Nanomaterials

Nanomaterials

Published by MDPI

Online ISSN: 2079-4991

Disciplines: Materials Science, Multidisciplinary; Nanoscience & Nanotechnology

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(a) Crystal structure of bulk WSe2; (b) EDX characterization of bulk WSe2 crystal; (c) SAED characterization of microscopic WSe2 flake. Yellow arrows with indices denote reciprocal lattice vectors. (d) Schematic view of PLAL.
(a) Typical TEM image of the synthesized WSe2 NPs; (b) SEM photographs at inclined view revealing the spherical shape of NPs; (c) EDX spectrum from the synthesized NPs showing the elemental composition of WSe2 NPs. Copper signal is from the TEM grid. (d) SAED on synthesized WSe2 NPs with the most visible dhkl lines; (e) TEM image of a single nanoparticle showing its polycrystalline structure; (f) Raman spectra of bulk WSe2 crystal and synthesized NPs, separated by centrifugation at different rotation speeds. Excitation wavelength was 532 nm.
Differential centrifugation of WSe2 NPs. (a) Size distributions and average sizes of nanoparticles, obtained at different rotational speeds and measured by counting on TEM image (violet curve) and by dynamic light scattering spectroscopy (blue curve). (b) Measured extinction spectra for WSe2 colloids with various NP average diameter 〈D〉. (c) Calculated extinction spectra (total and contributions from electric and magnetic dipole channels) for a spherical WSe2 NP with a homogenized isotropic dielectric function, obtained from bulk WSe2 crystal data in (d) as εav=2εo/3+εe/3. (d) Optical constants of bulk WSe2; (e) Image of bottles with centrifugated WSe2 colloidal solutions in DI water.
Photoheating response of WSe2 NPs. (a) Temperature-dependent Raman spectra at 532 nm excitation of WSe2 NPs. (b) Laser-induced heating (532 nm irradiation) and E2g1 peak position shift of WSe2 NPs and bulk crystal. (c) Dynamics of laser-induced heating of colloids by laser diode 830 nm, 1 W. (d) Measured extinction spectra of WSe2 and Si water colloids, normalized at photoheating wavelength 830 nm. (e) Time-resolved photoheating of WSe2 and Si colloids irradiated by the 830 nm laser; both heating (laser is on) and cooling (laser is off) steps of the experiment are shown. (f) Optical extinction and absorption curves of WSe2 colloid from (d), prepared for the photoheating experiment with a tunable laser source. Absorption curve is calculated using photothermal conversion coefficients, indicated with black arrows and obtained experimentally from the photoheating experiments at different laser wavelengths (see the main text).
SERS spectra of (a) rhodamine 6G (R6G) and (b) crystal violet (CV) in the concentration range 10−4–10−8 M adsorbed on WSe2 NPs substrate; (c) R6G and (d) CV in the concentration range 10−4–10−8 M adsorbed on MoS2 NPs substrate. Peaks marked by asterisks (*) correspond to MoS2.
Tungsten Diselenide Nanoparticles Produced via Femtosecond Ablation for SERS and Theranostics Applications

December 2024

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153 Reads

Andrei Ushkov

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Dmitriy Dyubo

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Aims and scope


Nanomaterials (ISSN 2079-4991) is an international, peer-reviewed, interdisciplinary scholarly open access journal, published semimonthly online by MDPI. It publishes reviews, regular research papers, communications, and short notes that are relevant to any field of study that involves nanomaterials, with respect to their science and application. Thus, theoretical and experimental articles will be accepted, along with articles that deal with the synthesis and use of nanomaterials. Articles that synthesize information from multiple fields, and which place discoveries within a broader context, will be preferred. There is no restriction on the maximum length of the papers. Our aim is to encourage scientists to publish their experimental and theoretical research in as much detail as possible. Full experimental or methodical details, or both, must be provided for research articles. Computed data or files regarding the full details of the experimental procedure, if unable to be published in a normal way, can be deposited as supplementary material.

Nanomaterials is dedicated to a high scientific standard. All manuscripts undergo a rigorous reviewing process and decisions are based on the recommendations of independent reviewers.

Nanomaterials are materials with typical size features in the lower nanometer size range and characteristic mesoscopic properties; for example quantum size effects. These properties make them attractive objects of fundamental research and potential new applications. The scope of Nanomaterials covers the preparation, characterization and application of all nanomaterials.

Recent articles


Intraperitoneal (I.P.) and Intrascrotal (I.S.) Injection Studies.
Cont.
A Review of the Carcinogenic Potential of Thick Rigid and Thin Flexible Multi-Walled Carbon Nanotubes in the Lung
  • Article
  • Full-text available

January 2025

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6 Reads

Omnia Hosny

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Hiroyuki Tsuda

Citation: Ahmed, O.H.M.; Naiki-Ito, A.; Takahashi, S.; Alexander, W.T.; Alexander, D.B.; Tsuda, H. A Review of the Carcinogenic Potential of Thick Rigid and Thin Flexible Multi-Walled Carbon Nanotubes in the Lung. Nanomaterials 2025, 15, 168. Abstract: The carcinogenic potential of MWCNTs is not well defined. Currently, IARC has classified MWCNT-7 as a Group 2 B material, possibly carcinogenic to humans, and all other MWCNTs as Group 3 materials, inadequate evidence in experimental animals for their carcinogenicity and not classifiable as to their carcinogenicity to humans. In this review we discuss studies that investigated the lung toxicity of well characterized MWCNTs in mice and rats. Intraperitoneal and intrascrotal injection studies identified rigid MWCNTs as hazardous materials. The assessment of lung toxicity of MWCNTs in short and medium term instillation and inhalation studies were not conclusive; therefore, these studies do not confirm the hazard of MWCNTs. However, two-year carcinogenicity studies indicate that MWCNT-7 and other MWCNTs, both thick rigid MWCNTs and thin flexible MWCNTs, are carcinogenic in test animals. Therefore, the carcinogenicity of MWCNTs in experimental animals should be reassessed.


