Characteristics Of Nanostructures Research Articles

Interplay Between Calcination Temperature and Alkaline Oxygen Evolution of Electrospun High-Entropy (Cr1/5Mn1/5Fe1/5Co1/5Ni1/5)3O4 Nanofibers.

Spinel-structured transition metal (TM) oxides have shown great potential as a sustainable alternative to platinum group metal-based electrocatalysts. Among them, high-entropy oxides (HEOs) with multiple TM-cation sites are suitable for engineering octahedral redox-active centers to enhance the catalyst reactivity. This paper reports on the preparation of electrospun (Cr1/5Mn1/5Fe1/5Co1/5Ni1/5)3O4 nanofibers (NFs) and their evaluation as electrocatalysts. Its main aim is to unveil the nanostructural features that play a key role in the alkaline oxygen evolution reaction. Differing calcination temperature (300-800°C) and duration (2 or 4h) leads to different morphology of the NFs, crystallinity of the oxide, density of defects, and cation distribution in the lattice, which reflect in different electrocatalytic behaviors. The best performance (overpotential and Tafel slope at 10mAcm-2: 325mV and 40mVdec-1, respectively) pertains to the NFs calcined at 400°C for 2h. To gain a deeper understanding of their electrocatalytic properties, the pristine NFs are investigated by a combination of analytical techniques. In particular, broadband electric spectroscopy reveals that the mobility of oxygen vacancies in the best electrocatalyst is associated to very fast local dielectric relaxations of metal coordination octahedral geometries and experimentally demonstrates the key role of O-deficient octahedra.

Study on the Effect of Coal Grain Size on the Morphology of Soot Generated During Combustion

This study performed an experimental exploration to analyze the influence of different grain sizes of coal on the nanostructure and morphological parameters of soot generated during combustion. Initially, primary and mature soot samples were gained from the combustion flames of two different grain sizes of coal (less than 150 μm, named sample #1, and 6–8 mm, named sample #2) by using thermophoresis sampling technology. Subsequently, the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to investigate and analyze the soot samples, with the aim of obtaining their morphological parameters and nanostructure characteristics. The TEM images indicate that the nascent soot produced during the flame formed by small-sized coal is relatively uniform, with individual particles 8–14 nm in size. The grain size of the nascent soot produced by large-sized coal is much larger, within a wide range of 50–350 nm. Additionally, the nanostructures of the nascent soot particles produced by samples #1 and #2 mainly consist of upright parallel crystal stripes. The crystal stripes of the soot particles formed by sample #1 have obvious microcrystalline structures, whereas only a small amount of microcrystalline structure is found at the edge of sample #2. Compared with sample #2, the soot formed during the combustion of sample #1 exhibits a denser crystalline structure. The SEM results indicate that the mature soot agglomerates formed in sample #2 are larger and more in quantity compared to sample #1. Furthermore, the mature soot agglomerates formed in sample #2 have a stronger coagulation performance and a more compact structure than that formed in sample #1.

Advanced neutron and [formula omitted]-ray shielding characteristics of nanostructured (90-x)Al-xGd2O3 composites reinforced by tungsten

This study introduces a composite material designed to offer exceptional mechanical strength and superior radiation shielding characteristics. By integrating tungsten into an aluminum Al-matrix with varying Gd2O3 content, we developed composites that meet the needful demands of mechanical durability and radiation protection in nuclear applications. The composites, synthesized via mechanical milling and sintering methods in planetary ball mills, have nominal compositions of (90-x)Al-xGd2O3 (x = 5, 10, 15 wt%) supplemented with 10 %W. The XRD analysis revealed phase structure transformations correlated with increased milling durations, while SEM-EDAX provided detailed morphological and elemental insights. TEM study confirmed a homogeneous distribution of nanocrystalline powders after 30 hours of milling while DSC thermographs indicated variations in thermal properties dependent on the Gd2O3 and tungsten content. The enhanced mechanical strength with higher concentrations of gadolinium and tungsten was characterized by Vickers microhardness tests. Neutron and γ-ray shielding properties were calculated using MCNP6.2 simulation code and Phy-X/PSD software. The thermal neutron macroscopic cross-section increased exponentially with higher Gd2O3 content, achieving values of 23.3 cm⁻¹ for 5 wt%, 48.4 cm⁻¹ for 10 wt%, and 73.7 cm⁻¹ for 15 wt%. Fast neutron removal cross-section also showed an increasing trend. The γ-ray linear attenuation coefficient decreased with increasing energy, but the Al-15Gd2O3-10 %W composite exhibited the highest LAC values, indicating superior γ-ray absorption capabilities. Correspondingly, the HVL values were lowest for the Al-15Gd2O3-10 %W composite. These findings demonstrate that Al-Gd2O3-W composites are promising materials for advanced industrial applications requiring robust mechanical properties and effective radiation shielding.

