Wet Chemical Synthesis Route Research Articles

Highly active novel CeTi2O6/g-C3N5 photocatalyst with extended spectral response towards removal of endocrine disruptor 2, 4-dichlorophenol in aqueous medium

Heterogeneous photocatalysis process is emerging technology for the removal of toxic pollutants, but the photocatalytic responses of the widely studied materials like TiO2 and ZnO are still not good enough under the visible light and NIR region. Herein, we have prepared a highly proficient novel visible light active heterojunction photocatalyst using low bandgap semiconductor carbon nitride (g-C3N5) and cerium titanate (CeTi2O6). The CeTi2O6/g-C3N5 heterojunction with hefty surface area and fabulous visible-light response was achieved by a simple wet chemical synthesis route. The structural and morphological features of the CeTi2O6/g-C3N5 heterojunctions were premeditated by the X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), elemental analysis (EDS), and X-ray photoelectron spectroscopy (XPS) studies respectively. The CeTi2O6/g-C3N5 heterojunction exhibited outstanding photocatalytic response under the visible light towards the degradation of endocrine rupture material 2,4-dichlorophenol (2,4-DCP) than its single components. Radicals trapping experiments confirmed that the superoxide radicals, as well as hydroxide radicals, played the most prominent role in the removal of 2, 4 DCP. This study will offer new insight into the development of novel low bandgap g-C3N5 based stable photocatalyst materials with tunable bandgap for the degradation of hazardous pollutants.

Direct Imaging of Dopant and Impurity Distributions in 2D MoS2.

Molybdenum disulfide (MoS2 ) nanosheet is a two-dimensional (2D) material with high electron mobility and with high potential for applications in catalysis and electronics. MoS2 nanosheets are synthesized using a one-pot wet-chemical synthesis route with and without Re doping. Atom probe tomography reveals that 3.8 at% Re is homogeneously distributed within the Re-doped sheets. Other impurities are also found integrated within the material: light elements including C, N, O, and Na, locally enriched up to 0.1 at%, as well as heavy elements such as V and W. Analysis of the nondoped sample reveals that the W and V likely originate from the Mo precursor. It is shown how wet-chemical synthesis results in an uncontrolled integration of species from the solution that can affect the material's activity. The results of this work are expected to contribute to an improved understanding of the relationships linking composition to properties of 2D transition-metal dichalcogenide materials.

Retrospection of polymer capped LaPO4: Eu3+ luminescent nano phosphor for ingenious solid state lighting

In the present work, the optical properties of LaPO4:Eu3+ luminescent nano phosphors passivated with different capping agents have been probed in depth. Nano particles of Lanthanum orthophosphate nano phosphor were successfully synthesized employing wet chemical synthesis route. The structural properties were investigated through XRD, SEM and, TEM whereas the optical properties were explored using photo luminescent characterizations along with afterglow studies. The PL emission intensity peaks were observed at 588nm, 593 nm, 613 nm and 621 nm corresponding to 5D0-7F1 and 5D0-7F2 spectroscopic transitions and are supposed to emit orange-red energy spectrum. With the help of diffuse reflectance spectroscopy, the optical band gaps of differently capped phosphors were calculated employing Kubelka Munk equations.

In-situ N-doped MnCO3 anode material via one-step solvothermal synthesis: Doping mechanisms and enhanced electrochemical performances

In-situ N-doped MnCO3 microcrystal was prepared by a mild one-step solvothermal process for the first time. The influences of N-doping on microstructures and electrochemical performances of MnCO3 microcrystal have been investigated systematically. A plausible mechanism for the in-situ N-doping in MnCO3 also has been proposed. It is found that nitrogen was successfully doped into the MnCO3 by the substitution of lattice oxygen, generating a specific defect structure with oxygen vacancies and narrowing the band gap of MnCO3 effectively from 5.021 to 3.885 eV. When used as anode material, the as-obtained N-doped MnCO3 exhibits outstanding electrochemical performances: it delivers a large capacity of 685 mAh g−1 after 600 cycles at 1 C; exhibits a superior high-rate performance and long-term stability with a high capacity of 437 mAh g−1 even after 1000 cycles at a very large current rate of 5 C. Compared with the pristine MnCO3, such the outstanding electrochemical performances of N-doped MnCO3 should be attributed to the specific defect structure provided by N-doping, which can not only create more active sites for lithium storage, but also improve the poor electronic conductivity of MnCO3. This work can offer an effective and facile strategy to realize in-situ N-doping by wet chemical synthesis route, as well as enhance the electrochemical performances of transition metal carbonates.

