Elemental Dispersive X-ray Spectroscopy Research Articles

Fabrication, catalytic activity, metal sensing ability and electrochemical evaluation of nano silver particles for supercapacitor applications

In this work, stable, spherical silver nanoparticles (MAgNp) were prepared via a green synthesis method using flowers of Myristica fragrans (nutmeg). This flower is abundant in phytochemicals such as saponins that can be utilized as reductants to produce silver nanoparticles. The synthesized nanoparticles were examined using a variety of physico-chemical methods, including transmission electron microscopy (TEM), Dynamic light scattering (DLS), elemental dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV–VIS spectrometer. EDX study confirmed the crystalline and face-centered cubic (FCC) structure of AgNP. The majority of particles are present with a higher percentage intensity at an average size of 58.77 nm as revealed in the TEM image, PDI was found to be 0.055. MAgNPs demonstrated perfect activity in the catalytic degradation of methylene blue dye (88 %) and para-nitrophenol (98 %), both anthropogenic pollutants. These nanoparticles were further used as plasmonic sensors to detect heavy metals like Fe(II) and Hg(II) in an aqueous solution. The minimum detection limit was found to be 0.2 mM for Hg(II) and 10 μM for Fe(II) with good linearity. The electrochemical properties of MAgNPs were studied using a carbon supercapacitor electrode coated with MAgNPs. Results from cyclic voltammetry were also determined, and they showed a high specific capacitance of 41 F/gm at 5 mV/s scan rate.

Synergistic augmentation of dielectric and photocatalytic properties of ZnO via Ag nanoparticle integration

This study investigates the effect of Ag incorporation on dielectric and photocatalytic properties of the ZnO matrix. The synthesized samples were characterized using X-ray diffraction (XRD), diffused reflectance spectroscopy (DRS), scanning electron microscopy (SEM), elemental dispersive X-ray spectroscopy (EDX), impedance spectroscopy, and UV–visible infrared spectroscopy. XRD confirmed the successful synthesis of Ag/ZnO nanocomposites without any secondary phase. SEM micrographs showed discs and rods-like morphology of ZnO and Ag NPs, respectively. Furthermore, an increased agglomeration was also observed in the nanocomposite as the concentration of Ag NPs was increased in Ag/ZnO Nanocomposite. The dielectric study revealed that the incorporation of Ag nanoparticles (Nps) increased the dielectric constant of ZnO by 100 times (102 Hz), with minimal tangent loss in Ag/ZnO (20 %). Complex plane plots disclosed the presence of two relaxation processes with different relaxation times in the synthesized samples. The metallic nature of Ag NPs contributed to the reduction of the charge transfer resistance of the nanocomposite. Furthermore, the enhanced dielectric behavior was ascribed to the formation of micro/nano capacitors due to the interaction of conductive Ag NPs with relatively less conducting ZnO grains. The photocatalytic performance of the synthesized nanocomposites was also evaluated for the degradation of methylene blue. The presence of Ag NPs increased the photocatalytic activity due to its enhanced conductivity and sluggish electron-hole recombination. Ag/ZnO (20 %) nanocomposite showed the best photocatalytic activity with a reaction rate of 0.239 min−1. The exceptional dielectric properties demonstrate the potential of Ag/ZnO nanocomposites for low-frequency applications. Furthermore, the enhanced photocatalytic activity of ZnO upon Ag inclusion discloses the potential of the synthesized nanocomposite for water remediation applications.

In Situ Synthesis of Bare Silver Nanoparticles on Paper and Its Response to Copper (II) Ions

This study synthesized bare silver nanoparticles on paper and evaluated its response to copper (Cu(II)) ions to assess its potential as colorimetric sensing platform. The nanoparticles were synthesized in-situ on paper using silver nitrate and sodium borohydride as precursor and reducing agent, respectively. No stabilizer or functionalizing agent was added. A two-factor three-level full factorial design with varying concentration of reagents was employed in the synthesis process. The resulting sensor was successfully characterized using diffuse reflectance spectroscopy and scanning electron microscopy with elemental dispersive x-ray spectroscopy. The sensor was exposed to varying Cu(II) concentrations ranging from 1 to 30 mM and the developed color changes were analyzed using a computer imaging software. The changes in color were quantified using mean gray values from the imaging software. Based on the results, as the concentration of Cu(II) ions increased, the final mean gray value of the paper increased as well. The papers were observed to marginally lighten in color potentially due to the decrease in silver atoms or its interaction with copper. The relationship between Cu(II) concentration and the ratio of final and initial mean gray value was determined and although a weak linear relation existed from 1 to 30 mM, a positive slope supported the increase in mean gray value within the range tested. The changes in the elemental composition of the sensor due to exposure to Cu(II) ions were studied. Finally, the response of the sensor towards other metal ions was compared to that of Cu(II) in a selectivity study.

