Field Emission Scanning Electron Microscopy Images Research Articles

Endosperm structure and Glycemic Index of Japonica Italian rice varieties.

Given that rice serves as a crucial staple food for a significant portion of the global population and with the increasing number of individuals being diagnosed with diabetes, a primary objective in genetic improvement is to identify and cultivate low Glycemic Index (GI) varieties. This must be done while ensuring the preservation of grain quality. 25 Italian rice genotypes were characterized calculating their GI "in vivo" and, together with other 29 Italian and non-Italian genotypes they were studied to evaluate the grain inner structure through Field Emission Scanning Electron Microscopy (FESEM) technique. Using an ad-hoc developed algorithm, morphological features were extracted from the FESEM images, to be then inspected by means of multivariate data analysis methods. Large variability was observed in GI values (49 to 92 with respect to glucose), as well as in endosperm morphological features. According to the percentage of porosity is possible to distinguish approximately among rice varieties having a crystalline grain (< 1.7%), those intended for the preparation of risotto (> 5%), and a third group having intermediate characteristics. Waxy rice varieties were not united by a certain porosity level, but they shared a low starch granules eccentricity. With reference to morphological features, rice varieties with low GI (<55) seem to be characterized by large starch granules and low porosity values. Our data testify the wide variability of Italian rice cultivation giving interesting information for future breeding programs, finding that the structure of the endosperm can be regarded as a specific characteristic of each variety.

Evaluation of substrate temperature role on the structural, morphological, optical, and mechanical properties of magnetron sputtered Cu2Se thin films

Copper Selenide (Cu2Se) thin films were deposited on a float glass substrate using magnetron sputtering with a radio frequency (RF) source at a power of 70 W and by varying substrate temperatures (Tsub) from 50 °C to 400 °C with an interval of 50 °C. The influence of the Tsub on the morphological, structural, and mechanical characteristics of Cu2Se thin films was investigated using the Grazing Incidence X-ray diffraction (GIXRD), Raman spectra, Field Emission Scanning Electron Microscopy (FESEM) combined with energy-dispersive spectroscopy (EDS) and Nanoindentation. The results of the GIXRD analysis suggest that the cubic Cu2-xSe phase could be observed when the deposition took place at Tsub of 50 to 200 °C. However, for the films that were deposited at temperatures higher than this range, i.e., from 250 °C to 400 °C, the elements Cu and Se formed an intermediate phase. Raman bands assigned at 261 cm−1 confirm the cubic-Cu2Se phase. The average grain size measured from FESEM images increase with varying Tsub from 50 °C to 400 °C with a value of 230 nm to 320 nm. The variation in the Tsub results in the evolution of the microstructure and EDS shows the variation in the stoichiometric ratio of deposition. The energy of the band gap decreases with an increase in Tsub, leading to the overlapping of energy levels. The nanoindentation tests show that the hardness dropped as the Tsub increased from 50 °C to 400 °C. The Cu2Se film deposited at Tsub 50 °C had the highest hardness value of 1.91 ± 0.47 GPa.

Exploration of properties (crystallographic, morphological, optical) of nano cobalt aluminate synthesized by facile sol–gel method: Effects of sintering temperature

The present work reports on the facile sol–gel synthesis of CoAl2O4 nanoparticles using cobalt nitrate and aluminum nitrate as the metal salts and citric acid and glycerol as chelating agents. The consequence of sintering temperature on the structure, particle size, morphology, composition, zeta potential, color, and reflectance spectra at neutral pH condition were explored with various instrumental techniques. The CoAl2O4 nanoparticles were characterized with Powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FESEM), Energy dispersive spectroscopy (EDS), Nanoparticle size analyzer, Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV–Vis-DRS) and CIE-Lab colorimetric method. From the data of PXRD, the crystallite size and peak profile analysis were investigated by four different models. It was found that the average crystallite size varied in the range of 28.01–320.97 nm and single-phase cubic CoAl2O4 was formed without any impurity. The average particle size of CoAl2O4 nanoparticles was discerned from the FESEM images using ImageJ software and from a nanoparticle size analyzer. The average particle sizes were increased with the increasing sintering temperature. The values of zeta potential found in all of the samples represented high dispersion stability. From the colorimetry of CoAl2O4 nanoparticles, the CIE-La*b* output illustrated high purity and brightness and the spectra.

