High-resolution Field-emission Scanning Electron Microscopy Research Articles

Unravelling the Anisotropic Behavior of Nickel—Wires Prepared through External Magnetic Field Assisted Hydrazine Reduction Method

Ni wires, prepared through a hydrazine reduction, were exposed to external magnetic fields of different geometrical shape and configuration during the synthesis denoted as Ni-Non-Magnetic, Ni-Double, Ni-Single, Ni-Ring. Their effect on the wire morphology, magnetization and magnetic anisotropy was then investigated via various characterization techniques viz. X-ray diffraction (XRD), high-resolution field emission scanning electron microscopy (HR-FESEM), and vibrating sample magnetometer (VSM). The polycrystalline single phase of the Ni-wires with face centered cubic symmetry was confirmed through the analysis of XRD patterns. Analysis of HR-FESEM images revealed that the Ni-particles were aligned in form of wire-like morphology. The Ni-single sample formed the wires with minimum diameter compared to the parent sample. The magnetization measurements performed at 300 K and 50 K demonstrated the ferromagnetic behavior of all the samples. The room temperature saturation magnetization (MS) and anisotropy constant (K) of the Ni-wires were reduced upon providing the external field during synthesis. However, the low temperature (50 K) magnetization behavior was rather opposing, indicating enhanced values of MS and K. Among all, Ni-ring sample showed maximum anisotropy with a value of 3.84 × 104 erg/cm3 at 50 K. The ambiguous nature of the anisotropic constant and saturation magnetization ascribed partly to the variation in diameters of Ni-wires and to the intermittent spin-spin exchange interactions of unaligned/partially aligned particles during the synthesis. Briefly, in the present study, it was established that the morphology and magnetic anisotropy of the Ni-wires could be tailored through the external magnetic field assisted synthesis method.

The Terrestrial Plastisphere: Diversity and Polymer-Colonizing Potential of Plastic-Associated Microbial Communities in Soil.

The concept of a ‘plastisphere microbial community’ arose from research on aquatic plastic debris, while the effect of plastics on microbial communities in soils remains poorly understood. Therefore, we examined the inhabiting microbial communities of two plastic debris ecosystems with regard to their diversity and composition relative to plastic-free soils from the same area using 16S rRNA amplicon sequencing. Furthermore, we studied the plastic-colonizing potential of bacteria originating from both study sites as a measure of surface adhesion to UV-weathered polyethylene (PE) using high-magnification field emission scanning electron microscopy (FESEM). The high plastic content of the soils was associated with a reduced alpha diversity and a significantly different structure of the microbial communities. The presence of plastic debris in soils did not specifically enrich bacteria known to degrade plastic, as suggested by earlier studies, but rather shifted the microbial community towards highly abundant autotrophic bacteria potentially tolerant to hydrophobic environments and known to be important for biocrust formation. The bacterial inoculates from both sites formed dense biofilms on the surface and in micrometer-scale surface cracks of the UV-weathered PE chips after 100 days of in vitro incubation with visible threadlike EPS structures and cross-connections enabling surface adhesion. High-resolution FESEM imaging further indicates that the microbial colonization catalyzed some of the surface degradation of PE. In essence, this study suggests the concept of a ‘terrestrial plastisphere’ as a diverse consortium of microorganisms including autotrophs and other pioneering species paving the way for those members of the consortium that may eventually break down the plastic compounds.

Surface functionalisation of multi-walled carbon nanotubes with tris(2-aminoethyl)amine and their characterisation

Carbon nanotubes are widely employed in various applications because of its excellent properties. However, they generally suffer from the low dispersion into aqueous solutions. Many applications of carbon nanotubes require previous surface functionalisation. In present study, we report the surface functionalisation of multi-walled carbon nanotubes (MWCNTs) by grafting a tris(2-aminoethyl)amine (TAA) via a facile method. The pristine MWCNTs and TAA-functionalised MWCNTs (MWCNTs-TAA) are characterised by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and Raman spectroscopy, thermal gravimetric analysis (TGA). The TEM image of MWCNTs-TAA exhibits significantly improved dispersion of the MWCNTs. The high-resolution FE-SEM images clearly show the opening ends of nanotubes after TAA functionalisation. The increase in nanotube diameters of MWCNTs-TAA is observed compared to the pristine MWCNTs. The strong absorption peak at 1530 cm−1 from FTIR spectra for MWCNTs-TAA indicates that the amine groups are successfully grafted onto the surface of MWCNTs. The TGA curves of MWCNTs-TAA reveal a weight loss in the temperature range of 200 to 450 °C attributed to the decomposition of the amine groups, and the highest weight loss is obtained to be 22.14 wt% after 12 h reaction time. This work demonstrates the facile and efficient method to functionalise MWCNTs with TAA.