Novel Janus [formula omitted]-Au[formula omitted]XY (X/Y = S, Se, Te) monolayers with ultra-high carrier mobility: A first-principles study

In this paper, we theoretically propose a series of Janus α-Au4XY (X/Y = S, Se, Te; X ≠ Y) monolayers and investigate their structural stability, electronic features, and transport properties based on first-principle calculations. It is indicated that Janus α-Au4XY monolayers have a structurally stable and can be synthesized experimentally. Janus α-Au4XY monolayers exhibit a low Young’s modulus and their mechanical features are slightly anisotropic. At the ground state, Janus α-Au4XY monolayers possess semiconducting characteristics with very steep band dispersions near the conduction band minimum, which is expected to ultra-high electron mobility. The electronic features of Janus α-Au4XY are highly sensitive to the biaxial strains ɛxy, particularly the applied compressive biaxial strains. Interestingly, the transitions from the semiconductor to the metal phases are observed in all three configurations of α-Au4XY at ɛxy=−6%. Janus α-Au4XY monolayers exhibit superior transport characteristics with the electron mobility reaching up to 3.20×105 cm2V−1s−1 (α-Au4SSe monolayer). Our findings not only explore the outstanding electronic and transport features of Janus α-Au4XY nanostructures but also indicate their potential applications in nanoelectronics and nanoelectromechanical devices.

Unveiling the influence of dopants on structural, defect chemistry, morphological and optical characteristics of NiO nanostructures

Abstract In this paper, undoped and doped (Fe, Co and Fe-Co) nickel oxide (NiO) nanostructures have been synthesized using co-precipitation method. Prepared samples were characterized for the structural, compositional, morphological and optical properties using x-ray diffraction, scanning electron microscopy (SEM), Energy dispersive spectrocopy (EDS), UV-visible spectroscopy and photoluminescence spectroscopy. Structural analysis confirmed the single cubic phase formation of undoped and doped samples. Defect chemistry showed that Fe-Co co-doped NiO possesses a lower density of defects than other samples. SEM results revealed the agglomeration of particles. EDS results confirmed the presence of Ni, O, Fe and Co in the respective undoped and doped samples. Optical analysis revealed the band edge shifts with the incorporation of dopants in the NiO crystal lattice confirmed the variation of band gap energy. Emission peaks were observed in the UV and visible regions. The Incorporation of dopants in the crystal lattice causes variation of emission centers. Surface oxygen vacancies and imperfections significantly impact the emission characteristics of NiO. Variable spectral response of NiO with dopant incorporation has potential for optoelectronic applications.

Hierarchical Heterojunctions of Metal Sulfide WS2 Nanosheets/Metal Oxide In2O3 Nanofibers for an Efficient Detection of Formaldehyde.

The construction of transition metal dichalcogenides (TMDs) heterojunctions for high-performance gas sensors has garnered significant attention due to their capacity to operate at low temperatures. Herein, we realize two-dimensional (2D) WS2 nanosheets in situ grown on one-dimensional (1D) In2O3 nanofibers to form heterostructures for formaldehyde (HCHO) gas sensors. Capitalizing on the p-n heterojunctions formed between WS2 and In2O3, coupled with the high surface-to-volume ratio characteristic of 1D nanostructures, the WS2/In2O3 NFs sensor demonstrated an elevated gas response of 12.6 toward 100 ppm HCHO at 140 °C, surpassing the performance of the pristine In2O3 sensor by a factor of two. Meanwhile, the sensor presents remarkable repeatability, rapid response/recovery speed, and good long-term stability. The superior sensing capabilities of WS2/In2O3 NFs heterojunction are attributed to the combined impact of the increased charge transfer and the presence of more sites for gas adsorption. The research endows a potent approach for fabricating TMD heterojunctions to significantly enhance the gas sensing properties of gas sensors at relatively low temperatures.