Enhanced photoelectrochemical performance of quantum dot-sensitized solar cell using Cu2+ co-doped CdS and CdSe nanoscrystals.

Today, nanoscrystals are researched and developed very quickly because of their advantages in many areas of life. One of the potential applications is quantum dot-sensitized solar cells. This is a green, clean, environmentally friendly cell, and has been studied by scientists since 2000. In this study, we fabricated photoanodes with Cu2+ ions co-doped into cadmium sulfide (CdS) and cadmium selenide (CdSe) nanoscrystals by successive ionic layer adsorption and reaction, and chemical bath deposition methods to improve absorption spectral intensity of films. The results showed that the absorption intensity increased by eight times compared with our previous results on Cu2+ ions doped with CdSe nanoscrystals. The CdS:Cu2+ film is optimized at 2% doping, the efficiency is 4.6819%, and the current density is 27.3501 mA.cm-2, which is higher when compared with the Cu2+ ion only doped into the CdSe quantum dot (19.915 mA.cm-2). In addition, the composition of the photoanode was determined by surface and cross-sectional field-emission scanning electron microscope images, and the structure of the film was determined by X-ray diffraction, energy-dispersive X-ray spectroscopy mapping and X-ray photoelectron spectroscopy. Finally, the film's optical properties were studied by ultraviolet-visible spectroscopy, photoluminescence spectroscopy and electrochemical properties by electrochemical impedance spectroscopy. The results obtained have been discussed and presented in great detail.

Impact of a precise pH value change on the characteristics of deposited tin monosulphide films onto a flexible substrate

The chemical bath deposition technique (CBD) is considered the cheapest and easiest compared with other deposition techniques. However, it is highly sensitive to effective parameter deposition values such as pH, temperature, and so on. The pH value of the reaction solution has a direct impact on both the nucleation and growth rate of the film. Consequently, this study presents a novel investigation into the effect of a precise change in the pH reaction solution value on the structural, morphological, and photoresponse characteristics of tin monosulphide (SnS) films. The films were grown on a flexible polyester substrate with pH values of 7.1, 7.4, and 7.7. The X-ray diffraction patterns of the grown films at pH 7.1 and 7.4 confirmed their polycrystalline nature. Additionally, an observed alteration in the crystal structure occurred as the pH value increased from 7.1 to 7.4, resulting in a transition from an orthorhombic crystal structure to a cubic crystal structure. In contrast, the XRD pattern of the grown film at pH 7.7 revealed that it was amorphous. The field-emission scanning electron microscopy images revealed a flower-like morphology for the grown film at 7.1, whereas the grown films at 7.4 and 7.7 revealed a grain morphology. The results also showed that the pH values were also having an important effect on the energy gap value (Eg) of films; the Eg values were 1.46, 1.57, and 1.65 eV for pH 7.1, 7.4, and 7.7, respectively. The photodetectors fabricated using grown films exhibited excellent photoresponse characteristics when subjected to near-infrared (750 nm) illumination. It was also demonstrated that the photodetector using the cubic structure film possessed faster response times and greater sensitivity than the photodetector using the orthorhombic structure film.

Machine learning-guided morphological property prediction of 2D electrospun scaffolds: the effect of polymer chemical composition and processing parameters.

