Field Emission Scanning Electron Microscopy Images Research Articles

Optical and electrochemical properties of manganese oxide (Mn3O4) nanoparticles: Investigating the influence of calcination temperature on supercapacitor performance

In this study, we investigate the influence of calcination temperature on the structural, optical, and electrochemical properties of Mn3O4 nanoparticles synthesized through a chemical co-precipitation route. Field-Emission Scanning Electron Microscopy (FESEM) images depict the formation of highly agglomerated, spherical-shaped particles. At calcination temperatures of 700 °C and 900 °C, the observation reveals the emergence of flat pellets and rod-like structures. The X-ray Diffraction (XRD) patterns confirm the presence of the Mn3O4 phase in M0 and M1 samples. However, the sample calcined at 500 °C (M3) showed a mixed phase of Mn3O4 and Mn2O3. Upon further calcination at 700 and 900 °C, this mixed phase undergoes complete transformation into the Mn2O3 phase. The change in absorption onset and photoluminescence intensity of samples is found with an increase in calcination temperature due to the crystal growth and phase modification. Furthermore, the synthesized samples are employed as electrode materials for supercapacitor applications. The sample calcined at 300 °C (M1) in three-electrode system demonstrated the specific capacitance (Csp) of 273.3 F/g at 0.5 A/g in an alkaline medium. The asymmetric cell assembled by using M1 and Hibiscus cannabinus stem-derived carbon material (HBC-900) delivered higher Csp of 205.7 F/g at 0.5 A/g. In addition, asymmetric supercapacitor device exhibited a high energy and power density of 43.1 Wh/kg and 476.2 W/kg with 82.07 % of initial Csp retention over 10,000 cycles at 10 A/g, which makes the sample M1 as the potential electrode material for supercapacitor application.

Influence of NaOH Concentration on Structural, Morphological, Optical, and Electrical Characterization of Perovskite Sodium Bismuth Titanate Prepared by Hydrothermal Method

The hydrothermal method successfully prepares a lead-free sodium bismuth titanate (NBT) perovskite film. The prepared films were studied structurally, and morphologically using X-ray diffraction, and field-emission scanning electron microscopy (FESEM), respectively. Varying the concentration of NaOH showed a noticeable effect on the properties studied. Good crystallization of NBT perovskite films without impurities was obtained at 18 and 20 M concentrations, where the crystalline size was 14 nm according to the Scherer equation. Also, when varying the concentration of NaOH, a similar film thickness was obtained through a cross-section of the FESEM images. It was observed that there was a difference in the intensity of the peaks of the photoluminescence spectra of the prepared films with a change in the concentration of NaOH, which confirms a change in the concentration of oxygen vacancies. The activation energy of the prepared films was deduced from the Arrhenius plot, as it showed small values in the films prepared with a low concentration of NaOH. The results showed that the maximum value of mobility of NBT films was at 20 M of NaOH concentration through the Hall Effect.

Structural and Electrical Properties of Li Substituted Mg Nano Ferrites: Prepared by Citrate-gel Auto Combustion Method

LixMg1−xFe2O4 where x=0.0to0.5with0.1 nano ferrites were synthesized by citrate gel auto combustion. Using a field-emission scanning electron microscope (FE-SEM) and the X-ray diffraction technique, their structural and topographical studies were examined. The prepared nano ferrites’ single-phase cubic spinel along the Fd3m space group is confirmed by the structural investigation. The synthesized samples were found to have a crystalline size of 20–26 nm, as determined by the Debye–Scherrer formula. Lattice parameter variation observed for the samples indicates dopant atoms into a crystal lattice can also lead to changes in the lattice constant. FE-SEM images revealed the clear grain and grain boundaries with agglomerated structure and it varied between 33.6 nm-24.4 nm. Two bands observed in Fourier transform infrared spectroscopy illustrates the M-O band in tetrahedral and octahedral sites. Dielectric parameters of the sample observed by LCR meter. Single semicircle behavior observed in impedance spectra. Dielectric constant and dielectric loss decreased as increasing frequency explained by Koop’s theory of mechanism. AC conductivity increasing trend observed with frequency, mobility of charge carrier active at high frequency domain.