Iota-Carrageenan/Chitosan Nanoparticles via Coacervation: Achieving Stability for Tiny Particles

Rosecler S. Klein

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Débora A. de Almeida

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Ariel C. de Oliveira

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Alessandro F. Martins

This study investigated the influence of parameters such as pH condition, polyelectrolyte concentration, polymer ratio, and order of addition of the commercial polyelectrolytes chitosan and iota-carrageenan (ι-carrageenan) on the formation of polymeric nanoparticles in suspension (coacervates). A preliminary purification step of the polymers was essential for obtaining stable nanoparticles with small sizes as impurities, particularly metal ions that interfere with complexation, are removed by dialysis. Microparticles (13.5 μm in dry diameter) are obtained when aliquots of chitosan solution are poured into the ι-carrageenan solution. In general, an excess of chitosan results in the formation of agglomerated particles. The addition of an aliquot of ι-carrageenan solution (30 mL at 0.6 mg/mL and pH 4.0) to the chitosan solution (6.0 mL at 0.3 mg/mL and pH 4.0) leads to dispersed nanoparticles with a hydrodynamic radius of 278 ± 5 nm, a zeta potential of −31 ± 3 mV, and an average dry diameter of 45 ± 11 nm. The hydrodynamic radius increases as the pH rises. The partial deprotonation of ι-carrageenan chains enhances the interaction with water molecules, causing the particles to swell. These findings contribute to the fundamental understanding of polyelectrolyte complexation processes in aqueous suspension and provide insights for developing stable nanomaterials for potential practical applications.


Figure 2. Water contact angle (WCA) images: (A) plain Co; (B) BA on Co; (C) TBA on Co; and (D)
Figure 2. Water contact angle (WCA) images: (A) plain Co; (B) BA on Co; (C) TBA on Co; and (D) BTBA on Co. Nanomaterials 2025, 15, x FOR PEER REVIEW 7 of 15
Figure 3. Comparison of XPS spectra of bare and SAM treated on cobalt (A) BA on cobalt (B) TBA on cobalt, and (C) BTBA on cobalt. AFM-IR spectra (D-F) represent the average infrared spectra for BA, TBA, and BTBA SAMs on cobalt, respectively, in the 1500-1700 cm −1 range. The broad peaks centered around ~1580 cm −1 corresponds to the asymmetric stretching of the carboxylate headgroup, confirming monolayer formation.
Investigating Benzoic Acid Derivatives as Potential Atomic Layer Deposition Inhibitors Using Nanoscale Infrared Spectroscopy

January 2025

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8 Reads

Saumya Satyarthy

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Mark Cheng

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Ayanjeet Ghosh

Area-selective atomic layer deposition (AS-ALD) is a technique utilized for the fabrication of patterned thin films in the semiconductor industry due to its capability to produce uniform and conformal structures with control over thickness at the atomic scale level. In AS-ALD, surfaces are functionalized such that only specific locations exhibit ALD growth, thus leading to spatial selectivity. Self-assembled monolayers (SAMs) are commonly used as ALD inhibiting agents for AS-ALD. However, the choice of organic molecules as viable options for AS-ALD remains limited and the precise effects of ALD nucleation and exposure to ALD conditions on the structure of SAMs is yet to be fully understood. In this work, we investigate the potential of small molecule carboxylates as ALD inhibitors, namely benzoic acid and two of its derivatives, 4-trifluoromethyl benzoic acid (TBA), and 3,5-Bis (trifluoromethyl)benzoic acid (BTBA) and demonstrate that monolayers of all three molecules are viable options for applications in ALD blocking. We find that the fluorinated SAMs are better ALD inhibitors; however, this property arises not from the hydrophobicity but the coordination chemistry of the SAM. Using nanoscale infrared spectroscopy, we probe the buried monolayer interface to demonstrate that the distribution of carboxylate coordination states and their evolution is correlated with ALD growth, highlighting the importance of the interfacial chemistry in optimizing and assessing ALD inhibitors.