Among various methods for fabricating polymeric tissue engineering scaffolds, electrospinning stands out as a relatively simple technique widely utilized in research. Numerous studies have delved into understanding how electrospinning processing parameters and specific polymeric solutions affect the physical features of the resulting scaffolds. However, owing to the complexity of these interactions, no definitive approaches have emerged. This study introduces the use of Simplified Molecular Input Line Entry System (SMILES) encoding method to represent materials, coupled with machine learning algorithms, to model the relationships between material properties, electrospinning parameters and scaffolds' physical properties. Here, the scaffolds' fiber diameter and conductivity have been predicted for the first time using this approach. In the classification task, the voting classifier predicted the fibers diameter with a balanced accuracy score of 0.9478. In the regression task, a neural network regressor was architected to learn the relations between parameters and predict the fibers diameter with R2 = 0.723. In the case of fibers conductivity, regressor and classifier models were used for prediction, but the performance fluctuated due to the inadequate information in the published data and the collected dataset. Finally, the model prediction accuracy was validated by experimental electrospinning of a biocompatible polymer (i.e., polyvinyl alcohol and polyvinyl alcohol/polypyrrole). Field-emission scanning electron microscope (FE-SEM) images were used to measure fiber diameter. These results demonstrated the efficacy of the proposed model in predicting the polymer nanofiber diameter and reducing the parameter space prior to the scoping exercises. This data-driven model can be readily extended to the electrospinning of various biopolymers.

Synthesis, characterization, and photocatalytic activities of green sol-gel ZnO nanoparticles using Abelmoschus esculentus and Salvia officinalis: A comparative study versus co-precipitation-synthesized nanoparticles

BackgroundThe development of green chemistry methods involving plant-based nanoparticle synthesis presents an affordable and eco-friendly approach for wastewater treatment and color removal. This study aimed to synthesize ZnO nanoparticles using the sol-gel method with Salvia officinalis and Abelmoschus esculentus plants, examining their photocatalytic efficiency for organic dye removal. MethodsTo compare the properties of ZnO nanoparticles, another type of ZnO-NPs was synthesized using the co-precipitation method. The characterization of synthesized nanoparticles was performed using thermogravimetric analysis (TGA-DTG), X-ray diffraction (XRD), Dynamic Light Scattering (DLS), Zeta potential (ZP), field emission scanning electron microscopy (FE-SEM), Energy Dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), and UV–Vis spectrophotometry. ResultsBased on XRD results, the average crystalline size of nanoparticles was calculated using the Debye-Scherer equation for synthesized nanoparticles using the S. officinalis at 22.99 nm and for the A. esculentus at 29.79 nm, and for the co-precipitation method at 18.83 nm. The FE-SEM images showed spherical ZnO nanoparticles. Photocatalytic properties of ZnO-NPs were investigated for remove of methylene blue organic dye in the presence of UV light. The pH 10 was identified as the best pH, which had the highest percentage of color degradation. All three types of nanoparticles were tested by up to 360 min to optimize the dyeing time. For A. esculentus, the highest percentage of color removal occurred in the first 90 min (41.0 %), for S. officinalis nanoparticles between 75 and 90 min (86.9 %), and for chemically synthesized nanoparticles between 30 and 45 min (100 %). ConclusionsIn conclusion, the best MB dye degradation capacity belonged to co-precipitation ZnO nanoparticles followed by S. officinalis and A. esculentus nanoparticles.

Study of rectifying properties and true Ohmic contact on Sn doped V2O5 thin films deposited by spray pyrolysis method

