Nanomaterials

13 pages, 5837 KiB

Open AccessArticle

The Stability of Hybrid Perovskites with UiO-66 Metal–Organic Framework Additives with Heat, Light, and Humidity

by Ivan S. Zhidkov, Ming-Hsuan Yu, Andrey I. Kukharenko, Po-Chun Han, Seif O. Cholakh, Wen-Yueh Yu, Kevin C.-W. Wu, Chu-Chen Chueh and Ernst Z. Kurmaev

Nanomaterials 2022, 12(23), 4349; https://doi.org/10.3390/nano12234349 - 6 Dec 2022

Cited by 6 | Viewed by 2652

Abstract

This study is devoted to investigating the stability of metal–organic framework (MOF)-hybrid perovskites consisting of CH₃NH₃PbI₃ (MAPbI₃) and UiO-66 without a functional group and UiO-66 with different COOH, NH₂,and F functional groups under external [...] Read more.

This study is devoted to investigating the stability of metal–organic framework (MOF)-hybrid perovskites consisting of CH₃NH₃PbI₃ (MAPbI₃) and UiO-66 without a functional group and UiO-66 with different COOH, NH₂,and F functional groups under external influences including heat, light, and humidity. By conducting crystallinity, optical, and X-ray photoelectron spectra (XPS) measurements after long-term aging, all of the prepared MAPbI3@UiO-66 nanocomposites (with pristine UiO-66 or UiO-66 with additional functional groups) were stable to light soaking and a relative humidity (RH) of 50%. Moreover, the UiO-66 and UiO-66-(F)₄ hybrid perovskite films possessed a higher heat tolerance than the other two UiO-66 with the additional functional groups of NH₂ and COOH. Tthe MAPbI3@UiO-66-(F)₄ delivered the highest stability and improved optical properties after aging. This study provides a deeper understanding of the impact of the structure of hybrid MOFs on the stability of the composite films. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Perovskite Solar Cells)

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15 pages, 3647 KiB

Open AccessArticle

Nano-Dimensional Carbon Nanosphere Supported Non-Precious Metal Oxide Composite: A Cathode Material for Sea Water Reduction

by Jayasmita Jana, Tran Van Phuc, Jin Suk Chung, Won Mook Choi and Seung Hyun Hur

Nanomaterials 2022, 12(23), 4348; https://doi.org/10.3390/nano12234348 - 6 Dec 2022

Cited by 9 | Viewed by 1918

Abstract

Generation of hydrogen fuel at cathode during the electrolysis of seawater can be economically beneficial considering the vast availability of the electrolyte although it faces sluggishness caused by the anode reactions. In this regard a carbon nanosphere-protected CuO/Co₃O₄ (CCuU) composite [...] Read more.

Generation of hydrogen fuel at cathode during the electrolysis of seawater can be economically beneficial considering the vast availability of the electrolyte although it faces sluggishness caused by the anode reactions. In this regard a carbon nanosphere-protected CuO/Co₃O₄ (CCuU) composite was synthesized through heat treatment and was used as the cathode material for electrocatalytic seawater splitting. CCuU showed a significantly low overpotential of 73 mV@10 mA cm⁻², Tafel slope of 58 mV dec⁻¹ and relatively constant activity and morphology over a long time electrocatalytic study. A synergy within metal oxide centers was observed that boosted the proton-electron transfer at the active site. Moreover, the presence of carbon support increased the electroactive surface area and stability of the composite. The activity of the CCuU was studied for HER in KOH and alkaline NaCl solution to understand the activity. This work will pave the way for designing mesoporous non-precious electrocatalysts towards seawater electrocatalysis. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Nanocomposites for Electrochemical Applications)

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13 pages, 6255 KiB

Open AccessArticle

Theoretical and Computational Analysis of a Wurtzite-AlGaN DUV-LED to Mitigate Quantum-Confined Stark Effect with a Zincblende Comparison Considering Mg- and Be-Doping

by Horacio I. Solís-Cisneros, Yaoqiao Hu, Jorge L. Camas-Anzueto, Rubén Grajales-Coutiño, Abdur-Rehman Anwar, Rubén Martínez-Revuelta, Héctor R. Hernández-de-León and Carlos A. Hernández-Gutiérrez

Nanomaterials 2022, 12(23), 4347; https://doi.org/10.3390/nano12234347 - 6 Dec 2022

Cited by 5 | Viewed by 2302

Abstract

In this work, an AlGaN-based Deep-Ultraviolet Light-Emitting Diode structure has been designed and simulated for the zincblende and wurtzite approaches, where the polarization effect is included. DFT analysis was performed to determine the band gap direct-to-indirect cross-point limit, AlN carrier mobility, and activation [...] Read more.

In this work, an AlGaN-based Deep-Ultraviolet Light-Emitting Diode structure has been designed and simulated for the zincblende and wurtzite approaches, where the polarization effect is included. DFT analysis was performed to determine the band gap direct-to-indirect cross-point limit, AlN carrier mobility, and activation energies for p-type dopants. The multiple quantum wells analysis describes the emission in the deep-ultraviolet range without exceeding the direct-to-indirect bandgap cross-point limit of around 77% of Al content. Moreover, the quantum-confined Stark effect on wavefunctions overlapping has been studied, where Al-graded quantum wells reduce it. Both zincblende and wurtzite have improved electrical and optical characteristics by including a thin AlGaN with low Al content. Mg and Be acceptor activation energies have been calculated at 260 meV and 380 meV for Be and Mg acceptor energy, respectively. The device series resistance has been decreased by using Be instead of Mg as the p-type dopant from 3 kΩ to 0.7 kΩ. Full article

(This article belongs to the Section Theory and Simulation of Nanostructures)

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30 pages, 6958 KiB

Open AccessReview

MXene-Based Ink Design for Printed Applications

by Zahra Aghayar, Massoud Malaki and Yizhou Zhang

Nanomaterials 2022, 12(23), 4346; https://doi.org/10.3390/nano12234346 - 6 Dec 2022

Cited by 16 | Viewed by 3647

Abstract

MXenes are a class of two-dimensional nanomaterials with a rich chemistry, hydrophilic surface and mechano-ceramic nature, and have been employed in a wide variety of applications ranging from medical and sensing devises to electronics, supercapacitors, electromagnetic shielding, and environmental applications, to name a [...] Read more.

