loose contact mode between soot particles and catalysts. Among all the catalysts, the Pt₂/Ni_1.5Co_0.5AlO catalyst showed the highest catalytic activities for soot combustion (T₅₀ = 350 °C, TOF = 6.63 × 10⁻³ s⁻¹). Based on the characterization results, the catalytic mechanism for soot combustion is proposed: the synergistic effect of Pt and dual Ni/Co cations in the Pt/Ni_1.5Co_0.5AlO catalysts can promote the vital step of catalyzing NO oxidation to NO₂ in the NO-assisted soot oxidation mechanism. This insight into the synergistic effect of Pt and dual Ni/Co cations for soot combustion provides new strategies for reducing the amounts of noble metals in high-efficient catalysts. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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14 pages, 2228 KiB  

Open AccessArticle

Towards the Standardization of Photothermal Measurements of Iron Oxide Nanoparticles in Two Biological Windows

by Daniel Arranz, Rosa Weigand and Patricia de la Presa

Nanomaterials 2023, 13(3), 450; https://doi.org/10.3390/nano13030450 - 22 Jan 2023

Cited by 7 | Viewed by 2035

Abstract

A systematic study on laser-induced heating carried out in two biological windows (800 nm and 1053 nm) for Fe₃O₄ nanoparticles in water suspension showed evidence of the strong dependence of the specific absorption rate (SAR) on extrinsic parameters such as [...] Read more.

A systematic study on laser-induced heating carried out in two biological windows (800 nm and 1053 nm) for Fe₃O₄ nanoparticles in water suspension showed evidence of the strong dependence of the specific absorption rate (SAR) on extrinsic parameters such as the vessel volume or laser spot size. The results show that a minimum of 100 μL must be used in order to obtain vessel-size-independent SARs. In addition, at a constant intensity but different laser powers and spot size ratios, the SARs can differ by a three-fold factor, showing that the laser power and irradiated area strongly affect the heating curves for both wavelengths. The infrared molecular absorber IRA 980B was characterized under the same experimental conditions, and the results confirm the universality of the SARs’ dependence on these extrinsic parameters. Based on these results, we propose using solutions of IRA 980B as a standard probe for SAR measurements and employing the ratio SAR_{iron oxide}/SAR_{IRA 980B} to compare different measurements performed in different laboratories. This measurement standardization allows us to extract more accurate information about the heating performance of different nanoparticles. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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16 pages, 3889 KiB  

Open AccessArticle

Nonlinear Optical Properties of Zinc Oxide Nanoparticle Colloids Prepared by Pulsed Laser Ablation in Distilled Water

by Tarek Mohamed, Ali Farhan, Hanan Ahmed, Mohamed Ashour, Samar Mamdouh and Reinhold Schuch

Nanomaterials 2022, 12(23), 4220; https://doi.org/10.3390/nano12234220 - 28 Nov 2022

Cited by 16 | Viewed by 3158

Abstract

The nonlinear optical properties of zinc oxide nanoparticles (ZnONPs) in distilled water were measured using a femtosecond laser and the Z-scan technique. The ZnONPs colloids were created by the ablation of zinc bulk in distilled water with a 532 nm Nd: YAG laser. [...] Read more.

The nonlinear optical properties of zinc oxide nanoparticles (ZnONPs) in distilled water were measured using a femtosecond laser and the Z-scan technique. The ZnONPs colloids were created by the ablation of zinc bulk in distilled water with a 532 nm Nd: YAG laser. Transmission electron microscopy, an ultraviolet-visible spectrophotometer, and atomic absorption spectrophotometry were used to determine the size, shape, absorption spectra, and concentration of the ZnONPs colloids. The nonlinear absorption coefficient and nonlinear refractive index were measured at different excitation wavelengths and intensities. The nonlinear absorption coefficient of the ZnONPs colloids was found to be positive, caused by reverse saturable absorption, whereas the nonlinear refractive index was found to be negative due to self-defocusing in the ZnONPs. Both laser parameters, such as excitation wavelength and input intensity, and nanoparticle features, such as concentration and size, were found to influence the nonlinear optical properties of the ZnONPs. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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Supplementary File 1 (ZIP, 18552 KiB)

25 pages, 2761 KiB  

Open AccessArticle

Antimicrobial Properties of Zinc Oxide Nanoparticles Synthesized from Lavandula pubescens Shoot Methanol Extract

by Abu ElGasim A. Yagoub, Ghedeir M. Al-Shammari, Laila Naif Al-Harbi, Pandurangan Subash-Babu, Rasha Elsayim, Mohammed A. Mohammed, Mohammed Abdo Yahya and Sndos Z. A. Fattiny

Appl. Sci. 2022, 12(22), 11613; https://doi.org/10.3390/app122211613 - 15 Nov 2022

Cited by 24 | Viewed by 5281

Abstract

We report on employing in vitro biosynthesized ZnO nanoparticles using L. pubescens shoot methanol extract (50 and 100 mg LP–ZnO NPs) to examine their antimicrobial efficacy against Pseudomonas aeruginosa (ATCC27853), Staphylococcus aureus (ATCC 29213), Aspergillus niger (ATCC 16404 NA), and Aspergillus terreus (TCC 10029). [...] Read more.

We report on employing in vitro biosynthesized ZnO nanoparticles using L. pubescens shoot methanol extract (50 and 100 mg LP–ZnO NPs) to examine their antimicrobial efficacy against Pseudomonas aeruginosa (ATCC27853), Staphylococcus aureus (ATCC 29213), Aspergillus niger (ATCC 16404 NA), and Aspergillus terreus (TCC 10029). The formation and stability of the investigated ZnO nanoparticles were proven by transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), UV–vis spectroscopy, X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). The ZnO nanoparticles were rod-shaped (width: 10.76–30.93 nm). The nanoparticles in dimethyl sulfoxide (DMSO) outperformed their water counterparts in terms of their zones of inhibition (ZIs) (marginal means of 12.5 and 8.19 mm, respectively) and minimum inhibition concentrations (MICs) (means of 4.40 and 8.54 mg/mL, respectively). The ZI means for S. aureus, P. aeruginosa, A. terreus, and A. niger were 10.50, 6.13, 12.5, and 11.5 mm, respectively. When treating S. aureus and P. aeruginosa, the ZI of the 50 mg LP–ZnO NPs in water was better (14 mm), with a lower MIC and lower minimum bactericidal/fungicide concentrations (MBC/MFC) (7.22 and 4.88 mg/mL, respectively) than the ZnO and control drugs. The SEM images showed cellular alterations in the surface shapes after the LP–ZnO-NP treatments. Biosynthesized LP–ZnO NPs could have beneficial antibacterial properties, which could allow for future contributions to the development of new antimicrobial drugs. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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15 pages, 5930 KiB  

Open AccessArticle

Ultra-Light and Ultra-Low Thermal Conductivity of Elastic Silica Nanofibrous Aerogel with TiO2 Opacifier Particles as Filler

by Lixia Yang, Yang Ding, Mengmeng Yang, Yapeng Wang, Deniz Eren Erişen, Zhaofeng Chen, Qiong Wu and Guiyuan Zheng

Nanomaterials 2022, 12(22), 3928; https://doi.org/10.3390/nano12223928 - 8 Nov 2022

Cited by 12 | Viewed by 3211

Abstract

The thermal radiation phenomenon is more crucial than other thermal transportation phenomena at elevated temperatures (>300 °C). Therefore, infrared radiation resistance and its performance on thermal conduction of nanofibrous aerogel with Titanium oxide (TiO₂) filler have been investigated compared to control [...] Read more.

The thermal radiation phenomenon is more crucial than other thermal transportation phenomena at elevated temperatures (>300 °C). Therefore, infrared radiation resistance and its performance on thermal conduction of nanofibrous aerogel with Titanium oxide (TiO₂) filler have been investigated compared to control groups (silica nanofibrous aerogels with and without filler). Nanofibrous aerogel has been produced by electrospun silica nanofibers. Later, TiO₂ opacifier and a non-opacifier filled materials were prepared by a solution homogenization method and then freeze-dried to obtain particle-filled nanofibrous aerogel. Moreover, the thermal radiation conductivity of the composite was calculated by numerical simulation, and the effect of the anti-infrared radiation of the TiO₂ opacifier was obtained. The fascinating inhibited infrared radiation transmission performance (infrared transmittance ~67% at 3 μm) and excellent thermal insulation effect (thermal conductivity of 0.019 Wm⁻¹K⁻¹ at room temperature) and maximum compressive strengths (3.22 kPa) of silica nanofibrous aerogel with TiO₂ opacifier were verified. Excellent thermal insulation, compression and thermal stability properties show its potential for practical application in industrial production. The successful synthesis of this material may shed light on the development of other insulative ceramic aerogels. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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12 pages, 3316 KiB  

Open AccessArticle

Electrochemical Biosensor Based on Chitosan- and Thioctic-Acid-Modified Nanoporous Gold Co-Immobilization Enzyme for Glycerol Determination

by Caiyun Yan, Kaifeng Jin, Xiangyi Luo, Jinhua Piao and Fang Wang

Chemosensors 2022, 10(7), 258; https://doi.org/10.3390/chemosensors10070258 - 2 Jul 2022

Cited by 7 | Viewed by 2734

Abstract

An electrochemical biosensor based on chitosan- and thioctic-acid-modified nanoporous gold (NPG) co-immobilization glycerol kinase (GK) and glycerol-3-phosphate oxidase (GPO) was constructed for glycerol determination in wine. The NPG, with the properties of porous microstructure, large specific surface area, and high conductivity, was beneficial [...] Read more.

