Field Emission Scanning Electron Microscopy Images Research Articles

Design, fabrication, and evaluation of green mesoporous hollow magnetic spheres with antibacterial activity

Hollow silica nanostructures are receiving more attention due to their special features such as low density and very high surface-to-volume ratio compared to other types of nanoparticles. In this research, an efficient method for the synthesis of hollow magnetic spheres with antibacterial properties is investigated. These hollow magnetic spheres are prepared in several steps and identified by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDS), Elemental mapping, High-resolution transmission electron microscopy (HRTEM), and vibrating-sample magnetometer (VSM) techniques. Also, the antibacterial property of magnetic hollow spheres is investigated by the agar diffusion method on the Acinetobacter baumannii, Staphylococcus epidermidis, Proteus mirabilis, Staphylococcus aureus, and Pseudomonas aeruginosa. Due to the high surface-to-volume ratio, their contact level with the surrounding environment is extremely high, which increases the effectiveness of their antibacterial properties. The results of FTIR bond analysis show that TEOS precursor particles established surface bonds with CTAB activators during the synthesis process, and the presence of SiOSi bonds in the range (600–1320 cm−1) indicates the formation of silicate chains. The size of the nanoparticles based on the HRTEM images was estimated to be approximately 40 nm. FESEM images confirmed the spherical shape of nanoparticles with an average size of 350 nm. The antibacterial feature, porous walls and empty space inside the spheres made it possible to facilitate and control the drug release and use it in medicine, especially for wound healing. Also, due to the magnetic properties of the manufactured nanospheres, they can be used in many ways in medical fields, especially in the treatment of cancer. In the continuation of the work, it is suggested to use Ag/Fe3O4@@ magnetic hollow mesoporous spheres (HMS) as a suitable drug carrier due to increasing the efficiency and control of drug delivery with the capabilities of targeting/responding to stimuli, increasing the speed and effect of the drug.

Creating Nature-Inspired Surface Roughness and Modifying Surface Chemistry of PVDF Electrospun Fibers Using Low-Pressure Plasma towards Omniphobic Membrane for Long-term Distillation

Today, water scarcity as one of the world's most pressing challenges, has caused many concerns. Seawater desalination based on membrane distillation (MD) has been introduced as an effective solution to deal with this problem. The surface of membranes used in MD is required to be modified to guarantee long-term performance via creating resistance against membrane wetting by low surface tension feeds. In this regard, beetle skin-inspired roughness was created on the surface of poly(vinylidene fluoride) (PVDF) electrospun fibers using low-pressure plasma technique. Synergistically, 1H, 1H, 2H, 2H-perfluorooctyl acrylate (PFOA) was polymerized on the fiber surface to modify its chemistry. In other words, using the plasma polymerization technique, the membrane surface energy was reduced thanks to (1) the increase in membrane surface roughness and (2) the change in the membrane surface chemistry, as confirmed by field-emission scanning electron microscope (FESEM) imaging, X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. These changes led to an omniphobic membrane repelling water, engine oil and isopropanol with contact angles of 150°, 135°, and 119°, respectively. The long-term performance of the developed omniphobic membrane was demonstrated by conducting air gap membrane distillation (AGMD) for a duration as long as 600 min using a feed solution containing 3.5 wt% NaCl and 0.6 mM sodium dodecyl sulfate (SDS), which is ten times better than the performance of pristine membrane (60 min). Overall, the surface modification technique considered in this work yields an omniphobic membrane with stable long-term performance without compromising the membrane flux and salt rejection.

