Morphology Of Precursor Research Articles

Controllable preparation of porous ZnO microspheres with a niosome soft template and their photocatalytic properties

Using Span80/ polyethyleneglycol 400 (PEG400)/H2O niosome as a soft template, Zn(NO3)2·6H2O as zinc source, urea as alkali source and cinnamate as directing agent, three dimensional (3D) sphere-like ZnO hierarchical nanostructures assembled with numerous nanospheres were fabricated by a simple, one-step hydrothermal route. In the process, cinnamate played a crucial role for the formation of ZnO hierarchical nanostructures, which was acted as morphology director, and demonstrate that the zinc carbonate hydroxide hydrate(ZCHH) precursor can be transformed utterly to ZnO porous microspheres after calcination. The effects of reactant and additive concentrations on the morphology and size of the nanospheres were studied and the possible formation mechanism of the ZHC nanostructures is discussed in this paper. Based on the statistical results from SEM images of the nanospheres, these hydrozincite nanospheres assemble into the sphere-like ZCHH respectively. Results indicate that ZnO retained the morphology of the ZCHH precursor following calcination at 400°C for 2h. The photocatalytic results indicated that the ZnO exhibited higher photocatalytic activity than that of the reported nanostructured ZnO, The great enhancement was mainly ascribed to their unique hierarchical nanostructures and high BET surface.

Preparation of MgO nanomaterials by microemulsion-based oil/water interface precipitation

This paper presented a novel microemulsion-based method for the preparation of MgO nanomaterials. Briefly, in a paraffin-in-water microemulsion system, we firstly synthesized Mg5(CO3)4(OH)2·4H2O/paraffin composites, the precursor of MgO, via an interface-controlled homogenous precipitation. By calcinating the composite precursor at different temperatures, MgO nanomaterials with varied morphologies could be obtained. A flower-like 3D hierarchical structure was achieved when applying lower calcination temperatures, which indeed preserves the morphology of the composite precursor. While at higher calcination temperatures, one can get the well-defined MgO nanoparticles. The prepared materials were thoroughly characterized by XRD, SEM and BET methods, and their application as adsorbents to remove Congo red from wastewater was demonstrated.

Influence of synthetic conditions on the structure and electrical properties of nanofibrous polyanilines and their nanofibrous carbonized forms

Nanofibrous polyanilines (PANIs) were synthesized by several oxidative polymerization pathways that have in common the presence of excess oxidant(s) (ammonium peroxydisulfate and its mixture with hydrogen peroxide), the absence of added acid, and the absence of external template (self-assembly process). Conducting forms of the synthesized PANI nanofibers (re)doped with various acids were further used as precursors for carbonization process to obtain nanofibrous carbonaceous materials (Carb-PANIs). Morphology, molecular structure, surface properties and electrical characteristics of PANI nanofibrous precursors and their carbonized counterparts were studied by scanning electron microscopy, Raman spectroscopy, by measurements of ζ-potential and determination of isoelectric points, as well as by measurements of electrical conductivity.

Scanning tunneling microscopy and density functional theory investigations on molecular self-assembly of graphene on Ru(0 0 0 1)

Investigations on the bottom-up fabrication of graphene with 1,3,5-triphenylbenzene as precursor on Ru(0001) was carried out using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. Upon annealing 1,3,5-triphenylbenzene overlayer on Ru(0001) at 550°C, the precursors dehydrogenated and coalesced into graphitized flakes, and subsequent annealing up to 600°C results in complete graphene conversion. The migration behavior and close-packing morphology of precursors were captured during STM measurements, and DFT calculations indicated that the inter-molecular interaction is responsible for the accumulation and close-packing of the precursors. The noticeable increment in the dehydrogenation barrier from 1.27eV for monomer adsorption to 1.62eV for dimer adsorption is well consistent with the observed drastic reduction of the graphitization temperature at lower precursor coverage, suggesting the crucial influence of inter-molecular vdW interaction on the dehydrogenation process.

Comparison of morphologies of a uranyl peroxide precursor and calcination products

An understanding of the relationships between morphologic signatures of uranium oxide materials and precursor materials used to prepare them would be valuable for determining process history of intercepted materials. Here, three different high purity uranium oxide materials were prepared from a single source of uranyl peroxide hydrate (UO2(O2)·xH2O) to determine variability of texture between the precipitate precursor and calcination products. Scanning electron microscopy images of the materials were characterized using a lexicon of descriptors. Analyses revealed that morphologic textures of calcination products were indeed equivalent to that of the UO2(O2)·xH2O precipitate, revealing a morphologic signature for forensic analyses of process history.

The cytoskeletal arrangements necessary to neurogenesis.

During the process of neurogenesis, the stem cell committed to the neuronal cell fate starts a series of molecular and morphological changes. The understanding of the physio-pathology of mechanisms controlling the molecular and morphological changes occurring during neuronal differentiation is fundamental to the development of effective therapies for many neurologic diseases. Unfortunately, our knowledge of the biological events occurring in the cell during neuronal differentiation is still poor. In this study, we focus preliminarily on the relevance of the cytoskeletal rearrangements, which earlier drive the morphology of the neuronal precursors, and later the migrating/mature neurons. In fact, neuritogenesis, neurite branching, outgrowth and retraction are seminal to the development of a fully functional nervous system. With this in mind, we highlight the importance of iPSC technology to study the processes of cytoskeletal-driven morphological changes during neuronal differentiation.