Unravelling the Cu and Ce Effects in MnO2-Based Catalysts for Low-Temperature CO Oxidation

January 2025

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2 Reads

Egor D. Blinov

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Ekaterina V. Kulchakovskaya

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Nikolai A. Sokovikov

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Olga V. Vodyankina

Cu-containing and Ce-modified OMS-2 catalysts were prepared at various calcination temperatures using the hydrothermal method and tested for low-temperature CO oxidation. The structure, chemical compositions, and physical–chemical properties of the catalysts were characterized using XRD, N2 physisorption, XRF, Raman spectroscopy, SEM, high-resolution TEM with EDX, TPR-H2, and XPS. The incorporation of Cu into the Ce-OMS-2 sample facilitated the transformation of pyrolusite into cryptomelane, as confirmed by Raman spectroscopy data. In the light-off mode, the Cu/Ce-OMS-2-300 and Cu/OMS-2 samples exhibited higher activity in low-temperature CO oxidation (T90 = 115 and 121 °C, respectively) compared to sample Cu/Ce-OMS-2-450. After a long-run stability test, the Cu/Ce-OMS-X samples demonstrated excellent performance: the T80 increased by 16% and 7% for the samples calcined at 300 °C and 450 °C, respectively, while the T80 for the Cu/OMS-2 increased by 40%. The Cu/OMS-2 and Cu/Ce-OMS-2-300 samples were found to have an increased content of nanodispersed copper sites on their surfaces. These copper sites contributed to the formation of the Cu2+-O-Mn4+ interface, which is responsible for the CO oxidation. The presence of Ce3+ in the catalyst was found to increase its stability in the presence of water vapor due to the higher reoxidation ability in comparison with Ce-free sample Cu/OMS-2.


A comparison of laccase-like catalytic kinetic parameters of Cu-BL with other free laccase and laccase simulators reported before.
A Colorimetric and Fluorescent Dual-Mode Sensor Based on a Smartphone-Assisted Laccase-like Nanoenzyme for the Detection of Tetracycline Antibiotics

January 2025

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3 Reads

Hongyue Chen

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Zining Wang

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Qi Shi

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Shuang Liu

A copper-based nanoenzyme (Cu-BL) co-modified by L-L-lysine and 2-2-amino terephthalic acid has laccase-like activity and fluorescence characteristics. Based on this, a colorimetric and fluorescent dual-mode sensor was developed to visually and quantitatively detect tetracycline antibiotics (TCs), including tetracycline (TC), chlortetracycline (CTC), and oxytetracycline (OTC). In the colorimetric detection system, TCs can inhibit the generation of singlet oxygen (1O2) and weaken the ability of 2,4-dichlorophenol (2,4-DP) to be oxidized into pink-colored quinone substances. The linear ranges are 0.5–80 μM, 1–80 μM, and 0.25–80 μM, and the detection limits are 0.27 μM, 0.22 μM, and 0.26μM, respectively. In addition, due to the inner filter effect, tetracycline antibiotics can interact with Cu-BL, and with the increase in tetracycline antibiotic concentration, the fluorescence intensity will decrease. In addition, the smartphone sensing platform is combined with the colorimetric signal for the rapid and visual quantitative detection of tetracycline antibiotics. Generally speaking, the colorimetric/fluorescence dual-mode sensor demonstrates good stability, high specificity, and strong anti-interference capabilities, highlighting its practical application potential. This work is expected to offer novel insights for the development of multifunctional nanoenzymes and the integration of a multi-mode sensing platform.


Engineering Nonvolatile Polarization in 2D α-In2Se3/α-Ga2Se3 Ferroelectric Junctions

January 2025

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8 Reads

Peipei Li

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Delin Kong

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Jin Yang

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[...]

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Mingzeng Peng

The advent of two-dimensional (2D) ferroelectrics offers a new paradigm for device miniaturization and multifunctionality. Recently, 2D α-In2Se3 and related III–VI compound ferroelectrics manifest room-temperature ferroelectricity and exhibit reversible spontaneous polarization even at the monolayer limit. Here, we employ first-principles calculations to investigate group-III selenide van der Waals (vdW) heterojunctions built up by 2D α-In2Se3 and α-Ga2Se3 ferroelectric (FE) semiconductors, including structural stability, electrostatic potential, interfacial charge transfer, and electronic band structures. When the FE polarization directions of α-In2Se3 and α-Ga2Se3 are parallel, both the α-In2Se3/α-Ga2Se3 P↑↑ (UU) and α-In2Se3/α-Ga2Se3 P↓↓ (NN) configurations possess strong built-in electric fields and hence induce electron–hole separation, resulting in carrier depletion at the α-In2Se3/α-Ga2Se3 heterointerfaces. Conversely, when they are antiparallel, the α-In2Se3/α-Ga2Se3 P↓↑ (NU) and α-In2Se3/α-Ga2Se3 P↑↓ (UN) configurations demonstrate the switchable electron and hole accumulation at the 2D ferroelectric interfaces, respectively. The nonvolatile characteristic of ferroelectric polarization presents an innovative approach to achieving tunable n-type and p-type conductive channels for ferroelectric field-effect transistors (FeFETs). In addition, in-plane biaxial strain modulation has successfully modulated the band alignments of the α-In2Se3/α-Ga2Se3 ferroelectric heterostructures, inducing a type III–II–III transition in UU and NN, and a type I–II–I transition in UN and NU, respectively. Our findings highlight the great potential of 2D group-III selenides and ferroelectric vdW heterostructures to harness nonvolatile spontaneous polarization for next-generation electronics, nonvolatile optoelectronic memories, sensors, and neuromorphic computing.


Spectroscopic Ellipsometry and Correlated Studies of AlGaN-GaN HEMTs Prepared by MOCVD

January 2025

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1 Read

Yanlian Yang

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Yao Liu

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Yaoze Li

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[...]