In this paper, V2O5 thin-films were deposited on glass substrates by using the ultrasonically nebulized spray pyrolysis technique. Doping concentration of 1 %, 2 %, and 7 % of Sn, in V2O5 thin-films is studied by using metal–semiconductor-metal (MSM) based device structure. X-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM) were used to analyze the surface morphology of the thin films. The XRD spectroscopic analysis shows the crystal size of above-mentioned samples, to be respectively 39 nm, 58 nm, 60 nm and 72 nm. The FESEM images showed the enhancement of crystal size with increase in Sn doping concentration. The optical properties of Sn doping on V2O5 thin film were studied by using UV–Vis spectrometer. The UV–Vis spectroscopic analysis shows that the absorption coefficient values decrease with increase in concentration of Sn metal doping in V2O5 thin film. The activation energies of all thin-film samples were calculated from Arrhenius plots and were found to be 0.938 eV, 1.101 eV, 1.11 eV and 1.169 eV, respectively, for all the thin-film samples mentioned above. The MSM based structure was fabricated by using a shadow mask and thermal evaporation. Later, the I-V characteristics of all the thin films were obtained by using semiconductor parameter analyzed at a biased voltage between −50 V and + 50 V with a step size of 1 V. Rectification ratio of the V2O5 films is significantly enhanced as the doping concentration increases. It was found that the rectification ratio of undoped V2O5 thin films increased linearly from 1.018 to 1.059 with an increase in temperature from room temperature to 130 °C. Similar trend was followed for 1 % (from 1.079 to 1.198), 2 % (from 1.081 to 1.224) and 7 % (from 1.095 to 1.311) Sn doped films. These results show the potential application of V2O5 thin films in the field of optoelectronics and thin film gas sensors.

Fabrication and characterization of gold nanoparticles using alginate: In vitro and in vivo assessment of its administration effects with swimming exercise on diabetic rats.

Gold nanoparticles (AuNPs) have unique features that might lead to the development of a new class of diabetic medicines. AuNPs were biosynthesized utilizing sodium-alginate. UV-Vis-spectroscopy, Fourier transforms infrared, field emission scanning electron microscopy (FESEM), and energy dispersive X-ray were used to examine the particles. The potential of AuNPs for improving the diabetes condition was examined along with swimming in rats. FESEM image revealed the spherical morphology with an average particle size of 106.6 ± 20.8 nm. In the diabetic group, serum glucose, blood urea nitrogen (BUN), creatinine, cholesterol, and triglyceride (TG) levels were significantly higher than the control group. Low-density lipoprotein (LDL) was significantly higher and high-density lipoprotein (HDL) was significantly lower in the diabetic group compared to the control group. Malondialdehyde (MDA) levels were also significantly higher in the D group. However, in the groups treated with swimming and gold, these parameters were significantly improved. Specifically, serum-glucose, BUN, creatinine, cholesterol, and TG levels were significantly reduced, while LDL was significantly decreased in the diabetic + swimming + AuNPs group and HDL was significantly increased in the diabetic + AuNPs group. MDA levels were significantly decreased in the treated groups, and other antioxidants were significantly improved in the diabetic + swimming + AuNPs group. Catalase levels were also significantly improved in the D + gold group. It can be concluded that both AuNPs and swimming can decrease diabetic complications.

Low-energy extraction of lignocellulose nanofibers from fresh Musa basjoo pseudo-stem

This study presents a novel approach for the extraction of cellulose nanofibers (CNF) and lignocellulose nanofibers (LCNF) from Musa basjoo pseudo-stems, a relative of bananas, without the need for extensive drying. Instead, wet pseudo-stems were compressed and treated with NaOH solutions at varying temperatures and durations. The extracted material exhibited the characteristic peaks of cellulose I in X-ray diffraction (XRD) patterns, similar to those obtained from dried pseudo-stems. Fourier-transform infrared (FT-IR) spectroscopy confirmed the presence of cellulose I in the treated material and lignocellulose nanofiber clearly shown at 1600-1500, 1421, 1365, and 1161 cm-1. Composition analysis by Van Soest fiber analysis revealed a higher cellulose content in the treated material of wet pseudo-stems compared to that obtained from dried pseudo-stems, indicating the effectiveness of this low-energy extraction method. Meanwhile, field-emission scanning electron microscopy (FE-SEM) images demonstrated clear LCNF in the nanometer scale fibers after NaOH treatment. Overall, this study successfully demonstrated the extraction of LCNF from wet pseudo-stems of Musa basjoo with NaOH treatment at 70°C for 3 hours with 80% extraction result, providing a more efficient and low-energy approach for utilizing waste from Musa basjoo and bananas.