Effect of oxidation temperature on physical properties of polycrystalline β-Ga2O3 grown by thermal oxidation of GaN in O2 ambient from 900 to 1400 °C

This study aimed to investigate the effect of oxidation temperature on the physical properties of β-Ga2O3 grown by thermal oxidation of GaN in the O2 ambient at high oxidation temperatures from 900 to 1400 °C. Notably, the analysis of the oxidation temperatures ranging from 1100 to 1400 °C remains unexplored in the other studies. The effects of the oxidation temperature on the physical properties were investigated via X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy (FESEM). At all oxidation temperatures, XPS results revealed oxygen deficiency. The top FESEM images indicated disordered nanocolumn structures on the surface of the oxide layer, which increased in abundance with oxidation temperatures exceeding 1100 °C. Energy-filtered high-resolution transmission electron microscopy images and the selected area electron diffraction patterns revealed that the top nanocolumns and the oxidized layer comprised polycrystalline β-Ga2O3. Additionally, the cross-sectional lamellae prepared through focused ion beam milling revealed an increase in the thickness of the β-Ga2O3 layer with oxidation temperature. To account for the variations in the oxide layer thickness, the oxidation temperatures were classified into two ranges of 900–1100 °C and 1100–1400 °C for calculating the activation energy. Moreover, this study assumed that the activation energy required for the oxidation process remained constant within each temperature interval. According to Arrhenius's model, the activation energy from 900 to 1100 °C was calculated to be 286.15 kJ/mol (2.97 eV). Furthermore, the activation energy from 1100 to 1400 °C was determined to be 111.33 kJ/mol (1.15 eV).

Comparative Study of Rare Earth Nd and Sm Doping on the Structural, Morphological, Optical, Magnetic, and Electromagnetic Traits of Mg-Zn-Cu Spinel Nanoferrites

In the current study, the magnetic nanoparticles of neodymium and samarium substituted Mg-Zn-Cu, with a chemical composition of Mg0.5Zn0.5Cu0.05RxFe1.95-xO4 (x = 0.05; R = Nd, Sm) were produced via the sol-gel auto-combustion route. XRD indicates the evolution of a cubic symmetry having Fd3m space group and no impurities at the room temperature. The FESEM images show the irregularly shaped and agglomerated grains in all samples. FTIR examination reveals the stretching vibrations among the metal cations and anions at interstitial vacancies. The M-H graphs demonstrates that the prepared nanoferrites have low rentivity (0.18–0.84 emu g−1) and coercivity (11.25–34.03 Oe) indicating the formation of superparamagnetic nature. From the electromagnetic traits, the observed sample’s real magnetic permeability (μ″) and permittivity (ε′) along with dielectric loss and magnetic loss reduced with increasing applied field frequency, indicating the typical behaviour of spinel nanoferrites. This may be explained by Maxwell-Wagner interfacial polarisation and the electron hopping among the ferrous and ferric ions. The variations in coercivity, anisotropy constant, and electromagnetic traits provide strong evidence that all of the samples are thermally stable and have the potential to be used in solenoids and transformers, and also, in the more resistive devices that operate at the high frequency.

The influence of the physicochemical processes on the electrical response of Al/p-Si structure with etched surface

In this paper, the electrochemical etching process is used for surface modification of the p-Si wafer, named as porous silicon (PS), in the metal–semiconductor (MS) type Schottky diode (SD) with a structure of Al/p-Si. Five regions of PS wafer with different etching rates are selected for comparison of them which are called P2, P3, P4, and P5 (P1 is the reference area without porosity). The morphological, structural, and electrical properties of the PS used in the MS-type SD are investigated using field-emission scanning electron microscope (FE-SEM) images, energy dispersive X-ray (EDX) analysis, and current–voltage (I–V) characteristics, respectively. The FE-SEM images show a meaningful effect on the porosity. The EDX spectrum demonstrates the importance of the chemical effects in addition to the physical changes in the porosity process of the p-Si wafer. The reverse-saturation current (I0), ideality factor (n), barrier height at zero-bias (ΦB0), and series/shunt electrical resistances are also computed and compared. Some of these parameters (n, Rs, BH) are determined using different methods, namely Thermionic emission (TE), Cheung functions, and modified Norde, and they exhibit strong agreement with each other. The energy-dependent profiles of surface states (Nss) are estimated from the I–V data by considering the voltage dependence of ΦB (V) and n(V). All the experimental findings indicate that the etching process of the p-Si wafer significantly influences the electrical performance of the Al/p-Si Schottky diode by increasing the extent of etching.