Enhanced photocatalytic performance of milkvetch-derived biochar via ZnO–Ce nanoparticle decoration for reactive blue 19 dye removal

In this research, the photocatalytic removal of reactive blue 19 (RB19) dye is investigated employing zinc oxide/cerium (ZnO@Ce) nanoparticles decorated with biochar under LED irradiation. Synthesis of ZnO@Ce nanoparticles decorated with biochar was performed utilizing the co-precipitation procedure and, then, the texture and morphology of the fabricated nanocomposite were analyzed using energy dispersive X-ray (EDX), field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), and Fourier transform infrared (FTIR) spectroscopy techniques. Moreover, FE-SEM images demonstrate that ZnO–Ce nanoparticles were successfully decorated on the surface of biochar. The specific surface areas of biochar and biochar/ZnO–Ce were 519.75 and 636.52 m2/g, respectively. To achieve the maximum yield in the removal of RB19 dye, the effects of operating variables including dye concentration, LED lamp power, biochar@ZnO–Ce catalyst dose, pH and H2O2 dose were explored. Besides, the maximum percentage of RB19 dye removal was 96.47% under optimal conditions, i.e. catalyst dosage of 100 mg, H2O2 dosage of 1 mL, pH of 9, initial dye concentration of 5 ppm, LED power of 50 W, and reaction time of 140 min. Furthermore, the kinetic analysis reveals that the removal of RB19 dye follows the pseudo-first order kinetic model, with calculated values of a reaction rate constant of 0.045 min−1 and a correlation coefficient of R2 = 0.99, respectively. Moreover, the reusability and recyclability of biochar@ZnO/Ce nanocatalyst was promising over five runs, with only a 6.08% decrease in RB19 dye removal efficiency. Therefore, it can be concluded that the biochar @ZnO/Ce photocatalyst can be promisingly applied for the removal of azo dyes in aqueous solutions.

Green synthesis, characterisation and antibacterial activities of Strobilanthes crispus-mediated silver nanoparticles (SC-AGNPS) against selected bacteria

This study aims to characterize and determine the antibacterial activities of synthesized Strobilanthes crispus-mediated AgNPs (SC-AgNPs) against Streptococcus mutans, Escherichia coli and Pseudomonas aeruginosa. S. crispus water extract acts as a reducing and capping agent in the synthesis of AgNPs. The synthesized AgNPs were characterized by using UV-Vis spectrophotometer, dynamic light scattering (DLS), field emission scanning electron microscope (FESEM), X-ray diffractometer (XRD) and Fourier transform infra-red (FTIR). FESEM images showed a rough surface with a spherical shape. The average size distribution of 75.25 nm with a polydispersity index (PDI) of 0.373. XRD analysis matched the face-centred cubic structure of silver. FTIR analysis revealed a shifted peak from 1404.99 to 1345.00 cm−1. MIC and MBC values of SC-AgNPs were 1.25 mg/mL and 2.5 mg/mL against E. coli, P. aeruginosa and S. mutans, respectively. Time-kill assay showed that SC-AgNPs significantly reduced bacterial growth as compared to non-treated bacteria. Morphologies of bacteria treated with SC-AgNPs were shrunk, lysed, irregular and smaller as compared to control. SC-AgNPs significantly disrupted the gene expression of eae A, gtf B and Pel A (p < 0.05). This study indicated that the synthesized SC-AgNPs were stable with enhanced antibacterial activities.

Green synthesized ZnO@CuO nanocomposites using Achyranthes aspera leaves extract for dielectric applications