An electrochemical biosensor based on chitosan- and thioctic-acid-modified nanoporous gold (NPG) co-immobilization glycerol kinase (GK) and glycerol-3-phosphate oxidase (GPO) was constructed for glycerol determination in wine. The NPG, with the properties of porous microstructure, large specific surface area, and high conductivity, was beneficial for protecting the enzyme from inactivation and denaturation and enhancing electron transfer in the modified electrode. The co-immobilization of the enzyme by chitosan-embedding and thioctic-acid-modified NPG covalent bonding was beneficial for improving the catalytic performance and stability of the enzyme-modified electrode. Ferrocene methanol (Fm) was used as a redox mediator to accelerate the electron transfer rate of the enzyme-modified electrode. The fabricated biosensor exhibited a wide determination range of 0.1–5 mM, low determination limit of 77.08 μM, and high sensitivity of 9.17 μA mM⁻¹. Furthermore, it possessed good selectivity, repeatability, and stability, and could be used for the determination of glycerol in real wine samples. This work provides a simple and novel method for the construction of biosensors, which may be helpful to the application of enzymatic biosensors in different determination scenarios. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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16 pages, 4370 KiB  

Open AccessArticle

Promising Novel Barium Carbonate One-Dimensional Nanostructures and Their Gas Sensing Application: Preparation and Characterization

by Nagih M. Shaalan

Chemosensors 2022, 10(6), 230; https://doi.org/10.3390/chemosensors10060230 - 17 Jun 2022

Cited by 2 | Viewed by 2670

Abstract

Recently, barium carbonate-based nanomaterials have been used for sensor and catalysis applications. The sensing performance can be improved with a suitable one-dimensional nanostructure. In this regard, novel nanosized BaCO₃ materials were fabricated by a one-pot designed thermal evaporation system. Ten milligrams of [...] Read more.

Recently, barium carbonate-based nanomaterials have been used for sensor and catalysis applications. The sensing performance can be improved with a suitable one-dimensional nanostructure. In this regard, novel nanosized BaCO₃ materials were fabricated by a one-pot designed thermal evaporation system. Ten milligrams of Ba as raw material were used to deposit BaCO₃ nanostructures at a pressure of 0.85 torr and a temperature of 850 °C in a partial oxygen atmosphere of the ambient. This simple method for fabricating novel BaCO₃ nanostructures is presented here. X-ray diffraction was indexed on the orthorhombic polycrystalline structure of the prepared BaCO₃. The nanostructures deposited here could be described as Datura-like structures linked with nanowires of 20–50 nm in diameter and 5 µm in length. The BaCO₃ nanostructure prepared by the current method exhibited a semiconductor-like behavior with an activation energy of 0.68 eV. This behavior was ascribed to the nature of the morphology, which may possess large defective points. Thus, this nanostructure was subjected to gas sensing measurements, showing high activity toward NO₂ gas. The proposed sensor also underwent deep investigation toward NO₂ at various gas concentrations and working. The response and recovery time constants were recorded in the ranges of 6–20 s and 30–150 s, respectively. The sensor showed its reversibility toward NO₂ when the sensor signal was repeated at various cycles of various concentrations. The sensor was exposed to different levels of humidity, showing high performance toward NO₂ gas at 250 °C. The sensor exhibited fast response and recovery toward NO₂ gas. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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10 pages, 5566 KiB  

Open AccessArticle

Simple Synthesis and Characterization of Shell-Thickness-Controlled Ni/Ni₃C Core-Shell Nanoparticles

by Sun-Woo Kim, Jae Chul Ro and Su-Jeong Suh

Nanomaterials 2022, 12(12), 1954; https://doi.org/10.3390/nano12121954 - 7 Jun 2022

Cited by 4 | Viewed by 2683

Abstract

Ni/Ni₃C core-shell nanoparticles with an average diameter of approximately 120 nm were carburized via a chemical solution method using triethylene glycol. It was found that over time, the nanoparticles were covered with a thin Ni₃C shell measuring approximately 1–4 [...] Read more.

Ni/Ni₃C core-shell nanoparticles with an average diameter of approximately 120 nm were carburized via a chemical solution method using triethylene glycol. It was found that over time, the nanoparticles were covered with a thin Ni₃C shell measuring approximately 1–4 nm, and each Ni core was composed of poly grains. The saturation magnetization of the core-shell nanopowders decreased in proportion to the amount of Ni₃C. The synthesis mechanism of the Ni/Ni₃C core-shell nanoparticles was proposed through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analyses. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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13 pages, 3032 KiB  

Open AccessArticle

Sonochemical-Assisted Biogenic Synthesis of Theophrasite β-Ni(OH)₂ Nanocluster Using Chia Seeds Extract: Characterization and Anticancer Activity

by Hanaa A. Hassanin and Amel Taha

Nanomaterials 2022, 12(11), 1919; https://doi.org/10.3390/nano12111919 - 3 Jun 2022

Cited by 8 | Viewed by 2821

Abstract

Theophrasite β-Ni(OH)₂ nanocluster were fabricated via the sonochemical-assisted biogenic method using chia seeds extract as a reducing and stabilizing agent. The optical and morphological feature of the synthesized nanocluster was characterized using UV-Vis, FTIR, FE-SEM-EDS, HR-TEM, DLS, XPS, and XRD analysis. According [...] Read more.

Theophrasite β-Ni(OH)₂ nanocluster were fabricated via the sonochemical-assisted biogenic method using chia seeds extract as a reducing and stabilizing agent. The optical and morphological feature of the synthesized nanocluster was characterized using UV-Vis, FTIR, FE-SEM-EDS, HR-TEM, DLS, XPS, and XRD analysis. According to FE-SEM and HR-TEM images of the synthesized materials, β-Ni(OH)₂ nanocluster illustrates the hexagonal particle shape with an average size of 5.8 nm, while the EDS results confirm the high purity of the synthesized nanocluster. Moreover, the XRD pattern of the synthesized materials shows typical peaks that match the reference pattern of the Theophrasite form of β-Ni(OH)₂ with a hexagonal crystal system. The XPS analysis illustrates that the prepared samples exhibit both Ni²⁺ and Ni³⁺ with the predominance of Ni²⁺ species. Additionally the in-vitro cytotoxic activity of β-Ni(OH)₂ nanocluster is tested against the MCF7 cell lines (breast cancer cells). The MTT assay results proved that the synthesized β-Ni(OH)₂ nanocluster has potent cytotoxic activity against breast cancer cell lines (IC₅₀: 62.7 μg/mL). Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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Supplementary File 1 (ZIP, 624 KiB)

12 pages, 2302 KiB  

Open AccessArticle

Visible-Light-Driven Ag-Doped BiOBr Nanoplates with an Enhanced Photocatalytic Performance for the Degradation of Bisphenol A

by Chu-Ya Wang, Qi Zeng, Li-Xia Wang, Xin Fang and Guangcan Zhu

Nanomaterials 2022, 12(11), 1909; https://doi.org/10.3390/nano12111909 - 2 Jun 2022

Cited by 12 | Viewed by 2841

Abstract

Based on the low utilization rate of visible light and the high-charge carriers-recombination efficiency of bismuth oxybromide (BiOBr), in this work, noble metal Ag was used to modify BiOBr, and Ag-doped BiOBr nanoplates (Ag-BiOBr) were obtained through a one-step hydrothermal method. Compared with [...] Read more.

Based on the low utilization rate of visible light and the high-charge carriers-recombination efficiency of bismuth oxybromide (BiOBr), in this work, noble metal Ag was used to modify BiOBr, and Ag-doped BiOBr nanoplates (Ag-BiOBr) were obtained through a one-step hydrothermal method. Compared with BiOBr, the absorption edge of Ag-BiOBr showed a redshift from 453 nm to 510 nm, and the absorption efficiency of visible light was, obviously, improved. Bisphenol A (BPA) was chosen as the target pollutant, to evaluate the photocatalytic performance of the samples. Ag_0.1-BiOBr showed the highest degradation efficiency. The intrinsic photocatalytic activity of Ag_0.1-BiOBr, under visible light, was approximately twice as high as that of BiOBr. In this way, a new visible-light-driven photocatalyst was proposed, to fight against organic pollution, which provides a promising strategy for water and wastewater treatment. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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13 pages, 3217 KiB  

Open AccessArticle

Removal of Chromium(VI) by Nanoscale Zero-Valent Iron Supported on Melamine Carbon Foam

by Qiming Li, Meili Liu, Xuchun Qiu, Xiang Liu, Malcom Frimpong Dapaah, Qijian Niu and Liang Cheng

Nanomaterials 2022, 12(11), 1866; https://doi.org/10.3390/nano12111866 - 30 May 2022

Cited by 8 | Viewed by 2848

Abstract

The overuse of chromium (Cr) has significantly negatively impacted human life and environmental sustainability. Recently, the employment of nano zero-valent iron (nZVI) for Cr(VI) removal is becoming an emerging approach. In this study, carbonized melamine foam-supported nZVI composites, prepared by a simple impregnation–carbonization–reduction [...] Read more.

The overuse of chromium (Cr) has significantly negatively impacted human life and environmental sustainability. Recently, the employment of nano zero-valent iron (nZVI) for Cr(VI) removal is becoming an emerging approach. In this study, carbonized melamine foam-supported nZVI composites, prepared by a simple impregnation–carbonization–reduction method, were assessed for efficient Cr(VI) removal. The prepared composites were characterized by XPS, SEM, TEM, BET and XRD. Batch experiments at different conditions revealed that the amount of iron added, the temperature of carbonization and the initial Cr(VI) concentration were critical factors. Fe@MF-12.5-800 exhibited the highest removal efficiency of 99% Cr(VI) (10 mg/L) at neutral pH among the carbonized melamine foam-supported nZVI composites. Its iron particles were effectively soldered onto the carbonaceous surfaces within the pore networks. Moreover, Fe@MF-12.5-800 demonstrated remarkable stability (60%, 7 days) in an open environment compared with nZVI particles. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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13 pages, 2470 KiB  

Open AccessCommunication

Investigating Organic Vapor Sensing Properties of Composite Carbon Nanotube-Zinc Oxide Nanowire

by Mostafa Shooshtari, Saeideh Pahlavan, Saeideh Rahbarpour and Hasan Ghafoorifard

Chemosensors 2022, 10(6), 205; https://doi.org/10.3390/chemosensors10060205 - 29 May 2022

Cited by 11 | Viewed by 2837

Abstract

The low operating temperature of nanowire gas sensors along with their high surface-to-volume ratio are two factors that make gas sensors more practical. In this paper, the growth of ZnO nanowires on a vertically aligned CNT forest is reported. The utilized method for [...] Read more.