Syngas production from electrochemical reduction of CO2 at high current density using oxide derived Zn/Cu nanocomposite

Reduction of CO2 in an electrochemical reactor may become a future technology for the production of syngas. This technology uses CO2 and water co-electrolysis and has the potential to produce variable CO/H2 ratio, which can become feedstock for various processes. However, developing an electrocatalyst selective for ERC is a great challenge. Further, high current density and low overpotential are essential for the electroreduction of the ERC. In this paper, oxide derived Zn/Cu electrocatalysts with different concentrations of Cu is reported using facile wet chemical synthesis route for the tunable syngas production. Physico-chemical analysis of the electrocatalysts revealed that by varying the concentration of Cu into the oxide derived Zn/Cu composite, fraction of Cu distributed into the ZnO crystal and composite form can be tunned. This inturn generates a synergic effect and reduces the charge transfer resistance towards ERC. By controlling the Cu concentration in the oxide derived Zn/Cu electrocatalyst CO/H2 ratio can be tunned over a wide range (0.84, 0.76, 0.25) at different current densities (20.4, 8.8, 37 mA/cm2). Oxide derived Zn/Cu electrocatalyst shows potential for electrochemical reduction of CO2 to syngas with tunnable CO/H2 ratio by utilizing renewable energy.

Augmented antibacterial efficacies of the aluminium doped ZnO nanoparticles against four pathogenic bacteria

An ingenious study aimed to understand the influence of crystallite size, surface defects and morphology of the aluminium doped ZnO nanoparticles on their enhancement of antibacterial activities are reported herein. A cost effective wet chemical synthesis route was adopted for the synthesis of aluminium doped ZnO nanoparticles. X-ray diffraction analysis substantiates the hexagonal phase of the aluminium doped ZnO nanoparticles. The original contributions of the respective crystallite sizes and lattice strains of the synthesized nanoparticles are realized by size-strain plot (SSP) analysis. The UV-vis spectroscopic analysis revealed that the band gaps of the synthesized samples are widened on aluminium doping. The surface defects and vacancies present in the synthesized samples are revealed by the room temperature photoluminescence analysis. FESEM micrographs of the samples reveals that the crystallite sizes of ZnO decreases with the increase in aluminium content and a change in platelet to narrow sized spherical morphology. An investigation on the antibacterial activities of the aluminium doped ZnO nanoparticles was performed on Escherichia coli, Proteus mirabilis, Enterococcus faecalis and Staphylococcus aureus bacteria. The aluminium doping in ZnO leads to an enhanced antibacterial activity. The 5%Al:ZnO nanoparticle sample shows the highest antibacterial efficiency of 117% for the Proteus mirabilis bacterium. These results clearly demonstrate that the aluminium doped ZnO nanoparticles are promising candidates for antibacterial applications.

Low-cost uncooled MWIR PbSe quantum dots photodiodes.

A mid-wave infrared (MWIR) uncooled PbSe-QDs/CdS p–n heterojunction photodiode has been fabricated using a wet-chemical synthesis route. This offers a low-cost alternative to traditional monocrystalline photodiodes relying on molecular beam epitaxy (MBE) technology. It was demonstrated that the post-annealing is critical to tailor the photoresponse wavelength and to improve the performance of photodiodes. After annealing at 673 K in air for 0.5 h, the ligand-free PbSe-QDs/CdS photodiode exhibits a MWIR spectral photoresponse with a cutoff wavelength of 4.2 μm at room temperature. Under zero-bias photovoltaic mode, the peak responsivity and specific detectivity at room temperature are 0.36 ± 0.04 A W−1 and (8.5 ± 1) ×108 cm Hz1/2 W−1, respectively. Temperature-dependent spectral response shows an abnormal intensity variation at temperatures lower than 200 K. This phenomenon is attributed to the band alignment transition from type II to type I, resulting from the positive temperature coefficient of PbSe. In addition, it was proved that In doped CdSe (CdSe:In) films could be used as a promising new candidate of infrared transparent conductive electrodes, paving the way for monolithic integration of uncooled low-cost MWIR photodiodes on Si readout circuitry.