Sound absorption and thermal insulation performance of sustainable fruit stone panels

The sound absorption and thermal insulation behavior of panels made of different fruit stones, including peach, apricot, plum, date, and black cherry, were investigated. To this end, samples in the crushed and uncrushed forms were fabricated with thicknesses of 30 and 50 mm. The FE-SEM (Field Emission Scanning Electron Microscopy) and Atomic Force Microscopy (AFM) images showed that the studied stones have different morphological and topological surfaces, which in turn lead to different sound absorption coefficients (SACs) and effective thermal conductivities (Keff). It was found that smaller fruit stones with higher surface roughness generally have higher noise reduction coefficients, and this was more pronounced for samples of 50 mm thickness. In addition, samples in the crushed form enjoyed superior sound absorption performance compared with their uncrushed counterparts. The SAC peak in the crushed form appeared at lower frequencies and its value was higher than that of the uncrushed stones. Moreover, when the air gap was introduced, all samples showed excellent sound absorption at frequencies of 400–600 Hz. It was found that, while an increase in sample thickness led to an enhancement in SAC at low and middle frequencies, the Keff values did not significantly change. Uncrushed samples demonstrated enhanced thermal insulation properties compared to their crushed counterparts. The Keff values of the specimens were found to be in the range of 0.087–0.204 W.m−1 K−1, indicating the good thermal insulation performance of the panels. The frequency-dependent SACs of fruit stone panels were predicted using the Johnson-Champox-Allard and Attenborough models, and acceptable consistency was observed.

A TEM study of nanostructures and interfaces in the hot-press sintered ZrB2–SiC–Si3N4 composites

A fully dense ZrB2–30 vol% SiC composite containing 5 wt% Si3N4 and 4 wt% phenolic resin (1.6 wt% carbon) was sintered using the hot-pressing route under the external pressure of 10 MPa at 1900 ºC for 2 h. The microstructural evolution and interfacial phenomena were scrutinized using advanced microscopy facilities such as high-resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). The FESEM images showed the ZrB2 and SiC grains without any evidence of Si3N4. The formation of the hexagonal BN (hBN) phase was proven in the sintered composite. The hBN nanosheets had a graphite-like morphology with an average thickness of 20 nm. This phase has a perpendicular orientation to the pressure direction and prevents abnormal ZrB2 grain growth. Two types of ZrB2/SiC interfaces were detected, which exhibited an amorphous phase along with the grain boundary and a clean/smooth interface, resulting from the Si3N4 addition. HRTEM and inverse fast Fourier transform (IFFT) observations disclosed that the d-spacing value in the ZrB2 grain (0.335 nm) is higher than those reported in the literature. Furthermore, it was found that the exerted pressure during the sintering distorted atomic planes. The presence of numerous dislocations within the ZrB2 grains confirmed dislocation creep as the main densification mechanism.

INFLUENCE OF ANNEALING TEMPERATURE ON ZINC OXYSULPHIDE THIN FILMS PROPERTIES DEPOSITED BY THERMAL SPRAY TECHNIQUE

This article studies the effects of annealing temperatures on the stoichiometry, structure, and optical characteristics of Zinc Oxysulphide thin films deposited on glass substrates using the thermal spray method. The annealing was done in the air under a temperature of 150 ºC, 250 ºC and 350 ºC. Field Emission Scanning Electron Microscopy (FESEM), X-ray diffractometry (XRD), and a UV-Vis Spectrophotometer were utilized to examine the thin films' morphological, structure, and optical characteristics as grown and annealed samples. It has been observed that the film thickness decreases as the annealing temperature increases. The XRD pattern demonstrates that as-prepared and annealed samples at 250C, and 350C are amorphous, while film annealed at 150 C is crystalline with the hexagonal phase and orientated along (110) plane. FESEM image of the as-prepared Zinc Oxysulphide thin films shows flower-like sheet nanostructures. However, for the annealed samples, the FESEM images show cone-like with a combination of sheets and aggregate nanoparticles. EDX analysis reveals the presence of Zn, O as well as sulfur. The transmittance of the film decreases from 63% to 37% and the band gap energy reduces slightly from 3.99 to 3.92 eV as the annealing temperature increase.

