Nanomaterials

14 pages, 5152 KiB

Open AccessArticle

Water-Soluble Lead Sulfide Nanoparticles: Direct Synthesis and Ligand Exchange Routes

by Saar Pfeffer, Vladimir Ezersky, Sofiya Kolusheva and Yuval Golan

Nanomaterials 2024, 14(14), 1235; https://doi.org/10.3390/nano14141235 - 22 Jul 2024

Viewed by 1414

Colloidal semiconductor nanoparticles (NPs) represent an emergent state of matter with unique properties, bridging bulk materials and molecular structures. Their distinct physical attributes, such as bandgap and photoluminescence, are intricately tied to their size and morphology. Ligand passivation plays a crucial role in [...] Read more.

Colloidal semiconductor nanoparticles (NPs) represent an emergent state of matter with unique properties, bridging bulk materials and molecular structures. Their distinct physical attributes, such as bandgap and photoluminescence, are intricately tied to their size and morphology. Ligand passivation plays a crucial role in shaping NPs and determining their physical properties. Ligand exchange (LE) offers a versatile approach to tailoring NP properties, often guided by Pearson’s Hard–Soft Acid–Base theory. Lead sulfide (PbS), a semiconductor of considerable interest, exhibits size-dependent tunable bandgaps from the infrared to the visible range. Here, we present two methods for synthesizing water-soluble, polyvinylpyrrolidone (PVP)-coated PbS NPs. The first involves direct synthesis in an aqueous solution while utilizing PVP as the surfactant for the formation of nano-cubes with a crystal coherence length of ~30 nm, while the second involves LE from octadecylamine-coated PbS truncated nano-cubes to PVP-coated PbS NPs with a crystal coherence length of ~15 nm. Multiple characterization techniques, including X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, and thermal gravimetric analysis, confirmed the results of the synthesis and allowed us to monitor the ligand exchange process. Our findings demonstrate efficient and environmentally friendly approaches for synthesizing PVP-coated PbS NPs. Full article

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21 pages, 5067 KiB

Open AccessFeature PaperArticle

In-Situ Hydrothermal Fabrication of ZnO-Loaded GAC Nanocomposite for Efficient Rhodamine B Dye Removal via Synergistic Photocatalytic and Adsorptive Performance

by Kehinde Shola Obayomi, Sie Yon Lau, Zongli Xie, Stephen R. Gray and Jianhua Zhang

Nanomaterials 2024, 14(14), 1234; https://doi.org/10.3390/nano14141234 - 22 Jul 2024

Cited by 2 | Viewed by 1892

Abstract

In this work, zinc oxide (ZnO)/granular activated carbon (GAC) composites at different ZnO concentrations (0.25M-ZnO@GAC, 0.5M-ZnO@GAC, and 0.75M-ZnO@GAC) were prepared by an in-situ hydrothermal method and demonstrated synergistic photocatalytic degradation and adsorption of rhodamine B (RhB). The thermal stability, morphological structure, elemental composition, [...] Read more.

In this work, zinc oxide (ZnO)/granular activated carbon (GAC) composites at different ZnO concentrations (0.25M-ZnO@GAC, 0.5M-ZnO@GAC, and 0.75M-ZnO@GAC) were prepared by an in-situ hydrothermal method and demonstrated synergistic photocatalytic degradation and adsorption of rhodamine B (RhB). The thermal stability, morphological structure, elemental composition, crystallographic structure, and textural properties of developed catalysts were characterized by thermal gravimetric analysis (TGA/DTG), scanning electron microscopy equipped with energy dispersive-x-ray (SEM-EDS), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analysis. The successful loading of ZnO onto GAC was confirmed by SEM-EDS and XRD analysis. The BET surface areas of GAC, 0.25M-ZnO@GAC, 0.5M-ZnO@GAC, and 0.75M-ZnO@GAC were 474 m²/g, 450 m²/g, 453 m²/g, and 421 m²/g, respectively. The decrease in GAC could be attributed to the successful loading of ZnO on the GAC surface. Notably, 0.5M-ZnO@GAC exhibited the best photocatalytic degradation efficiency of 82% and 97% under UV-A and UV-C light over 120 min, attributed to improved crystallinity and visible light absorption. The photocatalytic degradation parameters revealed that lowering the RhB concentration and raising the catalyst dosage and pH beyond the point of zero charge (PZC) would favor the RhB degradation. Photocatalytic reusability was demonstrated over five cycles. Scavenger tests revealed that the hydroxyl radicals (^•OH), superoxide radicals (O₂^−•), and photoinduced hole (h⁺) radicals play a major role during the RhB degradation process. Based on the TOC results, the RhB mineralization efficiency of 79.1% was achieved by 0.5M-ZnO@GAC. Additionally, GAC exhibited a strong adsorptive performance towards RhB, with adsorption capacity and the RhB removal of 487.1 mg/g and 99.5% achieved within 90 min of equilibrium time. The adsorption characteristics were best described by pseudo-second-order kinetics, suggesting chemical adsorption. This research offers a new strategy for the development of effective photocatalyst materials with potential for wider wastewater treatment applications. Full article

(This article belongs to the Special Issue Novel Nanostructured Materials and Their Applications in Wastewater Treatment)

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25 pages, 35692 KiB

Open AccessArticle

A Systematic Microfluidic Study of the Use of Diluted Silica Sols to Enhance Oil Displacement

by Andrey I. Pryazhnikov, Maxim I. Pryazhnikov, Alexander S. Lobasov and Andrey V. Minakov

Nanomaterials 2024, 14(14), 1233; https://doi.org/10.3390/nano14141233 - 22 Jul 2024

Cited by 1 | Viewed by 1120

Abstract

The paper presents the results of a systematic microfluidic study of the application of nanosuspensions for enhanced oil recovery. For the first time, approximately a dozen nanosuspensions prepared by the dilution of silica sols as displacement fluids were considered. The concentration of nanoparticles [...] Read more.

The paper presents the results of a systematic microfluidic study of the application of nanosuspensions for enhanced oil recovery. For the first time, approximately a dozen nanosuspensions prepared by the dilution of silica sols as displacement fluids were considered. The concentration of nanoparticles in the suspensions varied from 0.125 to 2 wt%, and their size ranged from 10 to 35 nm. Furthermore, the silica sols under consideration differed in their compositions of functional groups and pH. The effects of concentration, nanoparticle size, fluid flow rate, and the viscosity of the displaced oil were investigated using microfluidic technology. The microfluidic experiments demonstrated that the application of nanosuspensions for water flooding has significant potential. The efficiency of oil displacement by nanosuspensions was found to increase significantly (up to 30%) with the increasing concentration and decreasing average size of nanoparticles. The application of nanosuspensions for the enhancement of oil recovery is most appropriate for reservoirs with highly viscous oil. Full article

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15 pages, 18156 KiB

Open AccessArticle

Effect of BaTiO₃ Filler Modification with Multiwalled Carbon Nanotubes on Electric Properties of Polymer Nanocomposites

by Maxim Sychov, Xingyu Guan, Sergey Mjakin, Lyubov Boridko, Nikolay Khristyuk, Marina Gravit and Semen Diachenko

Nanomaterials 2024, 14(14), 1232; https://doi.org/10.3390/nano14141232 - 22 Jul 2024

Viewed by 1109

Abstract

Two ranges of dielectric permittivity (k) increase in polymer composites upon the modification of BaTiO₃ filler with multiwalled carbon nanotubes (MWCNTs) are shown for the first time. The first increase in permittivity is observed at low MWCNT content in the [...] Read more.