Ag metal organic frameworks nanocomposite modified electrode for simultaneous electrochemical detection of copper (II) and lead (II)

The detection of biologically important metal ions such as Cu(II) and Pb(II) ions using an electrochemical approach at sensitive level is gaining great attention to reveal the health conditions of patients with serious diseases such as rickets, bone deterioration, and heart disease that are associated with these metal ions as well as environmental hazards. Thus, rapid and efficient detection methods for these metal ions are in great demand. In this study, we developed an ideal protocol using silver metal–organic framework (Ag@MOF) nanoparticles for the detection of Cu(II) and Pb(II) metal ions. Ag@MOF was synthesized by a reflux method, and the working electrode was prepared by coating Ag@MOF onto ITO glass. Compared with the bare ITO electrode, the Ag@MOF/ITO working electrode exhibited a more sensitive electrochemical performance for the detection of Cu(II) and Pb(II) metal ions through the complexation between the inner core hydroxyl groups of Ag@MOF and the metal ions. The crystallographic and structural analyses of Ag@MOF were carried out by X-ray diffraction analysis and Fourier transform infrared spectroscopy, while morphological analysis was performed by high-resolution transmission electron microscopy and field-emission scanning electron microscopy. X-ray photoelectron spectroscopy was performed to investigate the surface electronic states of silver in Ag@MOF. The cyclic voltammetry results showed that Cu(II) and Pb(II) metal ions can be detected using the Ag@MOF working electrode, which exhibited a more sensitive performance compared with the bare ITO working electrode. Our study shows that the developed electrochemical sensor is ideal for the detection of various metal ions.

Synthesis of 2,5-furandicarboxylic acid-enriched-chitosan for anti-inflammatory and metal ion uptake

The main aim of the present study is to synthesize a hitherto unreported polymer of chitosan (CS) and 2,5-furandicarboxylic acid (FDCA) derived from renewable biomass resources. For this purpose, CS was chosen which had -NH2 groups as abundant active sites. Synthesis of 2,5-furandicarboxylic acid-enriched-chitosan polymer (CS-FDCA) was carried out by reaction involving EDC-NHS coupling reagents. The structure of CS-FDCA polymer was confirmed by various characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), X-ray powder diffraction (XRD), high resolution-field emission scanning electron microscope (HR-FESEM), and thermogravimetric analysis (TGA). Moreover, CS and CS-FDCA were scrutinized to examine their efficacies towards ameliorate inflammation via detection of lipopolysaccharide (LPS) induced nitric oxide (NO) production. As compared to CS, CS-FDCA with low concentration (1.0 μM) exhibited the better efficacy to reduce the NO production. Furthermore, CS-FDCA polymer showed high as 12.6% of Cu2+ ion uptake while CS showed 9.2% of Cu2+ ion uptake. Overall, it can be inferred that CS-FDCA polymer is expected to be used for biomedical application and for the removal of metal contaminants from industrial wastewater.

ICMMS-2: Zinc Oxide nano-rods: Challenges for Glucose Biosensors

Zinc oxide nano-rod thin films (ZNR) will be deposited on silicon substrate (ZNRS) and borosilicate glass capillary tube tip (0.5 and 0.7 µm as inner and outer diameters, respectively) (ZNRT) using both Sol-Gel (SG) and aqueous chemical growth (ACG) techniques for glucose biosensor fabrication. It will be functionalized with membranes or enzymes to produce selective glucose biosensor for glucose concentration measurements in extracellular solutions. The prepared thin film samples provided a favourable environment for the glucose oxidase (GOD) immobilization and introduced a shuttling way for electronic communication between electrodes and GOD. The prepared ZNRS and ZNRT structures and morphologies will be characterized by X-ray diffraction (XRD) and Field emission high resolution scanning electron microscopy (FESEM).