Field application of Ca-doped ZnO nanoparticles to maize and wheat plants

Nanoparticles play a vital role in modern agriculture to provide the nutrients required by plants. Herein, we report the preparation of calcium-doped zinc oxide nanoparticles (CZO NPs) via a simple and cost-effective co-precipitation method, with the aim of realizing increased fertilizer response. The synthesized nanoparticles were analyzed to study their physicochemical properties using various characterization techniques. The X-ray diffraction pattern showed a small shift in peak position towards higher values of 2θ and reduced crystal size after the zinc oxide (ZnO) matrix had been doped with Ca. Field-emission scanning electron microscopy images clearly revealed a grain-like surface morphology. The X-ray photoelectron spectroscopy study produced evidence of Zn2+ substitution by Ca2+ and enhanced Zn–O bond strengths in the CZO samples. Two major crops, maize (Zea mays L.) and wheat (Triticum aestivum L.) were selected to study the impact of the CZO NP-based nanofertilizer on plant growth. During the study, the effect of the CZO-based fertilizer on growth parameters such as seed germination, root and shoot length, plant height, root and stem width, number of leaves, and leaf size was studied based on comparisons with control plants. We observed significantly increased plant growth parameters after the application of the CZO NP-based fertilizers.

Characterization of Ce3+ and Eu3+ doped and co-doped ZnO nanoparticles for luminescence applications

This paper investigates the synthesis of Ce3+ and Eu3+ doped, as well as co-doped ZnO nanoparticles using the solution combustion route. The nanoparticles exhibit a hexagonal wurtzite structure of ZnO with crystallite sizes ranging from 19 to 22 nm. Structural parameters, including lattice constants, bond lengths, and bond angles, are evaluated. Morphological diversity is observed in field-emission scanning electron microscopy images. The diffuse reflectance spectroscopy results reveal an energy band gap of 3.20 eV for undoped ZnO nanoparticles. The energy band gap value slightly decreases for Eu-doped ZnO and certain (Ce, Eu) co-doped ZnO nanoparticles. Photoluminescence (PL) excitation peaks are attributed to energy levels of native defects in the ZnO band gap, along with f–d and f–f transitions of rare-earth ions (Ce3+, Eu3+). The PL emission spectra under different excitation wavelengths (350 nm, 394 nm, and 465 nm) display varied peak positions. ZnO co-doped with 0.96 mol% of Ce3+ and 0.92 mol% of Eu3+ emerges as a promising material for luminescence applications, exhibiting a significant increase in green emission intensity. Consequently, this study represents a novel contribution to the field of ZnO-based luminescent materials.

Glass Transition Temperature and Mechanical Properties of Poly(Ethylene Carbonate)/Organoclay Composites

Poly(ethylene carbonate) (PEC) is a form of aliphatic polycarbonate, a biodegradable polymer made via the copolymerization of carbon dioxide and epoxides. The poor thermal stability and mechanical properties of these aliphatic carbonates are attributed to the carbon structure's flexibility, which restricts their applications. By combining PEC with organoclay CP180, this study addressed the weaknesses of PEC with organoclay addition. A physical blending technique was employed to generate PEC/organoclay composites with a 10-50 wt.% ratio of organoclay. The blended material's thermal characteristics were analyzed using differential scanning calorimetry (DSC), and the mechanical characteristics were measured using a universal tensile machine. The Field Emission Scanning Electron Microscopy (FESEM) analysis determined the blends' morphology. Before the torque value for all curves grew with the addition of CP180 material to the PEC matrix, it became constant. It reached a high value due to the shear-thickening behavior of the PEC matrix with organoclay addition. Tg of PEC increased by more than 7°C by 40 wt.% organoclay addition, as evident in the hindrance of PEC flexibility, significantly increased the toughness of this PEC. From the FESEM images, the formation of large silicate starts to aggregate effectively, lowering the interfacial area between organoclay and PEC as the clay content continues to rise, as shown by 50 wt.% organoclay addition.

