Field Emission Research Articles

Nanostructure of TiO\(_{2}\) and WO\(_{3}\) multilayer films deposited on ITO glass for electrochromic enhanced photocatalytic activity

The photocatalytic activity (PA) by electrochromic (EC) enhancement of single and multilayer films of TiO2, WO3, TiO2/WO3, and WO3/TiO2 was investigated. All films were deposited from metal on an ITO glass substrate using direct current (DC) magnetron sputtering via an oblique angle deposition (OAD) technique at 85°. Subsequently, a thermal oxidation (TO) process at 500℃ was applied for the samples to form metal oxide films. The morphology, elemental composition, crystal structure, and optical properties were studied by using field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD), and UV-vis spectroscopy, respectively. The photocatalytic properties were investigated by showing the degradation rate of methylene blue (MB) solution as an organic pollutant that was examined under ultraviolet irradiation of 300 µW∙cm‒2. The film samples were investigated by comparing the pre-color and colored states that were achieved through the EC process. The EC properties of WO3 led to increased charge insertion on the film surface. This observation was further supported by cyclic voltammetry (CV) testing, which revealed a higher current density for the thin film samples. The photodegradation results showed that the samples in the colored state exhibited a significantly higher degradation rate of MB compared to the pre-color state.

A semiconducting supramolecular Co(II)-metallogel based resistive random access memory (RRAM) design with good endurance capabilities.

A highly efficient approach for synthesizing a supramolecular metallogel of Co(II) ions, denoted as CoA-TA, has been established under room temperature and atmospheric pressure conditions. This method employs the metal-coordinating organic ligand benzene-1,3,5-tricarboxylic acid as a low molecular weight gelator (LMWG) in DMF solvent. A comprehensive analysis of the mechanical properties of the resulting supramolecular Co(II)-metallogel was conducted through rheological investigation, considering angular frequency and thixotropic study. The hierarchical rocky network structure of the supramolecular Co(II)-metallogel was unveiled using field emission scanning electron microscopy (FESEM). Transmission electron microscopic (TEM) analysis showed rod-shaped structures via low-magnification high angle annular dark field (HAADF) bright field scanning transmission electron microscopic (STEM) imaging, while energy dispersive X-ray (EDX) elemental mapping confirmed its primary chemical constituents. The formation mechanism of the metallogel was examined via fourier transform infrared spectroscopy (FTIR) spectroscopy. The nature of the synthesized CoA-TA metallogel was affirmed through powder X-ray diffraction (PXRD) analysis. Furthermore, this study involved fabrication of Schottky diode structures in a metal-semiconductor-metal geometry based on cobalt(II) metallogel (CoA-TA), enabling observation of charge transport behavior. Remarkably, a resistive random access memory (RRAM) device utilizing cobalt(II) metallohydrogel (CoA-TA) demonstrated bipolar resistive switching at room temperature and under ambient conditions. The switching mechanism was investigated, revealing the formation and rupture of conductive filaments between metal electrodes that govern the resistive switching behavior. This RRAM device exhibited an impressive ON/OFF ratio (~ 414) and exceptional endurance over 5000 switching cycles. These structures offer great potential for diverse applications such as non-volatile memory design, neuromorphic computing, flexible electronics and optoelectronics. Their advantages lie in their fabrication process, reliable resistive switching behavior and overall performance stability.

Layer-by-Layer Deposition of Hollow TiO2 Spheres with Enhanced Photoelectric Conversion Efficiency for Dye-Sensitized Solar Cell Applications