Graphene quantum dots (GQDs) decorated Co-Zn ferrite: Structural, morphological, dielectric, and magnetic properties

GQDs/Co0.5Zn0.5Fe2O4 nanocomposite was synthesized using a facile sonication-assisted approach. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), elemental dispersive X-ray spectroscopy (EDX), impedance analyzer and vibrating sample magnetometer (VSM) were employed to characterize the synthesized samples. The XRD data confirmed the formation of GQDs, Co-Zn ferrite and GQDs/Co-Zn ferrite nanocomposite with no detectable impurity peaks. FTIR results identified the presence of GQDs in GQDs/Co-Zn ferrite nanocomposite. The morphological study revealed the decoration of spherical GQDs on the surface of Co-Zn ferrite. Complex impedance plane plots showed the contribution of the relaxation phenomenon associated with grain and grain boundaries in observed dielectric properties of the nanocomposite. The inclusion of GQDs led to the enhancement of the dielectric constant of the nanocomposite at low frequencies. GQDs/Co0.5Zn0.5Fe2O4 showed superparamagnetic properties which makes it a potential material to be used as a contrast agent in magnetic resonance imaging (MRI) applications.

Material gradients in gastropod radulae and their biomechanical significance: a combined approach on the paludomid Lavigeria grandis

The radula, a chitinous membrane spiked with teeth, is the molluscan autapomorphy for the gathering and processing of food. The teeth, as actual interfaces between the organism and the ingesta, act as load transmitting regions and have to withstand high stresses during foraging — without structural failure or high degrees of wear. Mechanisms contributing to this were studied previously in paludomid gastropods from Lake Tanganyika. For some species, gradients in hardness and Young’s modulus along the teeth were detected, enabling the bending and relying of teeth onto the next row, distributing the stresses more equally. The here presented study on one of them — Lavigeria grandis — aims at shedding light on the origin of these functional gradients. The mechanical properties were identified by nanoindentation technique and compared to the elemental composition, determined by elemental dispersive X-ray spectroscopy (EDX, EDS). This was done for the complete radular (mature and immature tooth rows), resulting in overall 236 EDX and 700 nanoindentation measurements. Even though teeth showed regional differences in elemental composition, we could not correlate the mechanical gradients with the elemental proportions. By applying confocal laser scanning microscopy (CLSM), we were finally able to relate the mechanical properties with the degree of tanning. CLSM is a common technique used on arthropod cuticle, but was never applied on radular teeth before. In general, we found that nanoindentation and CLSM techniques complement one another, as for example, CLSM is capable of revealing heterogeneities in material or micro-gradients, which leads to a better understanding of the functionalities of biological materials and structures.

Deciphering Highly Sensitive Non-Enzymatic Glucose Sensor Based on Nanoscale CuO/PEDOT-MoS2 Electrodes in Chronoamperometry

The present work demonstrates fabrication of a non-enzymatic glucose sensor based on CuO nanoparticles deposited over poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymer infiltrated with nanoscale MoS2. Structural, morphological and elemental analyses of the fabricated sensor electrodes were performed via different characterization techniques like X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), elemental dispersive X-ray spectroscopy (EDX), and Fourier transform infra-red spectroscopy (FT-IR). The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies of the hybrid nanoelectrode (CuO/PEDOT-MoS2) exhibited better redox activity and electron transfer kinetics, as compared with the CuO/PEDOT and CuO only systems. Accordingly, the electrochemical parameters of all the systems were determined and compared at large. The CuO/PEDOT-MoS2 hybrid electrode system offered a significant enhancement in the electroactive area (∼1.47 cm2) and rate constant (0.76 s−1) upon oxidizing glucose into gluconic acid. In the CV responses, an augmented activity was monitored at +0.6 V which was considered as the dc bias potential in the chronoamperometric experiment for detecting glucose suitably. The sensor electrode yielded a low LOD of 0.046 μM and with a sensitivity magnitude as high as 829 μA mM−1 cm−2 over a wide linear range, between 30 μM to 1.06 mM of glucose concentration. Deployment of organic-inorganic nanomaterial based non-enzymatic sensor would find immense scope in non-clinical diagnostics and pharmaceutical applications for fast, convenient and smart sensing.