Two ranges of dielectric permittivity (k) increase in polymer composites upon the modification of BaTiO₃ filler with multiwalled carbon nanotubes (MWCNTs) are shown for the first time. The first increase in permittivity is observed at low MWCNT content in the composite (approximately 0.07 vol.%) without a considerable increase in dielectric loss tangent and electrical conductivity. This effect is determined by the intensification of filler–polymer interactions caused by the nanotubes, which introduce Brønsted acidic centers on the modified filler surface and thus promote interactions with the cyanoethyl ester of polyvinyl alcohol (CEPVA) polymer binder. Consequently, the structure of the composites becomes more uniform: the permittivity increase is accompanied by a decrease in the lacunarity (nonuniformity) of the structure and an increase in scale invariance, which characterizes the self-similarity of the composite structure. The permittivity of the composites in the first range follows a modified Lichtenecker equation, including the content of Brønsted acidic centers as a parameter. The second permittivity growth range features a drastic increase in the dielectric loss tangent and conductivity corresponding to the percolation effect with the threshold at 0.3 vol.% of MWCNTs. Full article

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15 pages, 4439 KiB

Open AccessEditor’s ChoiceArticle

Photocatalytic CO₂ Reduction Using Zinc Indium Sulfide Aggregated Nanostructures Fabricated under Four Anionic Conditions

by I-Hua Tsai and Eric Wei-Guang Diau

Nanomaterials 2024, 14(14), 1231; https://doi.org/10.3390/nano14141231 - 20 Jul 2024

Viewed by 1309

Abstract

Zinc indihuhium sulfide (ZIS), among various semiconductor materials, shows considerable potential due to its simplicity, low cost, and environmental compatibility. However, the influence of precursor anions on ZIS properties remains unclear. In this study, we synthesized ZIS via a hydrothermal method using four [...] Read more.

Zinc indihuhium sulfide (ZIS), among various semiconductor materials, shows considerable potential due to its simplicity, low cost, and environmental compatibility. However, the influence of precursor anions on ZIS properties remains unclear. In this study, we synthesized ZIS via a hydrothermal method using four different anionic precursors (ZnCl₂/InCl₃, Zn(NO₃)₂/In(NO₃)₃, Zn(CH₃CO₂)₂/In(CH₃CO₂)₃, and Zn(CH₃CO₂)₂/In₂(SO₄)₃), resulting in distinct morphologies and crystal structures. Our findings reveal that ZIS produced from Zn(CH₃CO₂)₂/In₂(SO₄)₃ (ZIS-AceSO₄) exhibited the highest photocatalytic CO₂ reduction efficiency, achieving a CO production yield of 134 μmol g⁻¹h⁻¹. This enhanced performance is attributed to the formation of more zinc and indium vacancy defects, as confirmed by EDS analysis. Additionally, we determined the energy levels of the valence band maximum (VBM) and the conduction band minimum (CBM) via UPS and absorption spectra, providing insights into the band alignment essential for photocatalytic processes. These findings not only deepen our understanding of the anionic precursor’s impact on ZIS properties but also offer new avenues for optimizing photocatalytic CO₂ reduction, marking a significant advancement over previous studies. Full article

(This article belongs to the Section Energy and Catalysis)

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19 pages, 9067 KiB

Open AccessArticle

Infrared Lightwave Memory-Resident Manipulation and Absorption Based on Spatial Electromagnetic Wavefield Excitation and Resonant Accumulation by GdFe-Based Nanocavity-Shaped Metasurfaces

by Cheng Chen, Chuang Zhang, Taige Liu, Zhe Wang, Jiashuo Shi and Xinyu Zhang

Nanomaterials 2024, 14(14), 1230; https://doi.org/10.3390/nano14141230 - 20 Jul 2024

Viewed by 842

Abstract

An arrayed nanocavity-shaped architecture consisting of the key GdFe film and SiO₂ dielectric layer is constructed, leading to an efficient infrared (IR) absorption metasurface. By carefully designing and optimizing the film system configuration and the surface layout with needed geometry, a desirable [...] Read more.

An arrayed nanocavity-shaped architecture consisting of the key GdFe film and SiO₂ dielectric layer is constructed, leading to an efficient infrared (IR) absorption metasurface. By carefully designing and optimizing the film system configuration and the surface layout with needed geometry, a desirable IR radiation absorption according to the spatial magnetic plasmon modes is realized experimentally. The simulations and measurements demonstrate that GdFe-based nanocavity-shaped metasurfaces can be used to achieve an average IR absorption of ~81% in a wide wavelength range of 3–14 μm. A type of the patterned GdFe-based nanocavity-shaped metasurface is further proposed for exciting relatively strong spatial electromagnetic wavefields confined by a patterned nanocavity array based on the joint action of the surface oscillated net charges over the charged metallic films and the surface conductive currents including equivalent eddy currents surrounding the layered GdFe and SiO₂ materials. Intensive IR absorption can be attributed to a spatial electromagnetic wavefield excitation and resonant accumulation or memory residence according to the GdFe-based nanocavity-shaped array formed. Our research provides a potential clue for efficiently responding and manipulating and storing incident IR radiation mainly based on the excitation and resonant accumulation of spatial magnetic plasmons. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications (Second Edition))

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10 pages, 2234 KiB

Open AccessArticle

Enhancing Interfacial Lithiophilicity and Stability with PVDF/In(NO₃)₃ Composite Separators for Durable Lithium Metal Anodes

by Zhuzhu Du, Xin Chen, Hongfang Du, Ying Zhao, Yuhang Liu and Wei Ai

Nanomaterials 2024, 14(14), 1229; https://doi.org/10.3390/nano14141229 - 20 Jul 2024

Viewed by 1358

Abstract

Separator modification is a promising method for advancing lithium metal anodes; however, achieving homogeneous lithium-ion flux and uniform plating/stripping processes remains challenging. In this work, we introduce a novel approach by developing a composite separator, termed PVDF-INO, which integrates In(NO₃)₃ [...] Read more.

Separator modification is a promising method for advancing lithium metal anodes; however, achieving homogeneous lithium-ion flux and uniform plating/stripping processes remains challenging. In this work, we introduce a novel approach by developing a composite separator, termed PVDF-INO, which integrates In(NO₃)₃ (INO) into polyvinylidene fluoride (PVDF) to create a 12 μm thick layer. This addition significantly enhances the interaction between the separator and the electrolyte, creating a lithophilic matrix that ensures an even distribution of lithium ions. This uniform ion distribution promotes consistent lithium deposition and dissolution, resulting in a durable, dendrite-free lithium metal anode. Moreover, the PVDF-INO separator not only enhances the affinity with electrolytes but also maintains stable lithium-ion flux, which is essential for reliable and safe battery operation. Consequently, it sustains operation over 750 h in a Li||Li symmetric battery configuration, with a low overpotential of just 28 mV. Additionally, full cells equipped with LiFePO₄ cathodes and the PVDF-INO separator exhibit superior cycling performance, maintaining a capacity retention of 92.9% after 800 cycles at 1 C. This work paves the way for significant advancements in the field of lithium metal batteries, offering a promising solution to longstanding energy storage challenges. Full article

(This article belongs to the Section Energy and Catalysis)

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10 pages, 2334 KiB

Open AccessArticle

Micro-to-Nanoscale Characterization of Femtosecond Laser Photo-Inscribed Microvoids

by Matilde Sosa, Maxime Cavillon, Thomas Blanchet, Gergely Nemeth, Ferenc Borondics, Guillaume Laffont and Matthieu Lancry

Nanomaterials 2024, 14(14), 1228; https://doi.org/10.3390/nano14141228 - 20 Jul 2024

Cited by 2 | Viewed by 1454

Abstract

Fiber Bragg gratings are key components for optical fiber sensing applications in harsh environments. This paper investigates the structural and chemical characteristics of femtosecond laser photo-inscribed microvoids. These voids are at the base of type III fs-gratings consisting of a periodic array of [...] Read more.