Synthesis of cerium-doped gadolinium gallium aluminum garnet (GGAG:Ce) scintillating powder via solvothermal method

The powder material Gd3Ga3Al2O12:Ce (GGAG doped with Cerium) has garnered significant attention in radiation detection due to its high light yield and rapid decay time. Despite its potential, the synthesis of high-quality and reproducible GGAG:Ce scintillating powder remains a considerable challenge. In this study, we present a solvothermal approach with an annealing temperature of 1300 °C for producing cerium-doped GGAG powder with varying concentrations (4, 2, and 0.5 mol%). The structural and luminescent characteristics were meticulously examined using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL), radioluminescence (RL) spectroscopy, and X-ray photoelectron spectroscopy (XPS). XRD analysis confirmed the single-cubic phase garnet structure of the synthesized powder. By comparing the intermediate solvothermal products synthesized at different sintering temperatures (900 °C for 3 h and 1300 °C for 1 and 3 h), a direct correlation between solvothermal conditions and the structure/property relationships of the product was established. FESEM images revealed an ellipsoidal to irregular morphology of the as-synthesized GGAG:Ce microparticles, ranging from 0.1 to 0.3 μm, regardless of the Ce concentration. PL spectra demonstrated a strong emission peak at approximately 550 nm, characteristic of Ce3+ ions. RL data confirmed the peak luminescence at around 550 nm, with an almost twofold increase in intensity as the concentration of Ce3+ increased from 0.5 mol% to 4 mol%. XPS data disclosed the Ce3+/Ce4+ ratio in solvothermally synthesized GGAG:Ce, wherein Ce loading of 4 mol% demonstrated the increase in Ce3+ concentration to 95%, whereas the concentration of Ce4+ decreased to 5%. Notably, the highest luminescence efficiency was achieved with GGAG:Ce at a 4 mol% concentration. Thus, the solvothermal method employed in GGAG:Ce synthesis presents a straightforward approach, yielding rapid results with precise control over particle morphology and size.

Sago-shaped embedded Nanolayers of WO3/NiO/gC3N4 Nanohybrids for natural degradation of environmental pollutants: A photocatalytic sunlight mediated approach

In recent years the applicability of semiconductor nanomaterials is almost in every field of science and technology. In the current study, hybrid nanomaterials containing tungsten trioxide (WO3) and nickel oxide (NiO) supported on graphitic carbon nitride (gC3N4) were prepared by a simple hydrothermal technique. Synthesis was sequential requiring the individual preparation of gC3N4 and WO3 as preliminary. The desired composition of gC3N4, WO3, nickel nitrate, and a base was transferred to an autoclave and maintained at 180°C for 18 h. The resulting inorganic/organic hybrid was filtered, washed, dried, and named as inorganic/organic hybrid nanocomposite (HNC). Various compositions of HNC were prepared and characterized by Fourier transform infrared spectrometer (FT-IR), Ultra Violet-Visible Diffuse reflectance spectrometer (UV–Vis-DRS), X-ray diffractometer (XRD), and Field emission scanning electron microscope (FE-SEM). The FE-SEM images showed a sago-shaped embedded particle in gC3N4 layers with a 40–60 nm particle size. The band gap energy was found to be 2.69 eV from UV–Vis-DRS analysis. This proves the promising activity of sago-shaped HNC under sunlight radiation. Various preliminary and kinetic studies were conducted, and HNC possessed excellent photocatalytic activity for the degradation of an organic dye under sunlight. The photocatalytic activity for the degradation of dye by the prepared HNC was found to be two-fold when compared to the activity of pristine gC3N4 under sunlight irradiation.

Biopolymer blend composite films based on polyvinyl alcohol/ chitosan/ grape seed extract via green approach for flexible optoelectronic devices

The flourishing environmental concerns have grabbed the attention of researchers developing environmentally supportive materials in various fields. A green approach was used to create biopolymer blend composites based on polyvinyl alcohol (PVA) and chitosan (CS) doped with various concentrations of grape seed (GS). Various analytical techniques, such as Fourier-transform infrared spectroscopy (FTIR), UV–visible (UV) spectra, field emission scanning electron microscope (FE-SEM) and differential scanning calorimetry (DSC) were used to evaluate the optical, structural and thermal properties of the prepared blend composites. The optical properties of blend composites were determined by UV spectroscopy and the findings revealed that absorption intensity increased with increasing GS, while bandgap energy decreased from 4.18 eV for pure blend to 2.91 eV for blend/15 wt% GS. The homogeneous distribution of GS particles in the biopolymer blend was identified with FE-SEM images. DSC results showed that increasing the GS content increased the glass transition temperature of the blend composites. The AC conductivity and dielectric constant were measured using the LCR meter. The conductivity rises with increasing frequency and dosage of GS, with the greatest conductivity obtained at 15 wt% loading. In comparison to a pure blend, it was discovered that the inclusion of 15 wt% GS enhanced the tensile strength by 50%, hardness by 17% and the reduction in elongation at break by 19 %. As a consequence, environmentally friendly PVA/CS/GS biopolymer blend composites with excellent mechanical, thermal, electrical, and dielectric parameters might be a viable green option for flexible electronic, electrochemical and energy storage devices.