Investigating the Electrical, Power Factor, and Figure of Merit Characteristics of Cadmium Oxide Nanostructures Fabricated via Thermal Evaporation in Vacuum

A cadmium dioxide nanostructure was fabricated on silicon and quartz substrates through oblique angle deposition (OAD). The synthesis involved the initial thermal evaporation of high-purity cadmium metal films at varying deposition angles on the substrates, followed by a 1.5-hour oxidation process at 773 K in a conventional furnace to produce cadmium oxide nanostructures. X-ray diffraction (XRD) analysis revealed the development of crystalline structures within the cadmium oxide (CdO) films. The deposition angle exhibited a significant impact, influencing the preferred orientation along the (111) planes more substantially than the normal incident angle. I-V measurements and assessments of electrical conductivity were conducted under both light and dark conditions for the CdO films. The photocurrent generated in an oblique (Al/CdO/p-Si/Al) heterojunction exceeded that of a standard detector under illumination. The investigation explored the thermoelectric properties of CdO nanomaterials, including the figure of merit (M), power factor (P.F.), and Seebeck coefficient (S), for both normally deposited and obliquely deposited films. The results demonstrated an enhancement in the figure of merit with oblique deposition, potentially attributed to increased roughness, resulting in reduced thermal conductivity and an elevated figure of merit. All findings indicated superior performance for deposition angles (θº = 50º & 70º) in comparison to normal deposition (θº = 0º).

Nanostructural Influence on Optical and Thermal Properties of Butterfly Wing Scales Across Forest Vertical Strata.

Butterfly wing scales feature complex nanostructures that influence wing coloration and various mechanical and optical properties. This configuration plays a key role in ecological interactions, flight conditions, and thermoregulation, facilitated by interactions with environmental electromagnetic energy. In tropical forests, butterflies occupy distinct vertical habitats, experiencing significant light and temperature variations. While wing nanostructures have been widely studied, their variation across different vertical flight preferences remains underexplored. This study investigates the wing nanostructures of 12 tropical butterfly species from the Nymphalidae family, focusing on their optical, morphological, and thermal properties across different forest strata. We analyzed the optical response through diffuse reflectance in the UV, Vis, and NIR ranges, correlating these findings with nanostructural configuration and thermal stability using thermogravimetric analysis (TGA). Our results reveal a significant correlation between flight stratification and wing optical responses, alongside distinct nanostructural features within each stratum. This study demonstrates the variability in butterfly wing nanostructures along the vertical stratification of the forest to cope with environmental conditions, raising new questions for future research on eco-evolutionary flight and thermal adaptations. Additionally, this underscores the importance of understanding how these structural adaptations influence butterfly interactions with their environment and their evolutionary success across different forest strata.

Structurally-constrained wrinkled NiO nanomembranes for high-performance lithium and sodium storage

In light of its exceptional capacity and safety features, nickel oxide (NiO) has emerged as a highly promising electrode material for advanced lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), which operate through conversion mechanisms, meeting the growing demand for high-efficiency rechargeable batteries. To address the capacity degradation challenges associated with NiO anodes, we present an innovative approach involving the fabrication of wrinkled NiO nanomembranes through magnetron sputtering deposition followed by thermal treatment. This distinctive three-dimensional, ultra-thin architecture integrates nanostructural and microstructural features that effectively reduce ionic diffusion distances and mitigate dimensional fluctuations during cycling, thereby markedly enhancing the electrochemical performance and reliability. Specifically, for lithium storage, these wrinkled NiO nanomembranes achieve an impressive reversible specific capacity of 773 mA h g−1 at 100 mA g−1, with excellent rate capability of 468 mA h g−1 at 5000 mA g−1 and long-term cycling performance, maintaining 523 mA h g−1 at 500 mA g−1 even after 1000 cycles. Likewise, for sodium storage, they exhibit a substantial reversible capacity of 288 mA h g−1 at 50 mA g−1 and retain 202 mA h g−1 at 200 mA g−1 after 100 cycles. These findings underscore the promising application of wrinkled NiO nanomembranes as robust anodic materials for high-performance LIBs and SIBs.