The low operating temperature of nanowire gas sensors along with their high surface-to-volume ratio are two factors that make gas sensors more practical. In this paper, the growth of ZnO nanowires on a vertically aligned CNT forest is reported. The utilized method for ZnO growth was a rapid microwave-assisted hydrothermal route, which facilitates low-temperature and ultra-fast fabrication. Organic vapor sensing properties of fabricated samples were studied in response to different alcoholic vapors at a wide operating temperature range of 25 to 300 °C. Enhancement of the gas response was observed with increasing operating temperature. Moreover, the effect of the ZnO nanowire length on organic vapor sensing properties of CNT-ZnO samples was investigated. Results proved that CNT-ZnO samples with long ZnO wires exhibit higher sensitivity to examined analytes. Different length ZnO nanowires were attained via variation of the microwave exposure time and power. Fabrication parameters were selected based on numerous runs. The length of ZnO synthesized at each distinct run was calculated based on SEM micrographs of the samples. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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24 pages, 2977 KiB  

Open AccessArticle

Electric Energy Storage Effect in Hydrated ZrO₂-Nanostructured System

by Alexander S. Doroshkevich, Andriy I. Lyubchyk, Boris L. Oksengendler, Tatyana Yu. Zelenyak, Nurbol O. Appazov, Andriy K. Kirillov, Tatyana A. Vasilenko, Alisa A. Tatarinova, Oksana O. Gorban, Viktor I. Bodnarchuk, Nadejda N. Nikiforova, Maria Balasoiu, Diana M. Mardare, Carmen Mita, Dorin Luca, Matlab N. Mirzayev, Asif A. Nabiyev, Evgeni P. Popov, Anca Stanculescu, Tatyana E. Konstantinova and Yulia V. Aleksiayenakadd Show full author list remove Hide full author list

Nanomaterials 2022, 12(11), 1783; https://doi.org/10.3390/nano12111783 - 24 May 2022

Cited by 3 | Viewed by 2972

Abstract

The dimensional effect of electric charge storage with a density of up to 270 μF/g by the hydrated ZrO₂-nanoparticles system was determined. It was found that the place of localization of different charge carriers is the generalized heterophase boundary-nanoparticles surface. The [...] Read more.

The dimensional effect of electric charge storage with a density of up to 270 μF/g by the hydrated ZrO₂-nanoparticles system was determined. It was found that the place of localization of different charge carriers is the generalized heterophase boundary-nanoparticles surface. The supposed mechanism of the effect was investigated using the theory of dispersed systems, the band theory, and the theory of contact phenomena in semiconductors, which consists of the formation of localized electronic states in the nanoparticle material due to donor–acceptor interaction with the adsorption ionic atmosphere. The effect is relevant for modern nanoelectronics, microsystem technology, and printed electronics because it allows overcoming the basic physical restrictions on the size, temperature, and operation frequency of the device, caused by leakage currents. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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11 pages, 7077 KiB  

Open AccessArticle

A General Way to Fabricate Chain-like Ferrite with Ultralow Conductive Percolation Threshold and Wideband Absorbing Ability

by Cong Chen, Haitao Dong, Jiayuan Wang, Wen Chen, Denghui Li, Meng Cai and Kun Zhou

Nanomaterials 2022, 12(9), 1603; https://doi.org/10.3390/nano12091603 - 9 May 2022

Cited by 4 | Viewed by 2101

Abstract

The magnetic nanochain-like material has been regards as one of the most promising electromagnetic (EM) absorbing material but remains a challenging. Herein, magnetic chain-like ferrite (included Fe₃O_4, CoFe₂O₄ and NiFe₂O₄) are successfully produced [...] Read more.

The magnetic nanochain-like material has been regards as one of the most promising electromagnetic (EM) absorbing material but remains a challenging. Herein, magnetic chain-like ferrite (included Fe₃O_4, CoFe₂O₄ and NiFe₂O₄) are successfully produced through a general solvothermal method, using PVP as the structural-liking agent. Experimental results confirm the ultimate sample possess a 3-dimensional chain-like structure which are constructed by numerous ferrite’s nanoparticles with ~60 nm in diameter. Their electromagnetic parameters can be also manipulated by such a chain structure, especially the dielectric loss, where a sharply increases can be observed on within a lower filling ratio. It greatly benefits to the EM absorbing property. In this article, the electromagnetic absorption layer made with a lower content of ferrite possess the excellent electromagnetic absorption ability, where the optimized effective absorption band was nearly 6.4 GHz under a thickness of 1.8 mm. Moreover, the filling ratio is only 30 wt%. Our method for designing of chain-like magnetic material can be helpful for producing wideband electromagnetic absorption in a low filling ratio. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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9 pages, 3670 KiB  

Open AccessArticle

Development of a Simultaneous Process of Surface Modification and Pd Nanoparticle Immobilization of a Polymer Substrate Using Radiation

by Naoto Uegaki, Satoshi Seino, Yuji Takagi, Yuji Ohkubo and Takashi Nakagawa

Nanomaterials 2022, 12(9), 1463; https://doi.org/10.3390/nano12091463 - 25 Apr 2022

Cited by 4 | Viewed by 2456

Abstract

Pd nanoparticles were immobilized on an acrylonitrile–butadiene–styrene copolymer (ABS) substrate using ionizing radiation. The samples were prepared by irradiating plastic zipper packs containing ABS substrates and a Pd(NO₃)₂ aqueous solution with a high-energy electron beam (4.8 MeV). Pd nanoparticles immobilized [...] Read more.

Pd nanoparticles were immobilized on an acrylonitrile–butadiene–styrene copolymer (ABS) substrate using ionizing radiation. The samples were prepared by irradiating plastic zipper packs containing ABS substrates and a Pd(NO₃)₂ aqueous solution with a high-energy electron beam (4.8 MeV). Pd nanoparticles immobilized on the ABS substrate surfaces were observed using scanning electron microscopy (SEM). The chemical state of Pd was found to be coordinated to a carbonyl group or a metallic state by X-ray photoelectron spectroscopy (XPS) measurements. The peel strength of the Cu film on the Pd/ABS samples was 0.7 N/mm or higher. This result shows that the prepared Pd/ABS samples have high adhesion strength, despite not undergoing treatments such as etching with chromic acid. This method is expected to immobilize metal nanoparticles, not only on plastic plates but also on various other materials. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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12 pages, 2512 KiB  

Open AccessArticle

An Operando X-ray Absorption Spectroscopy Study on Sensing Characteristics of Vertically Aligned ZnO Thin Film for Methane Gas Sensors

by Suriya Duangmanee, Yingyot Poo-arporn, Pattanaphong Janphuang, Pimchanok Leuasoongnoen, Surangrat Tonlublao, Phitsamai Kamonpha, Natawan Saengchai, Narong Chanlek, Chatree Saisombat, Pinit Kidkhunthod and Rungtiva P. Poo-arporn

Nanomaterials 2022, 12(8), 1285; https://doi.org/10.3390/nano12081285 - 9 Apr 2022

Cited by 5 | Viewed by 2440

Abstract

In this work, a simple, facile growth approach for a vertically aligned ZnO thin film is fabricated and its application towards methane gas sensors is demonstrated. ZnO thin film was prepared by a combination of hydrothermal and sputtering methods. First, a ZnO seed [...] Read more.

In this work, a simple, facile growth approach for a vertically aligned ZnO thin film is fabricated and its application towards methane gas sensors is demonstrated. ZnO thin film was prepared by a combination of hydrothermal and sputtering methods. First, a ZnO seed layer was prepared on the substrate through a sputtering technique, then a ZnO nanorod was fabricated using a hydrothermal method. The surface morphology of the ZnO film was observed by scanning electron microscopy (SEM). A ZnO nanorod coated on the dense seed layer is clearly visible in the SEM image. The average size of the hexagonal-shaped ZnO rod was around 50 nm in diameter, with a thickness of about 1 mm. X-ray absorption near-edge structures (XANES) were recorded to characterize the structural properties of the prepared film. The obtained normalized Zn K-edge XANES of the film showed the characteristic features of ZnO, which agreed well with the standard ZnO sample. The measurement of Zn K-edge XANES was performed simultaneously with the sensing response. The results showed a good correlation between sensor response and ZnO structure under optimal conditions. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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15 pages, 5135 KiB  

Open AccessArticle

Low-Cost Surface Enhanced Raman Scattering for Bio-Probes

by Blessing Adewumi, Martin Feldman, Debsmita Biswas, Dongmei Cao, Li Jiang and Naga Korivi

Solids 2022, 3(2), 188-202; https://doi.org/10.3390/solids3020013 - 7 Apr 2022

Cited by 2 | Viewed by 3186

Abstract

Raman Spectroscopy is a well-known method for identifying molecules by their spectroscopic “fingerprint”. In Surface Enhanced Raman Scattering (SERS), the presence of nanometallic surfaces in contact with the molecules enormously enhances the spectroscopic signal. Raman enhancing surfaces are often fabricated lithographically or chemically, [...] Read more.