Micro-cracks and micro-fractures reveal radular tooth architecture and its functional significance in the paludomid gastropod Lavigeria grandis.

Most molluscan taxa forage with their radula, a chitinous membrane with embedded teeth. The teeth are the actual interfaces between the animal and its ingesta and serve as load-transmitting regions. During foraging, these structures have to withstand high stresses without structural failure and withouta high degree of wear. Mechanisms contributing to this failure- and wear-resistancewere well studied in the heavily mineralized teeth of Polyplacophora and Patellogastropoda, but for the rather chitinous teeth of non-limpet snails, we are confronted with a large gap in data. The work presented here on the paludomid gastropod Lavigeria grandis aims to shed some light on radular tooth composition and its contribution to failure- and wear-prevention in this type of radula. The teeth were fractured and the micro-cracks studied in detail by scanning electron microscopy, revealing layers within the teeth. Two layers of distinct fibre densities and orientations were detected, covered by a thin layer containing high proportions of calcium and silicon, as determined by elemental dispersive X-ray spectroscopy. Our results clearly demonstrate the presence of failure- and wear-prevention mechanisms in snail radulae without the involvement of heavy mineralization-rendering this an example of a highly functional biological lightweight structure. This article is part of the theme issue 'Nanocracks in nature and industry'.

Enhanced xylene sensing performance using Ag-V2O5 loaded mesoporous graphitic carbon nitride.

A 3-dimensional ordered cubic mesoporous Ag-V2O5 loaded graphitic carbon nitride (mpg-CN) hybrid was fabricated via a facile nanocasting technique using mesoporous silica as the hard template and its sensing response towards xylene gas was investigated in detail. The physicochemical properties of the as prepared nanocomposite were estimated by transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental dispersive X-ray spectroscopy (EDX) and BET surface area analysis. The hybridized Ag-V2O5/mpg-CN nanocomposite prepared by template inversion of KIT-6 silica showed temperature reliant response towards the detection of common VOCs (xylene, formaldehyde, 2-propanol and benzene) usually found in our indoor environment. Sensing response values of 4.9 for 50 ppm and 12.7 for 500 ppm were reported for xylene gas at an operating temperature of 40 °C. Besides, average response/recovery times of 6.1/4.1 s (xylene), 7.7/5.1 s (formaldehyde), 8.7/6.6 s (2-propanol) and 9.5/8.4 s (benzene) were recorded for Ag-V2O5/mpg-CN, which demonstrated the potential of utilizing the as-prepared sensor in commercial real-time sensing applications.

Greenly synthesized silver nanoparticles for supercapacitor and electrochemical sensing applications in a 3D printed microfluidic platform

Herein, Silver nanoparticles (AgNPs) decorated pencil graphite electrodes (PGEs), with assimilation of Chitosan (CS), as a versatile electrode material for supercapacitor and electrochemical sensing application have been reported. The AgNPs were prepared by employing a green synthesis method using marigold flower s extract. Marigold flower contains lutein, which can be used as a reductant. The morphology and crystal structure of the prepared nanomaterial was characterized by Field emission scanning electron microscopy (FESEM), Elemental Dispersive X-Ray Spectroscopy (EDX), Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), UV-VIS Spectrophotometer and X-ray photoelectron spectroscopy (XPS). The prepared hybrid material, PGE/AgNPs/CS was utilized in an electrochemical 3D printed microfluidic device for supercapacitor and electrochemical sensing of H2O2. As a supercapacitor, the device provided a remarkable storage capacity of 367.16 mF cm−2at a current density of 1 mA cm−2 with high cyclic stability over 1500 charge-discharge cycle. Subsequently, H2O2 sensing with the same electrode in a three-electrode microfluidic system gave a LOD of 0.52 µM within a linear range of 1-10 µM. In addition, the effect of common interfering species, including ascorbic acid (AA), uric acid (UA) dopamine (DA) and xanthine (XN) were thoroughly investigated. Thus, the prepared hybrid electrode material showed excellent electrochemical activity for the supercapacitor and electrochemical sensing of H2O2, which can be further assessed for other relevant applications.