ZnO@CuO Nanocomposites (NCPs) were synthesized using Achyranthes aspera plant’s leaves extract with varying weight percents of 25, 50 and 75 of ZnO. The leaves extract was prepared using laboratory distilled water with the help of magnetic stirrer at a temperature of 60ᵒC. An appropriate amount of zinc nitrate and copper nitrate were then mixed in the extract. ZnO@CuO NCPs were obtained after calcination of paste at a temperature of 400ᵒC. The annealed samples were characterized using various characterization techniques such as x-ray diffraction (XRD) spectroscopy, field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy and UV–vis spectrophotometry. FESEM images showed spherical morphology for CuO and ZnO@CuO NCPs, whereas, ZnO exhibited nanocapsules like morphology. The XRD patterns and FTIR spectra of green synthesized CuO and ZnO confirmed the formation of single-phase crystalline structure with monoclinic and hexagonal lattices. The XRD patterns of ZnO@CuO NCPs exhibited both phases corresponding to CuO and ZnO. FTIR spectra indicated all characteristic absorption bands of CuO and ZnO nanoparticles, which along with XRD Patterns confirmed the formation of ZnO@CuO NCPs. The optical band gap energy was calculated through Tauc’s relation using UV-Vis absorbance data and was found in the range of 1.54–3.05 eV. Optical band gap for nanocomposites is slightly less than that of pure ZnO and CuO nanoparticles. Dielectric studies established that the nanocomposites ZnO@CuO (25 and 50 wt% of ZnO) possess higher dielectric constant (K), dielectric loss and AC conductivity. ZnO@CuO (50 wt%) exhibits maximum dielectric constant of 14.49 × 103 with moderate dielectric loss. Hence, ZnO@CuO (50 wt%) could be a potential candidate for high K value device applications like capacitors and supercapacitors.

Nanocomposite Fe3O4-MWCNTs based on femtosecond pulsed laser ablation for catalytic degradation

Magnetite nanoparticle/multi-walled carbon nanotube composites (Fe3O4/MWCNTs) were prepared using femtosecond pulsed laser ablation of iron target immersed in functionalized MWCNTs by facile one-pot synthesis of pulsed laser ablation in liquid environmental for catalytic degradation of 4-ntrophenol from aqueous solution. The easily obtained magnetic nanocomposites were systematically characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). According to XRD, magnetite is the magnetic phase that has formed. A network of MWCNTs is seen in the FESEM image, together with nano‑iron oxides. Raman spectroscopy revealed that the reduction of the sp2 bond domains due to the strong contacts between iron oxide and MWCNT increased the D/G ratio, which may lead to structural distortions in the nanotubes. From FT-IR, the presence of new peaks in the finger print region related to Fe-O-Fe in Fe3O4, indicates that Fe3O4 has been successfully loaded onto the surface of MWCNTs. In addition, the prepared magnetic nanocomposite showed outstanding catalytic reduction activity for 4-NP when compared to MWCNTs and Fe3O4. The results demonstrated that the prepared nanocomposite could be a promising nanocatalyst for the catalytic reduction of 4-NP. The straightforward, speedy, and dependable Fe3O4/MWCNTs-based approach was found to be a possibly relevant technology for the targeted removal of pollutants and the treatment of wastewater.

Effect of Annealing on the Physical Properties of LaFeO&lt;sub&gt;3&lt;/sub&gt; Perovskite Nanomaterial Prepared by Co-Precipitation Method for H&lt;sub&gt;2&lt;/sub&gt; Generation

Nanocrystalline LaFeO3 (LFO) perovskite material was synthesized by a co-precipitation method using water bath technique. The properties of LFO perovskite nanoparticles has been thoroughly investigated for as deposited and annealed samples. The sample prepared was annealed at 800°C in the environmental air. X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and UV-visible spectroscopy were used to study structural, morphological, compositional and optical features. The X-ray diffraction study confirmed the formation of an orthorhombic LFO nanostructure. FESEM images showed the formation of a random distribution of nanoparticles with high porosity. EDS results showed the stoichiometric amount of La, Fe and O. Using UV-visible spectra, the energy band gap of the samples was discovered to be 2.1 eV and 2.34 eV for the as-deposited and annealed sample, respectively. This finding suggests that the LFO nanostructures created by this method can function as a photocatalytic material.