Fiber Bragg gratings are key components for optical fiber sensing applications in harsh environments. This paper investigates the structural and chemical characteristics of femtosecond laser photo-inscribed microvoids. These voids are at the base of type III fs-gratings consisting of a periodic array of microvoids inscribed at the core of an optical fiber. Using high-resolution techniques such as quantitative phase microscopy, electron transmission microscopy, and scattering-type scanning near-field IR optical microscopy, we examined the structure of the microvoids and the densified shells around them. We also investigated the high-temperature behavior of the voids, revealing their evolution in size and shape under step isochronal annealing conditions up to 1250 °C. Full article

(This article belongs to the Special Issue Advanced Manufacturing on Nano- and Microscale)

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12 pages, 1696 KiB

Open AccessCommunication

Raman Study of Novel Nanostructured WO₃ Thin Films Grown by Spray Deposition

by Andreea Gabriela Marina Popescu, Ioan Valentin Tudose, Cosmin Romanitan, Marian Popescu, Marina Manica, Paul Schiopu, Marian Vladescu, Mirela Petruta Suchea and Cristina Pachiu

Nanomaterials 2024, 14(14), 1227; https://doi.org/10.3390/nano14141227 - 19 Jul 2024

Cited by 5 | Viewed by 1925

Abstract

The present communication reports on the effect of the sprayed solution volume variation (as a thickness variation element) on the detailed Raman spectroscopy for WO₃ thin films with different thicknesses grown from precursor solutions with two different concentrations. Walls-like structured monoclinic WO [...] Read more.

The present communication reports on the effect of the sprayed solution volume variation (as a thickness variation element) on the detailed Raman spectroscopy for WO₃ thin films with different thicknesses grown from precursor solutions with two different concentrations. Walls-like structured monoclinic WO₃ thin films were obtained by the spray deposition method for further integration in gas sensors. A detailed analysis of the two series of samples shows that the increase in thickness strongly affects the films’ morphology, while their crystalline structure is only slightly affected. The Raman analysis contributes to refining the structural feature clarifications. It was observed that, for 0.05 M precursor concentration series, thinner films (lower volume) show less intense peaks, indicating more defects and lower crystallinity, while thicker films (higher volume) exhibit sharper and more intense peaks, suggesting improved crystallinity and structural order. For higher precursor concentration 0.1 M series, films at higher precursor concentrations show overall more intense and sharper peaks across all thicknesses, indicating higher crystallinity and fewer defects. Differences in peak intensity and presence reflect variations in film morphology and structural properties due to increased precursor concentration. Further studies are ongoing. Full article

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

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17 pages, 9947 KiB

Open AccessArticle

Combined Electrochemical Deposition and Photo-Reduction to Fabricate SERS-Active Silver Substrates: Characterization and Application for Malachite Green Detection in Aquaculture Water

by Yu-Xuan Li, Yi-Ting Chen, Cheng-Tse Chang, Chao Yi (Anso) Ting, Yaumalika Arta, Mei-Yao Wu, Tsunghsueh Wu, Yu-Shen Lin and Yang-Wei Lin

Nanomaterials 2024, 14(14), 1226; https://doi.org/10.3390/nano14141226 - 19 Jul 2024

Viewed by 1242

Abstract

This research introduces a novel approach using silver (Ag) nanostructures generated through electrochemical deposition and photo-reduction of Ag on fluorine-doped tin oxide glass substrates (denoted as X-Ag-Ag_yFTO, where ‘X’ and ‘y’ represent the type of light source and number of deposited [...] Read more.

This research introduces a novel approach using silver (Ag) nanostructures generated through electrochemical deposition and photo-reduction of Ag on fluorine-doped tin oxide glass substrates (denoted as X-Ag-Ag_yFTO, where ‘X’ and ‘y’ represent the type of light source and number of deposited cycles, respectively) for surface-enhanced Raman spectroscopy (SERS). This study used malachite green (MG) as a Raman probe to evaluate the enhancement factors (EFs) in SERS-active substrates under varied fabrication conditions. For the substrates produced via electrochemical deposition, we determined a Raman EF of 6.15 × 10⁴ for the Ag₂FTO substrate. In photo-reduction, the impact of reductant concentration, light source, and light exposure duration were examined on X-Ag nanoparticle formation to achieve superior Raman EFs. Under optimal conditions (9.0 mM sodium citrate, 460 nm blue-LED at 10 W for 90 min), the combination of blue-LED-reduced Ag (B-Ag) and an Ag₂FTO substrate (denoted as B-Ag-Ag₂FTO) exhibited the best Raman EF of 2.79 × 10⁵. This substrate enabled MG detection within a linear range of 0.1 to 1.0 µM (R² = 0.98) and a detection limit of 0.02 µM. Additionally, the spiked recoveries in aquaculture water samples were between 90.0% and 110.0%, with relative standard deviations between 3.9% and 6.3%, indicating the substrate’s potential for fungicide detection in aquaculture. Full article

(This article belongs to the Special Issue Advances in Green Nanotechnology: From Nanoparticles' Green Synthesis to Their Applications in Engineering)

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17 pages, 5355 KiB

Open AccessFeature PaperArticle

Tunable Hydrogen-Related Defects in ZnO Nanowires Using Oxygen Plasma Treatment by Ion Energy Adjustment

by Alexandre Dieulesaint, Odette Chaix-Pluchery, Matthieu Weber, Fabrice Donatini, Ana Lacoste, Vincent Consonni and Eirini Sarigiannidou

Nanomaterials 2024, 14(14), 1225; https://doi.org/10.3390/nano14141225 - 19 Jul 2024

Cited by 1 | Viewed by 1145

Abstract

The chemical bath deposition (CBD) process enables the deposition of ZnO nanowires (NWs) on various substrates with customizable morphology. However, the hydrogen-rich CBD environment introduces numerous hydrogen-related defects, unintentionally doping the ZnO NWs and increasing their electrical conductivity. The oxygen-based plasma treatment can [...] Read more.

The chemical bath deposition (CBD) process enables the deposition of ZnO nanowires (NWs) on various substrates with customizable morphology. However, the hydrogen-rich CBD environment introduces numerous hydrogen-related defects, unintentionally doping the ZnO NWs and increasing their electrical conductivity. The oxygen-based plasma treatment can modify the nature and amount of these defects, potentially tailoring the ZnO NW properties for specific applications. This study examines the impact of the average ion energy on the formation of oxygen vacancies (V_O) and hydrogen-related defects in ZnO NWs exposed to low-pressure oxygen plasma. Using X-ray photoelectron spectroscopy (XPS), 5 K cathodoluminescence (5K CL), and Raman spectroscopy, a comprehensive understanding of the effect of the oxygen ion energy on the formation of defects and defect complexes was established. A series of associative and dissociative reactions indicated that controlling plasma process parameters, particularly ion energy, is crucial. The XPS data suggested that increasing the ion energy could enhance Fermi level pinning by increasing the amount of V_O and favoring the hydroxyl group adsorption, expanding the depletion region of charge carriers. The 5K CL and Raman spectroscopy further demonstrated the potential to adjust the ZnO NW physical properties by varying the oxygen ion energy, affecting various donor- and acceptor-type defect complexes. This study highlights the ability to tune the ZnO NW properties at low temperature by modifying plasma process parameters, offering new possibilities for a wide variety of nanoscale engineering devices fabricated on flexible and/or transparent substrates. Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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11 pages, 2141 KiB

Open AccessArticle

Effect of Substitutional Metallic Impurities on the Optical Absorption Properties of TiO₂

by Eduardo Cisternas, Rodrigo Aguilera-del-Toro, Faustino Aguilera-Granja and Eugenio E. Vogel

Nanomaterials 2024, 14(14), 1224; https://doi.org/10.3390/nano14141224 - 19 Jul 2024

Cited by 2 | Viewed by 1028

Abstract

(TiO₂) is both a natural and artificial compound that is transparent under visible and near-infrared light. However, it could be prepared with other metals, substituting for Ti, thus changing its properties. In this article, we present density functional theory calculations for [...] Read more.