From environmental issue to purification aid: Novel positively charged functionalized algal biochar as robust modifier of composite nanofiltration membranes

Robust membrane modifiers were achieved for the first time by functionalizing the algal biochar of unique porous structure. The biochar was prepared through the pyrolysis of Cladophora glomerata, the most widespread freshwater macroalga, functionalized by diethylenetriamine and dendrimer poly(amidoamine), and employed to fabricate positively charged composite nanofiltration membranes. The presence of hydrophilic functionalizers of positive charge on the membrane was verified through Fourier transform infrared and energy dispersive X-ray analyses and atomic force microscopy and zeta potential measurements were performed to determine surface roughness and confirm positive charge of the modified membranes. Dispersion of modifiers on the surface and morphology of the were also revealed through field-emission scanning electron microscopy images. It has shown that, compared to the pristine membrane, pure water fluxes were increased by 214% and 185%, and water contact angles were reduced from 66.1° to 39.5° and 43.3° in those modified by biochar functionalized with dendrimer poly(amidoamine) and diethylenetriamine, respectively. More than 90% dye rejections and salt and heavy metals removals were recorded for the membranes possessed 0.6 wt% of modifiers. Finally, a comparative study conducted between the novel modifier introduced in this study and those reported in the literature, indicated that C. glomerata biochar decorated with amine functional groups could be considered as a robust and practical alternative to the common modifiers used to manipulate nanocomposite membranes characteristics.

Physical characterization, magnetic interactions and DC electrical resistivity properties of La3+ substituted NiZnCd nano ferrites

In this article, we substituted La3+ ions to explore the structural, magnetic, and DC electrical resistivity properties of Ni0.5Zn0.4Cd0.1Fe2-xLaxO4 (x = 0.0, 0.02, 0.04, 0.06, and 0.08) nano-structured spinel ferrites. We employed X-ray diffraction (XRD), Field-emission scanning electron microscopy (FESEM) with Energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), Vibrating sample magnetometry (VSM), and electrical measurements to characterize the studied samples, which were synthesized using the sol–gel auto-combustion process. XRD analysis confirmed that the prepared materials formed a single-phase nanostructure. Using Debye-Scherer's formula, we calculated the average crystallite size, which ranged from 29.01 to 21.52 nm. FESEM images demonstrated that each sample exhibited spherical nanocrystalline behavior. The variations of the prepared samples were confirmed constitutionally by EDX. The FTIR data revealed two absorption bands for all synthesized materials at υ1 = 562.18 to 590.51 cm−1 and υ2 = 410.18 to 430.51 cm−1, corresponding to the tetrahedral and octahedral sites of the spinel structure, respectively. Vibrant sample magnetometry spectra were utilized to investigate how La3+-doping affects the magnetic characteristics of NiZnCd ferrite. Due to enhanced La3+-doping, saturation magnetization, and coercivity values decreased. The La3+ doping of NiZnCd nano ferrites resulted in changes in saturation magnetization (from 83.66 to 69.57 emu/g), coercivity (from 33.75 to 60.51 Oe), and remanence magnetization (from 29.62 to 33.12 emu/g). These variations suggest the potential utility of the samples for magnetic recording and memory applications. The semiconducting behavior has been confirmed by the DC electrical resistivity measured values using a two-probe method. Data on DC electrical resistivity were also utilized to determine carrier concentration and activation energy, establishing a connection with La3+ replacement.