The spectral properties and dispersion parameters of electrospun nanofibers Poly(vinyl alcohol/ Poly(acrylamide)

Electrospun nanofibers based on polyvinyl alcohol (PVA), polyacrylamide (PAAm), and a PVA-PAAm blend (50/50 wt.%) were effectively made a room temperature(RT) and a voltage of (12kV). The products were studied using Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy(FT-IR) and Ultraviolet-visible (UV–Vis) spectroscopy. The result of FESEM analysis showed that the polymer PVA, PAAm, and blend samples produced a random distribution of fine fibres at an average diameter of (214.12, 317.1, 157.65) nm with a smooth surface. In addition, the FESEM images demonstrate the fibres' suitability for use in gas sensing applications due to their branching fibres and porosity surface. XRD showed that the film polymeric of PVA, PAAm polymeric blend PVA-PAAm was seen to have a semicrystalline nature. According to the FTIR analysis, the PVA and PAAm networks in the PVA-PAAm polymer nanofibers were entangled due to the powerful hydrogen bond contact between the PAAm and PVA chains. Observed around (3473.79 and 3414) cm-1 were attributed to the N–H vibration and overlapped to O–H stretching. The spectra of the prepared films exhibit prominent absorption peaks, which are at the wavelength range (200-320) nm. PVA-PAAm polymer nanofibers decrease the energy gap from 3.70eV to 3.40eV. The Wemple-DiDomenico model was used to derive dispersion parameters such as dispersion energy, single oscillator energy, Urbach energy, the static refractive index and the moments of optical spectra the result of calculating by this model was compatible with that value calculated by the Tauc relation. While increased which qualifies them to be used in the electronic devices.

Green synthesis of novel green ceramic-based nanoparticles prepared by sol-gel technique for diverse industrial application

Excellent characteristics and a wide range of applications made nanotechnology a key focus for modern researchers. However, environment-friendly and cost-effective measures still need to be taken to synthesize nanoparticles. This research focused on synthesizing Green Ceramic-based Nanoparticles (GCNPs) using the sol-gel method. This method is environment-friendly and cost-effective. Different analytical techniques were employed to characterize the obtained GCNPs. Crystallographic parameters were obtained through the X-ray diffraction (XRD) analysis. Morphological analysis was performed by Field Emission Scanning Electron Microscope (FESEM) analysis. The presence of different elements was identified by elemental analysis (EDX). Various functional groups present in the GCNPs were identified by Fourier Fourier-transformed infrared Spectroscopy (FTIR) analysis. XPS and zeta potential analyses composition characterization and surface charge stability, respectively. Antibacterial strains against E. coli were performed. The FTIR analysis confirmed the presence of different organic compounds in the synthesized GCNPs which helped to increase bacterial inhibition in the antibacterial test. The FESEM images confirmed irregularity in the shape and aggregation of the synthesized GCNPs. The minimum average particle size was obtained from sample S2 which is 376.35 nm. EDX analysis confirmed the presence of silicon particles in the GCNPs. The crystalline nature of the GCNPs was assured by XRD analysis. The silicon percentages were higher than the other atoms shown by the XPS analysis. A significant amount of bacterial inhibition which was 18.0 mm obtained from sample S3. Finally, GCNPs were prepared, characterised, and significantly applied for diverse implementation for the safety of the healthcare field on a broad scale.