MXenes are a class of two-dimensional nanomaterials with a rich chemistry, hydrophilic surface and mechano-ceramic nature, and have been employed in a wide variety of applications ranging from medical and sensing devises to electronics, supercapacitors, electromagnetic shielding, and environmental applications, to name a few. To date, the main focus has mostly been paid to studying the chemical and physical properties of MXenes and MXene-based hybrids, while relatively less attention has been paid to the optimal application forms of these materials. It has been frequently observed that MXenes show great potential as inks when dispersed in solution. The present paper aims to comprehensively review the recent knowledge about the properties, applications and future horizon of inks based on 2D MXene sheets. In terms of the layout of the current paper, 2D MXenes have briefly been presented and followed by introducing the formulation of MXene inks, the process of turning MAX to MXene, and ink compositions and preparations. The chemical, tribological and rheological properties have been deeply discussed with an eye to the recent developments of the MXene inks in energy, health and sensing applications. The review ends with a summary of research pitfalls, challenges, and future directions in this area. Full article

(This article belongs to the Special Issue Nanocomposite Design for Energy-Related Applications)

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13 pages, 4997 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Antiviral Properties against SARS-CoV-2 of Nanostructured ZnO Obtained by Green Combustion Synthesis and Coated in Waterborne Acrylic Coatings

by Julia de O. Primo, Jamille de S. Correa, Dienifer F. L. Horsth, Arkaprava Das, Marcin Zając, Polona Umek, Ruddy Wattiez, Fauze J. Anaissi, Rob C. A. Onderwater and Carla Bittencourt

Nanomaterials 2022, 12(23), 4345; https://doi.org/10.3390/nano12234345 - 6 Dec 2022

Cited by 7 | Viewed by 2541

Abstract

The COVID-19 pandemic has increased the need for developing disinfectant surfaces as well as reducing the spread of infections on contaminated surfaces and the contamination risk from the fomite route. The present work reports on the antiviral activity of coatings containing ZnO particles [...] Read more.

The COVID-19 pandemic has increased the need for developing disinfectant surfaces as well as reducing the spread of infections on contaminated surfaces and the contamination risk from the fomite route. The present work reports on the antiviral activity of coatings containing ZnO particles obtained by two simple synthesis routes using Aloe vera (ZnO-aloe) or cassava starch (ZnO-starch) as reaction fuel. After detailed characterization using XRD and NEXAFS, the obtained ZnO particles were dispersed in a proportion of 10% with two different waterborne acrylic coatings (binder and commercial white paint) and brushed on the surface of polycarbonates (PC). The cured ZnO/coatings were characterized by scanning electron microscopes (SEM) and energy-dispersive X-ray spectroscopy (EDS). Wettability tests were performed. The virucidal activity of the ZnO particles dispersed in the waterborne acrylic coating was compared to a reference control sample (PC plates). According to RT-PCR results, the ZnO-aloe/coating displays the highest outcome for antiviral activity against SARS-CoV-2 using the acrylic binder, inactivating >99% of the virus after 24 h of contact relative to reference control. Full article

(This article belongs to the Special Issue Applications of Nanomaterials in Diagnostics and Therapeutics)

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14 pages, 4088 KiB

Open AccessArticle

Mechanism of Random Telegraph Noise in 22-nm FDSOI-Based MOSFET at Cryogenic Temperatures

by Yue Ma, Jinshun Bi, Hanbin Wang, Linjie Fan, Biyao Zhao, Lizhi Shen and Mengxin Liu

Nanomaterials 2022, 12(23), 4344; https://doi.org/10.3390/nano12234344 - 6 Dec 2022

Cited by 3 | Viewed by 2532

Abstract

In the emerging process-based transistors, random telegraph noise (RTN) has become a critical reliability problem. However, the conventional method to analyze RTN properties may not be suitable for the advanced silicon-on-insulator (SOI)-based transistors, such as the fully depleted SOI (FDSOI)-based transistors. In this [...] Read more.

In the emerging process-based transistors, random telegraph noise (RTN) has become a critical reliability problem. However, the conventional method to analyze RTN properties may not be suitable for the advanced silicon-on-insulator (SOI)-based transistors, such as the fully depleted SOI (FDSOI)-based transistors. In this paper, the mechanism of RTN in a 22-nm FDSOI-based metal–oxide–semiconductor field-effect transistor (MOSFET) is discussed, and an improved approach to analyzing the relationship between the RTN time constants, the trap energy, and the trap depth of the device at cryogenic temperatures is proposed. The cryogenic measurements of RTN in a 22-nm FDSOI-based MOSFET were carried out and analyzed using the improved approach. In this approach, the quantum mechanical effects and diffuse scattering of electrons at the oxide–silicon interface are considered, and the slope of the trap potential determined by the gate voltage relation is assumed to decrease proportionally with temperature as a result of the electron distribution inside the top silicon, per the technology computer-aided design (TCAD) simulations. The fitted results of the improved approach have good consistency with the measured curves at cryogenic temperatures from 10 K to 100 K. The fitted trap depth was 0.13 nm, and the decrease in the fitted correction coefficient of the electron distribution proportionally with temperature is consistent with the aforementioned assumption. Full article

(This article belongs to the Special Issue Innovative Semiconducting Materials Technology toward New-Generation Hardware Applications)

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13 pages, 8062 KiB

Open AccessArticle

Modeling of BN-Doped Carbon Nanotube as High-Performance Thermoelectric Materials

by Naiara L. Marana, Julio R. Sambrano and Silvia Casassa

Nanomaterials 2022, 12(23), 4343; https://doi.org/10.3390/nano12234343 - 6 Dec 2022

Cited by 3 | Viewed by 1798

Abstract

Ternary BNC nanotubes were modeled and characterized through a periodic density functional theory approach with the aim of investigating the influence on the structural, electronic, mechanical, and transport properties of the quantity and pattern of doping. The main energy band gap is easily [...] Read more.

Ternary BNC nanotubes were modeled and characterized through a periodic density functional theory approach with the aim of investigating the influence on the structural, electronic, mechanical, and transport properties of the quantity and pattern of doping. The main energy band gap is easily tunable as a function of the BN percentage, the mechanical stability is generally preserved, and an interesting piezoelectric character emerges in the BNC structures. Moreover, C@(BN)_1−xC_x double-wall presents promising values of the thermoelectric coefficients due to the combined lowering of the thermal conductivity and increase of charge carriers. Computed results are in qualitative agreement with the little experimental evidence and therefore can provide insights on an atomic scale of the real samples and direct the synthesis towards increasingly performing hybrid nanomaterials. Full article

(This article belongs to the Section Theory and Simulation of Nanostructures)

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12 pages, 6628 KiB

Open AccessArticle

Studies on Oxygen Permeation Resistance of SiCN Thin Film and RRAM Applications

by Myeong-Ho Song, Woon-San Ko, Geun-Ho Kim, Dong-Hyeuk Choi and Ga-Won Lee

Nanomaterials 2022, 12(23), 4342; https://doi.org/10.3390/nano12234342 - 6 Dec 2022

Cited by 1 | Viewed by 2058

Abstract

In this study, a silicon carbon nitride (SiCN) thin film was grown with a thickness of 5~70 nm by the plasma-enhanced chemical vapor deposition (PECVD) method, and the oxygen permeation characteristics were analyzed according to the partial pressure ratio (PPR) of tetramethylsilane (4MS) [...] Read more.