Fabricating photoanodes with a strong light-scattering effect can improve the photoconversion efficiency of dye-sensitized solar cells (DSSCs). In this work, a facile microwave hydrothermal process was developed to prepare Au@TiO2 core–shell nanostructures, and then the Au core was removed by etching, resulting in hollow TiO2. Morphological characterizations such as field emission scanning and transmission electron microscopy measurements have been used for the successful formation of core–shell and hollow TiO2 nanostructures. Next, we attempted to deposit the different-sized hollow TiO2-based microspheres simultaneously on the surface of small-sized TiO2 nanoparticles-based compact film as light-scattering layers via electrophoretic deposition. The deposited hollow TiO2 microspheres constitute bi- and tri-layers that not only improve the light-harvesting properties but also speed up the photogenerated charge transfer. Compared to commercial TiO2 compact film (4.75%), the resulting bi-layer and tri-layered films-based DSSCs displayed power conversion efficiencies of 6.33% and 8.08%, respectively. It is revealed that the deposited bi- and tri-layered films can enhance the light absorption ability via multiple photon reflection. This work validates a novel and controllable strategy to develop light-scattering layers with increased light-harvesting properties for highly efficient dye-sensitized solar cells.

ZnS Thin Films Prepared Using Spray Pyrolysis Technique

It is well known that spray pyrolysis of an aqueous solution of thiourea and zinc acetate onto a glass substrate at spray rates of (3 mlmin-1) may successfully synthesize thin coatings of zinc sulfide. The impact of several substrate temperatures (150, 200, 300, and 400 oC) on the structural and optical characteristics was also discussed in this research. Field emission scanning electron microscopy (FESEM), UV-Vis-NIR spectrometry, and X-ray diffraction (XRD) were used to characterize the films. On each one of the deposited ZnS sheets, a cubic structure was seen. On the other hand, the temperature of the substrate appeared to affect the crystallinity and morphology. It was discovered that as the substrate temperature was lowered, the bandgap value of ZnS films somewhat rose. Furthermore, it is most likely that the Zn(S,O) production inside the solid solution is responsible for the fluctuations seen in the 3.5-3.8 eV region.

Wear properties of Al6061/SiC + B4C + TiC hybrid composites produced by vacuum infiltration method

Abstract In the study, hybrid metal matrix composite (HMMC) structures were produced by vacuum infiltration method (VIM) using Al6061 alloy and varying amounts of SiC, B4C, and TiC ceramic powder pairs. Age-hardening processes were applied to these HMMCs. After heat treatment, wear behavior was examined under different loads using the pin-on-disc test method. All Al6061 hybrid composites exhibited better wear performance than unreinforced Al6061. In the wear tests of composite samples, the lowest volume loss and therefore the highest wear resistance were obtained in Al6061 3 wt.% B4C + SiC composites under 5 N force. The lowest wear resistance due to the highest volume loss was determined in Al6061/1 wt.% TiC + B4C composites under 15 N force. Abrasive and adhesive wear characteristics were observed in field emission scanning electron microscopy(FESEM) images of worn surfaces. Additionally, wear debris, smearing, and deep grove formations were determined on the surface. In the EDS analysis performed on the worn surface, O and Fe elements were found in addition to the elements that are likely to be in the structure (such as Al, B, C, Ti, Si, and Mg). The wear tests caused the formation of oxide layers on the sample surfaces.

Threshold Gain Reduction in Tandem Semiconductor Nano-Lasers

It is shown that a significant reduction in the threshold gain of electrically pumped semiconductor nano-lasers may be achieved in bridge-connected tandem semiconductor nano-lasers. Optimization of the design is achieved by exploring the impact of bridge length and width on the threshold gain. In addition, a detailed examination is also made of the emission patterns of the structure. It is found that a trade-off emerges between threshold gain and beam quality where multi-lobed far field emission may be associated with the lowest threshold gains.

Effect of Iodine Doped Pentacene Thin Film on the Performance of Organic Light Emitting Diode

The study investigated the effect of iodine-doped pentacene film as a buffer layer in an organic light-emitting diode (OLED). In this study, an ITO (indium tin oxide)-based sample is used as a reference device for comparative purposes. In OLED devices, the buffer layers were deposited using the doping of iodine vapor with the pentacene materials under proper conditions. The thermal treatment of the doped pentacene film results in increasing the conductivity of the buffer layer. Surface morphology for the bilayer anode was carried out by FESEM (Field Emission Scanning Electron Microscope) analysis. In our work, maximum luminance of 2345 cd/m2 and current efficiency of 5.4 cd/A are obtained, along with more stability performance under annealing treatment in the device structure of FTO/iodine-doped pentacene (30 nm)/TPD [N, N′-Bis(3-methyl phenyl)-N, N′-diphenylbenzidine] (44 nm)/Alq3 [Tris(8-hydroxyquinoline)aluminum(III)] (52 nm)/LiF (lithium fluoride) (5 nm)/Al (aluminum) (110 nm).