(TiO₂) is both a natural and artificial compound that is transparent under visible and near-infrared light. However, it could be prepared with other metals, substituting for Ti, thus changing its properties. In this article, we present density functional theory calculations for Ti_(1−x)A_xO₂, where A stands for any of the eight following neutral substitutional impurities, Fe, Ni, Co, Pd, Pt, Cu, Ag and Au, based on the rutile structure of pristine TiO₂. We use a fully unconstrained version of the density functional method with generalized gradient approximation plus the U exchange and correlation, as implemented in the Quantum Espresso free distribution. Within the limitations of a finite-size cell approximation, we report the band structure, energy gaps and absorption spectrum for all these cases. Rather than stressing precise values, we report on two general features: the location of the impurity levels and the general trends of the optical properties in the eight different systems. Our results show that all these substitutional atoms lead to the presence of electronic levels within the pristine gap, and that all of them produce absorptions in the visible and near-infrared ranges of electromagnetic radiation. Such results make these systems interesting for the fabrication of solar cells. Considering the variety of results, Ni and Ag are apparently the most promising substitutional impurities with which to achieve better performance in capturing the solar radiation on the planet’s surface. Full article

(This article belongs to the Topic Optical and Optoelectronic Properties of Materials and Their Applications)

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16 pages, 4825 KiB

Open AccessArticle

A Hybrid Structure to Improve Electrochemical Performance of SiO Anode Materials in Lithium-Ion Battery

by Jian Yu, Chaoran Zhang, Xiaolu Huang, Leifeng Cao, Aiwu Wang, Wanjun Dai, Dikai Li, Yanmeng Dai, Cangtao Zhou, Yaozhong Zhang and Yafei Zhang

Nanomaterials 2024, 14(14), 1223; https://doi.org/10.3390/nano14141223 - 19 Jul 2024

Cited by 4 | Viewed by 1793

Abstract

The wide utilization of lithium-ion batteries (LIBs) prompts extensive research on the anode materials with large capacity and excellent stability. Despite the attractive electrochemical properties of pure Si anodes outperforming other Si-based materials, its unsafety caused by huge volumetric expansion is commonly admitted. [...] Read more.

The wide utilization of lithium-ion batteries (LIBs) prompts extensive research on the anode materials with large capacity and excellent stability. Despite the attractive electrochemical properties of pure Si anodes outperforming other Si-based materials, its unsafety caused by huge volumetric expansion is commonly admitted. Silicon monoxide (SiO) anode is advantageous in mild volume fluctuation, and would be a proper alternative if the low initial columbic efficiency and conductivity can be ameliorated. Herein, a hybrid structure composed of active material SiO particles and carbon nanofibers (SiO/CNFs) is proposed as a solution. CNFs, through electrospun processes, serve as a conductive skeleton for SiO nanoparticles and enable SiO nanoparticles to be uniformly embedded in. As a result, the SiO/CNF electrochemical performance reaches a peak at 20% the mass ratio of SiO, where the retention rate reaches 73.9% after 400 cycles at a current density of 100 mA g⁻¹, and the discharge capacity after stabilization and 100 cycles are 1.47 and 1.84 times higher than that of pure SiO, respectively. A fast lithium-ion transport rate during cycling is also demonstrated as the corresponding diffusion coefficient of the SiO/CNF reaches ~8 × 10⁻¹⁵ cm² s⁻¹. This SiO/CNF hybrid structure provides a flexible and cost-effective solution for LIBs and sheds light on alternative anode choices for industrial battery assembly. Full article

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18 pages, 6209 KiB

Open AccessArticle

PEDOT-Doped Mesoporous Nanocarbon Electrodes for High Capacitive Aqueous Symmetric Supercapacitors

by Mohsina Taj, Vinay S. Bhat, Ganesan Sriram, Mahaveer Kurkuri, S. R. Manohara, Paola De Padova and Gurumurthy Hegde

Nanomaterials 2024, 14(14), 1222; https://doi.org/10.3390/nano14141222 - 18 Jul 2024

Cited by 2 | Viewed by 1967

Abstract

Poly(3,4-ethylenedioxythiophene) (PEDOT) and PEDOT-functionalized carbon nanoparticles (f-CNPs) were synthesized by in situ chemical oxidative polymerization and pyrolysis methods. f-CNP-PEDOT nanocomposites were prepared by varying the concentration of PEDOT from 1 to 20% by weight (i.e., 1, 2.5, 5, 10, and 20 wt%). Several [...] Read more.

Poly(3,4-ethylenedioxythiophene) (PEDOT) and PEDOT-functionalized carbon nanoparticles (f-CNPs) were synthesized by in situ chemical oxidative polymerization and pyrolysis methods. f-CNP-PEDOT nanocomposites were prepared by varying the concentration of PEDOT from 1 to 20% by weight (i.e., 1, 2.5, 5, 10, and 20 wt%). Several characterization techniques, such as field-emission scanning electron microscopy (FESEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR), X-ray diffraction (XRD), N₂ Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) analyses, as well as cyclic voltammetry (CV), galvanostatic charge discharge (GCD), and electrochemical impedance spectroscopy (EIS), were applied to investigate the morphology, the crystalline structure, the N₂ adsorption/desorption capability, as well as the electrochemical properties of these new synthesized nanocomposite materials. FESEM analysis showed that these nanocomposites have defined porous structures, and BET surface area analysis showed that the standalone f-CNP exhibited the largest surface area of 801.6 m²/g, whereas the f-CNP-PEDOT with 20 wt% exhibited the smallest surface area of 116 m²/g. The BJH method showed that the nanocomposites were predominantly mesoporous. CV, GCD, and EIS measurements showed that f-CNP functionalized with 5 wt% PEDOT had a higher capacitive performance compared to the individual f-CNPs and PEDOT constituents, exhibiting an extraordinary specific capacitance of 258.7 F/g, at a current density of 0.25 A/g, due to the combined advantage of enhanced electrochemical activity induced by PEDOT doping, and highly developed porosity of f-CNPs. Symmetric aqueous supercapacitor devices were fabricated using the optimized f-CNP-PEDOT doped with 5 wt% of PEDOT as active material, exhibiting a high capacitance of 96.7 F/g at 1.4 V, holding practically their full charge, after 10,000 charge–discharge cycles at 2 A/g, thus providing the highest electrical electrodes performance. Hereafter, this work paves the way for the potential use of f-CNP-PEDOT nanocomposites in the development of high-energy-density supercapacitors. Full article

(This article belongs to the Special Issue Recent Advances in Green Nanomaterials: Design and Applications)

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9 pages, 2576 KiB

Open AccessArticle

Growth of α-Ga₂O₃ from Gallium Acetylacetonate under HCl Support by Mist Chemical Vapor Deposition

by Tatsuya Yasuoka, Li Liu, Giang T. Dang and Toshiyuki Kawaharamura

Nanomaterials 2024, 14(14), 1221; https://doi.org/10.3390/nano14141221 - 18 Jul 2024

Cited by 3 | Viewed by 1237

Abstract

α-Ga₂O₃ films were grown on a c-plane sapphire substrate by HCl-supported mist chemical vapor deposition with multiple solution chambers, and the effect of HCl support on α-Ga₂O₃ film quality was investigated. The growth rate monotonically increased [...] Read more.