Raman Spectroscopy is a well-known method for identifying molecules by their spectroscopic “fingerprint”. In Surface Enhanced Raman Scattering (SERS), the presence of nanometallic surfaces in contact with the molecules enormously enhances the spectroscopic signal. Raman enhancing surfaces are often fabricated lithographically or chemically, but the throughput is low and the equipment is expensive. In this work a SERS layer was formed by the self-assembly of silver nanospheres from a hexane suspension onto an imprinted thermoplastic sheet (PET). In addition, the SERS layer was transferred and securely bonded to other surfaces. This is an important attribute for probes into solid specimen. Raman spectra were obtained with Rhodamine 6G (R6G) solution concentrations ranging from 1 mm to 1 nm. The methods described here produced robust and sensitive SERS surfaces with inexpensive equipment, readily available materials, and with no chemical or lithographic steps. These may be critical concerns to laboratories faced with diminishing funding resources. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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21 pages, 17461 KiB  

Open AccessArticle

Antibacterial Activity of Silver and Gold Particles Formed on Titania Thin Films

by Mantas Sriubas, Kristina Bockute, Paulius Palevicius, Marius Kaminskas, Zilvinas Rinkevicius, Minvydas Ragulskis, Sandrita Simonyte, Modestas Ruzauskas and Giedrius Laukaitis

Nanomaterials 2022, 12(7), 1190; https://doi.org/10.3390/nano12071190 - 2 Apr 2022

Cited by 13 | Viewed by 3592

Abstract

Metal-based nanoparticles with antimicrobial activity are gaining a lot of attention in recent years due to the increased antibiotics resistance. The development and the pathogenesis of oral diseases are usually associated with the formation of bacteria biofilms on the surfaces; therefore, it is [...] Read more.

Metal-based nanoparticles with antimicrobial activity are gaining a lot of attention in recent years due to the increased antibiotics resistance. The development and the pathogenesis of oral diseases are usually associated with the formation of bacteria biofilms on the surfaces; therefore, it is crucial to investigate the materials and their properties that would reduce bacterial attachment and biofilm formation. This work provides a systematic investigation of the physical-chemical properties and the antibacterial activity of TiO₂ thin films decorated by Ag and Au nanoparticles (NP) against Veillonella parvula and Neisseria sicca species associated with oral diseases. TiO₂ thin films were formed using reactive magnetron sputtering by obtaining as-deposited amorphous and crystalline TiO₂ thin films after annealing. Au and Ag NP were formed using a two-step process: magnetron sputtering of thin metal films and solid-state dewetting. The surface properties and crystallographic nature of TiO₂/NP structures were investigated by SEM, XPS, XRD, and optical microscopy. It was found that the higher thickness of Au and Ag thin films results in the formation of the enlarged NPs and increased distance between them, influencing the antibacterial activity of the formed structures. TiO₂ surface with AgNP exhibited higher antibacterial efficiency than Au nanostructured titania surfaces and effectively reduced the concentration of the bacteria. The process of the observation and identification of the presence of bacteria using the deep learning technique was realized. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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11 pages, 5286 KiB  

Open AccessArticle

Synthesis of Superionic Conductive Li_1+x+yAl_xSi_yTi_2−xP_3−yO₁₂ Solid Electrolytes

by Hyeonwoo Jeong, Dan Na, Jiyeon Baek, Sanggil Kim, Suresh Mamidi, Cheul-Ro Lee, Hyung-Kee Seo and Inseok Seo

Nanomaterials 2022, 12(7), 1158; https://doi.org/10.3390/nano12071158 - 31 Mar 2022

Cited by 6 | Viewed by 2529

Abstract

Commercial lithium-ion batteries using liquid electrolytes are still a safety hazard due to their poor chemical stability and other severe problems, such as electrolyte leakage and low thermal stability. To mitigate these critical issues, solid electrolytes are introduced. However, solid electrolytes have low [...] Read more.

Commercial lithium-ion batteries using liquid electrolytes are still a safety hazard due to their poor chemical stability and other severe problems, such as electrolyte leakage and low thermal stability. To mitigate these critical issues, solid electrolytes are introduced. However, solid electrolytes have low ionic conductivity and inferior power density. This study reports the optimization of the synthesis of sodium superionic conductor-type Li_1.5Al_0.3Si_0.2Ti_1.7P_2.8O₁₂ (LASTP) solid electrolyte. The as-prepared powder was calcined at 650 °C, 700 °C, 750 °C, and 800 °C to optimize the synthesis conditions and yield high-quality LASTP powders. Later, LASTP was sintered at 950 °C, 1000 °C, 1050 °C, and 1100 °C to study the dependence of the relative density and ionic conductivity on the sintering temperature. Morphological changes were analyzed using field-emission scanning electron microscopy (FE-SEM), and structural changes were characterized using X-ray diffraction (XRD). Further, the ionic conductivity was measured using electrochemical impedance spectroscopy (EIS). Sintering at 1050 °C resulted in a high relative density and the highest ionic conductivity (9.455 × 10⁻⁴ S cm⁻¹). These findings corroborate with the activation energies that are calculated using the Arrhenius plot. Therefore, the as-synthesized superionic LASTP solid electrolytes can be used to design high-performance and safe all-solid-state batteries. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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27 pages, 2691 KiB  

Open AccessReview

Recent Trends and Advances of Co₃O₄ Nanoparticles in Environmental Remediation of Bacteria in Wastewater

by Anuoluwapo Anele, Sherine Obare and Jianjun Wei

Nanomaterials 2022, 12(7), 1129; https://doi.org/10.3390/nano12071129 - 29 Mar 2022

Cited by 24 | Viewed by 3275

Abstract

Antibiotic resistance is a formidable global threat. Wastewater is a contributing factor to the prevalence of antibiotic-resistant bacteria and genes in the environment. There is increased interest evident from research trends in exploring nanoparticles for the remediation of antibiotic-resistant bacteria. Cobalt oxide (Co [...] Read more.

Antibiotic resistance is a formidable global threat. Wastewater is a contributing factor to the prevalence of antibiotic-resistant bacteria and genes in the environment. There is increased interest evident from research trends in exploring nanoparticles for the remediation of antibiotic-resistant bacteria. Cobalt oxide (Co₃O₄) nanoparticles have various technological, biomedical, and environmental applications. Beyond the environmental remediation applications of degradation or adsorption of dyes and organic pollutants, there is emerging research interest in the environmental remediation potential of Co₃O₄ nanoparticles and its nanocomposites on antibiotic-resistant and/or pathogenic bacteria. This review focuses on the recent trends and advances in remediation using Co₃O₄ nanoparticles and its nanocomposites on antibiotic-resistant or pathogenic bacteria from wastewater. Additionally, challenges and future directions that need to be addressed are discussed. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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16 pages, 6766 KiB  

Open AccessArticle

Chemoresistive Sensors for Cellular Type Discrimination Based on Their Exhalations

by Michele Astolfi, Giorgio Rispoli, Mascia Benedusi, Giulia Zonta, Nicolò Landini, Giuseppe Valacchi and Cesare Malagù

Nanomaterials 2022, 12(7), 1111; https://doi.org/10.3390/nano12071111 - 28 Mar 2022

Cited by 8 | Viewed by 2287

Abstract

The detection of volatile organic compounds (VOCs) exhaled by human body fluids is a recent and promising method to reveal tumor formations. In this feasibility study, a patented device, based on nanostructured chemoresistive gas sensors, was employed to explore the gaseous exhalations of [...] Read more.

The detection of volatile organic compounds (VOCs) exhaled by human body fluids is a recent and promising method to reveal tumor formations. In this feasibility study, a patented device, based on nanostructured chemoresistive gas sensors, was employed to explore the gaseous exhalations of tumoral, immortalized, and healthy cell lines, with the aim of distinguishing their VOC patterns. The analysis of the device output to the cell VOCs, emanated at different incubation times and initial plating concentrations, was performed to evaluate the device suitability to identify the cell types and to monitor their growth. The sensors ST25 (based on tin and titanium oxides), STN (based on tin, titanium, and niobium oxides), and TiTaV (based on titanium, tantalum and vanadium oxides) used here, gave progressively increasing responses upon the cell density increase and incubation time; the sensor W11 (based on tungsten oxide) gave instead unreliable responses to all cell lines. All sensors (except for W11) gave large and consistent responses to RKO and HEK293 cells, while they were less responsive to CHO, A549, and CACO-2 ones. The encouraging results presented here, although preliminary, foresee the development of sensor arrays capable of identifying tumor presence and its type. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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12 pages, 4706 KiB  

Open AccessArticle

Preparation of Hollow Niobium Oxide Nanospheres with Enhanced Catalytic Activity for Oxidative Desulfurization

by Yong Wang, Lei Ren, Zifeng Li and Feng Xin

Nanomaterials 2022, 12(7), 1106; https://doi.org/10.3390/nano12071106 - 28 Mar 2022

Cited by 3 | Viewed by 2404

Abstract

Hollow niobium oxide nanospheres were successfully synthesized by using prepared three-dimensional (3D) mesoporous carbon as the hard template. The 3D mesoporous carbon materials were prepared by using histidine as the carbon source and silica microspheres as the hard template. The samples were characterized [...] Read more.