Synthesis and characterization of p-CuO/n-ZnO heterostructured composite thin films for the detection of formaldehyde gas.

We report the synthesis and characterization of pure CuO and CuO-ZnO nanostructured composite thin films sprayed on particle-free glass substrates using chemical spray pyrolysis method. The films were systematically analyzed through microstructural, morphological, chemical, and gas-sensing studies. X-ray diffraction (XRD) studies confirmed the polycrystalline nature of the films, with a predominant monoclinic phase along the (002) direction. Key structural parameters, such as crystallite size, dislocation density, strain, and the number of crystallites per unit area, were reported from XRD analysis. Field emission scanning electron microscopy (FESEM) revealed a bundled-like morphology with uniform particle distribution, enhancing the surface area for effective gas interaction. X-ray photoelectron spectroscopy (XPS) results indicated that Cu and Zn ions existed predominantly in the 2+ oxidation state, contributing to the films' reactivity. Significantly, the gas sensing studies were investigated with static liquid distribution method, highlighting the remarkable performance of the 30 wt.% CuO-ZnO composite thin film. This composite exhibited a substantial response to 5 ppm formaldehyde at ambient conditions, showing a recovery time of 22 seconds and a response time of 15 seconds. These findings underscore the potential of CuO-ZnO composites for efficient formaldehyde gas sensing applications, marking a notable advancement in the field of environmental monitoring.

Supression of shielding effect of large area field emitter cathode in radio frequency gun environment

Abstract Utilisation of large area field emitters (LAFE) cathodes for rf gun injector hold promise for delivering compact, high power and high brightness electron beam for advanced accelerator technologies. LAFEs subjected to DC electric fields posses significant challenges due to the shielding effect which restricts emission from central emitters and decreases the overall current density. Mitigating the shielding effect of LAFE in rf gun environment is essential for meeting the desired beam quality requirement in an accelerator. The current distribution of LAFE under DC conditions depend on its various geometrical parameters such as emitter height, inter-emitter distance, aspect ratio, number of emitters. Additionally, in rf gunsetup, LAFEs are subjected to variable macroscopic electric field at different emitter position which can potentially alter the current distribution compared to DC fields. In this work, we have systematically studied the shielding effect properties of LAFE in rf gun environment under the influence of various LAFE parameters. A semi-analytical approachhas been adopted to estimate the current distribution which combines the analytically calculated field enhancement factor (γ) and numerically calculated applied rf field values. This new methodology was first validated using COMSOL simulation and then employed for field emission performance estimation of a LAFE cathode integrated in a½ cell S-band (2856 MHz) rf gun. The simulation results reveals that under favourable conditions, a Gaussian spatial distribution of beam can be obtained from LAFE thus countering the shielding effect typical in DC fields. By optimizing the LAFE parameters, the desired current and beam distribution pattern can be achieved. This study highlights the adoption of a promising approach for designing LAFE cathodes suitable for rf gun which can lead to advancement of field emission technologies for accelerator-related applications.

Development of Numerical Analysis Method for Cathode Sheath Considering Electron Emission From Cathode in Vacuum Arc

ABSTRACTIt is imperative to develop the simulation of vacuum arcs as a tool to aid electrode design in vacuum circuit breakers. Although the development of electromagnetic thermo‐fluid simulations for vacuum arcs has been reported, most of them do not take cathode sheath phenomena into account and have not been able to reproduce vacuum arc phenomena, especially cathode spots. As the first step, the cathode sheath voltage, cathode surface electric field, and temperature and field (T‐F) electron emission current were analyzed numerically on the basis of the space charge in the cathode sheath. In this study, the cathode sheath was assumed to exist when the charge density induced on the cathode surface is positive, and the temperature and density of vacuum arc plasma and cathode temperature, which are physical quantities obtained by electromagnetic thermo‐fluid simulation, were used as parameters of the analysis. As a result, the cathode sheath voltage, electric field, and electron emission current density can be calculated from the vacuum arc plasma temperature, density, and cathode temperature. Numerical results show that the electron emission current density has a dominant effect on the presence or absence of the cathode sheath.