α-Ga₂O₃ films were grown on a c-plane sapphire substrate by HCl-supported mist chemical vapor deposition with multiple solution chambers, and the effect of HCl support on α-Ga₂O₃ film quality was investigated. The growth rate monotonically increased with increasing Ga supply rate. However, as the Ga supply rate was higher than 0.1 mmol/min, the growth rate further increased with increasing HCl supply rate. The surface roughness was improved by HCl support when the Ga supply rate was smaller than 0.07 mmol/min. The crystallinity of the α-Ga₂O₃ films exhibited an improvement with an increase in the film thickness, regardless of the solution preparation conditions, Ga supply rate, and HCl supply rate. These results indicate that there is a low correlation between the improvement of surface roughness and crystallinity in the α-Ga₂O₃ films grown under the conditions described in this paper. Full article

(This article belongs to the Special Issue Advances in Wide-Bandgap Semiconductor Nanomaterials)

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17 pages, 6994 KiB

Open AccessArticle

Tailoring the Lithium Concentration in Thin Lithium Ferrite Films Obtained by Dual Ion Beam Sputtering

by Pilar Prieto, Cayetano Hernández-Gómez, Sara Román-Sánchez, Marina París-Ogáyar, Giulio Gorni, José Emilio Prieto and Aida Serrano

Nanomaterials 2024, 14(14), 1220; https://doi.org/10.3390/nano14141220 - 18 Jul 2024

Viewed by 1239

Abstract

Thin films of lithium spinel ferrite, LiFe₅O₈, have attracted much scientific attention because of their potential for efficient excitation, the manipulation and propagation of spin currents due to their insulating character, high-saturation magnetization, and Curie temperature, as well as [...] Read more.

Thin films of lithium spinel ferrite, LiFe₅O₈, have attracted much scientific attention because of their potential for efficient excitation, the manipulation and propagation of spin currents due to their insulating character, high-saturation magnetization, and Curie temperature, as well as their ultra-low damping value. In addition, LiFe₅O₈ is currently one of the most interesting materials in terms of developing spintronic devices based on the ionic control of magnetism, for which it is crucial to control the lithium’s atomic content. In this work, we demonstrate that dual ion beam sputtering is a suitable technique to tailor the lithium content of thin films of lithium ferrite (LFO) by using the different energies of the assisting ion beam formed by Ar⁺ and O₂⁺ ions during the growth process. Without assistance, a disordered rock-salt LFO phase (i.e., LiFeO₂) can be identified as the principal phase. Under beam assistance, highly out-of-plane-oriented (111) thin LFO films have been obtained on (0001) Al₂O₃ substrates with a disordered spinel structure as the main phase and with lithium concentrations higher and lower than the stoichiometric spinel phase, i.e., LiFe₅O₈. After post-annealing of the films at 1025 K, a highly ordered ferromagnetic spinel LFO phase was found when the lithium concentration was higher than the stoichiometric value. With lower lithium contents, the antiferromagnetic hematite (α-Fe₂O₃) phase emerged and coexisted in films with the ferromagnetic Li_xFe_6-xO₈. These results open up the possibility of controlling the properties of thin lithium ferrite-based films to enable their use in advanced spintronic devices. Full article

(This article belongs to the Special Issue Nanostructured Thin Films: Deposition Methods, Properties and Applications)

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16 pages, 5833 KiB

Open AccessArticle

Performance Enhancement of Ti/IrO₂-Ta₂O₅ Anode through Introduction of Tantalum–Titanium Interlayer via Double-Glow Plasma Surface Alloying Technology

by Mingshuai Guo, Yueren Liu, Yonglei Xin, Likun Xu, Lili Xue, Tigang Duan, Rongrong Zhao, Junji Xuan and Li Li

Nanomaterials 2024, 14(14), 1219; https://doi.org/10.3390/nano14141219 - 18 Jul 2024

Viewed by 1524

Abstract

Ti/IrO₂-Ta₂O₅ electrodes are extensively utilized in the electrochemical industries such as copper foil production, cathodic protection, and wastewater treatment. However, their performance degrades rapidly under high current densities and severe oxygen evolution conditions. To address this issue, we [...] Read more.

Ti/IrO₂-Ta₂O₅ electrodes are extensively utilized in the electrochemical industries such as copper foil production, cathodic protection, and wastewater treatment. However, their performance degrades rapidly under high current densities and severe oxygen evolution conditions. To address this issue, we have developed a composite anode of Ti/Ta-Ti/IrO₂-Ta₂O₅ with a Ta-Ti alloy interlayer deposited on a Ti substrate by double-glow plasma surface alloying, and the IrO₂-Ta₂O₅ surface coating prepared by the traditional thermal decomposition method. This investigation indicates that the electrode with Ta-Ti alloy interlayer reduces the agglomerates of precipitated IrO₂ nanoparticles and refines the grain size of IrO₂, thereby increasing the number of active sites and enhancing the electrocatalytic activity. Accelerated lifetime tests demonstrate that the Ti/Ta-Ti/IrO₂-Ta₂O₅ electrode exhibits a much higher stability than the Ti/IrO₂-Ta₂O₅ electrode. The significant improvement in electrochemical stability is attributed to the Ta-Ti interlayer, which offers high corrosion resistance and effective protection for the titanium substrate. Full article

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9 pages, 1056 KiB

Open AccessArticle

Magnetic Hardening: Unveiling Magnetization Dynamics in Soft Magnetic Fe–Ni–B–Nb Thin Films at Cryogenic Temperatures

by Ansar Masood, Liubov Belova and Valter Ström

Nanomaterials 2024, 14(14), 1218; https://doi.org/10.3390/nano14141218 - 18 Jul 2024

Viewed by 1139

Abstract

Recent advancements in amorphous materials have opened new avenues for exploring unusual magnetic phenomena at the sub-nanometer scale. We investigate the phenomenon of low-temperature “magnetic hardening” in heterogeneous amorphous Fe–Ni–B–Nb thin films, revealing a complex interplay between microstructure and magnetism. Magnetization hysteresis measurements [...] Read more.

Recent advancements in amorphous materials have opened new avenues for exploring unusual magnetic phenomena at the sub-nanometer scale. We investigate the phenomenon of low-temperature “magnetic hardening” in heterogeneous amorphous Fe–Ni–B–Nb thin films, revealing a complex interplay between microstructure and magnetism. Magnetization hysteresis measurements at cryogenic temperatures show a significant increase in coercivity (H_C) below 25 K, challenging the conventional Random Anisotropy Model (RAM) in predicting magnetic responses at cryogenic temperatures. Heterogeneous films demonstrate a distinct behavior in field-cooled and zero-field-cooled temperature-dependent magnetizations at low temperatures, characterized by strong irreversibility. This suggests spin-glass-like features at low temperatures, which are attributed to exchange frustration in disordered interfacial regions. These regions hinder direct exchange coupling between magnetic entities, leading to magnetic hardening. This study enhances the understanding of how microstructural intricacies impact magnetic dynamics in heterogeneous amorphous thin films at cryogenic temperatures. Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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16 pages, 4732 KiB

Open AccessArticle

Improved Proton Conductivity of Chitosan-Based Composite Proton Exchange Membrane Reinforced by Modified GO Inorganic Nanofillers

by Xinrui Guo, Zhongxin Zhang, Zhanyan Liu, Hui Huang, Chunlei Zhang and Huaxin Rao

Nanomaterials 2024, 14(14), 1217; https://doi.org/10.3390/nano14141217 - 17 Jul 2024

Cited by 2 | Viewed by 1260

Abstract

Non-fluorinated chitosan-based proton exchange membranes (PEMs) have been attracting considerable interest due to their environmental friendliness and relatively low cost. However, low proton conductivity and poor physicochemical properties have limited their application in fuel cells. In this work, a reinforced nanofiller (sulfonated CS/GO, [...] Read more.