In this study, a silicon carbon nitride (SiCN) thin film was grown with a thickness of 5~70 nm by the plasma-enhanced chemical vapor deposition (PECVD) method, and the oxygen permeation characteristics were analyzed according to the partial pressure ratio (PPR) of tetramethylsilane (4MS) to the total gas amount during the film deposition. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and X-ray reflectivity (XRR) were used to investigate the composition and bonding structures of the SiCN film. An atomic force microscope (AFM) was used to examine the surface morphology of the SiCN films to see the porosity. The analysis indicated that Si–N bonds were dominant in the SiCN films, and a higher carbon concentration made the film more porous. To evaluate the oxygen permeation, a highly accelerated temperature and humidity stress test (HAST) evaluation was performed. The films grown at a high 4MS PPR were more susceptible to oxygen penetration, which changed Si–N bonds to Si–N–O bonds during the HAST. These results indicate that increasing the 4MS PPR made the SiCN film more porous and containable for oxygen. As an application, for the first time, SiCN dielectric film is suggested to be applied to resistive random access memory (RRAM) as an oxygen reservoir to store oxygen and prevent a reaction between metal electrodes and oxygen. The endurance characteristics of RRAM are found to be enhanced by applying the SiCN. Full article

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

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45 pages, 76162 KiB

Open AccessReview

Advanced Nanostructured Materials for Electrocatalysis in Lithium–Sulfur Batteries

by Zihui Song, Wanyuan Jiang, Xigao Jian and Fangyuan Hu

Nanomaterials 2022, 12(23), 4341; https://doi.org/10.3390/nano12234341 - 6 Dec 2022

Cited by 16 | Viewed by 3048

Abstract

Lithium–sulfur (Li-S) batteries are considered as among the most promising electrochemical energy storage devices due to their high theoretical energy density and low cost. However, the inherently complex electrochemical mechanism in Li-S batteries leads to problems such as slow internal reaction kinetics and [...] Read more.

Lithium–sulfur (Li-S) batteries are considered as among the most promising electrochemical energy storage devices due to their high theoretical energy density and low cost. However, the inherently complex electrochemical mechanism in Li-S batteries leads to problems such as slow internal reaction kinetics and a severe shuttle effect, which seriously affect the practical application of batteries. Therefore, accelerating the internal electrochemical reactions of Li-S batteries is the key to realize their large-scale applications. This article reviews significant efforts to address the above problems, mainly the catalysis of electrochemical reactions by specific nanostructured materials. Through the rational design of homogeneous and heterogeneous catalysts (including but not limited to strategies such as single atoms, heterostructures, metal compounds, and small-molecule solvents), the chemical reactivity of Li-S batteries has been effectively improved. Here, the application of nanomaterials in the field of electrocatalysis for Li-S batteries is introduced in detail, and the advancement of nanostructures in Li-S batteries is emphasized. Full article

(This article belongs to the Special Issue Advances in Novel Nanostructured Materials for Electrocatalysis–Trends and Future)

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3 pages, 195 KiB

Open AccessEditorial

Metal Oxide Nanomaterials: From Fundamentals to Applications

by Yuanbing Mao and Santosh K. Gupta

Nanomaterials 2022, 12(23), 4340; https://doi.org/10.3390/nano12234340 - 6 Dec 2022

Viewed by 1883

Abstract

This Special Issue of Nanomaterials, “Metal Oxide Nanomaterials: From Fundamentals to Applications”, highlights the development and understanding of different types of metal oxide nanoparticles and their use for applications in luminescence, photocatalysis, water–oil separation, optoelectronics, gas sensors, energy-saving smart windows, etc [...] Full article

(This article belongs to the Special Issue Metal Oxide Nanomaterials: From Fundamental to Applications)

16 pages, 3597 KiB

Open AccessArticle

Plasmonic Modes and Fluorescence Enhancement Coupling Mechanism: A Case with a Nanostructured Grating

by Margherita Angelini, Eliana Manobianco, Paola Pellacani, Francesco Floris and Franco Marabelli

Nanomaterials 2022, 12(23), 4339; https://doi.org/10.3390/nano12234339 - 6 Dec 2022

Cited by 11 | Viewed by 2812

Abstract

The recent development and technological improvement in dealing with plasmonic metasurfaces has triggered a series of interesting applications related to sensing challenges. Fluorescence has been one of the most studied tools within such a context. With this in mind, we used some well [...] Read more.

The recent development and technological improvement in dealing with plasmonic metasurfaces has triggered a series of interesting applications related to sensing challenges. Fluorescence has been one of the most studied tools within such a context. With this in mind, we used some well characterized structures supporting plasmonic resonances to study their influence on the emission efficiency of a fluorophore. An extended optical analysis and a complementary investigation through finite-difference time-domain (FDTD) simulations have been combined to understand the coupling mechanism between the excitation of plasmonic modes and the fluorescence absorption and emission processes. The results provide evidence of the spectral shape dependence of fluorescence on the plasmonic field distribution together with a further relationship connected with the enhancement of its signal. It has made evident that the spectral region characterized by the largest relative enhancement closely corresponds to the strongest signatures of the plasmonic modes, as described by both the optical measurements and the FDTD findings. Full article

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

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4 pages, 577 KiB

Open AccessEditorial

Antimicrobial Nano Coatings

by Angela Ivask, Merja Ahonen and Karin Kogermann

Nanomaterials 2022, 12(23), 4338; https://doi.org/10.3390/nano12234338 - 6 Dec 2022

Cited by 1 | Viewed by 1595

Abstract

History has demonstrated that the uncontrolled fast thriving of potentially pathogenic microorganisms may lead to serious consequences and, thus, the approaches helping to control the microbial numbers in infectional hot-spots are necessary [...] Full article

(This article belongs to the Special Issue Antimicrobial Nano Coatings)

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20 pages, 4120 KiB

Open AccessArticle

X-ray Absorption Spectroscopy Study of Thickness Effects on the Structural and Magnetic Properties of Pr_2−δNi_1−xMn_1+xO_6−y Double Perovskite Thin Films

by Mónica Bernal-Salamanca, Javier Herrero-Martín, Zorica Konstantinović, Lluis Balcells, Alberto Pomar, Benjamín Martínez and Carlos Frontera

Nanomaterials 2022, 12(23), 4337; https://doi.org/10.3390/nano12234337 - 6 Dec 2022

Cited by 1 | Viewed by 2413

Abstract

In this work, we report a systematic study of the influence of film thickness on the structural and magnetic properties of epitaxial thin films of Pr_2−δNi_1−xMn_1+xO_6−y (PNMO) double perovskite grown on top of two different (001)-SrTiO [...] Read more.