Praseodymium induced symmetry switching and electrochemical characteristics of LaCoO3 nanostructures

A comparative study of the crystal structures and electrochemical characteristics of bulk and nanoscale La1-xPrxCoO3 (x = 0, 0.3 and 0.6) perovskites is made using synchrotron x-ray diffraction, cyclic voltammetry, and galvanostatic charge/discharge methods. It is shown that the sol-gel synthesized nano structures and bulk LaCoO3 exhibit different crystal structures, viz., rhombohedral [a = b = 5.4401 Å, c = 13.134 Å (on hexagonal axes), Z = 6, R3‾c] and monoclinic [am = 5.3865 Å, bm = 5.4482 Å, cm = 7.6365 Å, βm = 89.010°, Z = 4, I2/a], respectively. The evidence for CoO6 octahedra distortion in bulk LaCoO3 is also gathered from the three distinct Raman active modes at 518, 646, and 688 cm−1 emerging due to the Jahn-Teller effect, which, in-turn, reduces the crystal symmetry for achieving structure stabilization. This amounts to changes in Co–O bond lengths and Co–O–Co bond angles with promotion of t2g electron to eg level simultaneously for Co3+(3d6) to attain an intermediate spin state (S = 1) or higher. However, Pr-insertion induces phase transition to orthorhombic in both but with space group Pnma in nanostructures and equivalent Pbnm in bulk. The substitution effect on the specific capacitance (C) is opposite in nature, i.e., while ‘C’ decreases from 149 to 12 F/g in nano structures, it increases from 0.4 to 4 F/g in bulk with increase in Pr-content from x=0 to 0.6. A galvanostatic charge-discharge test of pristine nano LaCoO3 performed at a constant scan rate of 50 mVs−1 reveals electrode electrochemical stability by retaining 96 % of specific capacitance ∼82.5 F/g for 2000 cycles at least. The variation in the crystal structure and bond length and/or angle plays a key role in controlling the electrochemical performance of Pr-substituted LaCoO3 perovskites.

Photoluminescent carbon colloids prepared by laser fragmentation of carbon from waste coffee grounds

Colloidal suspensions of carbon nanostructures (CNSs) were prepared by laser fragmentation in various liquid media using heat-treated coffee grounds as carbon precursor. A study by calorimetry was done in powder of waste coffee grounds to determine the temperature of obtaining carbon. The experiments were carried out in two stages, the first one consisted in obtaining the carbon source, for which powder of waste coffee grounds was thermally treated in air. The as-obtained carbon was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy and infrared spectroscopy. In the second step the as-obtained carbon was separately dispersed in four liquid media (acetone, toluene, methanol and isopropyl alcohol) to be fragmented by using a ns-pulsed Nd:YAG laser at its 1064 nm fundamental emission. The morphological features of the carbon nanostructures were obtained by transmission electron microscopy, while the optical properties of the colloidal suspensions were characterized by UV-Vis and photoluminescence spectroscopies. Results indicate that carbon nanostructures are successfully obtained in the four liquid media after the fragmentation process. The four colloidal suspensions show photoluminescent properties, which are seen to depend on the liquid medium nature. We found that the liquid medium also influences the efficiency of the laser fragmentation.

Synthesis of Starfish-Shaped ZnS Nanostructures by Hydrothermal Method and Their Electrochemical Sensing of Dopamine.