Utilization of coalmine overburden-furnace slag and fly ash mixed cement-treated subbase/base course material for sustainable flexible pavements: mechanical performance and environmental impact.

The scarcity of conventional aggregates with tremendous growth in highway construction and the indiscriminate dumping of industrial waste materials in precious landfills has become a huge global concern. This study is aimed at utilizing wastes from various industries, including coalmine overburden (OB) dump, basic oxygen furnace (BOF) slag, and fly ash to produce suitable and sustainable cement-treated subbase/base course layers (CBSB/CTB) for flexible pavement construction. Response surface methodology was used to optimize the composition of the blended material considering unconfined compressive strength (UCS) and Poisson's ratio. Results demonstrated that 50% OB dump, 40% slag, 5% fly ash, and 5% cement achieved a 7-day UCS of 4.84MPa and Poisson's ratio of 0.25, in line with IRC:37-2018 guidelines. X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) analysis confirmed the presence of ettringite crystals, calcium-silicate-hydrate (C-S-H), and calcium-aluminosilicate-hydrate (C-A-S-H) gels which are the source of strength development in the blend. Further, a soaked California bearing ratio (CBR) of 136.08% and flexural strength of 2.06MPa after 7days and 28days of curing, respectively, demonstrates the overall strength of the stabilized waste. Approximately 4% weight loss was observed after wet-dry durability tests, indicating exceptional performance of the optimal blend in inclement weather conditions. Furthermore, the environmental impact of the blended material was studied through a leaching study. Fly ash had a high zinc (Zn) level, while BOF slag showed a rich concentrationof chromium (Cr), manganese (Mn), and iron (Fe) in the acid digestion test. In spite of this, the toxicity characteristics leaching procedure (TCLP) test indicated that the levels of heavy metals that leached from the stabilized material stayed considerably below the permissible limits set forth in Indian Standard, IS:10500 (2012). Finally, cost analysis showed a 51.6% reduction in construction cost with cement-treated industrial wastes instead of granular base/subbase made with conventional aggregates. The study recommends the suitability of the stabilized waste material as an alternate construction material for large-scale field applications, which could encourage the construction of flexible pavements that are environmentally benign, economical, and sustainable.

Enhanced photocatalytic degradation of organic pollutants by randomly oriented 2D SnS2 nanostructures

Abstract In this study, we present a bottom-up solvothermal technique using tin tetrachloride pentahydrate (SnCl4.5H2O) and thioacetamide as precursors to synthesize SnS2 nanostructures. Different solvents including isopropyl alcohol, ethanol (EN), and ethylene glycol were used in the reaction to enhance the photodegradation efficiency of organic pollutants, Methylene Blue (MB), and Tetracycline (TC) in an aqueous medium under simulated solar light irradiation. The SnS2 nanostructures synthesized with these solvents were characterized using various structural, morphological, and optical techniques, including x-ray diffraction, RAMAN, field emission scanning electron microscope, x-ray photoelectron spectroscopy, UV–Vis, and Brunauer–Emmett–Teller analysis. The choice of solvent was found to significantly affect the structural, morphological, and optical properties of the SnS2 nanostructures. Notably, the sample synthesized with EN as the solvent displayed a unique morphology, enhanced light-harvesting ability, efficient charge carrier separation, and a larger specific surface area, all of which contributed to its superior photocatalytic activity. This sample achieved 99.9% degradation of MB and 95% degradation of TC within 20 and 40 min, respectively. The kinetic analysis revealed maximum rate constant (k) values of 0.15242 min−1 for MB and 0.060 95 min−1 for TC, as determined by the pseudo-first-order kinetic model. We also discuss the plausible mechanism involving visible light-induced electron–hole pairs that generate reactive species, leading to the mineralization of dyes into H2O, CO2, and other gaseous products. The synthesized SnS2 nanostructures demonstrate significant potential for enhanced photocatalytic activity in organic pollutant degradation, underscoring their promise in addressing water pollution challenges.