In this work, we report a systematic study of the influence of film thickness on the structural and magnetic properties of epitaxial thin films of Pr_2−δNi_1−xMn_1+xO_6−y (PNMO) double perovskite grown on top of two different (001)-SrTiO₃ and (001)-LaAlO₃ substrates by RF magnetron sputtering. A strong dependence of the structural and magnetic properties on the film thickness is found. The ferromagnetic transition temperature (T_C) and saturation magnetization (Ms) are found to decrease when reducing the film thickness. In our case, the thinnest films show a loss of ferromagnetism at the film-substrate interface. In addition, the electronic structure of some characteristic PNMO samples is deeply analyzed using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements and compared with theoretical simulations. Our results show that the oxidation states of Ni and Mn ions are stabilized as Ni²⁺ and Mn⁴⁺, thus the ferromagnetism is mainly due to Ni²⁺-O-Mn⁴⁺ superexchange interactions, even in samples with poor ferromagnetic properties. XMCD results also make evident large variations on the spin and orbital contributions to the magnetic moment as the film’s thickness decreases. Full article

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10 pages, 2401 KiB

Open AccessArticle

A Single-Celled Metasurface for Multipolarization Generation and Wavefront Manipulation

by Ruonan Ji, Xin Guo, Zhichao Liu, Xianfeng Wu, Chuan Jin, Feng Liu, Xinru Zheng, Yang Sun and Shaowei Wang

Nanomaterials 2022, 12(23), 4336; https://doi.org/10.3390/nano12234336 - 6 Dec 2022

Viewed by 1683

Abstract

Due to their unprecedented ability to flexibly manipulate the parameters of light, metasurfaces offer a new approach to integrating multiple functions in a single optical element. In this paper, based on a single-celled metasurface composed of chiral umbrella-shaped metal–insulator–metal (MIM) unit cells, a [...] Read more.

Due to their unprecedented ability to flexibly manipulate the parameters of light, metasurfaces offer a new approach to integrating multiple functions in a single optical element. In this paper, based on a single-celled metasurface composed of chiral umbrella-shaped metal–insulator–metal (MIM) unit cells, a strategy for simultaneous multiple polarization generation and wavefront shaping is proposed. The unit cells can function as broadband and high-performance polarization-preserving mirrors. In addition, by introducing a chiral-assisted Aharonov–Anandan (AA) geometric phase, the phase profile and phase retardation of two spin-flipped orthogonal circular polarized components can be realized simultaneously and independently with a single-celled metasurface via two irrelevant parameters. Benefiting from this flexible phase manipulation ability, a vectorial hologram generator and metalens array with spatially varying polarizations were demonstrated. This work provides an effective approach to avoid the pixel and efficiency losses caused by the intrinsic symmetry of the PB geometric phase, and it may play an important role in the miniaturization and integration of multipolarization-involved displays, real-time imaging, and spectroscopy systems. Full article

(This article belongs to the Special Issue Metasurfaces for Photonic Devices: Theory and Applications)

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13 pages, 2217 KiB

Open AccessArticle

3D Composite PDMS/MWCNTs Aerogel as High-Performing Anodes in Microbial Fuel Cells

by Giulia Massaglia and Marzia Quaglio

Nanomaterials 2022, 12(23), 4335; https://doi.org/10.3390/nano12234335 - 6 Dec 2022

Cited by 5 | Viewed by 1834

Abstract

Porous 3D composite materials are interesting anode electrodes for single chamber microbial fuel cells (SCMFCs) since they exploit a surface layer that is able to achieve the correct biocompatibility for the proliferation of electroactive bacteria and have an inner charge transfer element that [...] Read more.

Porous 3D composite materials are interesting anode electrodes for single chamber microbial fuel cells (SCMFCs) since they exploit a surface layer that is able to achieve the correct biocompatibility for the proliferation of electroactive bacteria and have an inner charge transfer element that favors electron transfer and improves the electrochemical activity of microorganisms. The crucial step is to fine-tune the continuous porosity inside the anode electrode, thus enhancing the bacterial growth, adhesion, and proliferation, and the substrate’s transport and waste products removal, avoiding pore clogging. To this purpose, a novel approach to synthetize a 3D composite aerogel is proposed in the present work. A 3D composite aerogel, based on polydimethylsiloxane (PDMS) and multi-wall carbon nanotubes (MWCNTs) as a conductive filler, was obtained by pouring this mixture over the commercial sugar, used as removable template to induce and tune the hierarchical continuous porosity into final nanostructures. In this scenario, the granularity of the sugar directly affects the porosities distribution inside the 3D composite aerogel, as confirmed by the morphological characterizations implemented. We demonstrated the capability to realize a high-performance bioelectrode, which showed a 3D porous structure characterized by a high surface area typical of aerogel materials, the required biocompatibility for bacterial proliferations, and an improved electron pathway inside it. Indeed, SCMFCs with 3D composite aerogel achieved current densities of (691.7 ± 9.5) mA m⁻², three orders of magnitude higher than commercial carbon paper, (287.8 ± 16.1) mA m⁻². Full article

(This article belongs to the Special Issue 1D and 2D Nanomaterials for Energy Storage and Conversion)

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7 pages, 3325 KiB

Open AccessArticle

Innovative Variation in the Morphological Characteristics of Carbon Nanowalls Grown on a Molybdenum Disulfide Interlayer

by Chulsoo Kim, Kangmin Kim, Seokhun Kwon, Hyunil Kang, Byungyou Hong and Wonseok Choi

Nanomaterials 2022, 12(23), 4334; https://doi.org/10.3390/nano12234334 - 6 Dec 2022

Cited by 3 | Viewed by 1474

Abstract

Carbon is a material with interesting properties which exists in large quantities on Earth, so many studies involving carbon have been conducted. In particular, nano-sized carbon allotropes, referred to as carbon nanomaterials, comprise the subject of various studies currently underway. The electrical, chemical, [...] Read more.

Carbon is a material with interesting properties which exists in large quantities on Earth, so many studies involving carbon have been conducted. In particular, nano-sized carbon allotropes, referred to as carbon nanomaterials, comprise the subject of various studies currently underway. The electrical, chemical, physical properties of carbon nanowalls (CNWs) are modified by parameters such as surface density, height and thickness. These characteristics have significant effects on CNWs and can be adjusted as a growth interlayer. It was confirmed that the molybdenum disulfide (MoS₂) interlayer synthesized in this paper by radio frequency (RF) magnetron sputtering altered the morphological characteristics of the CNWs, including its shaped edge, pores diameter and density. We provide interesting results through FE-SEM, EDS and Raman analysis in this paper. Based on the Raman analysis, both the D-peak of carbon and the I_D/I_G ratio decreased. Through this study, the effect of MoS₂ on the morphological characteristics of CNWs was confirmed. Full article

(This article belongs to the Special Issue Growth, Characterization and Applications of Nanotubes (2nd Edition))

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12 pages, 5710 KiB

Open AccessArticle

The Low-Temperature Sol-Gel Synthesis of Metal-Oxide Films on Polymer Substrates and the Determination of Their Optical and Dielectric Properties

by Lyudmila Borilo, Vladimir Kozik, Alexander Vorozhtsov, Viktor Klimenko, Olga Khalipova, Alexander Agafonov, Tatiana Kusova, Anton Kraev and Yana Dubkova

Nanomaterials 2022, 12(23), 4333; https://doi.org/10.3390/nano12234333 - 6 Dec 2022

Viewed by 1554

Abstract

Photoactive, optically transparent heterostructures from silver nanowires and titanium dioxide were obtained by the sol-gel method on the surface of a polyethylene terephthalate film. The characteristics of optical transmission on the wavelength and those of dielectric permittivity, conductivity and dissipation on frequency in [...] Read more.