Introduction Dopamine serves an essential function as a neurotransmitter, influencing the regulation of movement, cognitive processes, and emotional states. The identification of abnormal dopamine levels is critical for clinical diagnoses and scientific research, given its links to various disorders, including depression, schizophrenia, and Parkinson's disease. The distinctive electrochemical characteristics, stability, and broad bandgap of zinc sulfide (ZnS) nanostructures render them particularly fascinating. The hydrothermal method is recognized as an effective and economical approach for the fabrication of ZnS nanostructures, exhibiting a range of morphologies. Utilizing this method to create ZnS nanostructures leads to the formation of structures characterized by extensive surface areas, hierarchical designs, and improved electrochemical properties. Aim The objective is to examine the electrochemical characteristics of ZnS starfish-shaped nanostructures produced through the hydrothermal technique and to assess their viability as a sensing platform for dopamine detection. Materials and methods To synthesize ZnS nanoflowers, stoichiometric amounts of transition metal salts were prepared: 10 mM of Zn(NO3)2•3H2O and 30 mM of sodium thiosulfate (Na2S2O3•5H2O) were dissolved in 30 mL of deionized water and stirred for 20 minutes. The solutions were then combined and transferred into a 100 mL Teflon autoclave reactor, which was heated at 200 °C for 12 hours in a furnace. This process utilized the hydrothermal technique to produce the desired ZnS nanoflowers. Result The crystalline arrangement of ZnS was validated by X-ray diffraction (XRD) analysis, aligning with the Joint Committee on Powder Diffraction Standards (JCPDS). Moreover, field emission scanning electron microscopy (FE-SEM) illustrated the particle morphology of ZnS, showing a range between 200 and 500 nm size. Additionally, the cyclic voltammetry results indicated that the modified electrode produced a greater current response than the bare electrode, highlighting its improved sensitivity to dopamine molecules. Conclusion ZnSnanoparticles were synthesized via a hydrothermal method and characterized using XRDand FE-SEM. These nanoparticles were used for electrochemical dopamine detection, showing potential for advanced sensing platforms. Integrating ZnS into microfluidic devices enables real-time dopamine monitoring, opening new possibilities for healthcare and neurochemical research. Exploring surface engineering techniques could further enhance the electrochemical performance of ZnS-based sensors.

Silicon quantum dot-enhanced thin-film nanocomposite membranes for efficient alcohol dehydration via pervaporation: A sustainable approach

This study explores the effectiveness of silicon quantum dots (SiQDs)—specifically, amine-functionalized (NSiQDs) and amine-hydroxyl-functionalized (NOSiQDs)—in optimizing thin-film nanocomposite (TFN) membranes for pervaporation dehydration of various alcohols. The SiQDs were integrated into the membranes via an innovative interfacial polymerization technique, involving the dispersion of SiQDs in an aqueous amine solution followed by polymerization with trimesoyl chloride. This approach ensured uniform integration of SiQDs, significantly enhancing the nanostructure and surface characteristics of the membranes. Such modifications led to improved water transport capabilities, substantially boosting pervaporation efficiency. Exceptional performance was demonstrated by the TFN-NOSiQDs(400) membranes, which achieved a peak permeation flux of 4195.8 g·m−2·h−1 and maintained over 99 wt% water concentration in the permeate when tested with a 70 wt% isopropanol/water solution at 25°C. Comprehensive long-term stability assessments confirmed the robustness and consistent functionality of the membranes, highlighting their suitability for industrial applications that demand reliable and efficient alcohol separation processes.

Shape tailored nano-ceria as high performance supercapacitor electrode material

Electrochemical energy storage devices herald a brighter future, offering efficient and sustainable solutions to meet the escalating global energy demands. The current work investigates the development and characterization of different ceria nanostructures (nanorod, nanocube, and nanopolyhedra) as effective electrode materials for supercapacitor applications. The electrode materials are systematically characterized using various spectroscopic and non-spectroscopic techniques. Galvanostatic charge-discharge, electrochemical impedance spectroscopy, and cyclic voltammetry techniques are used to evaluate the electrochemical performance of the electrode materials. The optimum material for the said application is cerium nanorod which has the maximum specific capacitance of 437.27 F/g in acid electrolytes. The current-voltage (I-V) characteristics of the ceria nanostructures exhibit hysteresis behavior; ceria nanorod showing coexistence of memristive and memcapacitive nature. The loop area of the hysteresis curve, derived from the ratio of OFF resistance to ON resistance (ROFF/RON) at 4 V, yields approximate values of 1.08, 1.33, and 1.57 for ceria nanocubes, ceria nanopolyhedra, and ceria nanorods, respectively. Impedance vs. frequency analysis of the samples was also carried out to study their electrical and transport properties. The results obtained from electrochemical analyses are complimented by electrical studies.