Mechanical properties of gelatin nano-hybrid mat reinforced by electrosprayed zein nanoparticles containing tarragon essential oil and in vitro release modeling

This research aimed to produce a nano-hybrid mat based on electrospun gelatin nanofibers (EGNFs) reinforced with electrosprayed zein nanoparticles (EZNPs) containing tarragon essential oil (TEO). TEO was first loaded at10%, 15%, and 20% w/w in the structure of EZNPs and used as a nano-biofiller to reinforce EGNFs mats. Field emission scanning electron microscopy (FESEM) images showed that using 15% w/w of the TEO in the structure of EZNPs led to the formation of particles with a uniform morphology and a smooth surface. Also, FESEM images revealed that increasing the level of nanoparticles from 0% to 10% w/w significantly reduced the diameter of EGNFs from 305.6 to 160.9 nm. The successful encapsulation of the TEO in the structure of EZNPs and the successful arrangement/incorporation of nanoparticles in the structure of EGNFs were confirmed using Fourier transform infrared analysis (FTIR). The EZNPs containing 15% w/w of TEO were employed in the EGNFs at 5%, 10%, and 15% w/w, and the used nanoparticles at10% w/w reinforced the tensile strength and Young's modulus of mats. The successful placement of EZNPs containing TEO in the EGNFs and the increase in thermal stability of TEO were confirmed by differential scanning calorimetry. In vitro release of TEO in simulated media proved that the dominant release mechanism is Fickian diffusion, and the best model describing the release behavior is Peleg's model. Using 10% EZNPs loaded with TEO is recommended to improve the mechanical properties and sustain the release of the essential oil in food systems and food packaging.

Mechanical, Microstructural, and Durability Properties of Soil Stabilized with Alkali-Activated Jarofix for Road Applications

In this study, we investigated the feasibility of jarofix [a zinc (Zn) smelter by-product] as a potential geopolymer binder in soil stabilization for road applications. Different combinations of soil–jarofix (SJ) mixtures were prepared using sodium hydroxide (NaOH), sodium silicate (Na2SiO3), and a combination of NaOH + Na2SiO3 as alkali activators. Unconfined compressive strength (UCS) tests were performed to examine the mechanical performance of SJ mixtures, and the effects of the jarofix content, curing conditions, and curing time were investigated. Changes that occurred during the geopolymerization process were further corroborated using field-emission scanning electron microscope (FESEM) images and energy-dispersive X-ray spectroscopy (EDS) analysis. Durability tests were also performed to examine the weathering resistance of selected SJ mixtures against 12 cycles of alternating wetting and drying. Based on the experimental results, the compressive strength of bare soil was increased 8.8 times, from 0.31 to 2.75 MPa, under ambient curing (AC, at 27 ± 2°C) conditions and 6 times, from 1.1 to 6.55 MPa, under dry curing (DC, at 60°C) conditions. This increase in compressive strength was attributed to the formation of sodium alumino-silicate hydrate (N–A–S–H) gel structures during the geopolymerization process, which led to a compact soil matrix, as confirmed by the FESEM images. The specimens cured under DC conditions showed greater strength improvement than those cured under AC conditions owing to the faster rate of the geopolymerization reaction at elevated temperatures. In addition, the Na2SiO3 and NaOH + Na2SiO3 solutions were found to be the most efficient alkali activators for the SJ mixtures cured under AC and DC conditions, respectively. This durability study revealed that the alkali-activated SJ mixtures exhibit a significantly smaller loss in mass than bare soil when exposed to 12 cycles of alternating wetting and drying. Moreover, the specimens cured under DC conditions were found to be more resistant to weathering than those cured under AC conditions. Overall, soil amended with 15% jarofix (through alkali activation) satisfies the minimum strength and durability criteria recommended by Indian standards for its use as a subbase and subgrade material. The current study shows that jarofix has the potential to be used as a geopolymer binder for soil stabilization, which can help the mining sector in minimizing the volume to be stored in tailings storage facilities.