Photoactive, optically transparent heterostructures from silver nanowires and titanium dioxide were obtained by the sol-gel method on the surface of a polyethylene terephthalate film. The characteristics of optical transmission on the wavelength and those of dielectric permittivity, conductivity and dissipation on frequency in the range of 25–1,000,000 Hz were investigated. Full article

(This article belongs to the Special Issue Chemical and Photoinduced Surface Modifications of Inorganic Nanoparticles and Their Applications)

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18 pages, 3805 KiB

Open AccessFeature PaperArticle

Surface Functionalization of Ti6Al4V-ELI Alloy with Antimicrobial Peptide Nisin

by Mari Lallukka, Francesca Gamna, Virginia Alessandra Gobbo, Mirko Prato, Ziba Najmi, Andrea Cochis, Lia Rimondini, Sara Ferraris and Silvia Spriano

Nanomaterials 2022, 12(23), 4332; https://doi.org/10.3390/nano12234332 - 6 Dec 2022

Cited by 10 | Viewed by 2731

Abstract

Implant-associated infections are a severe global concern, especially in the case of orthopedic implants intended for long-term or permanent use. The traditional treatment through systemic antibiotic administration is often inefficient due to biofilm formation, and concerns regarding the development of highly resistant bacteria. [...] Read more.

Implant-associated infections are a severe global concern, especially in the case of orthopedic implants intended for long-term or permanent use. The traditional treatment through systemic antibiotic administration is often inefficient due to biofilm formation, and concerns regarding the development of highly resistant bacteria. Therefore, there is an unfulfilled need for antibiotic-free alternatives that could simultaneously support bone regeneration and prevent bacterial infection. This study aimed to perform, optimize, and characterize the surface functionalization of Ti6Al4V-ELI discs by an FDA-approved antimicrobial peptide, nisin, known to hold a broad antibacterial spectrum. Accordingly, nisin bioactivity was also evaluated by in vitro release tests both in physiological and inflammatory pH conditions. Several methods, such as X-ray photoelectron spectroscopy (XPS), and Kelvin Probe atomic force microscopy confirmed the presence of a physisorbed nisin layer on the alloy surface. The functionalization performed at pH 6–7 was found to be especially effective due to the nisin configuration exposing its hydrophobic tail outwards, which is also responsible for its antimicrobial action. In addition, the first evidence of gradual nisin release both in physiological and inflammatory conditions was obtained: the static contact angle becomes half of the starting one after 7 days of soaking on the functionalized sample, while it becomes 0° on the control samples. Finally, the evaluation of the antibacterial performance toward the pathogen Staphylococcus aureus after 24 h of inoculation showed the ability of nisin adsorbed at pH 6 to prevent bacterial microfouling into biofilm-like aggregates in comparison with the uncoated specimens: viable bacterial colonies showed a reduction of about 40% with respect to the un-functionalized surface and the formation of (microcolonies (biofilm-like aggregates) is strongly affected. Full article

(This article belongs to the Special Issue Antibacterial Nanostructured Coatings)

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16 pages, 3170 KiB

Open AccessArticle

Electrosprayed CNTs on Electrospun PVDF-Co-HFP Membrane for Robust Membrane Distillation

by Lijo Francis and Nidal Hilal

Nanomaterials 2022, 12(23), 4331; https://doi.org/10.3390/nano12234331 - 6 Dec 2022

Cited by 11 | Viewed by 4315

Abstract

In this investigation, the electrospraying of CNTs on an electrospun PVDF-Co-HFP membrane was carried out to fabricate robust membranes for the membrane distillation (MD) process. A CNT-modified PVDF-Co-HFP membrane was heat pressed and characterized for water contact angle, liquid entry pressure (LEP), pore [...] Read more.

In this investigation, the electrospraying of CNTs on an electrospun PVDF-Co-HFP membrane was carried out to fabricate robust membranes for the membrane distillation (MD) process. A CNT-modified PVDF-Co-HFP membrane was heat pressed and characterized for water contact angle, liquid entry pressure (LEP), pore size distribution, tensile strength, and surface morphology. A higher water contact angle, higher liquid entry pressure (LEP), and higher tensile strength were observed in the electrosprayed CNT-coated PVDF-Co-HFP membrane than in the pristine membrane. The MD process test was conducted at varying feed temperatures using a 3.5 wt. % simulated seawater feed solution. The CNT-modified membrane showed an enhancement in the temperature polarization coefficient (TPC) and water permeation flux up to 16% and 24.6%, respectively. Field-effect scanning electron microscopy (FESEM) images of the PVDF-Co-HFP and CNT-modified membranes were observed before and after the MD process. Energy dispersive spectroscopy (EDS) confirmed the presence of inorganic salt ions deposited on the membrane surface after the DCMD process. Permeate water quality and rejection of inorganic salt ions were quantitatively analyzed using ion chromatography (IC) and inductively coupled plasma-mass spectrometry (ICP-MS). The water permeation flux during the 24-h continuous DCMD operation remained constant with a >99.8% inorganic salt rejection. Full article

(This article belongs to the Special Issue 70th Year Anniversary of Carbon Nanotube Discovery—Focus on Real World Solutions)

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20 pages, 5961 KiB

Open AccessArticle

Fe₃O₄-Halloysite Nanotube Composites as Sustainable Adsorbents: Efficiency in Ofloxacin Removal from Polluted Waters and Ecotoxicity

by Doretta Capsoni, Paola Lucini, Debora Maria Conti, Michela Bianchi, Federica Maraschi, Beatrice De Felice, Giovanna Bruni, Maryam Abdolrahimi, Davide Peddis, Marco Parolini, Silvia Pisani and Michela Sturini

Nanomaterials 2022, 12(23), 4330; https://doi.org/10.3390/nano12234330 - 6 Dec 2022

Cited by 10 | Viewed by 2343

Abstract

The present work aimed at decorating halloysite nanotubes (HNT) with magnetic Fe₃O₄ nanoparticles through different synthetic routes (co-precipitation, hydrothermal, and sol-gel) to test the efficiency of three magnetic composites (HNT/Fe₃O₄) to remove the antibiotic ofloxacin (OFL) [...] Read more.