Phase-Purity Na3V2 (PO4) 2F3 Embedded in the Carbon Matrix through Easy Polyol Synthesis As a Potential Cathode of High Performance Sodium Ion Batteries

In this study, a pseudo-layered Na super-ionic conductor (NASICON) of Na3V2(PO4)2F3 (NVPF)/C cathode for sodium-ion batteries is prepared successfully using a easy polyol refluxing process without any impurity phases. We confirmed that NVPF have tetragonal NASICON-type lattice with a space group of P42/mnm through The X-ray diffraction and Rietveld refinement. In this preparative method, polyol is used a solvent as well as a carbon source. The presence of nanosized NVPF particles in the carbon network is confirmed by high-resolution transmission electron microscopy (HR-TEM) and field-emission scanning electron microscopy (FE-SEM). The existence of carbon is analyzed by Raman scattering and elemental analysis. When applied as a Na-storage material in a potential window of 2.0–4.3 V, the electrode exhibits two plateaus at 3.7 and 4.2 V with an electrochemically active V3+/V4+ redox couple. In addition, after Na3V2(PO4)2F3/C was cycled about 1,500 at 15C, It maintaion capacity of ~ 88%. Moreover, at high current densities of 30 and 50 C, Na3V2(PO4)2F3/C cathode retains the specific discharge capacities of 108.4 and 105.9 mAh·g–1, respectively, the structural stability of the material prepared through a facile polyol refluxing method.

An image-based equation for estimating the prospective CO2 storage resource of organic-rich shale formations

An image-based volumetric equation for estimating the prospective CO2 mass storage resource potential for organic-rich shale formations has been developed using data obtained from advanced image analysis of Bakken Formation shale samples. The equation is a modification of the U.S. Department of Energy (DOE) National Energy Technology Laboratory’s (NETL’s) volumetric equation methodology for estimating the prospective CO2 mass storage resource for shale formations. The current equation enhances DOE’s version by systematically deriving expressions for calculating efficiency factors based on analysis of high-resolution field-emission scanning electron microscopy (FESEM) shale images. FESEM images are used to obtain improved nanoscale porosity estimates for the shale matrix and OM. The calculation of the efficiency factors associated with free-phase storage and CO2 adsorption onto solid surfaces are based on a ratio of connected-to-nonconnected porosity and the newly developed shared border analysis (SBA) method, respectively. The image-based equation described herein is structured so that it can be adapted and applied to other formation types by considering the specific mineralogy or matrix characteristics. Preliminary data used to illustrate the newly developed equation show that the Upper Bakken Shale (UBS) may have a lower prospective CO2 storage resource potential than the Lower Bakken Shale (LBS) by about 65 %. Although these results are neither optimized for each lithofacies nor represent the Bakken formation regional scale, they are encouraging for unfractured shale samples and serve as a useful starting point for future evaluations at the regional scale.

High-Resolution Imaging of Cellulose Organization in Cell Walls by Field Emission Scanning Electron Microscopy.

Field emission scanning electron microscopy (FESEM) is a powerful tool for analyzing surface structures of biological and nonbiological samples. However, when it is used to study fine structures of nanometer-sized microfibrils of epidermal cell walls, one often encounters tremendous challenges to acquire clear and undistorted images because of two major issues: (1) Preparation of samples suitable for high resolution imaging; due to the delicateness of some plant materials, such as onion epidermal cell walls, many things can happen during sample processing, which subsequently result in damaged samples or introduce artifacts. (2) Difficulties to acquire clear images of samples which are electron-beam sensitive and prone to charging artifacts at magnifications over 100,000×. In this chapter we described detailed procedures for sample preparation and conditions for high-resolution FESEM imaging of onion epidermal cell walls. The methods can be readily adapted for other wall materials.

Chitosan-based zeolite-Y and ZSM-5 porous biocomposites for H2 and CO2 storage

Sustainable energy is the most valuable clean and renewable energy for the future. A simple, robust, and inexpensive ecofriendly method has been developed here to prepare chitosan-based zeolite porous biocomposites via solvent exchange followed by calcination. The resulting chitosan-based zeolite biocomposites were characterized using advanced technologies including attenuated total reflection-infrared (ATR-IR) spectroscopy, X-ray powder diffraction (XRD) analysis, thermogravimetric analysis (TGA), high-resolution field-emission scanning electron microscopy (HR-FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and nitrogen adsorption-desorption isotherms. The Brunauer-Emmett-Teller (BET) surface area of the ZeY@CS composite (795 m2 g−1) was greater than those of ZSM-5@CS (444 m2 g−1), pure chitosan, pure zeolite Y, and ZSM-5. The chitosan-based zeolite biocomposites show enhanced gas storage for small molecule like CO2 and hydrogen. Therefore, chitosan-based zeolite biocomposites should be suitable for energy storage, carbon capture, and sequestration (CCS) applications.