Molecular layer deposition of hybrid silphenylene-based dielectric film

Molecular layer deposition (MLD) offers molecular level control in deposition of organic and hybrid thin films. This article describes a new type of inorganic–organic silicon-based MLD process where Aluminium chloride (AlCl3) and 1,4-bis(triethoxysilyl)benzene (BTEB) were used as precursors. Hybrid films were deposited at a temperature range of 300 to 500 °C and high growth per cycle (GPC) up to 1.94 Å was obtained. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) were used to analyze the appearance of the film surface. The hybrid film was amorphous in low-magnification FESEM images but some particulates appeared in high-magnification FESEM images (200 k). Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Time-of-flight elastic recoil detection analysis (ToF-ERDA), and X-ray photoelectron spectroscopy (XPS) were employed to analyze the structure and composition of the hybrid film. The ratio of Al/Si in the hybrid film was 0.8. The storage environment of the films affected their capacitance, dielectric constant, leakage performance, and breakdown voltage. A film stored in a high vacuum (10–6 mbar) environment had low leakage current density (< 10–6 A × cm−2 at an applied voltage of 28 V) and a dielectric constant of 4.94, which was much smaller than after storing in a humid ambient environment.Graphical abstract

Impact of 3D-printed PLA coatings on the mechanical and adhesion properties of AM60 magnesium alloys

This article investigates the impact of PLA (Polylactic Acid), an emerging bioplastic coating, fabricated with an additive manufacturing method (3D printing) on AM60 magnesium alloys. In addition to tensile testing, the adhesion of PLA on magnesium alloys with two epoxy and polyvinyl pyrrolidone adhesives was checked with the pull-off experiment. The strength of the bond between PLA and AM60 magnesium alloy was tested using two different adhesives, polyvinyl pyrrolidone and epoxy glue. The polyvinyl pyrrolidone adhesive resulted in an adhesion strength of 0.3 ± 0.02 MPa, whereas the epoxy glue resulted in a much stronger adhesion strength of 4.29 ± 0.71. Coating the AM60 magnesium alloy with PLA led to enhancements of 5.26 % in the yield stress (Syt), 7.79 % in the ultimate stress (Sut), 2.40 % in the elongation, and 2.34 % in the elastic module, as compared to the uncoated specimen. The fracture surface was also checked with FESEM (field-emission scanning electron microscopy) images. It was found that the fracture type for AM60 magnesium alloys with and without PLA coatings was brittle under tensile loading.

Dispersion stability analysis of copper sulphide nanoparticles in different medium

Nanoparticles (NPs) of covellite CuS have been synthesised using a modified polyol method at 160ºC - 165ºC without adding any extra surfactant. These NPs were charecterized by X-ray diffraction (XRD), Raman spectroscopy, Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive Analysis of X-ray (EDAX), Zeta potential and Dynamic Light Scattering (DLS) techniques. XRD data and three Raman modes confirm P63/mmc space group and hexagonal crystal structure of CuS NPs. EDAX data of Cu:S was slight differed from nominal 1:1 ratio due to extra S taken in synthesis. FESEM images show sheet-like NPs. The zeta potential (ξ) data analysis shows that the stability of the NPs is dependent on the dispersion medium, with high stability observed above pH 8.93 in an acidic medium. At pH 10.95, a highest ξ value of -37.64 mV is recorded in de-ionized water (DIW), while the nanoparticles are found to be unstable in ethanol and propanol as dispersion mediums. According to the hydrodynamic diameter (HD) data, the particles tend to agglomerate more quickly in ethanol and propanol compared to DIW. These findings are expected to be useful in various applications such as pigments in paints, batteries, pharmaceuticals, ceramics, and waste water treatment.

Highly Conducting Sc and Y co-doped Zirconia Solid Electrolyte Thin Films Prepared via Pulsed Laser Deposition for Solid Oxide Electrochemical Cells Applications