Reduction of Recombination Processes in PVC Photocatalytic Membranes Modified with Green Prepared Nanoparticles

The enhanced photocatalytic membranes were prepared by green synthesized Tin dioxide (SnO2) and manganese dioxide (MnO2) nanoparticles (NPs) blended with polyvinyl chloride (PVC) polymeric solution to produce a photocatalytic flat sheet membrane that was used in wastewater treatment. The surface and morphological structure of the produced membranes were studied using atomic force microscopy (AFM), and field emission scanning electron microscopy (FESEM). The elemental compositions and chemical bonding of the membranes were examined using Raman and Fourier transform infrared spectroscopy (FTIR). A sessile-drop approach was used to look at the membrane surface's hydrophilicity. Images of FESEM, AFM, Raman spectra, and FTIR analysis proved the existence of NPs on membrane surfaces. The modified membrane's hydrophilicity was significantly improved after NPs addition. Furthermore, Humic acid removal under darkness was enhanced for the modified membrane than the blank PVC. At the same time, it enhanced from 81% to 92, 100, and 99% for SnO2, MnO2, and SnO2/MnO2 respectively. The photocatalytic ability of the Photocatalytic membranes was examined in sunlight where it was found to be enhanced when exposed to sunlight as compared to when kept in the dark. The prepared membranes exhibited an enhancement removal performance. Both the water flux and the rejection were enhanced in sunlight. The SnO2/MnO2 photocatalytic membrane exhibited a better removal ability and good water flux. The potential utility of our research lies in its application within the water treatment industry, specifically as an effective technique for modifying PVC membranes.

Copper cobalt oxide microstructures resembling marigold flowers were created by solvothermal synthesis for high-performance supercapacitors

The cathode electrode material for the battery-type CuCo2O4 electrode's hybrid supercapacitor applications was investigated. CuCo2O4 (MFCCO) microstructures resembling marigold flowers were created using a straightforward solvothermal procedure. X-ray diffraction (XRD), selected area electron diffraction (SAED) pattern, field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure and morphology of the MFCCO. The flower-like shape, which comprised many nano-petals, was clearly visible in the FE-SEM image. Electrochemical experiments using the MFCCO electrode exhibit typical battery-type electrode materials. The CuCo2O4 electrode, which resembled a marigold flower, displayed good long-term cyclic stability and a maximum specific capacity of 627C g-1 at a current density of 0.5 A/g. The MFCCO electrode's high specific capacity, excellent cyclic stability, and low internal and charge transfer resistance supported the developed material's suitability as a positive electrode for hybrid supercapacitor applications.

Supercapacitor electrode properties of NiWO4 nanocrystals processed by thermal plasma and deposited on the FTO substrate

In this communication, nickel tungstate (NiWO4) nanocrystals were prepared using the coprecipitation method at 90 °C for 6 h and processed by thermal plasma (TP) at 600 °C for 1 h. X-ray diffraction (XRD), Rietveld refinement data, micro-Raman, and Fourier transform infrared (FT-IR) spectroscopies were employed to analyze their structure and optical data. The morphology was observed through field emission scanning electron microscopy (FE-SEM) images. Moreover, their supercapacitor electrode properties were investigated in detail. XRD patterns, Rietveld refinement, micro-Raman/FTIR spectra, and FE-SEM images confirm pristine NiWO4 nanocrystals with a monoclinic structure, symmetric and antisymmetric stretch vibrations of ONiO and OWO bonds, which are related to IR- and Raman-active vibrational modes, spherical shape with average crystal sized ~29.2 nm. These NiWO4 nanocrystals present a high specific capacitance of 351.26 F g−1 at 40 mV s−1, in comparison with NiWO4 nanocrystals processed in heat treatment conventional (120 F g−1 at 40 mV s−1), which can be applied as a stable cathodic electrode. These results suggest that NiWO4 nanocrystals processed by TP and deposited on FTO substrate are good candidates for use as electrodes for energy storage devices in the next generation of batteries.