Design and Activity of Supported Transition Metal Catalysts for Methane to Methanol Oxidation in Electrochemical Fuel Cell

Methane is a relatively inexpensive and abundant resource and its partial transformation to chemicals and chemical fuels presents attractive yet challenging pathways for its utilization. Conventional synthesis for methanol involve a multistep process involving steam reforming of methane with subsequent catalytic reactions, which require high energy input and run at high cost [1]. Alternatively, methane oxidation over catalyst surfaces in an electrochemical cell is a promising single-step approach to achieve a direct conversion of methane to methanol at lower temperatures and low cost [2]. Previous studies have demonstrated that methane can be electrochemically converted into methanol with high selectivity but with low overall conversion efficiency. Increasing the rate of methane conversion can be achieved by systematic improvement of the electrochemical cell design along with the concurrent development of new efficient catalysts materials. Methane oxidation is energetically challenging process and dual role of the catalysts involve first, activation of the relatively inert C-H bond enabling the oxidative hydroxylation, and methanol formation. Second, the effective catalysts should simultaneously inhibit the methanol oxidation, which proceeds with a much lower energy barrier and can result in the formation of formaldehyde, formic acid, carbon monoxide, and carbon dioxide. To date, a variety of the catalysts, among different supported metals (Pd, Ru, Au, Ag) and metal oxides (V2O5, Fe2O3, CoO, Mn2O3, MoO3, CrO), have been tested in electrochemical cell and shown promise for the direct oxidation of methane [2]. However, further systematic studies are essential for understanding the mechanism for methane oxidation, enabling catalysts rational design. On the other hand, bioinspired supported binuclear metal catalysts show potential for high selectivity and conversion [3], but have not yet been explored for electrochemical methane conversion. In this study, first-row transition metal oxides as well as single and binuclear catalysts, supported on well-defined crystalline 2D materials including carbides, oxides, and nitrides will be presented. The catalysts are synthesized with wet-chemical synthesis routes and subsequently fabricated in membrane electrode assembly for testing their activity, methanol selectivity, and conversion efficiency in an electrochemical fuel-cell-type reactor. In-depth structural and chemical analyses of catalysts using a combination of various transmission electron microscopy techniques, complimented with spectroscopy analyses is used to establish structure-property relationship. These insights will provide valuable basis for a scientific-guided approach toward the optimization of the known, and the identification of the new metal oxide and single-site supported catalysts for this challenging process. Ravi, M., et al, Angew. Chemie Int. Ed., 2017, 56, 26464.Tomita, A., et al, Angew. Chemie Int. Ed., 2008, 47, 1462.Starokon, E. V., Phys Chem. C., 2011, 115, 2155.