Synthesis of α-Fe2O3 decorated g-C3N4/ZnO ternary Z-scheme photocatalyst for degradation of tartrazine dye in aqueous media

Abstract In this study, we report the synthesis of a novel α-Fe2O3 decorated g-C3N4/ZnO (g-C3N4/ZnO@α-Fe2O3) ternary Z-scheme photocatalyst for degradation of organic dye. The g-C3N4/ZnO@α-Fe2O3 ternary nanocomposite was synthesized by using the direct pyrolysis and sol-gel methods. Different physicochemical methods were used to confirm the as-synthesized nanomaterials including Transmission electron microscopy, high-resolution field-emission scanning electron microscopy, Fourier Transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The as-synthesized different nanocomposite materials were used to investigate the photodegradation of tartrazine (Acid Yellow 23). Photoluminescence spectra revealed that the g-C3N4/ZnO@α-Fe2O3 ternary nanocomposite has lower recombination rate than pristine g-C3N4. The as-synthesized nanocomposite showed high photocatalytic activity towards degradation of tartrazine than that of g-C3N4, ZnO, ZnO@α-Fe2O3. Also, g-C3N4/ZnO@α-Fe2O3 nanocomposite can able to degrade 99.34% of tartrazine within 35 min under visible light irradiation. The g-C3N4/ZnO@α-Fe2O3 nanocomposite has a higher rate constant and excellent cyclic stability towards the photodegradation of tartrazine. The electrochemical impedance spectra results confirmed that the g-C3N4/ZnO@α-Fe2O3 nanocomposite has faster electron-transfer ability towards the electrode surface than that of g-C3N4, ZnO, and ZnO@α-Fe2O3 composite.

Shale-gas accumulation and pore structure characteristics in the lower Cambrian Niutitang shales, Cen-gong Block, South China

To evaluate pore networks of the lower Cambrian Niutitang Shale in the Cen-gong Block, multiple techniques, including geochemical analysis, low-pressure gas (CO2 and N2) adsorption, mercury intrusion capillary porosimetry (MICP) and field-emission scanning electron microscope (FE-SEM), were performed to investigate pore structure, including pore-size distribution (PSD), pore volume and surface area of black organic-rich shales from two wells to better understand the mechanism of shale-gas accumulation. Geochemical analysis shows that equivalent vitrinite reflectance ranges from 2.1 to 3.5% and are overmature. Surface areas and pore volumes of micropores calculated from CO2 adsorption, which vary from 8.23 to 37.39 m2/g and from 3.06 10−3 to 10.89 10−3 cm3/g, respectively, can provide large amounts of adsorptive sites for shale-gas accumulation. N2 adsorption shows reversed S-shaped isotherms, which are classified into type H2 and H3 hysteresis loops, indicative of ink-bottle pores and slit-or plate-like pores. N2 adsorption and MICP analysis indicates that the inorganic-associated pores in shales may play a significant role in the storage and production of hydrocarbons. High-resolution FE-SEM analysis suggests that OM pores (OMPs) are common in Niutitang samples with a dominant diameter less 50 nm, but a sample with the highest total organic carbon (TOC) of 10.01 wt% has few OMPs, whereas a sample with the TOC of 7.51 wt% has more OMPs. The percentage of OMP area vs total organic matter area (Øs) ranges from 1.70 to 7.92%. The pore structure characteristics of TX1 well, calculated by multiple techniques, are better than samples from TM1 well. In addition, pore types are dominated by interparticle, intraparticle and organic matter pores, and the minor amounts of OMPs in TM1 well indicates that most of the organic matter may have lost the potential to generate hydrocarbons owing to the release of formation pressure with some graphitisation and high-angle fractures larger in the TX1 well. TOC content, mineral composition and tectonically related thermal maturity may be the main controlling factors of the pore structure and the lower Cambrian Niutitang Shale demonstrates the greatest potential for shale-gas production in South China.