ADHESION OF STEEL CORD WITH CU-ZN-FE COATING IN COBALT-FREE COMPOUND

ABSTRACT The adhesion of steel cord with Cu-Zn-Fe coating in a cobalt-free skim compound in hot and humid conditions was investigated and compared with the current adhesion system consisting of brass-coated steel cord in cobalt-containing skim compound. Standard adhesion tests showed that the adhesion retention of Cu-Zn-Fe–coated cord in a cobalt-free compound was significantly improved with respect to current adhesion system. Advanced characterization of adhesion interphases by field emission scanning electron microscopic examination of cord-compound cross sections and X-ray photoelectron spectroscopy depth profiling revealed that incorporating the Fe element into the coating significantly reduces the dezincification of the metallic coating and prevented excessive growth of adhesion interphase. This results in high adhesion retention of Cu-Zn-Fe–coated steel cord in cobalt-free compound. Furthermore, a hypothesis was proposed to explain how the Fe element decreases the dezincification of the metallic coating in hot and humid conditions. Because Cu-Zn-Fe–coated cord eliminates the need for cobalt salts in the compound, using this cord in cobalt-free compounds generates a completely cobalt-free solution to tackle adhesion degradation and health risks of the current adhesion system.

Antibacterial and Photocatalytic Applications of Silver Nanoparticles Synthesized from Lacticaseibacillus rhamnosus

The biosynthesis of silver nanoparticles (AgNPs) presents an innovative and sustainable approach in nanotechnology with promising applications in fields such as medicine, food safety, and pharmacology. In this study, AgNPs were successfully synthesized using the probiotic strain Lacticaseibacillus rhamnosus (BCRC16000), addressing challenges related to stability, biocompatibility, and scalability that are common in conventional nanoparticle production methods. The formation of AgNPs was indicated by a color change from yellow to brown, and UV–visible spectrophotometry confirmed their presence with a characteristic absorption peak at 443 nm. Furthermore, Fourier transform infrared (FTIR) spectroscopy revealed the involvement of biomolecules in reducing silver ions, which suggests their role in stabilizing the nanoparticles. In addition, field emission scanning electron microscopy (FE-SEM) showed significant morphological and structural changes. At the same time, dynamic light scattering (DLS) and zeta potential analyses provided valuable insights such as average size (199.7 nm), distribution, and stability, reporting a polydispersity index of 0.239 and a surface charge of −36.3 mV. Notably, the AgNPs demonstrated strong antibacterial activity and photocatalytic efficiency, underscoring their potential for environmental and biomedical applications. Therefore, this study highlights the effectiveness of Lacticaseibacillus rhamnosus in the biosynthesis of AgNPs, offering valuable antibacterial and photocatalytic properties with significant industrial and scientific implications.

Morphological and structural analysis of monodispersive silica nanoparticles fabricated by Stober method for self-cleaning applications

Abstract In this work, silica nanoparticles have been synthesized via the Stober process on a p-type silicon substrate by spin coating method. Structural and morphological study has been carried out by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Microstructural analysis by Raman spectroscopy displays a prominent peak at 521 cm-1 which corresponds to crystalline silicon. Further, the elemental study by using energy dispersive x-ray spectroscopy (EDX) confirms the presence of silica with no other impurities. Besides, the wettability property has been studied by contact angle measurement and found to be around 130ο for the 6-layer coated thin film which is quasi-super-hydrophobic. The wettability results obtained signify promising properties for the development of self-cleaning devices and applications.