Challenges in the Fabrication of Ceramic Technetium Waste Forms

ABSTRACTIn this research we can demonstrate, that fission technetium-99 can be successfully immobilized as tetravalent cation in solid state refractory oxides such as pyrochlores and perovskites. Pyrochlores show excellent performance in ASTM C1220-10 type corrosion testing and have the ability to structurally bond Tc-99 and therefore avoid the formation of highly-mobile, pertechnetate species under conditions of a generic repository. We have fabricated lanthanide technetium oxides using either dry-chemical ceramic processing, or wet-chemical coprecipitation methods. Tc pyrochlores have shown better Tc retention and corrosion resistance compared with Tc-containing LAWE4-type borosilicate glass, combined with 50-times higher waste loading. However, mechanical properties (fracture toughness, compressive strength) of the pyrochlores are lacking and the microstructure shows high open porosity of about 50 %. To improve these properties we tested a variety of measures such as hot-pressing or the combination of hot pressing and high-temperature synthesis, but the improvement was minor and Tc and the surrogate Ru were partly reduced. The presence of metallic inclusions has strong impact on Tc retention and release rates increased more than tenfold. We have further developed a wet-chemical coprecipitation synthesis route followed by calcination and a 4-days high-temperature sintering cycle for the model composition Sm2(Ru0.5Ti0.5)2O7 where titanium oxide was added as sintering agent. The ceramic surrogate waste forms showed improved theoretical densities of about 73 % combined with sufficient mechanical strength, while maintaining ruthenium in the tetravalent state.

A comparative study of the properties of five-layered Aurivillius oxides A2Bi4Ti5O18 (A = Ba, Pb, and Sr) synthesized by different wet chemical routes

This paper reports the detailed study of the effect of different wet chemical synthesis routes (solution combustion, co-precipitation, and sol–gel route) on the microstructure, phase formation, dielectric, electrical, and ferroelectric properties of five-layered Aurivillius oxides: A2Bi4Ti5O18 (A = Ba, Pb, and Sr). Different synthesis parameters like the precursors used, synthesis temperature, and reaction time affects the morphology of the ceramics. Microstructure in turn influences the dielectric and ferroelectric properties. It was observed that the sol–gel-synthesized ceramics possess higher dielectric constant and remanent polarization, low dielectric loss due to lower conductivity in these samples as a result of higher density in these compounds as compared to those synthesized by other wet chemical synthesis routes such as solution combustion route and co-precipitation technique. The XRD data are used for phase analysis and surface morphology is studied using SEM images. Dielectric and electrical properties are investigated as a function of frequency and temperature.

Red Mn4+-Doped Fluoride Phosphors: Why Purity Matters.

Traditional light sources, e.g., incandescent and fluorescent lamps, are currently being replaced by white light-emitting diodes (wLEDs) because of their improved efficiency, prolonged lifetime, and environmental friendliness. Much effort has recently been spent to the development of Mn4+-doped fluoride phosphors that can enhance the color gamut in displays and improve the color rendering index, luminous efficacy of the radiation, and correlated color temperature of wLEDs used for lighting. Purity, stability, and degradation of fluoride phosphors are, however, rarely discussed. Nevertheless, the typical wet chemical synthesis routes (involving hydrogen fluoride (HF)) and the large variety of possible Mn valence states often lead to impurities that drastically influence the performance and stability of these phosphors. In this article, the origins and consequences of impurities formed during synthesis and aging of K2SiF6:Mn4+ are revealed. Both crystalline impurities such as KHF2 and ionic impurities such as Mn3+ are found to affect the phosphor performance. While Mn3+ mainly influences the optical absorption behavior, KHF2 can affect both the optical performance and chemical stability of the phosphor. Moisture leads to decomposition of KHF2, forming HF and amorphous hydrated potassium fluoride. As a consequence of hydrate formation, significant amounts of water can be absorbed in impure phosphor powders containing KHF2, facilitating the hydrolysis of [MnF6]2- complexes and affecting the optical absorption of the phosphors. Strategies are discussed to identify impurities and to achieve pure and stable phosphors with internal quantum efficiencies of more than 90%.

Wet-chemical synthesis of hexagonal plate-like niobate particles for lead-free piezoceramics

Hexagonal plate-like potassium-sodium niobate (KNN) perovskite particles with average width of 5.8 µm, thickness of 0.5 µm, and high aspect ratio over 10 were successfully prepared via low temperature surfactant-free wet-chemical synthesis and subsequent calcination. Forming potassium rich hydrate particles was a crucial step for modulating the plate-like morphology with well-defined hexagonal outline and uniform size distribution, the aspect ratio of which increased with increasing potassium content. Removal of crystal water in the KNN-hydrate took place at 150–250 °C and the weight loss was approximately 9%. The K+/Na+ ratio of the perovskite KNN plates obtained by calcination was consistent with the starting stoichiometry. This low-temperature wet-chemical synthesis route to KNN is expected to pave a low-cost scalable way for the mass production of plate-like template particles in the field of high-performance lead-free textured piezoceramics.