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Wenhong Sun

A series of AlGaN/GaN high-electron-mobility transistor (HEMT) structures, with an AlN thin buffer, GaN thick layer and Al0.25Ga0.75N layer (13–104 nm thick), is prepared by metal–organic chemical vapor deposition and investigated via multiple techniques. Spectroscopic ellipsometry (SE) and temperature-dependent measurements and penetrative analyses have achieved significant understanding of these HEMT structures. Bandgaps of AlGaN and GaN are acquired via SE-deduced relationships of refraction index n and extinguish coefficient k vs. wavelength λ in a simple but straightforward way. The optical constants of n and k, and the energy gap Eg of AlGaN layers, are found slightly altered with the variation in AlGaN layer thickness. The Urbach energy EU at the AlGaN and GaN layers are deduced. High-resolution X-ray diffraction and calculations determined the extremely low screw dislocation density of 1.6 × 108 cm−2. The top AlGaN layer exhibits a tensile stress influenced by the under beneath GaN and its crystalline quality is improved with the increase in thickness. Comparative photoluminescence (PL) experiments using 266 nm and 325 nm two excitations reveal and confirm the 2DEG within the AlGaN-GaN HEMT structures. DUV (266 nm) excitation Raman scattering and calculations acquired carrier concentrations in compatible AlGaN and GaN layers.


Figure 6. Map of strain and doping variation with respect to pristine samples (A) and PL spectra (B,C) of 1L-MoS2 flakes exfoliated on two different Au substrates of thickness equal to either 10 Figure 6. Map of strain and doping variation with respect to pristine samples (A) and PL spectra (B,C) of 1L-MoS 2 flakes exfoliated on two different Au substrates of thickness equal to either 10 nm (B) or 2 nm (C) before and after a thermal treatment. After the treatments, the samples were either allowed to cool down naturally or by exposing them to the ambient air prior to characterization, as indicated by the legend. The strain-doping map in panel (A) displays points calculated across the surface of the studied flakes as partially transparent, while their average is shown as a solid color. The data points in panels (B,C) represent the experimental data, and the continuous lines represent the fits with Gaussian bands.
Mild Temperature Thermal Treatments of Gold-Exfoliated Monolayer MoS2

January 2025

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4 Reads

Monolayer molybdenum disulfide is considered an extremely promising two-dimensional material for innovative electronics due to its direct bandgap and high charge-carrier mobility. The optical and electronic properties of monolayer MoS2 can, however, be strongly influenced by the specific synthesis route, posing challenges for industrial-scale production. In this study, we investigated the effects of moderate temperature thermal treatments under a controlled O2 atmosphere on the properties of monolayer MoS2 flakes. We found that the treatments can effectively tune the doping level of monolayer MoS2. Notably, 225 °C was identified as the optimal temperature for enhancing its optical emission properties. Our findings suggest that the removal of sulfur vacancies and impurities underlies these effects, demonstrating a promising approach for tuning the properties of monolayer MoS2 at mild temperatures.


Synthesis and Characterization of a Pla Scaffold with Pseudoboehmite and Graphene Oxide Nanofillers Added

January 2025

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1 Read

Rafael Vieira Maidana

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Antônio Hortêncio Munhoz

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Filipe Figueiredo Ramos

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Fábio Jesus Moreira de Almeida

In cases of severe injuries or burns, skin grafts (scaffolds) are often required as skin substitutes. In order not to harm the patient or the donor, biodegradable and biocompatible materials are used, which validates the search for heterografts such as poly (L-lactic acid)—PLA. However, natural polymers applied to the skin suffer great degradation in environments with large amounts of carbon and water or via binders with considerable resistivity, which implies little durability due to their low ductility. For the proposal, this work investigates PLA-based scaffolds modified with a mixture of pseudoboehmite (PB) and graphene oxide (GO), produced via the sol–gel route. The nanomaterials are incorporated into the polymer at different loadings, seeking to improve mechanical and thermal properties. Analyses via SEM, EDS, and XRD confirm the presence and distribution of these fillers. Tensile and flexural tests indicate that adding the filler can increase stress resistance, prevent deformations before failure, and increase toughness when compared to pure PLA.



Synthesis of Silver Nanoparticle/Multi-Walled Carbon Nanotube Composites and Their Application in Electronic Pastes

January 2025

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5 Reads

Zizhen Wang

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Ming Zhou

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Baoying Lu

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[...]

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Hui He

Silver nanoparticle-coated multi-walled carbon nanotube (Ag/MWNT) composites were prepared using a chemical plating method that effectively controls the overgrowth of silver nanoparticles, ensuring uniform particle size. Functionalization of the carbon nanotube surface with numerous functional groups facilitates the binding of silver ions to multi-walled carbon nanotubes (MWNTs). This process results in Ag/MWNT composites with a uniform distribution of silver nanoparticles, prepared through reduction via the silver mirror reaction. The impact of dispersants and reducing agents on the silver coating of carbon nanotubes was studied. The results revealed the formation of negatively charged functional groups (-COOH, -OH, -C=O, and -NH2) on the nanotube surface. These groups acted as nucleation sites for the formation of silver nanoparticles. These groups acted as nucleation sites for the formation of silver nanoparticles. Simultaneously, the Ag/MWNT composites demonstrated effective dispersion within the matrix, improving the electrical conductivity of the electronic paste by 32.1% and 33.1%. This improvement was attributed to the forming of a conductive pathway within the silver-modified composite. Ag/MWNT composites within the paste system improved interfacial contact between fillers and the matrix, enhancing their potential applications in thermal interface materials.