ZnO-modified glass capillaries as a portable photocatalytic reactor for real-time measurements

Abstract Here, we have developed a photocatalytic reactor using glass capillaries which acts both as a flow cell and a thin film-supported photocatalyst due to the Zinc Oxide (ZnO) nanostructures grown on the inner surface of the glass capillaries. The structural, morphological, elemental, and optical characteristics of the ZnO nanostructures were investigated through characterization methods such as x-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive x-ray spectroscopy (EDAX), UV–Visible spectroscopy, and Raman spectroscopy. Further, dye-sensitized ZnO nanostructures were used for photocatalytic application under visible light irradiation. A custom-made setup is developed using ZnO-modified glass capillaries for simultaneous decay and measurement of the dye degradation process under visible LED light. This developed model could have future technological applications in designing portable photocatalytic reactors that can accurately monitor the dye degradation process using real-time measurements.

The effect of solvent on the structural, morphological, optical and dielectric properties of SnO2 nanostructures

We investigate the effect of solvent, i.e., ethanol and deionized (DI) water, on the structural, optical, and dielectric characteristics of SnO2 nanostructures, synthesized via the hydrothermal method. Utilizing X-ray diffraction (XRD), we find the rutile phase for both nanostructures with average crystallite sizes of 12.53 nm and 6.62 nm for the samples synthesized using ethanol and DI water as solvents, respectively. The energy-dispersive X-ray spectroscopy (EDX) confirms the presence of Sn and O elements in both samples. Scanning electron microscopy (SEM) reveals that the samples prepared using ethanol and DI water exhibit nanorods and nanoflowers structures, respectively. The calculated band gap for SnO2 based on ethanol and DI water solvents is found to be 3.54 eV and 3.45 eV, respectively. The SnO2 nanostructure prepared by ethanol solvent demonstrates a higher dielectric constant which is attributed to higher defect density and more grain boundaries in it than in the sample synthesized using DI water. At low frequencies, the high tanδ values in the case of both nanostructures are explained based on space-charge polarization (SPC). The SnO2 prepared by DI water exhibits higher tangent loss than the one synthesized using ethanol because of its significant surface area. The significant amount of conducting grains in the SnO2 nanostructure while using ethanol solvent makes it a better conductive. Furthermore, the dielectric constant increases with increasing temperature which suggests considerable changes in the polarization behavior, while the tangent loss and conductivity demonstrate dependency on the temperature, indicating the promise of the nanostructures for electrical applications.

Effect of pH on hydroxyapatite coatings obtained by spray pyrolysis and their use as matrices for antibiotic adsorption by spin coating and release properties.

Calcium phosphate materials, particularly hydroxyapatite (HA), are extensively used in biomedical applications because of their prominence as primary inorganic constituents of human hard tissues. This study investigates the synthesis of HA coatings via spray pyrolysis using various precursors, including HA derived from bovine bone. The effects of pH on the formation and properties of HA coatings were systematically examined. Samples exposed to acidic conditions or left without pH adjustment led to the formation of HA, contrasting with the outcomes observed through dissolution methods. Different characterization techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), were employed to evaluate the quality and crystallinity of the coatings. Among the samples, those exhibiting superior crystallinity and nanostructured features, including bovine HA, were selected for further surface functionalization with the antibiotic enrofloxacin using spin coating. As expected, the antibiotic loading on each material's surface depended on the amount of HA deposited on the substrate. However, the desorption results indicated that, in all cases, desorption persisted beyond 38 h, implying that HA-loaded matrices could be effective systems for controlled and prolonged drug release, which could be useful in dental or orthopedic implants for inhibiting the growth of bacterial biofilms.

Surface-Enhanced Raman Scattering on Size-Classified Silver Nanoparticles Generated by Laser Ablation.