Hollow niobium oxide nanospheres were successfully synthesized by using prepared three-dimensional (3D) mesoporous carbon as the hard template. The 3D mesoporous carbon materials were prepared by using histidine as the carbon source and silica microspheres as the hard template. The samples were characterized by XRD, BET, SEM, TEM and other methods. The results show that the prepared niobium oxide nanospheres have a hollow spherical structure with an outer diameter of about 45 nm and possess a high specific surface area of 134.3 m²·g⁻¹. Furthermore, the 3D mesoporous carbon materials have a typical porous structure with a high specific surface area of 893 m²·g⁻¹. The hollow niobium oxide nanospheres exhibit high catalytic activity in oxidative desulfurization. Under optimal reaction conditions, the DBT conversion rate of the simulated oil is as high as 98.5%. Finally, a possible reaction mechanism is proposed. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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13 pages, 11069 KiB  

Open AccessArticle

A Green and Facile Microvia Filling Method via Printing and Sintering of Cu-Ag Core-Shell Nano-Microparticles

by Guannan Yang, Shaogen Luo, Tao Lai, Haiqi Lai, Bo Luo, Zebo Li, Yu Zhang and Chengqiang Cui

Nanomaterials 2022, 12(7), 1063; https://doi.org/10.3390/nano12071063 - 24 Mar 2022

Cited by 9 | Viewed by 3030

Abstract

In this work, we developed an eco-friendly and facile microvia filling method by using printing and sintering of Cu-Ag core-shell nano-microparticles (Cu@Ag NMPs). Through a chemical reduction reaction in a modified silver ammonia solution with L-His complexing agent, Cu@Ag NMPs with compact and [...] Read more.

In this work, we developed an eco-friendly and facile microvia filling method by using printing and sintering of Cu-Ag core-shell nano-microparticles (Cu@Ag NMPs). Through a chemical reduction reaction in a modified silver ammonia solution with L-His complexing agent, Cu@Ag NMPs with compact and uniform Ag shells, excellent sphericity and oxidation resistance were synthesized. The as-synthesized Cu@Ag NMPs show superior microvia filling properties to Cu nanoparticles (NPs), Ag NPs, and Cu NMPs. By developing a dense refill method, the porosity of the sintered particles within the microvias was significantly reduced from ~30% to ~10%, and the electrical conductivity is increased about twenty-fold. Combing the Cu@Ag NMPs and the dense refill method, the microvias could obtain resistivities as low as 7.0 and 6.3 μΩ·cm under the sintering temperatures of 220 °C and 260 °C, respectively. The material and method in this study possess great potentials in advanced electronic applications. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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16 pages, 39592 KiB  

Open AccessArticle

Catalytic Degradation of Anionic Organic Dye on Greenly Synthesized CuO/ZnO Nanocomposites

by Enshirah Da’na, Amel Taha and Manal Hessien

Appl. Sci. 2022, 12(6), 2910; https://doi.org/10.3390/app12062910 - 11 Mar 2022

Cited by 3 | Viewed by 2433

Abstract

CuO/ZnO nanocomposites were greenly prepared and tested for the catalytic degradation of methyl orange. The XRD analysis confirmed the existence of CuO and ZnO with crystallite sizes within the range of 15–30 nm. TEM and SEM images showed different morphological properties. The TGA [...] Read more.

CuO/ZnO nanocomposites were greenly prepared and tested for the catalytic degradation of methyl orange. The XRD analysis confirmed the existence of CuO and ZnO with crystallite sizes within the range of 15–30 nm. TEM and SEM images showed different morphological properties. The TGA analysis revealed a good thermal stability of the nanocomposite, with a total loss of less than 18% at a temperature of 700 °C. The nanocomposites were tested for the catalytic degradation of methyl orange under mild conditions with a catalyst mass/wastewater volume of 10 g/3 L, an initial dye concentration of 40 ppm, a pH of 4.5, and a degradation time of 3 h. The best efficiency of 49.1% was achieved by CuO nanoparticles (C), followed by 47.6%, which was obtained by 1C1Z. The degradation efficiency of ZnO (Z) was 16.4%, and it was increased by increasing the CuO precursor in the synthesis mixture, while adding ZnO to the CuO, resulting in a decrease in its catalytic performance. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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9 pages, 2484 KiB  

Open AccessArticle

Mechanism of Photocurrent Degradation and Contactless Healing in p-Type Mg-Doped Gallium Nitride Thin Films

by Xiaoyan Wu, Wei Li, Qingrong Chen, Caixia Xu, Jiamian Wang, Lingyuan Wu, Guodong Liu, Weiping Wang, Ting Li, Ping Chen and Long Xu

Nanomaterials 2022, 12(6), 899; https://doi.org/10.3390/nano12060899 - 9 Mar 2022

Cited by 4 | Viewed by 2899

Abstract

Light-induced degradation (LID) phenomenon is commonly found in optoelectronics devices. Self-healing effect in halide lead perovskite solar cells was investigated since the electrons and holes in the shallow traps could escape easily at room temperature. However, the degradation in the semiconductors could not [...] Read more.

Light-induced degradation (LID) phenomenon is commonly found in optoelectronics devices. Self-healing effect in halide lead perovskite solar cells was investigated since the electrons and holes in the shallow traps could escape easily at room temperature. However, the degradation in the semiconductors could not easily recover at room temperature, and many of them needed annealing at temperatures in the several hundreds, which was not friendly to the integrated optoelectronic semiconductor devices. To solve this problem, in this work, LID effect of photocurrent in p-type Mg-doped gallium nitride thin films was investigated, and deep defect and vacancy traps played a vital role in the LID and healing process. This work provides a contactless way to heal the photocurrent behavior to its initial level, which is desirable in integrated devices. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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10 pages, 3984 KiB  

Open AccessArticle

Production of Size-Controlled Gold Nanoclusters for Vapor–Liquid–Solid Method

by Alam Saj, Shaikha Alketbi, Sumayya M. Ansari, Dalaver H. Anjum, Baker Mohammad and Haila M. Aldosari

Nanomaterials 2022, 12(5), 763; https://doi.org/10.3390/nano12050763 - 24 Feb 2022

Cited by 6 | Viewed by 2506

Abstract

This study demonstrated the deposition of size-controlled gold (Au) nanoclusters via direct-current magnetron sputtering and inert gas condensation techniques. The impact of different source parameters, namely, sputtering discharge power, inert gas flow rate, and aggregation length on Au nanoclusters’ size and yield was [...] Read more.

This study demonstrated the deposition of size-controlled gold (Au) nanoclusters via direct-current magnetron sputtering and inert gas condensation techniques. The impact of different source parameters, namely, sputtering discharge power, inert gas flow rate, and aggregation length on Au nanoclusters’ size and yield was investigated. Au nanoclusters’ size and size uniformity were confirmed via transmission electron microscopy. In general, Au nanoclusters’ average diameter increased by increasing all source parameters, producing monodispersed nanoclusters of an average size range of 1.7 ± 0.1 nm to 9.1 ± 0.1 nm. Among all source parameters, inert gas flow rate exhibited a strong impact on nanoclusters’ average size, while sputtering discharge power showed great influence on Au nanoclusters’ yield. Results suggest that Au nanoclusters nucleate via a three-body collision mechanism and grow through a two-body collision mechanism, wherein the nanocluster embryos grow in size due to atomic condensation. Ultimately, the usefulness of the produced Au nanoclusters as catalysts for a vapor–liquid–solid technique was put to test to synthesize the phase change material germanium telluride nanowires. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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12 pages, 4293 KiB  

Open AccessArticle

ZnO Electrodeposition Model for Morphology Control

by Javier Orozco-Messana and Rubens Camaratta

Nanomaterials 2022, 12(4), 720; https://doi.org/10.3390/nano12040720 - 21 Feb 2022

Cited by 7 | Viewed by 2616

Abstract

In this research, a model for electrodeposition of zinc oxide (ZnO) nanostructures over indium-doped tin-oxide (ITO) glass using pulsed current and zinc chloride as source of zinc was proposed. For the model, reactions kinetics rate constants were evaluated by obtaining the reaction product [...] Read more.

In this research, a model for electrodeposition of zinc oxide (ZnO) nanostructures over indium-doped tin-oxide (ITO) glass using pulsed current and zinc chloride as source of zinc was proposed. For the model, reactions kinetics rate constants were evaluated by obtaining the reaction product solid mass of the various species through time using an electrochemical quartz crystal microbalance (EQCM). To obtain a mathematical model of the electrodeposition using Ansys CFX 2D simulation software, the reaction kinetics rates were used to calculate mass transfer in the volume closest to the surface. The model was applied to the experimental electrodeposition conditions to validate its accuracy. Dense wurtzite nanostructures with controlled morphology were obtained on a indium-doped tin-oxide (ITO) glass. Sample characterization was performed using high-resolution field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) on focused ion beam milled (FIBed) sheets from wurtzite mono-crystals. Average crystallite size was evaluated by X-ray diffraction (XRD) using the Scherrer equation, and superficial areas were evaluated by Brunauer, Emmett, and Teller (BET) method. Through the experimental results, a chemical model was developed for the competing reactions based on the speciation of zinc considering pH evolution, and kinetic constants, on the oxygen rich aqueous environment. Owing to the model, an accurate prediction of thickness and type of electrodeposited layers, under given conditions, is achieved. This allows an excellent control of the optical properties of Wurtzite as a photon absorber, for an efficient separation of the electron-hole pair for conduction of the electric charges formed. The large surface area, and small wurtzite crystallites evenly distributed on the thin film electrodeposited over the ITO conductive layer are promising features for later dye-sensitized photovoltaic cell production. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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11 pages, 2568 KiB  

Open AccessArticle

Electrochemical Detection of Ascorbic Acid in Oranges at MWCNT-AONP Nanocomposite Fabricated Electrode

by Pholoso Calvin Motsaathebe and Omolola Ester Fayemi

Nanomaterials 2022, 12(4), 645; https://doi.org/10.3390/nano12040645 - 15 Feb 2022

Cited by 29 | Viewed by 3514

Abstract

Ascorbic acid (AA) is an essential vitamin in the body, influencing collagen formation, as well as norepinephrine, folic acids, tryptophan, tyrosine, lysine, and neuronal hormone metabolism. This work reports on electrochemical detection of ascorbic acid (AA) in oranges using screen-print carbon electrodes (SPCEs) [...] Read more.