Figure 2. (a) Clean substrate (Si 2p core level) and heterojunction (C 1s core level) energy shifts upon laser excitation; (b) SPV dynamics after CuPc deposition at different film thicknesses (brown curves). The SPV relaxation curve of the clean substrate (green curves) is shown for comparison to highlight the enhancement of the SPV signal after CuPc deposition; (c) comparison between the clean substrate (Si 2p core level) and heterojunction (C 1s core level) SPV relaxation curves at longer time delays and the relative fits obtained by thermionic modeling.
Relevant parameters obtained by fitting the C 1s core level as a function of the film thick- ness. For more details on the fitting procedure, refer to the Supplementary Materials (Section S1).
Interfacial Charge Transfer Enhances Transient Surface Photovoltage in Hybrid Heterojunctions

January 2025

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2 Reads

Cristian Soncini

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Roberto Costantini

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Martina Dell’Angela

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Maddalena Pedio

The interfacial energy level alignment in the copper phthalocyanine/SiO2/p-Si(100) heterojunction has been studied in dark conditions and under illumination. The element-sensitivity of the time-resolved X-ray photoemission provides a real-time picture of the photoexcited carrier dynamics at the interface and within the film, enabling one to distinguish between substrate and molecular contributions. We observe a molecule-to-substrate charge transfer under photoexcitation, which is directly related to the transient modification of the band bending in the substrate due to the surface photovoltage effect. Our results show that charge generation in the heterojunction is driven by the molecular layer in contact with the substrate. The different molecular orientation at the interface creates a new channel for charge injection in the substrate under photoexcitation.


A Novel Nanomaterial-Based Approach for the Cryopreservation of Individual Sperm Cells Using Addressable Nanoliter Containers

January 2025

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3 Reads

Bat-Sheva Galmidi

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Yana Shafran

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Chen Shimon

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[...]

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Dror Fixler

The research and development of a matrix of Addressable Nanoliter Containers (ANLCs) is the focus of this work. ANLCs introduce a novel approach for cryopreserving single sperm cells. A significant increase in sperm cell mortality was observed after cryopreserving nanoliter-scale cell suspensions, attributed to the diffusion of water from the aqueous droplets into the surrounding oil phase. This process elevated the salt concentration within the droplets. A practical solution was devised by saturating the oil with water, significantly reducing the concentration gradient and, consequently, the diffusion. For ANLCs smaller than a few nanoliters, locating individual sperm cells within the containers became highly feasible. Using saturated oil, the survival rate reached 100%. Optical simulations were conducted to evaluate the impact of ANLCs on light scattering, enabling the selection of designs with minimal scattering. The simulations conclusively demonstrated that a cylindrical container with a flat bottom produced the least light scattering. This device was tested under clinical conditions in an in vitro fertilization (IVF) laboratory, revealing its strong potential as a practical tool for housing individual sperm cells. It enables characterization using interferometric indicators and facilitates the selection of sperm cells for IVF.


Fabrication and Optimization of Additively Manufactured Hybrid Nanogenerators for Wearable Devices

January 2025

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2 Reads

Khaled A. Eltoukhy

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Mohamed Fawzy Aly

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Marc Sarquella

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Mohamed Serry

This paper aims to fabricate a hybrid piezoelectric/triboelectric nanogenerator via fusion deposition modeling as a proof of concept in the wearable device industry. The nanogenerator structure consists of a TPU/ZnO nanocomposite and an Ecoflex layer. The nanocomposite layer is fabricated using two different weight percentages (15 wt% and 20 wt%) and poled piezoelectric sheets, generating 2.63 V to 3.46 V. Variations regarding the nanogenerator’s physical parameters were implemented to examine the effect on nanogenerator performance under different frequencies. The hybrid nanogenerator enabled energy harvesting for wearable devices. It was strapped on the side of the wrist to generate a potential difference with the motion of the wrist, creating a contact separation piezoelectric/triboelectric nanogenerator. Furthermore, a piezoelectric sheet was placed at the bottom of the wrist to harvest energy. The hybrid nanogenerator provided a maximum triboelectric response of 5.75 V and a maximum piezoelectric response of 2.85 V during wrist motion. The piezoelectric nanogenerator placed at the bottom of the wrist generated up to 4.78 V per wrist motion.


Growth parameters of the LDE GaAs QDs. The superscript indicates the layer thickness equivalent etching quantity, the etching material, and the deposition method. The subscript contains the fill amount, the filling material, and also the deposition method for filling nanoholes. The five-digit number is the internal sample number.
Wavelength range of GaAs QD samples with gradient-deposited filling amount. ∆λ corre- sponds to the span of the peak wavelength.
Growth parameters of the LDE InAs QDs.
Shutter-Synchronized Molecular Beam Epitaxy for Wafer-Scale Homogeneous GaAs and Telecom Wavelength Quantum Emitter Growth

Elias Kersting

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Hans-Georg Babin

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Nikolai Spitzer

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[...]