3:27 PM Abstract No. 25 Iodinated coating of decayed Y-90 microspheres to improve radiopacity with cone-beam computed tomography

To envelope SIR-Spheres (SS) with a chitosan/iodine shell in order to display greater contrast enhancement compared to non-coated control SS with cone-beam CT. Centrifuge 1000μL of radioactively inactive SS at 10,000 RPM for 10 minutes and remove excess water. Combine 7mL of Omnipaque (Op) solution (2% acetic acid, 3 mg/mL chitosan) with the pelleted SS and place on a shaker plate for 30 minutes. While shaking, add 7mL of 10 mg/mL TPP (in 100% Op) dropwise over 1 minute, and continue to shake for 30 minutes. Wash the sample by centrifuging at 14,000 RPM for 10 min then resuspending in diH2O. Continue these spin/wash cycles for a total of 3 washes. Remove 25μL of sample and place on a scanning electron microscope (SEM) stub for SEM and Elemental Dispersive X-Ray Spectroscopy (EDX) analysis. Transfer the remaining washed sample to a 1.5mL centrifuge tube for cone-beam CT assessment. In order to add additional coatings, the above steps were repeated. Cone beam CT imaging showed an increase in contrast resolution of double and triple coated SS when compared to control SS. Better contrast resolution was seen with triple coated SS when compared to double coated SS. SEM images of control SS, singe coated SS, double coated SS, and triple coated SS showed progressive layering of chitosan/Op coatings with each additional coating attempt. EDX elemental analysis results show a stepwise increase in iodine content when looking at control SS, single coated SS, double coated SS, and triple coated SS, with average iodine contents of 0%, 33.4%, 42.8%, and 63.0% respectively. The ability to intraoperatively assess SIRT dosage delivery would allow localization of treated and untreated regions. With this knowledge, other interventions can be applied to ensure a more efficacious treatment plan. In this study we were able to apply significant amounts of radiopaque iodine to the surface of SS. With the utilization of SEM, EDX, and cone-beam CT, we confirmed that we (1) successfully enveloped SS in crosslinked chitosan, (2) successfully entrapped iodinated molecules within this chitosan shell, and (3) successfully demonstrated visibility with cone-beam CT of SS with the iodinated shell.

Influenced of Cu<sup>2+</sup> Doped on Structural, Morphological and Optical Properties of Zn-Mg-Fe<sub>2</sub>O<sub>4</sub> Ferrite Prepared by Sol-Gel Method

The Zn0.5CuxMg0.5-xFe2O4 (where x = 0.0, 0.1, 0.2, 0.3 and 0.4) was prepared by sol-gel route and characterized in detail in terms of their structural, morphological, elemental and optical properties as a function of Cu concentration. X-ray diffractometer (XRD) results confirmed the formation of cubic spinel-type structure with average crystallized size in the range of 30.56 to 40.58 nm. Lattice parameter was found to decrease with Cu concentration due to the smaller ionic radius of Cu2+ ion. The HR-SEM images show morphology of the samples as prismatic shaped particles in agglomeration. The elemental dispersive X-ray Spectroscopy (EDX) confirmed the elemental composition of the as-prepared spinel ferrite material with respect to the initial concentration of the synthetic composition used for the material. The Fourier transform infrared (FTIR) spectroscopy confirmed the formation of spinel ferrite and showed the characteristics absorption bands around 463, 618, 876, 1116, 1442, 1622 and 2911 cm-1. The energy band gap was calculated for the samples were found to be in the range of 4.87 to 5.30 eV.

Preliminary Study on Synthesis of Composite rGO/Ni by Microwave Assisted Method

Composite reduced graphene oxide-nickel (rGO/Ni) was successfully synthesized by wet chemical process via microwave assisted method. The nickel fraction was varied 0%, 5% and 20%. Crystallinity, morphology, chemical composition, chemical bonding, and conductivity were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), 4 point probes and electrochemical impedance spectroscopy (EIS). Based on the XRD patterns, the crystal sizes were 1.62 nm for 5% rGO/Ni and 1.64 nm for 20% rGO/Ni respectively. Furthermore, vibration of C=C aromatic stretching was detected in the FTIR spectra, which corresponds to rGO fingerprint. These results give a new perspective on synthesis of composite rGO/Ni.