A Novel Wet-Chemical Route for Synthesis of Multiferroic AMnO3 (A = Gd, Tb, Dy) Particles and Its Structural, Optical and Magnetic Properties

Several multiferroic AMnO3 (A = Gd, Tb, Dy) particles were synthesized by microwave-assisted acrylamide gel route. The influence of A-site cation on the phase purity, surface morphologies, and optical and magnetic properties of the as-prepared multiferroic AMnO3 (A = Gd, Tb, Dy) particles was investigated. X-ray diffraction pattern, Fourier transform infrared spectroscopy, and Raman spectroscopy confirm the pure phase of the AMnO3 (A = Gd, Tb, Dy) particles exhibits an orthorhombic perovskite structure. Scanning electron microscopy (SEM) observation indicates that the surface morphology of AMnO3 (A = Gd, Tb, Dy) particles is significantly dependent on the A-site cation. The particle size of AMnO3 (A = Gd, Tb, Dy) particles increases with the increasing atomic number of A-site cation The optical band gap values of AMnO3 (A = Gd, Tb, Dy) particles decrease with an increase in the atomic number of A-site cation. Magnetization measurements show that these AMnO3 (A = Gd, Tb, Dy) particles exhibit magnetic ordering at low temperatures.

Toward reducing the formation temperature of diopside via wet-chemical synthesis routes using chloride precursors

Abstract Reducing the formation temperature of single-phase multioxides is one of the classic challenges in ceramic processing, including wet-chemical synthesis routes. Toward pursuing this aim for diopside (MgCaSi 2 O 6 ), the merit of different sol-gel and coprecipitation processes using the related chloride precursors followed by calcination was compared from the viewpoints of crystallinity and homogeneity. In accordance to the results, the use of the sol-gel techniques, directed with/without an alkaline catalyst, gave rise to the unfavorable creation of multiphase and low-crystallinity structures. Regarding the coprecipitation methods, the one-step addition of a precipitant agent is accompanied by an indirect low-temperature formation of nano-diopside, while a direct crystallization into this phase was explored in the dropwise condition, albeit with a lower crystallinity. Thus, by employing a suitable synthesis processing, it is feasible to take control of a wide range of nanoparticulate diopside-based structures achieved after a low-temperature calcination.

Polymer‐supported palladium: A hybrid system for multifunctional catalytic application

Polymer‐supported palladium was synthesized by applying a single‐step wet chemical synthesis route and the resultant composite material was characterized by means of various techniques. Infrared and UV–visible spectra provided information on the chemical structure of the polymer. Microscopy techniques showed the general morphology of the polymer. The oxidation state of palladium was determined using the X‐ray photoelectron spectroscopy method. The synthesized material was applied as a heterogeneous catalyst for the Heck coupling reaction and also as an electrocatalyst for the oxidation of cysteine.

Electrochemical Behaviour and Phase Evolutions during Sodiation/Desodiation of Na2Ti3O7 nanoparticles, Synthesized Via Sol-Gel Route, Decorating Carbon Nanotubes