Synthesis and Characterization of Aluminum Oxide Nanoparticles Prepared by Two Different Cold Plasma Jet Methods

In this paper, a cold plasma system utilizing a high voltage of 13.5 kV of alternative (AC) and direct current (DC) was used under atmospheric pressure with argon (Ar)-gas at a flow rate of 2.5 l/min and a flowing time of 4 min to synthesize aluminum oxide (AlO) nanoparticles (NP). From the results, when DC was used, it was found that the absorption spectrum starts at 303 nm and gradually falls to 870 nm. With AC, the absorption spectrum was at 330 nm and then began to fall to 902 nm. The energy gap when utilizing DC and AC was 3.49 and 3.44 eV respectively. The analysis of the X-ray diffraction (XRD) patterns showed the structure of the NPs was amorphous, matching the pattern 42-1746. At DC, the average size of NPs formed, as deduced from the XRD pattern, was 29.56 nm, and it was very close to what appeared in the field emission scanning electron microscopy (FESEM) images, in which the apparent NP size ranged between 20 and 50 nm. The XRD test gave an average NP size of 38.21 nm in AC, while the FESEM images showed a size range of 20 - 60 nm. At dc, the AlO NPs were aggregated and interconnected, and each set was connected to another set, as shown in the FESEM images. At AC, the shape of the synthesized AlO NPs was quasi-spherical, with slightly elongated particles connected.

Zinc oxide nanoparticles-reduced graphene oxide nanocomposite thin-film for β-D-glucose detection

This work presents a technique to detect β-D-glucose by using zinc oxide nanoparticles-reduced graphene oxide (ZnO NPs-rGO) nanocomposite thin-film. The ZnO NPs were synthesized by the direct precipitation method. The rGO was fabricated via hydrothermal treatment of graphene oxide (GO) powder. The optical properties of the nanocomposite thin-film were characterized via ultraviolet–visible, Raman and photoluminescence (PL) spectrometers. The morphology of the nanocomposite thin-film was obtained from a field emission scanning electron microscope (FESEM). Based on the optical result, the absorption peak was correlated with the excitation wavelength required to induce high PL spectra in the nanocomposite. Furthermore, the FESEM image displayed the spherical and non-uniform sized ZnO NPs on the sheet-like surface of rGO. For the β-D-glucose detection, changes in the wavelength and intensity peak of UV emission in PL spectra were investigated. From the results, a red-shift and reduction of peak intensity of UV emission was observed under 0.25 - 40 mM β-D-glucose concentration. A linear response, with a slope of 0.87 nm/mM and regression coefficient, R2 of 0.99 indicated that the detection range of the nanocomposite thin-film covers from high to low glucose levels. Furthermore, the highest sensitivity of 1.09 %/mM was obtained based on the percentage change of the peak intensity per mM glucose concentration. These observations signify the potential of detecting wide concentrations of β-D-glucose, making the nanocomposite material suitable for practical uses in glucose sensing and monitoring.

Environmental friendly approach on biosorption of Ag nanoparticles using Aspergillus terreus BIOS PTK 6 biomass: Optimization, kinetics and characterization studies

The present study focused on the biosorption of Aspergillus terreus dead biomass for the removal of silver nanoparticles (AgNPs) from aqueous solution. For the better removal of AgNPs, pH, temperature, incubation time, initial biomass concentration and agitation speed were optimized and AgNPs treated as well as control biosorbents were characterized using Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray spectroscopy (EDX) analyses. In our study, the optimum conditions of pH, temperature, incubation time, initial biomass concentration and agitation speed for the maximum removal of AgNPs was found to be 4, 30 °C, 200 min, 1 mg/mL and 125 rpm, respectively. Interestingly, in our study, Langmuir isotherm model was best correlated with the highest regression coefficient (R2) of 0.992 and the maximum biosorption was found to be 740.63 μg/mL. FTIR results showed that carboxyl, carbonyl and secondary amine groups were involved in the biosorption of AgNPs. FESEM images of AgNPs treated biosorbent depicted rough surface and the presence of AgNPs on the surface of biosorbent was clearly observed. EDX spectrum showed Ag peak, which confirmed the successful uptake of AgNPs by A. terreus dead biomass. Thus, our study shows that A. terreus could be used as a cost-effective eco-friendly biosorbent for AgNPs removal from aqueous solution. Therefore, exploiting the same fungus for both synthesis and removal of AgNPs could be a novel approach in the context of mycoremediation practices.

An enzyme-free sensor based on La-doped CoFe-layered double hydroxide decorated on reduced graphene oxide for sensitive electrochemical detection of urea.