Non-fluorinated chitosan-based proton exchange membranes (PEMs) have been attracting considerable interest due to their environmental friendliness and relatively low cost. However, low proton conductivity and poor physicochemical properties have limited their application in fuel cells. In this work, a reinforced nanofiller (sulfonated CS/GO, S-CS/GO) is accomplished, for the first time, via a facile amidation and sulfonation reaction. Novel chitosan-based composite PEMs are successfully constructed by the incorporation of the nanofiller into the chitosan matrix. Additionally, the effects of the type and amount of the nanofillers on physicochemical and electrochemical properties are further investigated. It is demonstrated that the chitosan-based composite PEMs incorporating an appropriate amount of the nanofillers (9 wt.%) exhibit good membrane-forming ability, physicochemical properties, improved proton conductivity, and low methanol permeability even under a high temperature and low humidity environment. When the incorporated amounts of S-CS/GO are 9 wt.%, the proton conductivity of the composite PEMs was up to 0.032 S/cm but methanol permeability was decreased to 1.42 × 10⁻⁷ cm²/s. Compared to a pristine CS membrane, the tensile strength of the composite membrane is improved by 98% and the methanol permeability is reduced by 51%. Full article

(This article belongs to the Section Energy and Catalysis)

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14 pages, 3362 KiB

Open AccessArticle

A Rapid, Efficient Method for Anodic Aluminum Oxide Membrane Room-Temperature Multi-Detachment from Commercial 1050 Aluminum Alloy

by Chin-An Ku, Chia-Wei Hung and Chen-Kuei Chung

Nanomaterials 2024, 14(14), 1216; https://doi.org/10.3390/nano14141216 - 17 Jul 2024

Cited by 1 | Viewed by 1548

Abstract

For commercial processes, through-hole AAO membranes are fabricated from high-purity aluminum by chemical etching. However, this method has the disadvantages of using heavy-metal solutions, creating large amounts of material waste, and leading to an irregular pore structure. Through-hole porous alumina membrane fabrication has [...] Read more.

For commercial processes, through-hole AAO membranes are fabricated from high-purity aluminum by chemical etching. However, this method has the disadvantages of using heavy-metal solutions, creating large amounts of material waste, and leading to an irregular pore structure. Through-hole porous alumina membrane fabrication has been widely investigated due to applications in filters, nanomaterial synthesis, and surface-enhanced Raman scattering. There are several means to obtain freestanding through-hole AAO membranes, but a fast, low-cost, and repetitive process to create complete, high-quality membranes has not yet been established. Here, we propose a rapid and efficient method for the multi-detachment of an AAO membrane at room temperature by integrating the one-time potentiostatic (OTP) method and two-step electrochemical polishing. Economical commercial AA1050 was used instead of traditional high-cost high-purity aluminum for AAO membrane fabrication at 25 °C. The OTP method, which is a single-step process, was applied to achieve a high-quality membrane with unimodal pore distribution and diameters between 35 and 40 nm, maintaining a high consistency over five repetitions. To repeatedly detach the AAO membrane, two-step electrochemical polishing was developed to minimize damage on the AA1050 substrate caused by membrane separation. The mechanism for creating AAO membranes using the OTP method can be divided into three major components, including the Joule heating effect, the dissolution of the barrier layer, and stress effects. The stress is attributed to two factors: bubble formation and the difference in the coefficient of thermal expansion between the AAO membrane and the Al substrate. This highly efficient AAO membrane detachment method will facilitate the rapid production and applications of AAO films. Full article

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19 pages, 7849 KiB

Open AccessArticle

Single Mesenchymal Stromal Cell Migration Tracking into Glioblastoma Using Photoconvertible Vesicles

by Olga A. Sindeeva, Polina A. Demina, Zhanna V. Kozyreva, Daria A. Terentyeva, Olga I. Gusliakova, Albert R. Muslimov and Gleb B. Sukhorukov

Nanomaterials 2024, 14(14), 1215; https://doi.org/10.3390/nano14141215 - 17 Jul 2024

Cited by 5 | Viewed by 1643

Abstract

Reliable cell labeling and tracking techniques are imperative for elucidating the intricate and ambiguous interactions between mesenchymal stromal cells (MSCs) and tumors. Here, we explore fluorescent photoconvertible nanoengineered vesicles to study mMSC migration in brain tumors. These 3 μm sized vesicles made of [...] Read more.

Reliable cell labeling and tracking techniques are imperative for elucidating the intricate and ambiguous interactions between mesenchymal stromal cells (MSCs) and tumors. Here, we explore fluorescent photoconvertible nanoengineered vesicles to study mMSC migration in brain tumors. These 3 μm sized vesicles made of carbon nanoparticles, Rhodamine B (RhB), and polyelectrolytes are readily internalized by cells. The dye undergoes photoconversion under 561 nm laser exposure with a fluorescence blue shift upon demand. The optimal laser irradiation duration for photoconversion was 0.4 ms, which provided a maximal blue shift of the fluorescent signal label without excessive laser exposure on cells. Vesicles modified with an extra polymer layer demonstrated enhanced intracellular uptake without remarkable effects on cell viability, motility, or proliferation. The optimal ratio of 20 vesicles per mMSC was determined. Moreover, the migration of individual mMSCs within 2D and 3D glioblastoma cell (EPNT-5) colonies over 2 days and in vivo tumor settings over 7 days were traced. Our study provides a robust nanocomposite platform for investigating MSC–tumor dynamics and offers insights into envisaged therapeutic strategies. Photoconvertible vesicles also present an indispensable tool for studying complex fundamental processes of cell–cell interactions for a wide range of problems in biomedicine. Full article

(This article belongs to the Special Issue Advanced Studies in Bionanomaterials)

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14 pages, 3389 KiB

Open AccessArticle

Colloidal Titanium Nitride Nanoparticles by Laser Ablation in Solvents for Plasmonic Applications

by Nikolaos Pliatsikas, Stavros Panos, Tamara Odutola, Spyridon Kassavetis, Chrysanthi Papoulia, Ilias Fekas, John Arvanitidis, Dimitris Christofilos, Eleni Pavlidou, Maria Gioti and Panos Patsalas

Nanomaterials 2024, 14(14), 1214; https://doi.org/10.3390/nano14141214 - 17 Jul 2024

Viewed by 1465

Abstract

Titanium nitride (TiN) is a candidate material for several plasmonic applications, and pulsed laser ablation in liquids (PLAL) represents a rapid, scalable, and environmentally friendly approach for the large-scale production of nanomaterials with customized properties. In this work, the nanosecond PLAL process is [...] Read more.

Titanium nitride (TiN) is a candidate material for several plasmonic applications, and pulsed laser ablation in liquids (PLAL) represents a rapid, scalable, and environmentally friendly approach for the large-scale production of nanomaterials with customized properties. In this work, the nanosecond PLAL process is developed, and we provide a concise understanding of the process parameters, such as the solvent and the laser fluence and pulse wavelength, to the size and structure of the produced TiN nanoparticles (NPs). TiN films of a 0.6 μm thickness developed by direct-current (DC) magnetron sputtering were used as the ablation targets. All laser process parameters lead to the fabrication of spherical NPs, while the laser pulse fluence was used to control the NPs’ size. High laser pulse fluence values result in larger TiN NPs (diameter around 42 nm for 5 mJ and 25 nm for 1 mJ), as measured from scanning electron microscopy (SEM). On the other hand, the wavelength of the laser pulse does not affect the mean size of the TiN NPs (24, 26, and 25 nm for 355, 532, and 1064 nm wavelengths, respectively). However, the wavelength plays a vital role in the quality of the produced TiN NPs. Shorter wavelengths result in NPs with fewer defects, as indicated by Raman spectra and XPS analysis. The solvent type also significantly affects the size of the NPs. In aqueous solutions, strong oxidation of the NPs is evident, while organic solvents such as acetone, carbides, and oxides cover the TiN NPs. Full article

(This article belongs to the Special Issue Progress of Nanoscale Materials in Plasmonics and Photonics)

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11 pages, 2770 KiB

Open AccessArticle

Growth of Monolayer MoS₂ Flakes via Close Proximity Re-Evaporation

by Blagovest Napoleonov, Dimitrina Petrova, Nikolay Minev, Peter Rafailov, Vladimira Videva, Daniela Karashanova, Bogdan Ranguelov, Stela Atanasova-Vladimirova, Velichka Strijkova, Deyan Dimov, Dimitre Dimitrov and Vera Marinova

Nanomaterials 2024, 14(14), 1213; https://doi.org/10.3390/nano14141213 - 17 Jul 2024

Cited by 3 | Viewed by 1392

Abstract

We report a two-step growth process of MoS₂ nanoflakes using a low-pressure chemical vapor deposition technique. In the first step, a MoS₂ layer was synthesized on a c-plane sapphire substrate. This layer was subsequently re-evaporated at a higher temperature to form [...] Read more.