Influence of Ce3+ Ion Doping on Structural and Magnetic Properties of Magnesium Nanoferrite

Pure and rare earth ion Ce3+-doped magnesium nanoferrite magnetic particles, i.e., MgFe2O4 and MgCexFe2−xO4 (x = 0.0, 0.025, 0.05, 0.075, and 0.1) were successfully fabricated using sol-gel technique, and qualitative studies were carried out using X-ray diffractometer (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), high-resolution field-emission scanning electron microscopy (HRFESEM) equipped with energy-dispersive spectroscopy (EDS), vibrating sample magnetometer (VSM), and electron paramagnetic resonance (EPR) techniques. X-ray diffraction analysis confirmed the crystalline phase of the synthesized samples with no extra phase. The crystallite size obtained from W-H plots follow the same trend as calculated using Scherrer method, and the strain decreases with increasing Ce3+ ion concentration indicating a lesser number of deformities. FTIR spectra revealed the shifting of lower-frequency band to the higher side with the larger radii Ce3+ ions. HRFESEM images reveal the reduction in stress on doping. No additional impurities are observed in synthesized samples as is confirmed by EDS analysis. The average particle size obtained by TEM are in agreement with XRD analysis. EPR studies showed an increase in g value and line width with doping. Magnetic measurements carried out at room temperature reveals the value of magnetization initially decreases up to x = 0.05 and afterwards increases with the addition of Ce3+ ions. These properties reveal superparamagnetic nature of cerium-doped magnesium nanoparticles and can be suitable for catalyst and humidity sensors.

Metal-induced Z-scheme CdS/Ag/g-C3N4 photocatalyst for enhanced hydrogen evolution under visible light: The synergy of MIP effect and electron mediator of Ag

Efficient photogenerated charge carriers separation and wide absorption wavelength range are important factors for improving photocatalytic performance and application potential of photocatalysts. Applying metal-induced photocatalysis and Z-scheme photocatalysis are two efficient ways to achieve the above aims. Herein, a metal-induced Z-scheme CdS/Ag/g-C3N4 photocatalyst was prepared for photocatalytic H2 evolution under visible light irradiation. X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), scanning electron microscopy (SEM), high resolution field emission scanning electron microscopy (HRSEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance (UV–vis DRS), photoluminescence spectrum (PL), transient photocurrent and electrochemical impedance spectroscopy (EIS) were performed to characterize the structures, optical and electrochemical properties. Results demonstrated that CdS/Ag/g-C3N4 (Ag 3 wt%, g-C3N4 15 wt%) exhibited superior photo-response performance and more efficient photogenerated carriers separation, compared to the counterparts. Owing to the desired properties of CdS/Ag/g-C3N4, high H2 evolution rate of 1376.0 μmol /h∙g in lactic acid scavenger solution was achieved, which was 3.12 and 1.76 times of those of CdS and CdS/g-C3N4. The roles of Ag on CdS/Ag/g-C3N4 were discussed, and it was believed that both metal-induced surface plasmon resonance effect and the Z-scheme electron mediator mechanism synergistically contributed to the enhanced performance. Possible mechanisms for photoelectrons transfer and photocatalytic H2 evolution were proposed.

Nanohexaconazole: synthesis, characterisation and efficacy of a novel fungicidal nanodispersion.

Here, the authors describe a simple method to formulate the nanodispersion of hexaconazole (hexa); henceforth, referred to as nanohexaconazole (N-hexa) that is water soluble and effective against several species of Aspergillus. Size and shape of the prepared nanocomposite was determined with high-resolution transmission electron microscopy and field-emission scanning electron microscopy. Nanohexaconazole structure was further confirmed by Fourier-transform infrared spectroscopy and gas chromatography-mass spectrometry. The antifungal efficacy of nanohexaconazole (N-hexa) was studied in vitro, compared with micronised hexaconazole (M-hexa) at different doses (5 ppm, 10 ppm and control) against two food pathogenic fungi: Aspergillus niger (MTCC 282, MTCC 2196 and BDS 113) and Aspergillus fumigatus through poisoned food technique. A dose-dependent significant growth inhibition was observed in nanohexaconazole (N-hexa) treated fungal sample compared with that of micronised hexaconazole (M-hexa). Micrographic studies for the morphological analysis of control and nanohexaconazole (N-hexa) treated fungal samples were done, exhibited an alternation in fungal morphology. Results showed that nanohexaconazole (N-hexa) is more efficacious than commercially available micronised hexaconazole (M-hexa). In future nanohexaconazole (N-hexa) could be a possible candidate for modern medical science and also reduce damage to the environment from injudicious use of pesticides.