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Arne Ludwig

Quantum dot (QD)-based single-photon emitter devices today are based on self-assembled random position nucleated QDs emitting at random wavelengths. Deterministic QD growth in position and emitter wavelength would be highly appreciated for industry-scale high-yield device manufacturing from wafers. Local droplet etching during molecular beam epitaxy is an all in situ method that allows excellent density control and predetermines the nucleation site of quantum dots. This method can produce strain-free GaAs QDs with excellent photonic and spin properties. Here, we focus on the emitter wavelength homogeneity. By wafer rotation-synchronized shutter opening time and adapted growth parameters, we grow QDs with a narrow peak emission wavelength homogeneity with no more than 1.2 nm shifts on a 45 mm diameter area and a narrow inhomogeneous ensemble broadening of only 2 nm at 4 K. The emission wavelength of these strain-free GaAs QDs is <800 nm, attractive for quantum optics experiments and quantum memory applications. We can use a similar random local droplet nucleation, nanohole drilling, and now, InAs infilling to produce QDs emitting in the telecommunication optical fiber transparency window around 1.3 µm, the so-called O-band. For this approach, we demonstrate good wavelength homogeneity and excellent density homogeneity beyond the possibilities of standard Stranski–Krastanov self-assembly. We discuss our methodology, structural and optical properties, and limitations set by our current setup capabilities.


Surface Properties of Coatings Based on Iron Amino-Functionalized Oxides Deposited on DH 36 Steel Plates for Shipbuilding

January 2025

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10 Reads

Maria Luisa Testa

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Carla Calabrese

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Valeria La Parola

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Leonarda Francesca Liotta

The development of eco-friendly paint formulations is part of the transition process to more sustainable materials, which involves many industries such as offshore and shipbuilding, where the deterioration of steel in seawater is a key factor. This article aims to produce innovative coatings and test their protective action on DH 36 steel plates. SiO2 and TiO2 were modified with amino groups and iron sites to be used as filler for the design of ecological paint formulations The antimicrobial features of both NH2 groups and iron ionic species were combined with the chemical and mechanical stability of silica and titania, with silica-based powders showing increased efficacy. The surface properties of the resulting coatings were examined by determination of thickness, water wettability, roughness, and cross-cut adhesion tests (before and after a degradation test in seawater according to ASTM D870-97 standards). Preliminary tests of the microbiological activity of the iron amino functionalized materials were carried out to monitor, as proof of concept, the growth of some bacterial strains through measurements of optical density. The findings indicate that these coatings not only provide effective corrosion protection but are promising for enhancing the durability and environmental performance of steel surfaces exposed to marine environments.


Improving Electrochemical Performance of Ultrahigh-Loading Cathodes via the Addition of Multi-Walled Carbon Nanotubes

January 2025

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5 Reads

Chan Ju Choi

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Tae Heon Kim

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Hyun Woo Kim

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[...]

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Jinhyup Han

Achieving high energy densities in lithium-ion batteries requires advancements in electrode materials and design. This study investigated the incorporation of multi-walled carbon nanotubes (MWCNTs) with high commercial viability as conductive additives into two types of high-nickel cathode materials, LiNi0.8Co0.1Mn0.1O2 and LiNi0.92Co0.07Mn0.01O2. To ensure a uniform distribution within the electrodes, MWCNTs were uniformly dispersed in the solvent using ultrasonication, the most effective and straightforward dispersion method. This enhancement improved both electronic and ionic conductivity, facilitating the formation of an efficient electron transfer network. Unlike the cells using only carbon black, the electrodes with MWCNTs exhibited lower internal resistances, facilitating higher lithium-ion diffusion. The cells with MWCNTs exhibited a capacity retention of 89.5% over their cycle life, and the cells with 2 wt% MWCNTs exhibited a superior rate capability at a high current density of 1 C. This study highlights that incorporating well-dispersed MWCNTs effectively enhances the electrochemical performance of ultrahigh-loading cathodes in lithium-ion batteries (LIBs), providing valuable insights into electrode design.


Optimization of GaN Bent Waveguides in the Visible Spectrum for Reduced Insertion Loss

Wendi Li

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Huiping Yin

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Qian Fang

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[...]

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Xin Li

The development of GaN-based photonic integrated chips has attracted significant attention for visible light communication systems due to their direct bandgap and excellent optical properties across the visible spectrum. However, achieving compact and efficient light routing through bent waveguides remains challenging due to high insertion losses. This paper presents a comprehensive investigation of GaN bent waveguides optimization for visible light photonic integrated chips. Through systematic simulation analysis, we examined the effects of bending angle, process optimization approaches, and geometric parameters on insertion loss characteristics. The back-side thinning process demonstrates superior performance compared to front-side etching, reducing the insertion loss of 90° bends from 1.80 dB to 0.71 dB. Further optimization using silver reflection layers achieves an insertion loss of 0.57 dB. The optimized structure shows excellent performance in the blue-green spectral range (420–500 nm) with insertion losses below 0.9 dB, providing practical solutions for compact GaN photonic integrated chips in visible light communications.