Scandia and yttria-stabilized zirconia (ScYSZ) have been widely used as electrolyte materials for solid oxide electrochemical cells (SOEC) applications due to its high ionic conductivity and stable mechanical and thermal properties. In this study, ScYSZ thin films were fabricated via pulsed laser deposition (PLD) method at substrate deposition temperature (Ts ) of 800 °C with varying oxygen oxygen partial pressures (). The as-deposited ScYSZ thin films were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and electrochemical impedance spectroscopy (EIS). XRD analysis revealed that all fabricated films, even with varying , have a polycrystalline cubic-fluorite structure. Morphological FESEM images revealed a good-quality dense ScYSZ electrolyte thin film with no visible cracks. Notably, a high total conductivity thin film of about 2.8x10-1 S/cm at 700 °C and low activation energy (Ea ) of 0.78 eV, from 500°Cto 700 °C, were achieved. Interestingly, the PLD-prepared ScYSZ dense solid electrolyte showed a higher total conductivity than the reported conductivities of zirconia-based solid oxide electrolytes.

Design and fabrication of fibrous media to facilitate autogenous smart self-healing properties in cracked-cementitious structures using polyethylene glycol (PEG) and silicon dioxide nanoparticles

A novel approach is introduced for smart of cracked cementitious structures using a fibrous media occupied by polyethylene glycol (PEG) and silicon dioxide (SiO2) nanoparticles. A series of fibrous media were designed and fabricated using different fiber types (polyethylene terephthalate (PET), hollow polyethylene terephthalate (HPET) and polypropylene (PP)), areal densities, thicknesses and porosities. The fibrous media was filled by PEG/SiO2 nanoparticles to perform further hydration and then healing the crack by capillary rise of water into the cracked paths. An analytical model was proposed to predict the minimum critical crack radius in cementitious structure to initiate smart release of nano-particles through fibrous media. The developed model calculates minimum crack radius based on properties of polymeric components and associate media’s porosity with capillary rise of nano-particles in accordance with Washburn’s equation. An artificial neural network (ANN) based on multilayer perceptron (MLP) was used to determine the most important parameter influencing self-healing efficiency. The self-healing efficiency of samples were also evaluated via ultrasonic test, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and X-Ray diffraction (XRD) analyses. CaCO3 formation and C-S-H growth deducted from FESEM image analysis and EDS/XRD results. The PET media showed more healing efficiency because of less crack radius. The areal density parameter was found to be the most effective parameter in reducing the capillary radius. The new proposed method is simple and applicable to promote hydration and crack filling of cement products such as canvas concrete.

Biogenic one-step synthesis of silver nanoparticles using Quisqualis indica linn flower extract: Characterization, molecular docking, and DFT studies

The present study reports a one-step, eco-friendly, and green synthesis route of silver nanoparticles (AgNPs) from the flower extract of Quisqualis indica Linn. Analytical techniques like Ultraviole-visible (UV–Vis), Field emission scanning electron microscope (FESEM), and X-ray diffraction (XRD) were used to investigate different physicochemical characteristics of AgNPs. The UV–Vis spectrum revealed the maximum absorption at 455 nm and FESEM images confirmed that the synthesis produces stable, polydisperse with a spherical, rod-shaped, triangular, and hexagon shape. XRD analysis at 2θ degrees of 38.1o, 44.3o, 64.7o, and 77.7o corresponding to the (111), (200), (220), and (311) planes, respectively, Bragg’s reflections of the face-centered cubic crystalline structure. Fourier transform infrared spectroscopy (FTIR) analysis suggested that the carbonyl and alcoholic groups of the different compounds of the extract of Quisqualis indica Linn flowers were majorly responsible for being the stabilizer and a capping agent of AgNPs. Furthermore, the quantum chemical parameters of β-Sitosterol (1), Brinzolamide (2), Gallic Acid (3), L-Asparagine (4), L-Proline (5), Quisqualic Acid (6), Quinoline-4-Carbonitrile (7), Quercetin (8), and Rutin (9) compounds present in the flowers of Quisqualis indica Linn are also calculated based on density functional theory (DFT). In silico study, a method such as molecular docking was carried out to determine the binding affinity of compounds (1–9) with presentations of Gram-positive bacteria (PDB ID: 2MLM) and Gram-negative bacteria (PDB ID-1KZN). Compounds (1), (2), (7) and (8) had a better score of binding toward the selected proteins. Overall, our findings shed light on the green synthesis of silver nanoparticles and it could be a potential candidate for the pharmaceutical industry against topical pathogens.