Quantifying dry supercritical CO2-induced changes of the Utica Shale

Traditionally, shale formations have been studied as sealing layers that prevent vertical migration of hydrocarbons and CO2 due to their low permeability and fracture porosity. Recent research has focused on storing CO2 in hydrocarbon-bearing shale formations that have already undergone depletion through primary production and using CO2 as a potential fracturing agent for unconventional reservoirs. The injected CO2 will interact with shale components (i.e. clays, organic matter) and affect rock properties through chemical alteration, matrix swelling/shrinkage, and related geomechanical effects. As changes in rock properties will impact both anthropogenic CO2 storage and hydraulic fracturing, it is imperative to increase our understanding of the CO2-shale interactions. In-situ Fourier Transform infrared (FT-IR) spectroscopy coupled with high temperature and pressure capability was used to examine the interaction of dry CO2 on Utica Shale, clay, and kerogen samples at the molecular scale and characterize vibrational changes of sorption bands sensitive to the gas-solid environment. The Utica Shale was also analyzed for micro and macro-scale chemical and physical changes before and after exposure to dry CO2 at subsurface storage conditions using surface relocation techniques via high-resolution field-emission scanning electron microscopy (FE-SEM). Brunauer-Emmett-Teller (BET) surface area/pore size analysis and quantitative adsorption isotherms were applied to understand changes in surface area, pore volumes, and understand the storage potential of CO2 in the Utica Shale sample. FT-IR and feature relocation via FE-SEM indicate carbonate formation and dissolution occurs in shale exposed to dry CO2. Results indicate that etching and pitting occur, with minor calcite precipitation along the surface of the shale sample. Quantitative isotherm results indicate that shales with a higher content of kerogen and illite-smectite clays would be expected to have the highest CO2 storage capacity provided these constituents were accessible for interaction.

Using X-ray computed tomography and micro-Raman spectrometry to measure individual particle surface area, volume, and morphology towards investigating atmospheric heterogeneous reactions

Heterogeneous reactions on the aerosol particle surface in the atmosphere play important roles in air pollution, climate change, and global biogeochemical cycles. However, the reported uptake coefficients of heterogeneous reactions usually have large variations and may not be relevant to real atmospheric conditions. One of the major reasons for this is the use of bulk samples in laboratory experiments, while particles in the atmosphere are suspended individually. A number of technologies have been developed recently to study heterogeneous reactions on the surfaces of individual particles. Precise measurements on the reactive surface area, volume, and morphology of individual particles are necessary for calculating the uptake coefficient, quantifying reactants and products, and understanding the reaction mechanism better. In this study, for the first time we used synchrotron radiation X-ray computed tomography (XCT) and micro-Raman spectrometry to measure individual CaCO3 particle morphology, with sizes ranging from 3.5–6.5μm. Particle surface area and volume were calculated using a reconstruction method based on software three-dimensional (3-D) rendering. The XCT was first validated with high-resolution field-emission scanning electron microscopy (FE-SEM) to acquire accurate CaCO3 particle surface area and volume estimates. Our results showed an average difference of only 6.1% in surface area and 3.2% in volume measured either by micro-Raman spectrometry or X-ray tomography. X-ray tomography and FE-SEM can provide more morphological details of individual CaCO3 particles than micro-Raman spectrometry. This study demonstrated that X-ray computed tomography and micro-Raman spectrometry can precisely measure the surface area, volume, and morphology of an individual particle.