Surface Functionalization of Nanocarriers with Anti-EGFR Ligands for Cancer Active Targeting

January 2025

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28 Reads

Alessandra Spada

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Sandrine Gerber-Lemaire

Active cancer targeting consists of the selective recognition of overexpressed biomarkers on cancer cell surfaces or within the tumor microenvironment, enabled by ligands conjugated to drug carriers. Nanoparticle (NP)-based systems are highly relevant for such an approach due to their large surface area which is amenable to a variety of chemical modifications. Over the past decades, several studies have debated the efficiency of passive targeting, highlighting active targeting as a more specific and selective approach. The choice of conjugation chemistry for attaching ligands to nanocarriers is critical to ensure a stable and robust system. Among the panel of cancer biomarkers, the epidermal growth factor receptor (EGFR) stands as one of the most frequently overexpressed receptors in different cancer types. The design and development of nanocarriers with surface-bound anti-EGFR ligands are vital for targeted therapy, relying on their facilitated capture by EGFR-overexpressing tumor cells and enabling receptor-mediated endocytosis to improve drug accumulation within the tumor microenvironment. In this review, we examine several examples of the most recent and significant anti-EGFR nanocarriers and explore the various conjugation strategies for NP functionalization with anti-EGFR biomolecules and small molecular ligands. In addition, we also describe some of the most common characterization techniques to confirm and analyze the conjugation patterns.


Figure 3. Test platform.
Figure 15. Simulation of the catalytic reaction of HCN.
Gas grouping situation.
Improved Selectivity of CeMnOx/Pt@SnO2 Laminated MOS Sensor for Hydrogen Cyanide Under Temperature Dynamic Modulation

January 2025

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2 Reads

Yadong Liu

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Yelin Qi

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Wen Yang

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[...]

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Ting Liang

Poor selectivity is one of the main bottlenecks restricting the development of metal oxide semiconductor (MOS) sensors. In this paper, using hydrogen cyanide (HCN) as the target gas, CeMnOx as the catalytic layer material and Pt@SnO2 as the gas-sensitive layer material, we have proposed a scheme to improve the selectivity of a catalytic layer/gas-sensitive layer-laminated MOS sensor under dynamic temperature modulation. We tested HCN and 12 kinds of battlefield environment simulation gases, and the results showed that the CeMnOx/Pt@SnO2 sensor, under the condition of temperature dynamic modulation (a constant temperature of 400 °C for the gas-sensitive layer and a variable temperature of room temperature to 400 °C for the catalytic layer; the heating and cooling rates were 200 °C/s, the highest temperature was maintained for 2 s, and the lowest temperature was maintained for 2 s), distinct characteristic peaks appeared on the G-T curves of the resistance response to HCN only. The quantification of the characteristic peaks was performed by peak heights, and the peak height of 5 mg/m3 HCN was obtained up to 0.104, while the peak heights of the other gases at the same concentration were up to 0.034. The peak height of HCN was significantly higher than that of other gases, which verified the high selectivity of the sensor for HCN. Meanwhile, the sensor also showed good sensitivity, response/recovery time, stability and anti-interference for HCN under the above temperature dynamic modulation. This work provides an important reference for the selectivity improvement of MOS sensors for HCN.


Comparison of β values and OL threshold among different materials.
A Cu(I)-Based MOF with Nonlinear Optical Properties and a Favorable Optical Limit Threshold

January 2025

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1 Read

The exploitation of high-performance third-order nonlinear optical (NLO) materials that have a favorable optical limit (OL) threshold is essential due to a rise in the application of ultra-intense lasers. In this study, a Cu-based MOF (denoted as Cu-bpy) was synthesized, and its third-order NLO and OL properties were investigated using the Z-scan technique with the nanosecond laser pulse excitation set at 532 nm. The Cu-bpy exhibits a typical rate of reverse saturable absorption (RSA) with a third-order nonlinear absorption coefficient of 100 cm GW−1 and a favorable OL threshold of 0.75 J cm−2 (at a concentration of 1.6 mg mL−1), which is lower than that of most NLO materials that have been reported on so far. In addition, a DFT calculation was performed and was in agreement with our experimental results. Furthermore, the mechanism of the third-order NLO properties was illustrated as one-photon absorption (1PA). These results investigate the relationship between the structure and the nonlinear optical properties of Cu-bpy, and provide an experimental and theoretical basis for its use in optical limiting applications.


Figure 1. (a) Crystal structure of AgGaS 2 and the [GaS 4 ], [AgS 4 ], and [Ag 2 Ga 2 S] tetrahedra. (b) S 2− displacement in chalcopyrite AgGaS 2 . (c) Energy levels of chalcopyrite AgGaS 2 exhibiting a nonzero direct energy gap at the Γ point. Reprinted with permission [12]. Copyright 2022, Wiley-VCH GmbH.
Figure 10. (a) Photographs and photoluminescence spectra of AgGaS2@ZnS nanocrystals with varied Ag/Ga or In/Ga ratios. Reproduced with permission [101]. Copyright 2020, American Chemical Society. (b) Photoluminescence spectra of AgGa0.6In0.4S2 and AgGa0.6In0.4S2@GaSx nanocrystals. Reproduced with permission [103]. Copyright 2018, American Chemical Society. (c) Absorption and photoluminescence spectra of AgGaS2 and AgGaS2@CdSeS nanocrystals, respectively. Reproduced with permission [105]. Copyright 2021, Elsevier Ltd.
NLO parameters of AgGaS 2 and typical AgGaS 2 -derived crystals with diamond-like structures.
A conclusion of wet-chemistry-synthesized AgGaS 2 and typical AgGaS 2 -derived nanocrystals.
AgGaS2 and Derivatives: Design, Synthesis, and Optical Properties