This study delved into the complex interplay between the nanostructural characteristics of nanoparticles and their efficacy in surface-enhanced Raman scattering (SERS) for sensitive detection of trace chemical substances. Silver nanoparticles were prepared for the SERS substrate by combining laser ablation, postannealing processes (up to 500 °C), and electrostatic mobility classification, allowing high-purity silver nanoparticles with controlling their sizes (40-100 nm) and aggregate structures. These nanoparticles were then inertially deposited on the substrates to create SERS-active surfaces, employing Rhodamine B as a probe to assess the impact of particle size, shape, and deposition density on SERS effectiveness. Our findings revealed that spherical nanoparticles, especially those approximately 50 nm in diameter, controlled to a spherical structure through gas-phase annealing at 500 °C and subsequent classification, yielded the most significant SERS enhancement. This optimal can be explained by the particle size response of the surface plasmon resonance, where the enhancement of the Raman signal for particles up to 50 nm (1/10 of the laser wavelength used in this study, 532 nm) arises from a balance between the enhancement of dipole moment and the number of "hot spot" regions (respectively proportional to the cube and inverse square of the diameters in theory, leading to a linear relationship between signal intensity and particle diameter); meanwhile, in larger size region than 50 nm, the Raman signal was decreased owing to the attribution of the phase difference between the electric field and dipole moment. Furthermore, we found that a deposition density of 2 μg resulted in nearly a single layer of particles, which is crucial for maximizing SERS hotspots and, consequently, the enhancement effect.

Tailoring the optoelectronic and spintronics properties of Cr-doped ZnS nanostructure thin films

This paper discusses the tailoring of the optoelectronic and spintronic of Cr3+-doped ZnS nanostructured electron beam evaporated thin films. The XRD measurements confirm the zinc blende cubic structure for the films with a preferred orientation along the (111) direction. The nanostructured features of the films were verified from the XRD and AFM results. The EDXS and XPS data show the stoichiometric chemical and electronic states of the films. Spectrophotometry measurements for the films show that the energy gap decreases from 3.67 eV to 3.43 eV as the Cr3+ increases from 0 at. % to 8.0 at.%. Such reduction of the Eg of the Cr3+-doped ZnS is attributed to the sp-d coupling. The strong PL asymmetric peak of the Cr3+-doped ZnS is observed, which is quenched and red shifted with increasing Cr doping level. Furthermore, the magnetic measurements show the occurrence of weak room temperature ferromagnetic behavior. On the other hand, the results further show that the magnetization increases with the increase of the Cr3+ dopants up to x = 0.05, then decreases with increasing the Cr doping above x = 0.05. This can be attributed to the development of the antiferromagnetic ordering.

Sodium-Alginate-Doped Lignin Nanoparticles for PBAT Composite Films to Dually Enhance Tensile Strength and Elongation Performance with Functionality.

It is a formidable challenge in thermoplastic/lignin composites to simultaneously boost tensile strength and elongation performance due to the rigidity of lignin. To address this issue, sodium-alginate-doped lignin nanoparticles (SLNPs) were prepared by combining solvent exchange and a coprecipitation method and used as an eco-friendly filler for poly(butylene adipate-co-terephthalate) (PBAT). The results indicated that the 1% polyanionic sodium alginate solution contributed to the formation of SLNP in lignin/THF solution. SLNP with a mean hydrodynamic diameter of ~500 nm and a Zeta potential value of -19.2 mV was obtained, indicating more hydrophobic lignin nanoparticles and a smaller number of agglomerates in SLNP suspension. Only 0.5 wt% SLNP addition improved the yield strength, tensile strength, and elongation at break by 32.4%, 31.8%, and 35.1% of the PBAT/SLNP composite films, respectively. The reinforcing effect resulted from the rigid aromatic structure of SLNP, whereas the enhanced elongation was attributed to the nanostructural feature of SLNP, which may promote boundary cracking. Additionally, the PBAT/SLNP composite films displayed excellent ultraviolet (UV) resistance with a UV shielding percentage near 100% for UVB and more than 75% for UVA, respectively. The addition of SLNP hindered water vapor, enhancing the moisture barrier properties. Overall, this study provides an effective strategy to eliminate the decrement in elongation performance for PBAT/lignin composites and suggest they are good candidates to be extensively utilized.