Supramolecular self-assembled carbon nitride for the degradation of tetracycline hydrochloride

Graphitic carbon nitride microspheres photocatalyst (CN-MCA) was prepared through supramolecular self-assembly with post-heating treatment, which starts from the combination of the raw materials melamine and cyanuric acid. The as-prepared samples were characterized in detail by X-ray diffraction, Fourier transform infrared spectroscopy, new high-resolution field-emission scanning electron microscopy, specific surface areas analysis, UV–Vis diffused reflectance spectrum, photoluminescence spectrum, and thermal analysis. The structural characterization results reveal that the as-prepared CN-MCA has the same chemical structure as CN-M, but appears as microspheres with nanoporous surfaces. Compared to the CN-M, CN-MCA microspheres exhibit higher specific surface areas, stronger optical absorption and lower PL intensity, which allow more active sites, more effective visible-light harvesting and more efficient migration rate of photogenerated charge. Consequently, we observed that CN-MCA microspheres exhibit higher photocatalytic activity in the photodegradation of tetracycline hydrochloride under visible light irradiation. Moreover, the degradation efficiency of tetracycline hydrochloric acid under 2 h of visible light irradiation was 80.54% when the dosage of CN-MCA was 1.0 g/L; the initial concentration of the tetracycline hydrochloride solution was 10 mg/L; and the initial pH was 7.

Influence of La3+ ion doping on physical properties of magnesium nanoferrites for microwave absorption application

Lanthanum (La3+ ions) doped magnesium ferrite nanoparticles i.e. MgLaxFe2−xO4 (x = 0, 0.05, 0.075, 0.1, 0.125) have been prepared using sol-gel technique. These as-prepared nanomagnetic particles were characterized by using X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), High resolution field emission scanning electron microscopy (HRFESEM) with energy dispersive spectroscopy (EDS), Transmission electron microscopy (TEM) and Vibrating sample magnetometer (VSM) techniques. X-ray diffraction analysis reveal that the samples are single phase cubic spinel crystals with size 12–15 nm. Lattice parameter increases with the increase in La3+ ion concentration. The induced strain calculated from Williamson-Hall plots shows that strain decreases from x = 0.0 to x = 0.075 and then increases from x = 0.1 to x = 0.125. FTIR spectra show that FeO stretching vibration peaks of octahedral (FeO6) and tetrahedral (FeO4) group broadness increases with lanthanum content due to gradual decrease in the grain size. These variations are attributed to lattice deformation induced by interparticle interactions, cation distribution, and La3+ ions concentration in the spinel structured samples. SEM micrographs revealed the existence of superfine particles and agglomerated patterns for higher La3+ ion content. The average particle size obtained from TEM images are in close agreement with the crystallite size calculated from the XRD patterns. The magnetic studies exhibited the saturation magnetization, retentivity, anisotropy constant and magnetic moment of the particles decrease with increasing La3+ ions concentration indicating the superparamagnetic nature of lanthanum doped magnesium ferrite samples.

HMTA-assisted uniform cobalt ions activated copper oxide microspheres with enhanced electrochemical performance for pseudocapacitors

Supercapacitors are being considered to be one of important electrochemical energy storage devices due to their high power density as compared with batteries and have remarkable applications. The large surface area transition metal oxides or hydroxides are excellent conductive materials and have been extensively used for supercapacitors. Herein, uniform copper oxide (CuO) and cobalt (Co) activated CuO (CuO:Co) microspheres were synthesized by a hexamethylenetetramine (HMTA)-assisted hydrothermal method. The HMTA was used as an additive surfactant to acquire the uniform microsphere morphology, which was confirmed by high-resolution field-emission scanning electron microscope and field-emission transmission electron microscope images. The phase form of the pristine CuO and CuO:Co powder samples was examined by X-ray diffraction patterns. For the application of pseudocapacitors, electrochemical studies were performed for the CuO and CuO:Co electrode materials in a three-electrode electrochemical cell system. The cyclic voltammetry and galvanostatic charge-discharge curves were measured at different scan rates and current densities, respectively, in 1 M KOH electrolyte solution. The calculated specific capacitance values of the CuO and CuO:Co electrodes were 77 and 284 F/g at a current density of 1 A/g, respectively. Interestingly, by incorporating small concentration of Co into CuO, the specific capacitance was enhanced approximately 4 times when compared with the pristine CuO electrode. The electrochemical impedance spectroscopy spectrum was analyzed for the pseudocapacitive behavior of CuO:Co electrode material. Furthermore, the CuO:Co electrode showed a capacitance retention (75.6%) after 1000 cycles at a current density of 3 A/g. Therefore, the obtained remarkable electrochemical results suggest that the low-cost CuO:Co electrode materials with improved electrochemical performance have promising applications in the field of pseudocapacitors.