The present work aimed at decorating halloysite nanotubes (HNT) with magnetic Fe₃O₄ nanoparticles through different synthetic routes (co-precipitation, hydrothermal, and sol-gel) to test the efficiency of three magnetic composites (HNT/Fe₃O₄) to remove the antibiotic ofloxacin (OFL) from waters. The chemical–physical features of the obtained materials were characterized through the application of diverse techniques (XRPD, FT-IR spectroscopy, SEM, EDS, and TEM microscopy, thermogravimetric analysis, and magnetization measurements), while ecotoxicity was assessed through a standard test on the freshwater organism Daphnia magna. Independently of the synthesis procedure, the magnetic composites were successfully obtained. The Fe₃O₄ is nanometric (about 10 nm) and the weight percentage is sample-dependent. It decorates the HNT’s surface and also forms aggregates linking the nanotubes in Fe₃O₄-rich samples. Thermodynamic and kinetic experiments showed different adsorption capacities of OFL, ranging from 23 to 45 mg g⁻¹. The kinetic process occurred within a few minutes, independently of the composite. The capability of the three HNT/Fe₃O₄ in removing the OFL was confirmed under realistic conditions, when OFL was added to tap, river, and effluent waters at µg L⁻¹ concentration. No acute toxicity of the composites was observed on freshwater organisms. Despite the good results obtained for all the composites, the sample by co-precipitation is the most performant as it: (i) is easily magnetically separated from the media after the use; (ii) does not undergo any degradation after three adsorption cycles; (iii) is synthetized through a low-cost procedure. These features make this material an excellent candidate for removal of OFL from water. Full article

(This article belongs to the Special Issue Nanoparticles in the Environment and Nanotoxicology)

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21 pages, 10925 KiB

Open AccessArticle

Stabilization of an Aqueous Bio-Based Wax Nano-Emulsion through Encapsulation

by Pieter Samyn and Vibhore K. Rastogi

Nanomaterials 2022, 12(23), 4329; https://doi.org/10.3390/nano12234329 - 6 Dec 2022

Cited by 8 | Viewed by 4994

Abstract

The emulsification of biowaxes in an aqueous environment is important to broaden their application range and make them suitable for incorporation in water-based systems. The study here presented proposes a method for emulsification of carnauba wax by an in-situ imidization reaction of ammonolysed [...] Read more.

The emulsification of biowaxes in an aqueous environment is important to broaden their application range and make them suitable for incorporation in water-based systems. The study here presented proposes a method for emulsification of carnauba wax by an in-situ imidization reaction of ammonolysed styrene (maleic anhydride), resulting in the encapsulation of the wax into stabilized organic nanoparticles. A parameter study is presented on the influences of wax concentrations (30 to 80 wt.-%) and variation in reaction conditions (degree of imidization) on the stability and morphology of the nanoparticles. Similar studies are done for encapsulation and emulsification of paraffin wax as a reference material. An analytical analysis with Raman spectroscopy and infrared spectroscopy indicated different reactivity of the waxes towards encapsulation, with the bio-based carnauba wax showing better compatibility with the formation of imidized styrene (maleic anhydride) nanoparticles. The latter can be ascribed to the higher functionality of the carnauba wax inducing more interactions with the organic nanoparticle phase compared to paraffin wax. In parallel, the thermal and mechanical stability of nanoparticles with encapsulated carnauba wax is higher than paraffin wax, as studied by differential scanning calorimetry, thermogravimetric analysis and dynamic mechanical analysis. In conclusion, a stable aqueous emulsion with a maximum of 70 wt.-% encapsulated carnauba wax was obtained, being distributed as a droplet phase in 200 nm organic nanoparticles. Full article

(This article belongs to the Special Issue Functional Nanostructured Materials—from Synthesis to Applications)

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26 pages, 7624 KiB

Open AccessArticle

Visible-Light Activation of Persulfate or H₂O₂ by Fe₂O₃/TiO₂ Immobilized on Glass Support for Photocatalytic Removal of Amoxicillin: Mechanism, Transformation Products, and Toxicity Assessment

by Francis M. dela Rosa, Marin Popović, Josipa Papac Zjačić, Gabrijela Radić, Marijana Kraljić Roković, Marin Kovačić, María José Farré, Boštjan Genorio, Urška Lavrenčič Štangar, Hrvoje Kušić, Ana Lončarić Božić and Mira Petrović

Nanomaterials 2022, 12(23), 4328; https://doi.org/10.3390/nano12234328 - 5 Dec 2022

Cited by 7 | Viewed by 2831

Abstract

Fe₂O₃/TiO₂ nanocomposites were fabricated via a facile impregnation/calcination technique employing different amounts iron (III) nitrate onto commercial TiO₂ (P25 Aeroxide). The as-prepared Fe₂O₃/TiO₂ nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy [...] Read more.

Fe₂O₃/TiO₂ nanocomposites were fabricated via a facile impregnation/calcination technique employing different amounts iron (III) nitrate onto commercial TiO₂ (P25 Aeroxide). The as-prepared Fe₂O₃/TiO₂ nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDXS), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller analysis (BET), electron impedance spectroscopy (EIS), photoluminescence spectroscopy (PL), and diffuse reflectance spectroscopy (DRS). As a result, 5% (w/w) Fe₂O₃/TiO₂ achieved the highest photocatalytic activity in the slurry system and was successfully immobilized on glass support. Photocatalytic activity under visible-light irradiation was assessed by treating pharmaceutical amoxicillin (AMX) in the presence and absence of additional oxidants: hydrogen peroxide (H₂O₂) and persulfate salts (PS). The influence of pH and PS concentration on AMX conversion rate was established by means of statistical planning and response surface modeling. Results revealed optimum conditions of [S₂O₈²⁻] = 1.873 mM and pH = 4.808; these were also utilized in presence of H₂O₂ instead of PS in long-term tests. The fastest AMX conversion possessing a zero-order rate constant of 1.51 × 10⁻⁷ M·min⁻¹ was achieved with the photocatalysis + PS system. The AMX conversion pathway was established, and the evolution/conversion of formed intermediates was correlated with the changes in toxicity toward Vibrio fischeri. Reactive oxygen species (ROS) scavenging was also utilized to investigate the AMX conversion mechanism, revealing the major contribution of photogenerated h⁺ in all processes. Full article

(This article belongs to the Special Issue Recent Advances in Nanomaterials for Removal of New Emerging Pollutants from Water/Wastewater)

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16 pages, 2951 KiB

Open AccessArticle

Evaluation of the Efficiency of Photoelectrochemical Activity Enhancement for the Nanostructured LaFeO₃ Photocathode by Surface Passivation and Co-Catalyst Deposition

by Victoria P. Chertkova, Aleksandra N. Iskortseva, Egor M. Pazhetnov, Natalia A. Arkharova, Sergey V. Ryazantsev, Eduard E. Levin and Victoria A. Nikitina

Nanomaterials 2022, 12(23), 4327; https://doi.org/10.3390/nano12234327 - 5 Dec 2022

Cited by 3 | Viewed by 2476

Abstract

Perovskite-type lanthanum iron oxide, LaFeO₃, is a promising photocathode material that can achieve water splitting under visible light. However, the performance of this photoelectrode material is limited by significant electron-hole recombination. In this work, we explore different strategies to optimize the [...] Read more.