Ascorbic acid (AA) is an essential vitamin in the body, influencing collagen formation, as well as norepinephrine, folic acids, tryptophan, tyrosine, lysine, and neuronal hormone metabolism. This work reports on electrochemical detection of ascorbic acid (AA) in oranges using screen-print carbon electrodes (SPCEs) fabricated with multi-walled carbon nanotube- antimony oxide nanoparticle (MWCNT-AONP) nanocomposite. The nanocomposite-modified electrode displayed enhanced electron transfer and a better electrocatalytic reaction towards AA compared to other fabricated electrodes. The current response at the nanocomposite-modified electrode was four times bigger than the bare electrode. The sensitivity and limit of detection (LOD) at the nanocomposite modified electrode was 0.3663 [AA]/µM and 140 nM, respectively, with linearity from 0.16–0.640 μM and regression value R² = 0.985, using square wave voltammetry (SWV) for AA detection. Two well-separated oxidation peaks were observed in a mixed system containing AA and serotonin (5-HT); and the sensitivity and LOD were 0.0224 [AA]/µA, and 5.85 µΜ, respectively, with a concentration range from 23 to 100 µM (R² = 0.9969) for AA detection. The proposed sensor outperformed other AA sensors reported in the literature. The fabricated electrode showed great applicability with excellent recoveries ranging from 99 to 107 %, with a mean relative standard deviation (RSD) value of 3.52 % (n = 3) towards detecting AA in fresh oranges. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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14 pages, 4246 KiB  

Open AccessArticle

CoO Nanozymes with Multiple Catalytic Activities Regulate Atopic Dermatitis

by Mao Mao, Xuejiao Guan, Feng Wu and Lan Ma

Nanomaterials 2022, 12(4), 638; https://doi.org/10.3390/nano12040638 - 14 Feb 2022

Cited by 14 | Viewed by 3408

Abstract

Herein, we prepared CoO nanozymes with three types of enzyme catalytic activities for the first time, which have SOD-like, CAT-like, and POD-like catalytic activities. This is the first study to report the preparation of CoO nanoparticles with three types of enzyme catalytic activities [...] Read more.

Herein, we prepared CoO nanozymes with three types of enzyme catalytic activities for the first time, which have SOD-like, CAT-like, and POD-like catalytic activities. This is the first study to report the preparation of CoO nanoparticles with three types of enzyme catalytic activities by the one-pot method. By modifying the surface of CoO nanozymes with a carboxyl group, its biocompatibility enhanced, so it can be used in the field of life sciences. In vitro cytotoxicity and anti-H₂O₂-induced ROS experiments proved that CoO nanozymes can protect HaCaT cells against ROS and cytotoxicity induced by H₂O₂. In addition, an atopic dermatitis (AD) mouse model was established by topical application of MC903, which verified the anti-inflammatory effect of CoO nanozymes on the AD mouse model. Traditional drugs for the treatment of AD, such as dexamethasone, have significant side-effects. The side-effects include skin burns, telangiectasias, and even serious drug dependence. CoO nano-enzymes have a low cytotoxicity and its multiple enzyme-like catalytic activities can effectively protect cells and tissues in ROS environments, which proves that CoO nano-enzymes have high application potential in the field of anti-inflammation. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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26 pages, 8886 KiB  

Open AccessArticle

Silver Nanoparticle Arrays onto Glass Substrates Obtained by Solid-State Thermal Dewetting: A Morphological, Structural and Surface Chemical Study

by Juan Agustín Badán, Elena Navarrete-Astorga, Rodrigo Henríquez, Francisco Martín Jiménez, Daniel Ariosa, José Ramón Ramos-Barrado and Enrique A. Dalchiele

Nanomaterials 2022, 12(4), 617; https://doi.org/10.3390/nano12040617 - 11 Feb 2022

Cited by 18 | Viewed by 4438

Abstract

Silver nanoparticles (NPs) on glass substrates were obtained by a solid-state thermal dewetting (SSD) process using vacuum-evaporated-silver precursor layers. An exhaustive investigation of the morphological, structural, and surface chemistry properties by systematically controlling the precursor film thickness, annealing temperature, and time was conducted. [...] Read more.

Silver nanoparticles (NPs) on glass substrates were obtained by a solid-state thermal dewetting (SSD) process using vacuum-evaporated-silver precursor layers. An exhaustive investigation of the morphological, structural, and surface chemistry properties by systematically controlling the precursor film thickness, annealing temperature, and time was conducted. Thin silver films with thicknesses of 40 and 80 nm were deposited and annealed in air by applying a combined heat-up+constant temperature–time program. Temperatures from 300 to 500 °C and times from 0 to 50 min were assayed. SSD promoted the morphological modification of the films, leading to the Ag NPs having a discrete structure. The size, shape, surface density, and inter-nanoparticle distance of the nanoparticles depended on the initial film thickness, annealing temperature, and time, exhibiting a cubic silver structure with a (111) preferred crystallographic orientation. The prepared NPs were found to be highly enriched in the Ag{111}/Ag{110}/Ag{100} equilibrium facets. SSD not only promotes NP formation but also promotes the partial oxidation from Ag to AgO at the surface level. AgO was detected on the surface around the nanoparticles synthesized at 500 °C. Overall, a broad framework has been established that connects process factors to distinguish resultant Ag NP features in order to develop unique silver nanoparticles for specific applications. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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15 pages, 6307 KiB  

Open AccessArticle

Biosynthesis and Characterizations of Silver Nanoparticles from Annona squamosa Leaf and Fruit Extracts for Size-Dependent Biomedical Applications

by Maria Malik, Muhammad Aamir Iqbal, Mariam Malik, Muhammad Akram Raza, Wajeehah Shahid, Jeong Ryeol Choi and Phuong V. Pham

Nanomaterials 2022, 12(4), 616; https://doi.org/10.3390/nano12040616 - 11 Feb 2022

Cited by 42 | Viewed by 4549

Abstract

Green synthesis differs in the way that the plant produces chemicals that act as reducing and stabilizing agents, and by adopting this green synthesis, we have synthesized silver nanoparticles (AgNPs) from the leaf and fruit extracts of Annona squamosa (also known as Sharifa), [...] Read more.

Green synthesis differs in the way that the plant produces chemicals that act as reducing and stabilizing agents, and by adopting this green synthesis, we have synthesized silver nanoparticles (AgNPs) from the leaf and fruit extracts of Annona squamosa (also known as Sharifa), where these extracts have played an important role as reducing and capping agents. The nanoparticles were synthesized as the consequence of a reduction that happened between plant extracts and the precursor solution. The prepared AgNPs were then characterized using scanning electron microscopy, UV-Visible spectroscopy, and X-ray diffraction to study their morphology, optical response, and crystallinity. A single distinctive absorption peak of colloidal AgNPs samples was observed at 430 nm and 410 nm for leaf and fruit extract samples, having an optical bandgap of 2.97 eV and 2.88 eV, respectively, with a spherical shape having a diameter in the range of 35–90 nm and 15–50 nm, respectively, whilst XRD studies supported the FCC cubic structure of the mediated AgNPs. These green synthesized AgNPs have a wide variety of uses, particularly in the biomedical domain, where they have the potential to treat numerous diseases and are reported to be efficient against antibacterial, anti-cancer, and anti-diabetic activities. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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10 pages, 4440 KiB  

Open AccessArticle

Direct Laser Interference Ink Printing Using Copper Metal–Organic Decomposition Ink for Nanofabrication

by Jun-Han Park, Jung-Woon Lee, Yong-Won Ma, Bo-Seok Kang, Sung-Moo Hong and Bo-Sung Shin

Nanomaterials 2022, 12(3), 387; https://doi.org/10.3390/nano12030387 - 25 Jan 2022

Cited by 7 | Viewed by 4095

Abstract

In this study, we developed an effective and rapid process for nanoscale ink printing, direct laser interference ink printing (DLIIP), which involves the photothermal reaction of a copper-based metal–organic decomposition ink. A periodically lined copper pattern with a width of 500 nm was [...] Read more.

In this study, we developed an effective and rapid process for nanoscale ink printing, direct laser interference ink printing (DLIIP), which involves the photothermal reaction of a copper-based metal–organic decomposition ink. A periodically lined copper pattern with a width of 500 nm was printed on a 240 μm-wide line at a fabrication speed of 17 mm/s under an ambient environment and without any pre- or post-processing steps. This pattern had a resistivity of 3.5 μΩ∙cm, and it was found to exhibit a low oxidation state that was twice as high as that of bulk copper. These results demonstrate the feasibility of DLIIP for nanoscale copper printing with fine electrical characteristics. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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18 pages, 6463 KiB  

Open AccessArticle

The Water-Based Synthesis of Platinum Nanoparticles Using KrF Excimer Laser Ablation

by Oana Andreea Lazar, Călin Constantin Moise, Anastas Savov Nikolov, Laura-Bianca Enache, Geanina Valentina Mihai and Marius Enachescu

Nanomaterials 2022, 12(3), 348; https://doi.org/10.3390/nano12030348 - 22 Jan 2022

Cited by 11 | Viewed by 2963

Abstract

Our work presents, for the first time, a comprehensive study of the synthesis of fully metallic platinum nanoparticles (Pt-NPs) involving the ablation process in double distilled water using a KrF excimer laser. To obtain detailed information on Pt-NP morphology and optical properties, prepared [...] Read more.