January 2025

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26 Reads

Silver gallium sulfide (AgGaS2) is a ternary A(I)B(III)X(VI)2-type semiconductor featuring a direct bandgap and high chemical stability. Structurally resembling diamond, AgGaS2 has gained considerable attention as a highly promising material for nonlinear optical applications such as second harmonic generation and optical parametric oscillation. In attempts to expand the research scope, on the one hand, AgGaS2-derived bulk materials with similar diamond-like configurations have been investigated for the enhancement of nonlinear optics performance, especially the improvement of laser-induced damage thresholds and/or nonlinear coefficients; on the other hand, nanoscale AgGaS2 and its derivatives have been synthesized with sizes as low as the exciton Bohr radius for the realization of potential applications in the fields of optoelectronics and lighting. This review article focuses on recent advancements and future opportunities in the design of both bulk and nanocrystalline AgGaS2 and its derivatives, covering structural, electronic, and chemical aspects. By delving into the properties of AgGaS2 in bulk and nanocrystalline states, this review aims to deepen the understanding of chalcopyrite materials and maximize their utilization in photon conversion and beyond.


Controllable Nano-Crystallization in Fluoroborosilicate Glass Ceramics for Broadband Visible Photoluminescence

January 2025

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8 Reads

A transparent fluoroborosilicate glass ceramic was designed for the controllable precipitation of fluoride nanocrystals and to greatly enhance the photoluminescence of active ions. Through the introduction of B2O3 into fluorosilicate glass, the melting temperature was decreased from 1400 to 1050 °C, and the abnormal crystallization in the fabrication process of fluorosilicate glass was avoided. More importantly, the controlled crystallizations of KZnF3 and KYb3F10 in fluoroborosilicate glass ceramics enhanced the emission of Mn2+ and Mn2+–Yb3+ dimers by 6.7 and 54 times, respectively. Moreover, the upconversion emission color of glass ceramic could be modulated from yellow to white and blue by adjusting the Yb3+ concentration. The well-designed glass ceramic is a novel and significant compound to simultaneously provide efficiently coordinated sites for transition metal and rare earth ions. More importantly, the design strategy opens a new way for engineering high-quality oxy-fluoride glass ceramics with properties of excellent stability, controllable nano-crystallization and high-efficiency photoluminescence.


A Low-Cost Electrochemical Cell Sensor Based on MWCNT-COOH/α-Fe2O3 for Toxicity Detection of Drinking Water Disinfection Byproducts

The disinfection of drinking water is essential for eliminating pathogens and preventing waterborne diseases. However, this process generates various disinfection byproducts (DBPs), which toxicological research indicates can have detrimental effects on living organisms. Moreover, the safety of these DBPs has not been sufficiently assessed, underscoring the need for a comprehensive evaluation of their toxic effects and associated health risks. Compared to traditional methods for studying the toxicity of pollutants, emerging electrochemical sensing technologies offer advantages such as simplicity, speed, and sensitivity, presenting an effective means for toxicity research on pollutants. However, challenges remain in this field, including the need to improve electrode sensitivity and reduce electrode costs. In this study, a pencil graphite electrode (PGE) was modified with carboxylated multi-walled carbon nanotubes (MWCNT-COOH) and nano-iron (III) oxide (α-Fe2O3) to fabricate a low-cost electrode with excellent electrocatalytic performance for cell-active substances. Subsequently, a novel cellular electrochemical sensor was constructed for the sensitive detection of the toxicity of three drinking water DBPs. The half inhibitory concentration (IC50) values of 2-chlorophenylacetonitrile (2-CPAN), 3-chlorophenylacetonitrile (3-CPAN), and 4-chlorophenylacetonitrile (4-CPAN) for HepG2 cells were 660.69, 831.76, and 812.83 µM, respectively. This study provides technical support and scientific evidence for the toxicity detection and safety assessment of emerging contaminants.


Anisotropic Elasticity, Spin–Orbit Coupling, and Topological Properties of ZrTe2 and NiTe2: A Comparative Study for Spintronic and Nanoscale Applications

January 2025

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8 Reads

The present work investigates the interfacial and atomic layer-dependent mechanical properties, SOC-entailing phonon band structure, and comprehensive electron-topological–elastic integration of ZrTe2 and NiTe2. The anisotropy of Young’s modulus, Poisson’s ratio, and shear modulus are analyzed using density functional theory with the TB-mBJ approximation. NiTe2 has higher mechanical property values and greater anisotropy than ZrTe2. Phonon dispersion analysis with SOC effects predicts the dynamic stability of both compounds. Thus, the current research unifies electronic band structure analysis, topological characterization, and elastic property calculation to reveal how these transition metal dichalcogenides are influenced by their structural, electronic, and mechanical properties. The results obtained in this work can be used in the further development of spintronic and nanoelectronic devices.


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4.4 (2023)

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8.5 (2023)

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33 days

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CHF 2,900

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