The emerging technology of sodium ion batteries has attracted a great deal of attention due to the abundant availability and cost efficiency of the concerned raw materials. The technology still needs improvements, primarily in terms of finding suitable anode material with superior Na-capacity, cyclic stability and also rate capability. This is mainly caused by graphitic carbon not being able to intercalate sodium, unlike in the case of lithium. Layered Na2Ti3O7, because of its low potential against Na/Na+and decent theoretical Na-capacity (~200 mAh/g), has emerged as a promising anode material among other Na-based intercalation compounds [1]. However, in addition to its poor rate capability owing to inherently low electronic conductivity in pristine form, its cyclic stability is also far from being satisfactory. Poor structural stability during sodiation/desodiation is one of the reasons for the same. Against this backdrop, the present work focuses on improving the overall electrochemical behaviour, not only by reducing size of the Na2Ti3O7 particles to nano-sized regime, but also by incorporating conducting reinforcements like multi-walled carbon nanotubes (MWCNTs). However, the challenges associated with synthesizing active materials having nanoscaled dimensions via facile and cost-effective wet-chemical synthesis routes, while at the same time achieving intimate contact with carbon nanotubes usually pose practical hindrances towards improving rate capability and cyclic stability of promising ceramic electrode materials. Developing MWCNTs-incorporated composite electrode slurry via the usual physical mixing route may not allow intimate contact; rather may lead to contamination. Growth of MWCNTs on electrode-active particles via vapour deposition is not a cost-effective and scalable process. These disadvantages have been overcome in our work by developing an innovative, but facile sol-gel based route, which helped in synthesizing Na2Ti3O7 nanoparticles with near-perfect control over stoichiometry and also in intimate contact with MWCNTs. In more precise terms, the sol-gel based route has been tuned for successfully developing Na2Ti3O7 nanoparticles with MWCNTs uniformly wrapped around them allowing intimate contact with the MWCNTs, as was clearly evident from the high-resolution TEM images. The results once again highlight the success of this route based on direct addition of MWCNTs into the ‘matrix’ sol, followed by rapid gelation and subsequent crystallization in presence of MWCNTs (for Na-ion battery electrode), as recently demonstrated also for LiFePO4-MWCNT electrodes (for Li-ion batteries) [2]. The specific Na-capacities, as recorded during galvanostatic cycling, were considerably higher upon incorporation of the MWCNTs, as compared to those with the active particles of the same size/composition, prepared using the same route, but sans MWCNTs. More importantly, the cyclic stability improved significantly in the presence of the MWCNTs. The differences were more notable at the higher current densities, signifying considerably improved rate capability. In more specific terms, for over a period of 100 discharge/charge cycles, the capacity retention for Na2Ti3O7/MWCNT was superior to that for Na2Ti3O7, sans MWCNTs, by a factor of ~16. Another important observation has been the significant reduction in voltage hysteresis in presence of the MWCNTs. In addition to increasing the overall electrical conductivity, the anchoring/buffering action provided by the MWCNTs against the high volume changes during phase transformation reactions, might possibly be some of the reasons for the higher capacity and improved cyclic stability in the case of MWCNTs-containing Na2Ti3O7 nanoparticles. The work, to be presented, also includes in-situ synchrotron X-Ray diffraction studies for obtaining better insights into some of the fundamental aspects concerning phase transformations during charge/discharge at such ultra-fine dimension, in the presence/absence of MWCNTs (in intimate contact) and also in the presence of impurity phases (as deliberately introduced). The results provide clarity on the sodiation/de-sodiation mechanisms and correlations between the electrochemical performances, phase assemblage and phase evolutions of Na2Ti3O7 and Na2Ti3O7/MWCNT anodes for Na-ion batteries. Keywords: Na2Ti3O7/MWCNT, Na-ion batteries, Cyclic stability, In-situ synchrotron X-Ray diffraction

Support Effect on the Water Gas Shift Activity of Chemical Vapor Deposition-Tailored-Pt/TiO2 Catalysts

In contrast to most wet chemical synthesis routes, chemical vapor deposition (CVD) offers many degrees of freedom for the structuring of Pt nanoparticle catalyst systems, which is a prerequisite for the examination of structure–function correlations in heterogeneous catalysis. Two different suitable metal–organic Pt precursors [MeCpPtMe3 and novel PtMe2(iBu-COD)] were employed to generate highly defined, very narrowly distributed Pt nanoparticles with high active surface areas on well-specified TiO2 supports of differing surface properties. The TiO2 supports and the Pt nanoparticles were thoroughly characterized and tested in the water gas shift reaction. The influence of the support particle size and its surface chemistry (hydroxyl groups) as well as the nature of the metal–organic precursors used on the water gas shift (WGS) activity were investigated by nanotechnological methods within this study. A further modification of the support material was done by Na deposition. This catalyst was found to be a ...