Our work presents, for the first time, a comprehensive study of the synthesis of fully metallic platinum nanoparticles (Pt-NPs) involving the ablation process in double distilled water using a KrF excimer laser. To obtain detailed information on Pt-NP morphology and optical properties, prepared colloids were characterized using High Resolution Scanning Transmission Electron Microscopy (HR-STEM) with advanced capabilities for Energy Dispersive X-ray Analysis (EDX), UV/Vis optical spectroscopy, and Direct Analysis in Real Time—Mass Spectrometry (DART-MS). The influence of the applied laser fluence and laser repetition rate (RR) values on the characteristics of the obtained Pt-NPs and the ablation process, respectively, were also analyzed. Spherical and spherical-like nanoparticles exhibiting aggregation were produced. The Pt-NP mean size values were between 2.2 ± 1.2 nm and 4.0 ± 1.0 nm, while their interplanar distance measurements showed a face-centered cubic (FFC) Pt lattice (111), as revealed by HR–STEM measurements, for all investigated samples. The smallest mean size of 2.2 nm of the Pt-NPs was obtained using a 2.3 J cm⁻² laser fluence at a 10 Hz RR, and the narrowest size distribution of the NPs was obtained with a 2.3 J cm⁻² laser fluence at a 40 Hz RR. A linear dependence of the Pt-NP diameters versus the laser repetition rate was found at a constant fluence of 2.3 J cm⁻². The proposed eco-friendly synthesis route of Pt-NPs, because of its relative simplicity, has the potential for use in industrial production. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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14 pages, 1925 KiB  

Open AccessArticle

Facile Synthesis of Silane-Modified Mixed Metal Oxide as Catalyst in Transesterification Processes

by Nugroho Pranyoto, Yuni Dewi Susanti, Immanuel Joseph Ondang, Artik Elisa Angkawijaya, Felycia Edi Soetaredjo, Shella Permatasari Santoso, Maria Yuliana, Suryadi Ismadji and Sandy Budi Hartono

Nanomaterials 2022, 12(2), 245; https://doi.org/10.3390/nano12020245 - 13 Jan 2022

Cited by 6 | Viewed by 2529

Abstract

The fast depletion of fossil fuels has attracted researchers worldwide to explore alternative biofuels, such as biodiesel. In general, the production of biodiesel is carried out via transesterification processes of vegetable oil with the presence of a suitable catalyst. A mixed metal oxide [...] Read more.

The fast depletion of fossil fuels has attracted researchers worldwide to explore alternative biofuels, such as biodiesel. In general, the production of biodiesel is carried out via transesterification processes of vegetable oil with the presence of a suitable catalyst. A mixed metal oxide has shown to be a very attractive heterogeneous catalyst with a high performance. Most of the mixed metal oxide is made by using the general wetness impregnation method. A simple route to synthesize silane-modified mixed metal oxide (CaO-CuO/C₆) catalysts has been successfully developed. A fluorocarbon surfactant and triblock copolymers (EO)₁₀₆(PO)₇₀(EO)₁₀₆ were used to prevent the crystal agglomeration of carbonate salts (CaCO₃-CuCO₃) as the precursor to form CaO-CuO with a definite size and morphology. The materials show high potency as a catalyst in the transesterification process to produce biodiesel. The calcined co-precipitation product has a high crystallinity form, as confirmed by the XRD analysis. The synthesized catalyst was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). The mechanism of surface modification and the effects of the catalytic activity were also discussed. The biodiesel purity of the final product was analyzed by gas chromatography. The optimum biodiesel yield was 90.17% using the modified mixed metal oxide CaO-CuO/C₆. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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12 pages, 7898 KiB  

Open AccessArticle

Non-Stacked γ-Fe₂O₃/C@TiO₂ Double-Layer Hollow Nanoparticles for Enhanced Photocatalytic Applications under Visible Light

by Xun Sun, Xiao Yan, Huijuan Su, Libo Sun, Lijun Zhao, Junjie Shi, Zifan Wang, Jianrui Niu, Hengli Qian and Erhong Duan

Nanomaterials 2022, 12(2), 201; https://doi.org/10.3390/nano12020201 - 7 Jan 2022

Cited by 11 | Viewed by 2409

Abstract

Herein, a non-stacked γ-Fe₂O₃/C@TiO₂ double-layer hollow nano photocatalyst has been developed with ultrathin nanosheets-assembled double shells for photodegradation phenol. High catalytic performance was found that the phenol could be completely degraded in 135 min under visible light, due [...] Read more.

Herein, a non-stacked γ-Fe₂O₃/C@TiO₂ double-layer hollow nano photocatalyst has been developed with ultrathin nanosheets-assembled double shells for photodegradation phenol. High catalytic performance was found that the phenol could be completely degraded in 135 min under visible light, due to the moderate band edge position (VB at 0.59 eV and CB at −0.66 eV) of the non-stacked γ-Fe₂O₃/C@TiO₂, which can expand the excitation wavelength range into the visible light region and produce a high concentration of free radicals (such as ·OH, ·O²⁻, holes). Furthermore, the interior of the hollow composite γ-Fe₂O₃ is responsible for charge generation, and the carbon matrix facilitates charge transfer to the external TiO₂ shell. This overlap improved the selection/utilization efficiency, while the unique non-stacked double-layered structure inhibited initial charge recombination over the photocatalysts. This work provides new approaches for photocatalytic applications with γ-Fe₂O₃/C-based materials. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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11 pages, 2748 KiB  

Open AccessArticle

Effect of Aluminum Doping Ratios on the Properties of Aluminum-Doped Zinc Oxide Films Deposited by Mist Chemical Vapor Deposition Method Applying for Photocatalysis

by Htet Su Wai and Chaoyang Li

Nanomaterials 2022, 12(2), 195; https://doi.org/10.3390/nano12020195 - 7 Jan 2022

Cited by 15 | Viewed by 3435

Abstract

Aluminum-doped zinc oxide film was deposited on a glass substrate by mist chemical vapor deposition method. The influence of different aluminum doping ratios on the structural and optical properties of zinc oxide film was investigated. The XRD results revealed that the diffraction peak [...] Read more.

Aluminum-doped zinc oxide film was deposited on a glass substrate by mist chemical vapor deposition method. The influence of different aluminum doping ratios on the structural and optical properties of zinc oxide film was investigated. The XRD results revealed that the diffraction peak of (101) crystal plane was the dominant peak for the deposited AZO films with the Al doping ratios increasing from 1 wt % to 3 wt %. It was found that the variation of AZO film structures was strongly dependent on the Al/Zn ratios. The intertwined nanosheet structures were obtained when Zn/O ratios were greater than Al/O ratios with the deposition temperature of 400 °C. The optical transmittance of all AZO films was greater than 80% in the visible region. The AZO film deposited with Al doping ratio of 2 wt % showed the highest photocatalytic efficiency between the wavelength of 475 nm and 700 nm, with the high first-order reaction rate of 0.004 min⁻¹ under ultraviolet radiation. The mechanism of the AZO film influenced by aluminum doping ratio during mist chemical vapor deposition process was revealed. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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11 pages, 2697 KiB  

Open AccessArticle

MOFs-Derived Zn-Based Catalysts in Acetylene Acetoxylation

by Mengli Li, Zhuang Xu, Yuhao Chen, Guowang Shen, Xugen Wang and Bin Dai

Nanomaterials 2022, 12(1), 98; https://doi.org/10.3390/nano12010098 - 29 Dec 2021

Cited by 17 | Viewed by 2727

Abstract

Metal–organic frameworks (MOFs)-derived materials with a large specific surface area and rich pore structures are favorable for catalytic performance. In this work, MOFs are successfully prepared. Through pyrolysis of MOFs under nitrogen gas, zinc-based catalysts with different active sites for acetylene acetoxylation are [...] Read more.

Metal–organic frameworks (MOFs)-derived materials with a large specific surface area and rich pore structures are favorable for catalytic performance. In this work, MOFs are successfully prepared. Through pyrolysis of MOFs under nitrogen gas, zinc-based catalysts with different active sites for acetylene acetoxylation are obtained. The influence of the oxygen atom, nitrogen atom, and coexistence of oxygen and nitrogen atoms on the structure and catalytic performance of MOFs-derived catalysts was investigated. According to the results, the catalysts with different catalytic activity are Zn-O-C (33%), Zn-O/N-C (27%), and Zn-N-C (12%). From the measurements of X-ray photoelectron spectroscopy (XPS), it can be confirmed that the formation of different active sites affects the electron cloud density of zinc. The electron cloud density of zinc affects the ability to attract CH₃COOH, which makes catalysts different in terms of catalytic activity. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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20 pages, 5722 KiB  

Open AccessArticle

Experimental Pore-Scale Study of a Novel Functionalized Iron-Carbon Nanohybrid for Enhanced Oil Recovery (EOR)

by Fatemeh Razavirad, Abbas Shahrabadi, Parham Babakhani Dehkordi and Alimorad Rashidi

Nanomaterials 2022, 12(1), 103; https://doi.org/10.3390/nano12010103 - 29 Dec 2021

Cited by 23 | Viewed by 2554

Abstract

Nanofluid flooding, as a new technique to enhance oil recovery, has recently aroused much attention. The current study considers the performance of a novel iron-carbon nanohybrid to EOR. Carbon nanoparticles was synthesized via the hydrothermal method with citric acid and hybridize with iron [...] Read more.