Size-resolved morphological properties of the high Arctic summer aerosol during ASCOS-2008

Abstract. The representation of aerosol properties and processes in climate models is fraught with large uncertainties. Especially at high northern latitudes a strong underprediction of aerosol concentrations and nucleation events is observed and can only be constrained by in situ observations based on the analysis of individual aerosol particles. To further reduce the uncertainties surrounding aerosol properties and their potential role as cloud condensation nuclei this study provides observational data resolved over size on morphological and chemical properties of aerosol particles collected in the summer high Arctic, north of 80° N. Aerosol particles were imaged with scanning and transmission electron microscopy and further evaluated with digital image analysis. In total, 3909 aerosol particles were imaged and categorized according to morphological similarities into three gross morphological groups: single particles, gel particles, and halo particles. Single particles were observed between 15 and 800 nm in diameter and represent the dominating type of particles (82 %). The majority of particles appeared to be marine gels with a broad Aitken mode peaking at 70 nm and accompanied by a minor fraction of ammonium (bi)sulfate with a maximum at 170 nm in number concentration. Gel particles (11 % of all particles) were observed between 45 and 800 nm with a maximum at 154 nm in diameter. Imaging with transmission electron microscopy allowed further morphological discrimination of gel particles in "aggregate" particles, "aggregate with film" particles, and "mucus-like" particles. Halo particles were observed above 75 nm and appeared to be ammonium (bi)sulfate (59 % of halo particles), gel matter (19 %), or decomposed gel matter (22 %), which were internally mixed with sulfuric acid, methane sulfonic acid, or ammonium (bi)sulfate with a maximum at 161 nm in diameter. Elemental dispersive X-ray spectroscopy analysis of individual particles revealed a prevalence of the monovalent ions Na+/K+ for single particles and aggregate particles and of the divalent ions Ca2+/Mg2+ for aggregate with film particles and mucus-like particles. According to these results and other model studies, we propose a relationship between the availability of Na+/K+ and Ca2+/Mg2+ and the length of the biopolymer molecules participating in the formation of the three-dimensional gel networks.

Structural characterization of Cu doped zinc ferri-chromites prepared by novel gel combustion route

The present study is investigated for Cu doped series of Zn1−x Cu x FeCrO4 (0.0 ≤ x ≤ 1.0) system prepared by sol–gel auto-combustion method. The as-claimed novelty of this route is in situ oxidizing environment of nitrate ions in gel increases rate of oxidation by lowering the decomposition temperature of component. The completion of solid state reaction was checked by thermogravimetric analysis while crystalline phase evolution was assessed by X-ray diffraction. All the compounds exhibit cubic spinel symmetry and lattice constant shows nonlinear behavior with copper content. A morphology of the grains formed was found by scanning electron microscope while element compositions by elemental dispersive X-ray spectroscopy. Infra-red spectral studies showed two fundamental bands correspond to the intrinsic vibrations of tetrahedral and octahedral complex. The results indicate that system transfers from normal to inverse spinel.

Synthesis and characterization of cobalt substituted zinc ferri-chromites prepared by sol–gel auto-combustion method

Mixed metal oxides having spinel structure shows interesting structural properties. In the present investigation, cobalt substituted zinc ferri-chromites were prepared by sol–gel auto-combustion method. The completion of solid state reaction and the formation of spinel phase were identified using X-ray diffraction technique. All the compounds exhibit cubic spinel symmetry and lattice constant shows an irregular trend with substitution of Co. Infra-red spectral studies shows an two strong bands, one around 600 cm−1 which is attributed to the intrinsic vibrations of tetrahedral complexes and the other at 400 cm−1 is due to octahedral one. The morphology and size of the particles was found out by scanning electron microscopy while the elemental compositions by elemental dispersive X-ray spectroscopy. The various compounds of the present system Zn1−xCoxFeCrO4 were also investigated for their thermal and electronic studies.

Synthesis, characterization and studies on magnetic and electrical properties of Mg ferrite with Cr substitution

Mixed metal oxides possessing spinel structure exhibit interesting structural, electrical, magnetic and catalytic properties. During the course of investigation, chromium substituted magnesium ferrites were synthesized by co-precipitation technique using NaOH at a pH of 9.5. Formation of spinel phase was identified using X-ray diffraction technique (CuKα 1.54056Å). All the compounds exhibited cubic spinel symmetry and lattice constant varied between 8.40 and 8.33Å. They showed decreasing trend with increase in concentration of chromium. Infra-red spectral studies showed two strong bands one around 600cm−1 which is attributed to the intrinsic vibrations of tetrahedral complexes and other at 400cm−1 is due to octahedral one. The morphology and size of the particles was found by scanning electron microscope while element compositions by elemental dispersive X-ray spectroscopy. The various compounds of the system MgFe2−xCrxO4 were also investigated for their thermal, electronic and magnetic hysteresis studies.