Damping and acoustic properties of nanosilica filled poly(styrene-acrylate) interpenetrating polymer networks (IPNs): Effect of nanocomposite preparation method

Research on noise pollution reduction has focused on utilizing damping coatings and polymer nanocomposites to enhance sound absorption. Nanosilica/poly(styrene-acrylate) nanocomposites as a water-based coating were prepared through in-situ emulsion polymerization and direct mixing methods at varying concentrations of 1, 2, and 3 wt% of nanosilica. Fourier transform infrared (FTIR) spectroscopy revealed that the inclusion of surfactant-containing micelles and a more extended synthesis period in the in-situ synthesis technique enhanced the interaction between silica nanoparticles and polymer chains. Dynamic light scattering (DLS) analysis showed a unimodal distribution and an acceptable range of polydispersity index (PDI) for neat and nanocomposite latexes. The addition of silica nanoparticles enhanced the stability of latex particles, especially evident in the direct mixing method. The field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images confirmed the better dispersion of nanoparticles within the polymer matrix in the in-situ method. The addition of nanosilica resulted in a significant increase in pseudoplastic behavior and viscosity, notably in the in-situ synthesis. In both the in-situ synthesis and direct mixing techniques, the addition of 1 wt% of nanosilica resulted in an increase in the damping factor of nanocomposite films to about 2. However, when the nanosilica content was further increased to 3 wt%, the damping factor decreased. Acoustic tests demonstrated improved sound absorption with silica nanoparticles, yielding noise reduction coefficient (NRC) values of 0.49 and 0.46 for in-situ synthesis and direct mixing. The direct mixing method notably enhanced tensile properties at all nanoparticle content levels. Dried nanocomposite films exhibited superior UV-blocking capabilities compared to neat polymer films.

Co3O4/rGO based nanocomposite architectures as electrodes for advanced energy storage and their pseudocapacitive attributes

In response to escalating global challenges in energy storage, this study embarked on captivating exploration of electrochemically proficient Co3O4 composites, seamlessly integrated with varying concentrations of reduced graphene oxide (5 %, 10 %, and 15 %). Using a single-step hydrothermal method, Co3O4 was synthesized, followed by a solvothermal process to produce Co3O4/rGO composites. These composites were then applied to Nickel Foam to fabricate electrodes. The structural properties of these novel Co3O4/rGO/NF electrodes were analyzed using X-ray Diffractometer, which confirmed the distinctive crystalline structure of Co3O4 and indicated no phase transformation after the introduction of rGO. Morphological analysis through a Field Emission Electron Microscope and Transmission Electron Microscope revealed layered structures and increasing porosity correlated with higher rGO concentrations. Electrochemical performance was rigorously tested through cyclic voltammetry, which verified the pseudocapacitive attributes of the samples. Additionally, galvanostatic charge-discharge studies highlighted that the electrode containing 15 % rGO demonstrated highest (Cs = 1360 Fg−1) at 1.7 Ag−1, with 86 % of cyclic retention after 5000 cycles. Electrochemical impedance spectroscopy further demonstrated superior conductivity, underscoring the potential of these electrodes'for supercapacitor applications.

Mentioned Magnesium Oxide Nanomaterials for Effective Adsorption of Congo Red Dye and Fluoride Ions From Aqueous Solutions

This study investigates the synthesis of nanostructured magnesium oxide (MgO) using the auto-combustion method with urea (MgO-U), glycine (MgO-G), and citric acid (MgO-C) as fuels, followed by subsequent calcination. The selection of fuel plays a crucial role in determining the morphology of the nanostructures.X-ray diffraction (XRD) analysis confirms that the samples exhibit a well-crystallized structure with the desired phase and are free of impurities. Field emission scanning electron microscopy (FESEM) shows that MgO-U nanoparticles have diameters ranging from 10 to 20nm, MgO-C nanoparticles from 60 to 80nm, and MgO-G nanoparticles from 80 to 100nm. These MgO nanomaterials are specifically engineered for adsorption applications, aimed at removing toxic organic dyes and fluoride ions from aqueous solutions. Results demonstrate that MgO-G nanoparticles exhibit superior adsorption activity compared to MgO-U and MgO-C nanoparticles, with maximum uptake capacities of 1429 and 14mg/g, respectively. The adsorption processes adhere to second-order kinetic model. These findings highlight the potential application of the synthesized MgO nanoparticles for mitigating water pollution by adsorbing pollutants from aqueous media.