We report a two-step growth process of MoS₂ nanoflakes using a low-pressure chemical vapor deposition technique. In the first step, a MoS₂ layer was synthesized on a c-plane sapphire substrate. This layer was subsequently re-evaporated at a higher temperature to form mono- or few-layer MoS₂ flakes. As a result, the close proximity re-evaporation enabled the growth of pristine MoS₂ nanoflakes. Atomic force microscopy analysis confirmed the synthesis of nanoclusters/nanoflakes with lateral dimensions of over 10 μm and a flake height of approximately 1.3 nm, demonstrating bi-layer MoS₂, whereas transmission electron microscopy analysis revealed triangular MoS₂ nanoflakes, with a diffraction pattern proving the presence of single crystalline hexagonal MoS₂. Raman data revealed the typical modes of high-quality MoS₂ nanoflakes. Finally, we presented the photocurrent dependence of a MoS₂-based photoresist under illumination with light-emitting diode of 405 nm wavelength. The measured current–voltage dependence across various luminous flux outlined the sensitivity of MoS₂ to polarized light and thus opens further opportunities for applications in high-performance photodetectors with polarization sensitivity. Full article

(This article belongs to the Special Issue Functional Two-Dimensional Materials, Thin Films and Coatings)

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17 pages, 6791 KiB

Open AccessArticle

Area-Selective Atomic Layer Deposition of Ru Using Carbonyl-Based Precursor and Oxygen Co-Reactant: Understanding Defect Formation Mechanisms

by Jayant Kumar Lodha, Johan Meersschaut, Mattia Pasquali, Hans Billington, Stefan De Gendt and Silvia Armini

Nanomaterials 2024, 14(14), 1212; https://doi.org/10.3390/nano14141212 - 16 Jul 2024

Viewed by 2850

Abstract

Area selective deposition (ASD) is a promising IC fabrication technique to address misalignment issues arising in a top–down litho-etch patterning approach. ASD can enable resist tone inversion and bottom–up metallization, such as via prefill. It is achieved by promoting selective growth in the [...] Read more.

Area selective deposition (ASD) is a promising IC fabrication technique to address misalignment issues arising in a top–down litho-etch patterning approach. ASD can enable resist tone inversion and bottom–up metallization, such as via prefill. It is achieved by promoting selective growth in the growth area (GA) while passivating the non-growth area (NGA). Nevertheless, preventing undesired particles and defect growth on the NGA is still a hurdle. This work shows the selectivity of Ru films by passivating the Si oxide NGA with self-assembled monolayers (SAMs) and small molecule inhibitors (SMIs). Ru films are deposited on the TiN GA using a metal-organic precursor tricarbonyl (trimethylenemethane) ruthenium (Ru TMM(CO)₃) and O₂ as a co-reactant by atomic layer deposition (ALD). This produces smooth Ru films (<0.1 nm RMS roughness) with a growth per cycle (GPC) of 1.6 Å/cycle. Minimizing the oxygen co-reactant dose is necessary to improve the ASD process selectivity due to the limited stability of the organic molecule and high reactivity of the ALD precursor, still allowing a Ru GPC of 0.95 Å/cycle. This work sheds light on Ru defect generation mechanisms on passivated areas from the detailed analysis of particle growth, coverage, and density as a function of ALD cycles. Finally, an optimized ASD of Ru is demonstrated on TiN/SiO₂ 3D patterned structures using dimethyl amino trimethyl silane (DMA-TMS) as SMI. Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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10 pages, 1866 KiB

Open AccessArticle

The Dynamic Modulation Doping Effect of Gas Molecules on an AlGaN/GaN Heterojunction Surface

by Ying Ma, Lin Shi, Liang Chen, Cai Chen, Yifang Hong, Hua Qin, Xiaodong Zhang, Yi Cui, Hongzhen Lin, Zhiqun Cheng, Fan Zhang, Linfeng Mao and Yong Cai

Nanomaterials 2024, 14(14), 1211; https://doi.org/10.3390/nano14141211 - 16 Jul 2024

Cited by 1 | Viewed by 1026

Abstract

AlGaN/GaN high-electron-mobility transistors (HEMTs) are widely used in high-frequency and high-power applications owing to the high two-dimensional electron gas (2DEG) concentration. However, the microscopic origin of the 2DEG remains unclear. This hinders the development of device fabrication technologies, such as threshold voltage modulation, [...] Read more.

AlGaN/GaN high-electron-mobility transistors (HEMTs) are widely used in high-frequency and high-power applications owing to the high two-dimensional electron gas (2DEG) concentration. However, the microscopic origin of the 2DEG remains unclear. This hinders the development of device fabrication technologies, such as threshold voltage modulation, current collapse suppression, and 2DEG concentration enhancement technologies, as well as AlGaN/GaN sensors with very high sensitivity to polar liquids. To clarify the 2DEG microscopic origin, we studied the effects of gas molecules on AlGaN/GaN surfaces through various experiments and first-principles calculations. The results indicated that the adsorption of gas molecules on the AlGaN/GaN surface is an important phenomenon, clarifying the microscopic origin of the 2DEG. This study elucidates the properties of AlGaN/GaN heterojunctions and promotes the development of new fabrication technologies for AlGaN/GaN devices. Full article

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14 pages, 652 KiB

Open AccessArticle

Quantum Transport through a Quantum Dot Coupled to Majorana Nanowire and Two Ferromagnets with Noncollinear Magnetizations

by Yu-Mei Gao, Yao-Hong Shen, Feng Chi, Zi-Chuan Yi and Li-Ming Liu

Nanomaterials 2024, 14(14), 1210; https://doi.org/10.3390/nano14141210 - 16 Jul 2024

Viewed by 1024

Abstract

We study the electron tunneling (ET) and local Andreev reflection (AR) processes in a quantum dot (QD) coupled to the left and right ferromagnetic leads with noncollinear ferromagnetisms. In particular, we consider that the QD is also side-coupled to a nanowire hosting Majorana [...] Read more.