Perovskite-type lanthanum iron oxide, LaFeO₃, is a promising photocathode material that can achieve water splitting under visible light. However, the performance of this photoelectrode material is limited by significant electron-hole recombination. In this work, we explore different strategies to optimize the activity of a nanostructured porous LaFeO₃ film, which demonstrates enhanced photoelectrocatalytic activity due to the reduced diffusion length of the charge carriers. We found that surface passivation is not an efficient approach for enhancing the photoelectrochemical performance of LaFeO₃, as it is sufficiently stable under photoelectrocatalytic conditions. Instead, the deposition of a Pt co-catalyst was shown to be essential for maximizing the photoelectrochemical activity both in hydrogen evolution and oxygen reduction reactions. Illumination-induced band edge unpinning was found to be a major challenge for the further development of LaFeO₃ photocathodes for water-splitting applications. Full article

(This article belongs to the Section Energy and Catalysis)

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34 pages, 6262 KiB

Open AccessReview

Modification of SnO₂ Electron Transport Layer in Perovskite Solar Cells

by Helen Hejin Park

Nanomaterials 2022, 12(23), 4326; https://doi.org/10.3390/nano12234326 - 5 Dec 2022

Cited by 6 | Viewed by 3884

Abstract

Rapid development of the device performance of organic-inorganic lead halide perovskite solar cells (PSCs) are emerging as a promising photovoltaic technology. Current world-record efficiency of PSCs is based on tin oxide (SnO₂) electron transport layers (ETLs), which are capable of being [...] Read more.

Rapid development of the device performance of organic-inorganic lead halide perovskite solar cells (PSCs) are emerging as a promising photovoltaic technology. Current world-record efficiency of PSCs is based on tin oxide (SnO₂) electron transport layers (ETLs), which are capable of being processed at low temperatures and possess high carrier mobilities with appropriate energy- band alignment and high optical transmittance. Modification of SnO₂ has been intensely investigated by various approaches to tailor its conductivity, band alignment, defects, morphology, and interface properties. This review article organizes recent developments of modifying SnO₂ ETLs to PSC advancement using surface and bulk modifications, while concentrating on photovoltaic (PV) device performance and long-term stability. Future outlooks for SnO₂ ETLs in PSC research and obstacles remaining for commercialization are also discussed. Full article

(This article belongs to the Special Issue New Advances for Halide Perovskite Materials and Applications)

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16 pages, 2266 KiB

Open AccessArticle

The Use of Pyrolytic Char Derived from Waste Tires in the Removal of Malachite Green from Dyeing Wastewater

by Dongliang Ji, Didi Gai, Yikun Xu, Zhaoqin Huang and Peitao Zhao

Nanomaterials 2022, 12(23), 4325; https://doi.org/10.3390/nano12234325 - 5 Dec 2022

Cited by 3 | Viewed by 1588

Abstract

The organic dye malachite green (MG) poses a potential risk of cancer and fertility loss in humans and aquatic organisms. This study focused on a modified pyrolytic char (PC) derived from waste tires to efficiently remove MG from wastewater. Modified PC has rich [...] Read more.

The organic dye malachite green (MG) poses a potential risk of cancer and fertility loss in humans and aquatic organisms. This study focused on a modified pyrolytic char (PC) derived from waste tires to efficiently remove MG from wastewater. Modified PC has rich -OH functional groups, higher BET (Brunauer-Emmett-Teller) surfaces of 74.4, 64.95, and 67.31 m²/g, and larger pore volumes of 0.52, 0.47, and 0.62 cm³/g for NaOH, Na₂CO₃, and CaO modification, respectively. The pseudo-second-order model fit the adsorption well, and the maximum equilibrium adsorption capacity was 937.8 mg/g for PC after CaO activation (CaO-PC). NaOH-modified PC (NaOH-PC) showed the best fit with the Langmuir model (R² = 0.918). It is suggested that alkali-modified waste tire pyrolytic char could be a potential adsorbent for removing MG from dye-containing wastewater. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for a Cleaner Environment and Environmental Health)

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12 pages, 2468 KiB

Open AccessArticle

The Effect of Y Doping on Monoclinic, Orthorhombic, and Cubic Polymorphs of HfO₂: A First Principles Study

by Eleonora Pavoni, Elaheh Mohebbi, Davide Mencarelli, Pierluigi Stipa, Emiliano Laudadio and Luca Pierantoni

Nanomaterials 2022, 12(23), 4324; https://doi.org/10.3390/nano12234324 - 5 Dec 2022

Cited by 13 | Viewed by 2421

Abstract

HfO₂ can assume different crystalline structures, such as monoclinic, orthorhombic, and cubic polymorphs, each one characterized by unical properties. The peculiarities of this material are also strongly related to the presence of doping elements in the unit cell. Thus, the present paper [...] Read more.

HfO₂ can assume different crystalline structures, such as monoclinic, orthorhombic, and cubic polymorphs, each one characterized by unical properties. The peculiarities of this material are also strongly related to the presence of doping elements in the unit cell. Thus, the present paper has the main purpose of studying and comparing twelve different systems characterized by diverse polymorphs and doping percentages. In particular, three different crystalline structures were considered: the monoclinic P2₁/c, the orthorhombic Pca2₁, and the cubic Fm $\bar{3}$ m phases of HfO₂. Each one has been studied by using Y as a doping agent with three different contents: 0% Y:HfO₂, 8% Y:HfO₂, 12% Y:HfO₂, and 16% Y:HfO₂. For all the systems, density functional theory (DFT) methods based on PBE/GGA, and on the HSE hybrid functionals were used to optimize the geometry as well as to study their optical properties. Depending on the polymorphs, Y affects the formation energy in different ways and causes changes in the optical properties. When the percentage of Y did not exceed 12%, a stabilization of the cubic phase fraction and an increase of the dielectric constant was observed. Additionally, the calculated optical bandgap energies and the refractive index are examined to provide an overview of the systems and are compared with experimental data. The bandgaps obtained are in perfect agreement with the experimental values and show a slight increase as the doping percentage grows, while only minor differences are found between the three polymorphs in terms of both refractive index and optical band gap. The adopted first principles study generates a reasonable prediction of the physical-chemical properties of all the systems, thus identifying the effects of doping phenomena. Full article

(This article belongs to the Special Issue First-Principle Calculation Study of Nanomaterials)

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14 pages, 4902 KiB

Open AccessArticle

Structural and Superconducting Proximity Effect of SnPb Bimetallic Nanoalloys

by Ashish Chhaganlal Gandhi, Krishtappa Manjunatha, Ting-Shan Chan and Sheng Yun Wu

Nanomaterials 2022, 12(23), 4323; https://doi.org/10.3390/nano12234323 - 5 Dec 2022

Viewed by 1495

Abstract

We report the superconducting properties between a conventional strong-coupled Pb and weak-coupled Sn superconductor. A series of Sn_rPb_1-r nanoalloys with various compositions r were synthesized, and their superconducting properties were measured using superconducting quantum interference devices (SQUIDs) magnetometer. Our results [...] Read more.