Sputtered nanocrystalline samarium doped CuO photoelectrode for efficient photoelectrochemical water splitting

Copper oxide (CuO) is a promising photoelectrode for photoelectrochemical (PEC) energy generation because of its fascinating properties, including high earth availability and inexpensive. In this context, samarium (Sm)-doped CuO thin films are deposited on a glass substrate through the sputtering technique to serve as photocatalysts in PEC water splitting. The structural characterizations of sputtered films were performed with X-ray diffraction (XRD) spectroscopy, while the morphology and elemental composition of all films were studied with the help of field-emission scanning electron microscopy (FE-SEM) connected with a dispersive energy X-ray analyzer. XRD pattern has shown that all films are polycrystalline with a preferred orientation of (−111) crystallographic plane. FE-SEM images and ImageJ analysis showed that all deposited particles are uniformly distributed as disassembled particles over the substrate area. The optical energy band gap (Eg) was increased by adding the Sm contents in the CuO films. The photocurrent density for the photoelectrode was improved by Sm dopants as compared to the pure sample and recorded its maximum value of − 4.66 mA/cm2 at ∼ − 0.385 V vs. RHE which was about 4 times higher than that of the pure sample with feasible photostability retention. Additionally, the value of the charge transfer resistor for the CuO photocathode with the smallest amount of Sm ions was the lowest as compared to other photocathodes. These results offer a practical method for creating a brand-new fabrication technique for PEC devices with remarkable water-splitting efficiency.

Thermal Evaporation Synthesis, Optical and Gas-Sensing Properties of ZnO Nanowires

The purpose of this study is to synthesize and explore the relationship between the optical properties and gas-sensing performance of ZnO nanowires (NWs). Well-aligned ZnO nanowire (NW) arrays were synthesized on a silicon substrate using the thermal evaporation method without any catalyst or additive. The structures, surface morphologies, chemical compositions, and optical properties of the products were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) together with energy-dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy, and their gas-sensing properties for NO2 were examined. The results showed that single-crystalline ZnO NWs with high density grow uniformly and vertically on a Si substrate. The FESEM and TEM images indicate that ZnO NWs have an average diameter of roughly 135–160 nm with an average length of roughly 3.5 μm. The results from XRD confirm that the ZnO NWs have a hexagonal wurtzite structure with high crystalline quality and are highly oriented in the [0001] direction (i.e., along the c-axis). The deconvoluted O 1s peak at ~531.6 eV (29.4%) is assigned to the oxygen deficiency, indicating that the ZnO NWs contain very few oxygen vacancies. This observation is further confirmed by the PL analysis, which showed a sharp and high-intensity peak of ultraviolet (UV) emission with a suppressed deep-level (DL) emission (very high: IUV/IDL &gt; 70), indicating the excellent crystalline quality and good optical properties of the grown NWs. In addition, the gas-sensing properties of the as-prepared ZnO NWs were investigated. The results indicated that under an operating temperature of 200 °C, the sensor based on ZnO NWs is able to detect the lowest concentration of 1.57 ppm of NO2 gas.

Characterization of green synthesized selenium nanoparticles (SeNPs) in two different indigenous halophilic bacteria