Surface Enhanced Raman Scattering-Based Sensing and Ultrafast Nonlinear Optical Properties of Silver-Hexagonal Boron Nitride Nanocomposites Achieved by Femtosecond Laser Ablation

This study investigated the surface-enhanced Raman spectroscopy (SERS) properties and nonlinear optical (NLO) behavior of silver nanoparticles (Ag NPs) decorated hexagonal boron nitride (hBN) nanocomposites. Although Ag NPs are known for their excellent plasmonic properties, their susceptibility to oxidation in ambient conditions significantly reduces SERS activity. To overcome this, a femtosecond laser-assisted single-step novel approach is developed for synthesizing hybrid Ag-hBN nanocomposites via ablating Ag target in a solution of exfoliated hBN nanosheets, forming uniformly embedded Ag NPs on hBN nanosheets. The morphological characteristics and elemental compositions were validated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). TEM analysis revealed that Ag NPs averaged 15 nm in size, while hBN nanosheets had lateral dimensions of approximately 250 nm. The SERS activity of the prepared nanocomposites was investigated using dye and explosive molecules, achieving detection sensitivities of 1 μM and 100 μM, respectively, with high reproducibility. These detection sensitivities are significant as they demonstrate the potential of the Ag-hBN nanocomposites for sensitive and reliable detection of trace amounts of analytes. Notably, the Ag-hBN nanocomposites showed enhanced SERS activity compared to pure Ag NPs, with a 2.5-fold improvement for Nile blue, 3.6-fold for methylene blue, and 2.4-fold for RDX. The current study also demonstrates that hBN prevents Ag NPs’ oxidation and preserves the SERS functionality even at elevated temperatures. Furthermore, the NLO properties of the nanocomposites were investigated using the standard Z-scan technique, revealing two-photon and three-photon absorption coefficients of 3×10−4 cm/GW and 6.5×10−5 cm3/GW2, respectively. The findings highlight the potential of Ag-hBN nanocomposites to enhance SERS and NLO devices, enabling future applications in sensing and photonics.

Enhancing Mechanical Strength and Microstructural Properties of Alkali-Activated Systems through Nano Graphene Oxide Dispersion and Polycarboxylate Ether Admixture

The dispersion of graphene oxide (GO) nanoparticles in alkali-activated concrete with / without superplasticizers can help in understanding the effect it has on its mechanical strength and microstructural properties. The dispersion of GO in alkali activator fluid of 10(M) and 12(M) with / without polycarboxylate ether (PCE) admixture has been explored in this study. The alkali activator solution of 10(M) NaOH solution with PCE shows better dispersion than 12(M) NaOH solution, as higher alkalinity leads to agglomeration of GO. The study investigated the effect of incorporating PCE in GO-based alkali-activated slag (AAS) mortar with 8(M), 10(M) and 12(M) of alkaline activator solution. The mechanical strength and microstructural characteristics of conventional AAS (without both GO and PCE), GO-based AAS (without PCE) and GO-based AAS with PCE of the respective molar concentration of activator fluid are analysed. The mechanical strength of the AAS mortars has been evaluated using compressive, flexural, and splitting tensile strength testing. The micro-structural and mineralogical characteristics of the binders are evaluated using Field Emission Scanning Electron Microscopy (FESEM with EDS), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The addition of only GO (0.06% of binder w/w) and the addition of both GO and PCE in AAS have shown up to 30% and 40% mechanical strength improvement with respect to conventional AAS, respectively. The effectiveness of PCE and percentages of strength improvement are higher with a lower molarity of activator fluid, and vice versa. Adding GO and PCE to the AAS system improves its hydration rate and denser microstructure, enhancing its strength.