Nanofluid flooding, as a new technique to enhance oil recovery, has recently aroused much attention. The current study considers the performance of a novel iron-carbon nanohybrid to EOR. Carbon nanoparticles was synthesized via the hydrothermal method with citric acid and hybridize with iron ($F{e}_3{O}_4$). The investigated nanohybrid is characterized by its rheological properties (viscosity), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analysis. The efficiency of the synthetized nanoparticle in displacing heavy oil is initially assessed using an oil–wet glass micromodel at ambient conditions. Nanofluid samples with various concentrations (0.05 wt % and 0.5 wt %) dispersed in a water base fluid with varied salinities were first prepared. The prepared nanofluids provide high stability with no additive such as polymer or surfactant. Before displacement experiments were run, to achieve a better understanding of fluid–fluid and grain–fluid interactions in porous media, a series of sub-pore scale tests—including interfacial tension (IFT), contact angle, and zeta potential—were conducted. Nanofluid flooding results show that the nanofluid with the medium base fluid salinity and highest nanoparticle concertation provides the highest oil recovery. However, it is observed that increasing the nanofluid concentration from 0.05% to 0.5% provided only three percent more oil. In contrast, the lowest oil recovery resulted from low salinity water flooding. It was also observed that the measured IFT value between nanofluids and crude oil is a function of nanofluid concentration and base fluid salinities, i.e., the IFT values decrease with the increase of nanofluid concentration and base fluid salinity reduction. However, the base fluid salinity enhancement leads to wettability alteration towards more water-wetness. The main mechanisms responsible for oil recovery enhancement during nanofluid flooding is mainly attributed to wettability alteration toward water-wetness and micro-dispersion formation. However, the interfacial tension (IFT) reduction using the iron-carbon nanohybrid is also observed but the reduction is not significant. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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10 pages, 17836 KiB  

Open AccessArticle

Ag–Au Core–Shell Triangular Nanoprisms for Improving p-g-C₃N₄ Photocatalytic Hydrogen Production

by Yali Guo, Anzhou Xu, Juan Hou, Qingcui Liu, Hailong Li and Xuhong Guo

Nanomaterials 2021, 11(12), 3347; https://doi.org/10.3390/nano11123347 - 10 Dec 2021

Cited by 9 | Viewed by 2711

Abstract

Ag–Au core–shell triangular nanoprisms (Ag@Au TNPs) have aroused extensive research interest in the field of hydrogen evolution reaction (HER) due to their strong plasmon effect and stability. Here, Ag@Au TNPs were fabricated by the galvanic-free replacement method. Then, we loaded them on protonated [...] Read more.

Ag–Au core–shell triangular nanoprisms (Ag@Au TNPs) have aroused extensive research interest in the field of hydrogen evolution reaction (HER) due to their strong plasmon effect and stability. Here, Ag@Au TNPs were fabricated by the galvanic-free replacement method. Then, we loaded them on protonated g-C₃N₄ nanoprisms (P–CN) by the electrostatic self-assembly method as an efficient plasmonic photocatalyst for HER. The hydrogen production rate of Ag@Au TNPs/P–CN (4.52 mmol/g/h) is 4.1 times higher than that of P–CN (1.11 mmol/g/h) under simulated sunlight irradiation, making it the most competitive material for water splitting. The formed Schottky junction helps to trap the hot electrons generated from Ag@Au TNPs, and the well-preserved tips of the Ag@Au TNPs can effectively generate an electromagnetic field to inhibit the photogenerated electron–holes pairs recombination. This study suggests that the rational design of Ag@Au TNPs by the galvanic-free replacement method is an effective co-catalyst for HER and boosting the additional combination of plasmonic metals and catalyst metals for the enhancement to HER. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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15 pages, 3372 KiB  

Open AccessArticle

Near-Ambient Pressure XPS and MS Study of CO Oxidation over Model Pd-Au/HOPG Catalysts: The Effect of the Metal Ratio

by Andrey V. Bukhtiyarov, Igor P. Prosvirin, Maxim A. Panafidin, Alexey Yu. Fedorov, Alexander Yu. Klyushin, Axel Knop-Gericke, Yan V. Zubavichus and Valery I. Bukhtiyarov

Nanomaterials 2021, 11(12), 3292; https://doi.org/10.3390/nano11123292 - 4 Dec 2021

Cited by 5 | Viewed by 3201

Abstract

In this study, the dependence of the catalytic activity of highly oriented pyrolytic graphite (HOPG)-supported bimetallic Pd-Au catalysts towards the CO oxidation based on the Pd/Au atomic ratio was investigated. The activities of two model catalysts differing from each other in the initial [...] Read more.

In this study, the dependence of the catalytic activity of highly oriented pyrolytic graphite (HOPG)-supported bimetallic Pd-Au catalysts towards the CO oxidation based on the Pd/Au atomic ratio was investigated. The activities of two model catalysts differing from each other in the initial Pd/Au atomic ratios appeared as distinctly different in terms of their ignition temperatures. More specifically, the PdAu-2 sample with a lower Pd/Au surface ratio (~0.75) was already active at temperatures less than 150 °C, while the PdAu-1 sample with a higher Pd/Au surface ratio (~1.0) became active only at temperatures above 200 °C. NAP XPS revealed that the exposure of the catalysts to a reaction mixture at RT induces the palladium surface segregation accompanied by an enrichment of the near-surface regions of the two-component Pd-Au alloy nanoparticles with Pd due to adsorption of CO on palladium atoms. The segregation extent depends on the initial Pd/Au surface ratio. The difference in activity between these two catalysts is determined by the presence or higher concentration of specific active Pd sites on the surface of bimetallic particles, i.e., by the ensemble effect. Upon cooling the sample down to room temperature, the reverse redistribution of the atomic composition within near-surface regions occurs, which switches the catalyst back into inactive state. This observation strongly suggests that the optimum active sites emerge under reaction conditions exclusively, involving both high temperature and a reactive atmosphere. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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17 pages, 4220 KiB  

Open AccessArticle

Smart Mn⁷⁺ Sensing via Quenching on Dual Fluorescence of Eu³⁺ Complex-Modified TiO₂ Nanoparticles

by Wenbin Yang, Siqi Niu, Yao Wang, Linjun Huang, Shichao Wang, Ketul C. Popat, Matt J. Kipper, Laurence A. Belfiore and Jianguo Tang

Nanomaterials 2021, 11(12), 3283; https://doi.org/10.3390/nano11123283 - 3 Dec 2021

Cited by 6 | Viewed by 2417

Abstract

In this work, titania (TiO₂) nanoparticles modified by Eu(TTA)₃Phen complexes (ETP) were prepared by a simple solvothermal method developing a fluorescence Mn⁷⁺ pollutant sensing system. The characterization results indicate that the ETP cause structural deformation and redshifts of [...] Read more.

In this work, titania (TiO₂) nanoparticles modified by Eu(TTA)₃Phen complexes (ETP) were prepared by a simple solvothermal method developing a fluorescence Mn⁷⁺ pollutant sensing system. The characterization results indicate that the ETP cause structural deformation and redshifts of the UV-visible light absorptions of host TiO₂ nanoparticles. The ETP also reduce the crystallinity and crystallite size of TiO₂ nanoparticles. Compared with TiO₂ nanoparticles modified with Eu³⁺ (TiO₂-Eu³⁺), TiO₂ nanoparticles modified with ETP (TiO₂-ETP) exhibit significantly stronger photoluminescence under the excitation of 394 nm. Under UV excitation, TiO₂-ETP nanoparticles showed blue and red emission corresponding to TiO₂ and Eu³⁺. In addition, as the concentration of ETP in TiO₂ nanoparticles increases, the PL intensity at 612 nm also increases. When ETP-modified TiO₂ nanoparticles are added to an aqueous solution containing Mn⁷⁺, the fluorescence intensity of both TiO₂ and ETP decreases. The evolution of the fluorescence intensity ratio (I₁/I₂) of TiO₂ and ETP is linearly related to the concentration of Mn⁷⁺. The sensitivity of fluorescence intensity to Mn⁷⁺ concentration enables the design of dual fluorescence ratio solid particle sensors. The method proposed here is simple, accurate, efficient, and not affected by the environmental conditions. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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12 pages, 4164 KiB  

Open AccessArticle

Biosynthesis of Zinc Oxide Nanoparticles Using Leaf Extract of Prosopis juliflora as Potential Photocatalyst for the Treatment of Paper Mill Effluent

by Ahmed M. Abbas, Sabah A. Hammad, Heba Sallam, Lamiaa Mahfouz, Mohamed K. Ahmed, Sayed M. Abboudy, Ahmed Ezzat Ahmed, Sadeq K. Alhag, Mostafa A. Taher, Sulaiman A. Alrumman, Mohammed A. Alshehri, Wagdi S. Soliman, Tabassum-Abbasi and Massaud Mostafa

Appl. Sci. 2021, 11(23), 11394; https://doi.org/10.3390/app112311394 - 1 Dec 2021

Cited by 15 | Viewed by 3169

Abstract

This paper reports on the manufacture of ZnO nanoparticles (ZnO NPs) from Prosopis juliflora leaf extracts. Various methods of characterization were used, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and transmission electron microscope TEM. ZnO NPs has a [...] Read more.

This paper reports on the manufacture of ZnO nanoparticles (ZnO NPs) from Prosopis juliflora leaf extracts. Various methods of characterization were used, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and transmission electron microscope TEM. ZnO NPs has a hexagonal wurtzite structure with a preferred orientation of 101 planes, according to XRD. The functional groups found in ZnO NPs isolated from leaves are responsible for the FT-IR peaks that correspond to them. The morphology of the produced nanoparticles is a sphere-like form, as shown in the SEM pictures. TEM examination revealed ZnO NPs with a size of 50–55 nm. These ZnO NPs were used to remediate pollutants in paper mill effluents, and they were able to remove 86% of the organic pollutants from the sample at 0.05 mg/L dose and reduce 89% of the organic pollutants during a 5-h reflex time. Meanwhile, for the photocatalysis of paper mill effluents, it has been noted that COD was removed by 74.30%, 63.23%, and 57.96% for the first, second, and third cycles, respectively. Full article

(This article belongs to the Topic Synthesis and Applications of Nanostructured Metals and Metal Oxides)

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