BackgroundIn the biological method, using nonpathogenic and extremophile bacteria systems are not only safe and highly efficient but also a trump card for synthesizing nanoparticles. Halomonas elongata QW6 IBRC-M 10,214 (He10214) and Salinicoccus iranensis IBRC-M 10,198 (Si10198), indigenous halophilic bacteria, can be used for synthesizing selenium nanoparticles (SeNPs).MethodsSeNP biosynthesis was optimized in two halophilic bacteria and characterized by UV–Vis, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), zeta potential, and energy dispersive X-ray (EDX).ResultsOptimized conditions for synthesizing SeNPs was at 300 °C at 150 rpm for 72 h and 6 mM or 8 mM concentration of Na2SeO3. UV–Vis indicated a sharp absorption peak at 294 nm. Spherical-shaped nanoparticles by a diameter of 30–100 nm were observed in FESEM and TEM microscopy images. The produced SeNPs were identified by a peak in FTIR spectra. In XRD analysis, the highest peak diffraction had a relationship with SeNPs. The zeta potential analysis showed SeNP production, and elemental selenium was confirmed by EDX.ConclusionsHalophilic bacteria, owing to easy manipulation to create optimization conditions and high resistance, could serve as appropriate organisms for the bioproduction of nanoparticles. The biological method, due to effectiveness, flexibility, biocompatibility, and low cost, could be used for the synthesis of reproducible and stable nanoparticles.

The importance of pore-fracture connectivity in overmature marine shale for methane occurrence and transportation

Pore-fracture connectivity is a critical factor in gas occurrence and transportation in shale plays. To investigate the limiting factors of multiscale pore-fracture connectivity, which might control methane occurrence and transportation in shale reservoirs, small-angle neutron scattering (SANS) under vacuum and high-pressure conditions incorporated with repeated mercury intrusion capillary pressure (MICP), and field emission-scanning electron microscopy (FE-SEM) imaging after Wood's metal (WM) impregnation were performed on overmature marine shale samples of the Wufeng-Longmaxi and Niutitang Formations from south China. Based on the electron micrographs of the WM-injected samples, it was found that the sealing of the pore system by brittle minerals is the root cause for a reduction in overall pore connectivity within the shale matrix. Aside from being favorable to the preservation of organic and clay mineral pores, brittle minerals however, resulted in the closure of pore network, thus, forming an isolated pore system. The novel approach of integrating repeated MICP measurement and FE-SEM imaging after WM impregnation provides a new evaluation method for pore-fracture connectivity of shale. The minimum fraction of pores within the overmature shales accessible to methane was at 38% and 78% within 100 nm. Moreover, because of confinement effects, the density of methane in a pore space less than 20 nm under high pressure was greater than that of an ideal gas under the same pressure conditions which even increased with decreasing of pore size to several times of its inert state and formed nanoscale methane clusters. The combination of contrast-matching SANS (CM-SANS) and repeated MICP measurements can effectively reveal the connectivity of pores within the matrix and the connectivity between such pores and microfractures, which helps to evaluate the distribution of closed pores and dominant transport spaces of gas in shale reservoirs. Overall, the pore-fracture connectivity in overmature marine shale controls the amount of gas that is supplied from matrix pores into fracture systems and also affects the density of the gas in pore spaces within the matrix.

Biosynthesis of sulfur-doped zinc oxide using bidara leaf extract

Incorporating non-metal elements through doping proves to be a highly effective strategy for expanding the photoresponse range of ZnO. This study prepared pristine ZnO and 1%S-doped ZnO through an environmentally friendly approach, employing the biosynthesis method using bidara leaf extract. The synthesized samples were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV-Vis spectroscopy to investigate the structure, morphology, and the optical properties of ZnO, respectively. The XRD analysis revealed a noticeable shift in the diffraction pattern towards smaller angles, indicating the successful incorporation of sulfur into the ZnO lattice. Additionally, FESEM images displayed a distinct modification in the morphology of the ZnO particles upon sulfur doping, accompanied by a reduction in particle size. UV-Vis spectroscopy confirmed that both ZnO and sulfur-doped ZnO exhibited optical absorption predominantly in the ultraviolet (UV) region. Notably, the presence of sulfur doping led to an increase in the optical absorption of ZnO, while simultaneously narrowing its energy bandgap. These findings highlight the potential of sulfur doping as an effective means to enhance the structural, morphological, and optical properties of ZnO semiconductor materials, thereby opening up possibilities for various optoelectronic applications.