Bifunctional activity of NiCo on carbon nanotube catalyst for oxygen reduction and evolution on anion exchange membrane-unitized regenerative fuel cells (AEM-URFCs)

Cobalt or nickel/cobalt on carbon nanotube (Co@CNT, NiCo@CNT) catalysts were synthesized by heat treatment of the metal-organic framework, ZIF-67. The X-ray patterns of the synthesized ZIF-67 and the catalysts confirmed their crystalline structures. The field-emission scanning electron microscopy (FESEM) images of ZIF-67 after pyrolysis showed that the dodecahedral crystalline structure of ZIF-67 was retained, and the organic ligands were converted into CNTs and graphitic carbon in an H2 gas environment. The transmission electron microscopy images of the synthesized catalysts confirm the presence of the Ni or Co atoms at the tips of the carbon nanotubes. The NiCo@CNT catalyst exhibited a higher surface area and larger pore volume than those of Co@CNT. X-ray photoelectron spectroscopy confirmed the presence of pyridinic nitrogen, which forms Co-Nx and Ni-Nx, active groups. In anion exchange membrane-unitized regenerative fuel cells (AEM-URFC), NiCo@CNT as a bifunctional oxygen electrode (BOE) catalyst showed a higher current density and lower Tafel slope compared to that of Co@CNT. The cell with the NiCo@CNT catalyst in BOE exhibits the highest current density of 130.0 mA cm−2 at 0.3 V (fuel cell mode) and 32.5 mA cm−2 at 2.0 V (water electrolyzer mode) among all catalysts. This cell exhibited a maximum 38.90 % round trip efficiency, which was comparable to that of the benchmark noble metal (Ir-black) catalyst (38.40 %).

Morphological, optical, and electrical properties of CoxCa(0.90-x)Ni0.10Fe2O4 based flexible metamaterial substrate for industrial chemical contamination sensing

State-of-the art research on conventional microwave substrates reveals limitations of restricted flexibility, poor adaptability to irregular surfaces, and reduced effectiveness in complex sensing environments, leading to the development of a flexible microwave substrate using Co–Ca ferrite for feasible applications in detecting industrial chemicals. In this paper, CoxCa (0.90-x) Ni0.10Fe2O4 (x = 0.25, 0.50, and 0.75) based flexible substrate is developed through the sol-gel method, and a rectangular enclosed cross-dumbbells (RECD) metamaterial structure is designed for industrial chemical contamination sensing. The X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) are used to morphological analysis of the nanoparticles of the substrate. XRD patterns shows the presence of crystalline phases, which facilitate the determination of strain within these materials. FESEM images demonstrate a structural composition characterized by nanosized grains and capillary-nanopores, where these nanosized grains are found uniformly distributed across the film's surface and results structural homogeneity. The synthesized nanoparticles are employed as a solid substrate utilizing PVA (polyvinyl alcohol) to ensure a uniform structure. The dielectric constant of the developed substrate is measured using the DAK 3.5 dielectric measurement kit, and it shows dielectric permittivity values ranging from 1.77 to 3.32 with loss tangents ranging from 0.031170 to 0.1929 for x = 25 % to x = 75 %. Metamaterial characteristics of the fabricated RECD structure on Co–Ca ferrite is analysed and μ-negative characteristics is achieved from 4.7 GHz to 6 GHz. Additionally, the reflection coefficient of the RECD metamaterial is also investigated for different bending condition up to an angle of 30ο. The simulated and measured S21 results strongly match each other. The sensing performance is evaluated for three concentrations of methanol and ethanol, demonstrating excellent contamination sensing capabilities with sequential frequency shifting. This study undoubtedly revealed that Co–Ca ferrite-based flexible metamaterial have great potential for high performance industrial chemical contamination sensing applications.