Reaction mechanism and morphology of the LiFePO4 materials synthesized by chemical solution deposition and solid-state reaction

The mechanism of a low temperature wet chemical route for synthesis of LiFePO4 cathode material for Li-ion batteries is presented. Using inorganic salts as precursors and diethylene glycol (DEG) as reaction media, nanosize LiFePO4 powder is obtained. The controversially discussed role of the polyol on this reaction has been clarified by in-situ FT-IR analysis of the gaseous reaction products and a full analysis of solid products. It is observed that DEG does not act as reducing agent for iron(II) salts, nor is it oxidized during the synthesis of LiFePO4. Generally, polyols are used to reduce the oxides and hydroxides into their corresponding metals. The nucleation of Li+, PO 43− and Fe2+-ions in the DEG solvent starts at temperatures 110°C, 130°C and 170°C, respectively. LiFePO4 precipitation from Li-carbonate, Fe(II)-oxalate dihydrate and ammonium dihydrogenphosphate as precursors is driven by thermal decomposition of the salts, intermediate formation and dehydration of amino-ethoxy-ethane, yielding 1,4-dioxane as volatile by-product. With the help of in-situ investigations reaction time and temperature could be minimized. Furthermore, the effect of the concentrations of Li+, Fe2+ and PO 43− ionic moieties on the morphology of LiFePO4 materials obtained by chemical solution deposition and solid state reaction are studied with the help of FT-IR analysis. LiFePO4 platelets morphology exhibited better discharge capacity than LiFePO4 agglomerate morphology. The solid product is characterized by X-ray diffraction, scanning electron microscopy and differential thermogravimetry combined with mass spectrometry and FT-IR.

Highly textured ZnO thin films grown using sol-gel route for gas sensing application

The crystalline orientation of metal oxide thin films often modulates their structural, optical as well as surface related properties. Viewing in the same line, in the present work we have systematically investigated the structural, micro structural, optical and gas sensing characteristics of highly textured zinc oxide (ZnO) thin films oriented along (002) crystalline planes. The ZnO thin films have been grown on quartz substrates by spin coating the precursor sol prepared through cost effective wet chemical synthesis route. The structural and micro structural characteristics of the grown films are studied using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) respectively. The optical properties of the synthesized films are investigated by analyzing the ultraviolet-visible (UV–VIS) and photoluminescence (PL) spectroscopy. From the recorded absorption spectra band gap energies of the films are estimated. The gas sensing characteristics of the grown films are investigated upon exposure to various toxic and combustible gases at different operating temperatures. Finally, the effect of crystalline orientation on the structural and optical properties and gas sensing characteristics of the grown ZnO thin films are explored.

Facile Preparation Approaches and Prospective Applications for Nanostructured Ferrites

With the development of synthesis of nanomaterials, magnetic ferrites and the traditional magnetic materials can be prepared by new methods, including top-down and bottom-up approaches. Ferrites are economic magnetic materials and are also being developed for new applications. Recent work on facile preparations and prospective applications for nanostructured ferrites will be discussed. Soft and hard ferrites are generally produced by ceramic routes in industry, but in present work, wet-chemical synthesis routes are utilized. Lithium ferrites were doped with Zn and Mg using co-precipitation method. They have shown promise in absorbers and sensors. Cobalt ferrite nanocrystals were prepared by a simplified sol-gel method namely the WOWS (without water and surfactants) sol-gel method. Cobalt ferrites with adjustable electrical properties have been obtained by doping a small amount of RE elements. Structural analysis of the prepared samples was done by X-ray diffraction (XRD). Lattice parameters and crystallite sizes were determined by using XRD data. Spinel structure was observed for all the prepared samples but with different space groups. DC electrical resistivity was measured as a function of temperature, and activation energies were determined from the Arrhenius plots for all the samples and their comparative study was done. Resistivity of all the samples was decreased with increase in temperature which indicated their semiconductor-like behavior. Polaron hopping was the major conducting mechanism as activation energies for all the samples were above 0.4 eV. The studied materials can be utilized in advanced electronics industries.