We study the electron tunneling (ET) and local Andreev reflection (AR) processes in a quantum dot (QD) coupled to the left and right ferromagnetic leads with noncollinear ferromagnetisms. In particular, we consider that the QD is also side-coupled to a nanowire hosting Majorana bound states (MBSs) at its ends. Our results show that when one mode of the MBSs is coupled simultaneously to both spin-up and spin-down electrons on the QD, the height of the central peak is different from that if the MBS is coupled to only one spin component electrons. The ET and AR conductances, which are mediated by the dot–MBS hybridization, strongly depend on the angle between the left and right magnetic moments in the leads. Interaction between the QD and the MBSs will result in sign change of the angle-dependent tunnel magnetoresistance. This is very different from the case when the QD is coupled to regular fermonic mode, and can be used for detecting the existence of MBSs, a current challenge in condensed matter physics under extensive investigations. Full article

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

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12 pages, 2033 KiB

Open AccessArticle

Potentiometric Studies on Ion-Transport Selectivity in Charged Gold Nanotubes

by Thomas T. Volta, Stevie N. Walters and Charles R. Martin

Nanomaterials 2024, 14(14), 1209; https://doi.org/10.3390/nano14141209 - 16 Jul 2024

Viewed by 1180

Abstract

Under ideal conditions, nanotubes with a fixed negative tube-wall charge will reject anions and transport-only cations. Because many proposed nanofluidic devices are optimized in this ideally cation-permselective state, it is important to know the experimental conditions that produce ideal responses. A parameter called [...] Read more.

Under ideal conditions, nanotubes with a fixed negative tube-wall charge will reject anions and transport-only cations. Because many proposed nanofluidic devices are optimized in this ideally cation-permselective state, it is important to know the experimental conditions that produce ideal responses. A parameter called C_crit, the highest salt concentration in a contacting solution that still produces ideal cation permselectivity, is of particular importance. Pioneering potentiometric studies on gold nanotubes were interpreted using an electrostatic model that states that C_crit should occur when the Debye length in the contacting salt solution becomes equivalent to the tube radius. Since this “double-layer overlap model” (DLOM), treats all same-charge ions as identical point charges, it predicts that all same-charged cations should produce the same C_crit. However, the effect of cation on C_crit in gold nanotubes was never investigated. This knowledge gap has become important because recent studies with a polymeric cation-permselective nanopore membrane showed that DLOM failed for every cation studied. To resolve this issue, we conducted potentiometric studies on the effect of salt cation on C_crit for a 10 nm diameter gold nanotube membrane. C_crit for all cations studied were, within experimental error, the same and identical, with values predicted by DLOM. The reason DLOM prevailed for the gold nanotubes but failed for the polymeric nanopores stems from the chemical difference between the fixed negative charges of these two membranes. Full article

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11 pages, 3434 KiB

Open AccessArticle

Helical Hybrid Nanostructure Based on Chiral M13 Bacteriophage via Evaporation-Induced Three-Dimensional Process

by Thanh Mien Nguyen, Sung-Jo Kim, Dae Gon Ryu, Jae Hun Chung, Si-Hak Lee, Sun-Hwi Hwang, Cheol Woong Choi and Jin-Woo Oh

Nanomaterials 2024, 14(14), 1208; https://doi.org/10.3390/nano14141208 - 16 Jul 2024

Viewed by 1687

Abstract

The use of naturally sourced organic materials with chirality, such as the M13 bacteriophage, holds intriguing implications, especially in the field of nanotechnology. The chirality properties of bacteriophages have been demonstrated through numerous studies, particularly in the analysis of liquid crystal phase transitions, [...] Read more.

The use of naturally sourced organic materials with chirality, such as the M13 bacteriophage, holds intriguing implications, especially in the field of nanotechnology. The chirality properties of bacteriophages have been demonstrated through numerous studies, particularly in the analysis of liquid crystal phase transitions, developing specific applications. However, exploring the utilization of the M13 bacteriophage as a template for creating chiral nanostructures for optics and sensor applications comes with significant challenges. In this study, the chirality of the M13 bacteriophage was leveraged as a valuable tool for generating helical hybrid structures by combining it with nanoparticles through an evaporation-induced three-dimensional (3D) printing process. Utilizing on the self-assembly property of the M13 bacteriophage, metal nanoparticles were organized into a helical chain under the influence of the M13 bacteriophage at the meniscus interface. External parameters, including nanoparticle shape, the ratio between the bacteriophage and nanoparticles, and pulling speed, were demonstrated as crucial factors affecting the fabrication of helical nanostructures. This study aimed to explore the potential of chiral nanostructure fabrication by utilizing the chirality of the M13 bacteriophage and manipulating external parameters to control the properties of the resulting hybrid structures. Full article

(This article belongs to the Special Issue Advanced Bioinspired Nanomaterials with Superwettability)

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17 pages, 9936 KiB

Open AccessArticle

Size-Dependent Thresholds in CuO Nanowires: Investigation of Growth from Microstructured Thin Films for Gas Sensing

by Christian Maier, Verena Leitgeb, Larissa Egger and Anton Köck

Nanomaterials 2024, 14(14), 1207; https://doi.org/10.3390/nano14141207 - 16 Jul 2024

Cited by 6 | Viewed by 1315

Abstract

An experimental characterization of cupric oxide nanowire (CuO NW) growth from thermally oxidized, microstructured Cu thin films is performed. We have systematically studied the influence of the thickness and dimension of Cu layers on the synthesis of CuO NW. The objective was to [...] Read more.

An experimental characterization of cupric oxide nanowire (CuO NW) growth from thermally oxidized, microstructured Cu thin films is performed. We have systematically studied the influence of the thickness and dimension of Cu layers on the synthesis of CuO NW. The objective was to determine the optimum Cu geometries for increased CuO NWs growth to bridge the gap between adjacent Cu structures directly on the chip for gas sensing applications. Thresholds for CuO-NW growth regarding film thickness and lateral dimensions are identified based on SEM images. For a film thickness of 560 nm, NWs with lengths > 500 nm start to grow from the edges of Cu structures with an area ≥ 4 µm². NWs growing from the upper surface were observed for an area ≥ 16 µm². NW growth between adjacent thermally oxidized thin films was analyzed. The study provides information on the most relevant parameters of CuO NWs growth, which is mandatory for integrating CuO NWs as gas sensor components directly on microchips. Based on this result, the gap size of the structure was varied to find the optimum value of 3 µm. Full article

(This article belongs to the Special Issue Functional Nanocomposites: From Strategic Design to Applications)

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14 pages, 4600 KiB

Open AccessArticle

Simulation and Experimental Investigation of the Effect of Pore Shape on Heat Transfer Behavior of Phase Change Materials in Porous Metal Structures

by Chao Chang, Bo Li, Baocai Fu, Xu Yang, Tianyi Lou and Yulong Ji

Nanomaterials 2024, 14(14), 1206; https://doi.org/10.3390/nano14141206 - 16 Jul 2024

Viewed by 1058

Abstract

With the gradual increase in energy demand in global industrialization, the energy crisis has become an urgent problem. Due to high heat storage density, small volume change, and nearly constant transition temperature, phase change materials (PCMs) provide a promising method to store thermal [...] Read more.

With the gradual increase in energy demand in global industrialization, the energy crisis has become an urgent problem. Due to high heat storage density, small volume change, and nearly constant transition temperature, phase change materials (PCMs) provide a promising method to store thermal energy. In this work, we designed and fabricated three kinds of porous metal structures with hexagonal, rectangular, and circular pores and explored the phase change process of PCMs within them. A two-dimensional numerical model was established to investigate the heat transfer process of PCMs within different shapes of porous metal structures and analyze the influence of heat source location on the thermal performance of the thermal storage units. Visualization experiments were also carried out to reveal the melting process of PCMs within different porous metal structures by a digital camera. The results show that paraffin in a porous metal structure with hexagonal pores has the fastest melting rate, while that in a porous metal structure with circular pores has the slowest melting rate. Under the bottom heating mode, the melting time of the paraffin in porous metal structures with hexagonal pores is shortened by 18.6% compared to that in porous metal structures with circular pores. Under the left heating mode, the corresponding melting time is shortened by 16.7%. These findings in this work will offer an effective method to design and optimize the structure of porous metal and improve the thermal properties of PCMs. Full article

(This article belongs to the Special Issue Advances in Nano-Enhanced Thermal Functional Materials)

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