We report the superconducting properties between a conventional strong-coupled Pb and weak-coupled Sn superconductor. A series of Sn_rPb_1-r nanoalloys with various compositions r were synthesized, and their superconducting properties were measured using superconducting quantum interference devices (SQUIDs) magnetometer. Our results reveal a superconducting proximity effect (SPE) between immiscible Sn and Pb granules in the range of r = 0.2~0.9, as a weak superconducting coupling can be established with the coexistence of phonon hardening and increased Ginzburg–Landau coherence length. Furthermore, our results provide new insights into improving the study of the superconducting proximity effect introduced by Sn doping. Full article

(This article belongs to the Special Issue Functionalized Magnetite Nanomaterials — Synthesis, Properties, and Applications)

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19 pages, 3739 KiB

Open AccessArticle

Rheological, Thermal and Mechanical Characterization of Toughened Self-Healing Supramolecular Resins, Based on Hydrogen Bonding

by Liberata Guadagno, Marialuigia Raimondo, Carlo Naddeo, Luigi Vertuccio, Salvatore Russo, Generoso Iannuzzo and Elisa Calabrese

Nanomaterials 2022, 12(23), 4322; https://doi.org/10.3390/nano12234322 - 5 Dec 2022

Cited by 9 | Viewed by 1480

Abstract

This paper proposes the design of toughened self-healing supramolecular resins able to fulfill functional and structural requirements for industrial applications. These new nanocomposites are based on compounds acting as promotors of reversible self-healing interactions. Electrically conductive carbon nanotubes, selected among those allowing to [...] Read more.

This paper proposes the design of toughened self-healing supramolecular resins able to fulfill functional and structural requirements for industrial applications. These new nanocomposites are based on compounds acting as promotors of reversible self-healing interactions. Electrically conductive carbon nanotubes, selected among those allowing to reach the electrical percolation threshold (EPT) with a very low amount of nanofiller, were dispersed in the self-healing polymeric matrix to contrast the electrical insulating properties of epoxy matrices, as required for many applications. The formulated supramolecular systems are thermally stable, up to 360 °C. Depending on the chemical formulation, the self-healing efficiency η, assessed by the fracture test, can reach almost the complete self-repairing efficiency (η = 99%). Studies on the complex viscosity of smart nanocomposites highlight that the effect of the nanofiller dominates over those due to the healing agents. The presence of healing compounds anchored to the hosting epoxy matrix determines a relevant increase in the glass transition temperature (T_g), which results in values higher than 200 °C. Compared to the unfilled matrix, a rise from 189 °C to 223 °C is found for two of the proposed formulations. Full article

(This article belongs to the Special Issue Advance in Nanostructured Polymers)

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18 pages, 4311 KiB

Open AccessArticle

A Comprehensive Study of Synthesis and Analysis of Anisotropic Iron Oxide and Oxyhydroxide Nanoparticles

by Elizaveta Chernova, Vladimir Botvin, Maria Galstenkova, Yulia Mukhortova, Dmitry Wagner, Evgeny Gerasimov, Maria Surmeneva, Andrei Kholkin and Roman Surmenev

Nanomaterials 2022, 12(23), 4321; https://doi.org/10.3390/nano12234321 - 5 Dec 2022

Cited by 12 | Viewed by 2517

Abstract

One-dimensional anisotropic nanoparticles are of great research interest across a wide range of biomedical applications due to their specific physicochemical and magnetic properties in comparison with isotropic magnetic nanoparticles. In this work, the formation of iron oxides and oxyhydroxide anisotropic nanoparticles (ANPs) obtained [...] Read more.

One-dimensional anisotropic nanoparticles are of great research interest across a wide range of biomedical applications due to their specific physicochemical and magnetic properties in comparison with isotropic magnetic nanoparticles. In this work, the formation of iron oxides and oxyhydroxide anisotropic nanoparticles (ANPs) obtained by the co-precipitation method in the presence of urea was studied. Reaction pathways of iron oxide and oxyhydroxide ANPs formation are described based on of X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and pulse magnetometry studies. It is shown that a nonmonotonic change in the Fe₃O₄ content occurs during synthesis. The maximum content of the Fe₃O₄ phase of 47.4% was obtained at 12 h of the synthesis. At the same time, the reaction products contain ANPs of α-FeOOH and submicron isotropic particles of Fe₃O₄, the latter formation can occur due to the oxidation of Fe²⁺ ions by air-oxygen and Ostwald ripening processes. A subsequent increase in the synthesis time leads to the predominant formation of an α-FeOOH phase due to the oxidation of Fe₃O₄. As a result of the work, a methodological scheme for the analysis of iron oxide and oxyhydroxide ANPs was developed. Full article

(This article belongs to the Section Inorganic Materials and Metal-Organic Frameworks)

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13 pages, 32224 KiB

Open AccessFeature PaperArticle

Tannic Acid as a Versatile Template for Silica Monoliths Engineering with Catalytic Gold and Silver Nanoparticles

by Irina Postnova and Yury Shchipunov

Nanomaterials 2022, 12(23), 4320; https://doi.org/10.3390/nano12234320 - 5 Dec 2022

Cited by 6 | Viewed by 2324

Abstract

Tannic acid in alkaline solutions in which sol-gel synthesis is usually performed with tetraethoxysilane is susceptible to various modifications, including formation of reactive radicals, oxidation under the action of atmospheric oxygen, self-association, and self-polymerization. Here, a precursor with ethylene glycol residues instead of [...] Read more.

Tannic acid in alkaline solutions in which sol-gel synthesis is usually performed with tetraethoxysilane is susceptible to various modifications, including formation of reactive radicals, oxidation under the action of atmospheric oxygen, self-association, and self-polymerization. Here, a precursor with ethylene glycol residues instead of ethanol was used, which made it possible to synthesize bionanocomposites of tannic acid and silica in one stage in neutral media under normal conditions without the addition of acid/alkali and organic solvents. Silica was fabricated in the form of optically transparent monoliths of various shapes with 2–4 nm pores, the radius of which well correlated with the size of a tannic acid macromolecule in a non-aggregated state. Polyphenol, which was remained in pores of silica matrix, served then as reducing agent to synthesize in situ gold and silver nanoparticles. As shown, these Au@SiO₂ and Ag@SiO₂ nanocomposites possessed localized surface plasmon resonance and high catalytic activity. Full article

(This article belongs to the Special Issue Design, Fabrication and Applications of Nanoporous Materials)

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Nanomaterials, Volume 12, Issue 23 (December-1 2022) – 242 articles

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