The successful synthesis ofLa-doped CoFe LDH@rGO nanocompositeis reported combiningthe advantages of LDH and rGO and shows promising performances in electrochemical sensors. The structure of the obtained nanocomposite was investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction pattern (XRD), and field emission scanning electron microscope images (FE-SEM). Then, it was directly utilized to construct a carbon paste electrode (CPE) for urea detection. The electrochemical performance of the sensor was evaluated by various electrochemical methods. The La-CoFe LDH@rGO electrode exhibited excellent electrocatalytic properties, including a wide linear workingrange of 0.001-23.5 mM, very high sensitivity of 1.07 ± 0.023 µA µM-1 cm-2, a low detection limit of 0.33 ± 0.11 µM, and rapid response time of 5 s towards urea detection at the working potential of 0.4 V. Furthermore, the sensor displayed a high selectivity in different matrices, appropriate reproducibility, and long shelf life without activity loss during 3 months of storage under ambient conditions. Further tests were performed on serum and milk samples to confirm the capability of the proposed sensor for practical applications, demonstrating a reasonable recovery of 94.8 to 102% with an RSD value below 3%. Consequently, the synergistic effect of each component led to the good electrocatalytic activity of the modified electrode towards urea.

The characterization of Ag-doped tin indium oxide/copper electrodes prepared by cold pressing method and their electrocatalytic efficiency in hydrogen production

In the present study, tin indium oxide (SnIn2O3) powder was synthesized by hydrothermal technique. In order to improve the structural property of SnIn2O3, a small amount of silver (Ag) nanoparticles was added into SnIn2O3 powder. Finally, the prepared Ag-doped SnIn2O3 (Ag@SnIn2O3) were embedded into copper (Cu) powder with different ratios. The electrocatalytically improved hetero-structured Ag@SnIn2O3/Cu materials were obtained by cold pressing method. The structural and morphological properties of different Ag@SnIn2O3/Cu materials were studied via X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). XRD pattern depicted In2O3 have both cubic and hexagonal crystal structures. FE-SEM images show that Ag@SnIn2O3 nanoparticles are homogeneously dispersed into Cu powder. The size of nanoparticles of Ag@SnIn2O3/Cu materials increases with increasing the ratio of Ag@SnIn2O3. Electrochemical impedance spectroscopy (EIS) and potentiodynamic (PD) polarization tests were carried out to investigate the electrocatalytic activities of the materials toward hydrogen evolution reaction (HER). Energy consumption and energy efficiency values for the HER on the materials were also calculated. Furthermore, the polarization resistances of the 1-Ag@SnIn2O3/Cu, 2.5-Ag@SnIn2O3/Cu, 5-Ag@SnIn2O3/Cu, and 10-Ag@SnIn2O3/Cu materials were determined as 127.4, 103.1, 552.4, and 558.7 Ω cm2, respectively after 5 days of electrolysis periods.

Synthesis of nano-selenium and its effects on germination and early seedling growth of four crop plants

In this work, nano-selenium (NSe) with different shapes (wires, rods, and spherical particles) was synthesized by a wet chemical method. These synthesized products were characterized by x-ray powder diffraction (XRD) analysis, a field emission scanning electron microscope (FE-SEM) with an energy dispersive x-ray analyzer, and Raman spectroscopy. FE-SEM images revealed that nanowires with an average diameter of 30–50 nm and length of 3–5 µm, nanorods with lengths of 400–800 nm and diameters of about 20–50 nm, and spherical-shaped nanoparticles (NPs) with diameters ranging from 40 to 60 nm were successfully synthesized. The XRD and Raman analysis confirmed that all the produced NSe samples exhibited hexagonal single-phase crystalline structure with no impurity phase. All three NSe products (SeNWs, SeNRs, and SeNPs) with a concentration range of 25–150 mg/l were used to investigate the impact of shape and concentration on seed germination and seedling vigor of four different crop species, namely, green bean, okra, wheat, and radish. The results revealed that NSe at low concentrations (≤50 mg/l for SeNWs and ≤100 mg/l for SeNRs and SeNPs) can promote seed germination, plant growth, and development of all the studied crop species. However, NSe can adversely affect the growth of plants at higher concentrations (≥75 mg/l for SeNWs).