Tuning the morphology of Co3O4 on Ni foam for supercapacitor application

NH4F was used as a vital additive to control the morphology of Co3O4 precursors through hydrothermal reaction, some novel growth mechanisms are proposed. Co3O4 materials were obtained via thermal decomposition for supercapacitor application.

Hydrothermal tuning of the morphology and particle size of hydrozincite nanoparticles using different counterions to produce nanosized ZnO as an efficient adsorbent for textile dye removal

The current study aimed to investigate the effect of counterions on hydrothermally synthesized hydrozincite (zinc hydroxide carbonate), which was thermally converted to generate ZnO nanostructures, which are an efficient nanoadsorbent for the removal of Reactive Black 5 (RB5) dye from wastewater. Hydrozincite nanospheres and flower-like structures were hydrothermally prepared using various zinc salts (sulfate, acetate, and nitrate) and ammonium carbonate in a molar ratio of 1:3, respectively, at 120 °C for 3 h. The morphology and crystallite size of the hydrozincite precursor were effectively controlled via the parameters of the hydrothermal reaction. Interestingly, sulfate was the optimum counterion, as zinc sulfate salt produced pure hydrozincite nanospheres with the smallest crystallite size (∼13.57 nm), which were consequently thermally decomposed at 400 °C for 1 h to produce pure nanosized ZnO (∼10 nm). The compositions of the as-synthesized products were determined by means of FT-IR, FE-SEM, HR-TEM, XRD, zeta potential, BET, and thermal analyses. An adsorption study showed a much higher adsorption capacity (80.9 mg g−1) of the as-prepared ZnO nanoparticles toward RB5 dye. The adsorption of RB5 dye followed pseudo-second-order kinetics. In addition, the equilibrium adsorption of RB5 dye was best described by a Langmuir isotherm model and the calculated thermodynamic parameters, ΔG0 (from −4.027 to −7.533 kJ mol−1), ΔH0 (30.798 kJ mol−1), and Ea (29.105 kJ mol−1), indicate the spontaneous, endothermic, and physisorptive nature of the adsorption process.

Facile preparation photocatalytically active CuO plate-like nanoparticles from brochantite

The dendrite-like brochantite Cu4[SO4](OH)6 microstructures were obtained by facile and cost effective precipitation method for preparation plate-like CuO nanostructures. The thermal stability and morphology of precursor investigated by XRD, TG-DTA and SEM methods. To estimate the thermal stability of precursor the series of brochantite annealing were carried out. According to XRD data above 400°C CuO is the only product of decomposition of brochantite. XRD, AFM, SEM, UV–vis spectroscopy were employed to characterize the product of brochantite calcination. The CuO is composed of plate-like nanoparticles with a length up to hundreds nanometers and thickness about 30nm. The investigation of photocatalytic activity shows high activity even in the absence of H2O2.

Room temperature ferromagnetism in Cu2+ doped TiO2 nanocrystals: The impact of their size, shape and dopant concentration

Cu2+ doped TiO2 nanocrystals were synthesized using dispersions of titania nanotubes in the presence of Cu2+ ions as a precursors. The morphologies of nanotubular titania precursors and resulted Cu2+ doped TiO2 nanocrystals were characterized by TEM. Structural and optical properties were studied by XRPD analysis and UV–vis spectroscopy in reflectance mode, respectively. Their magnetic properties were investigated using SQUID magnetometer. Tetragonal anatase crystalline structure was confirmed in all synthesized samples. Polygonal (d∼15nm) and spheroid like (length, up to 90nm) Cu2+ doped TiO2 nanocrystals in samples synthesized at different pHs were observed by TEM. Ferromagnetic ordering with almost closed loop (Hc∼200Oe) was detected in all Cu2+ doped TiO2 nanoparticle films. The saturation magnetization values varied depending on the Cu2+ concentration, nanoparticles shape, size and consequently different number of oxygen vacancies. This study revealed possibility to control magnetic ordering by changing the shape/aspect ratio of Cu2+ doped TiO2 nanocrystals.

The influence of Na species addition on the synthesis and catalytic activity of Na2Mo4O13/α-MoO3 as CWAO catalyst

The influence of added Na species amount on the formation of Na2Mo4O13/α-MoO3 hybrid catalysts and their catalytic wet air oxidation activity for the degradation of cationic red GTL at ambient conditions were systematically investigated. The structure and morphology of the catalyst precursors and the final Na2Mo4O13/α-MoO3 hybrid catalysts were examined using XRD and SEM analyses, which suggested that the active catalyst Na2Mo4O13/α-MoO3 with nanofiber morphology could be obtained in a much wider pH range by adding more Na species. The influence of some key parameters including reaction time, the volume of dye wastewater, testing temperature, and calcination temperature were evaluated. The mechanism involved was also explored using UV–vis and ESR analyses, which suggested that the benzene ring and azo linkage of dye molecules could be destroyed within 30–45min and the formation of OH radicals is critical for the high activity. By adding more Na species, the removal of both total organic carbon (TOC) and chemical oxygen demand (COD) could also be accelerated. Cycling tests suggested that the catalysts were very robust, and the degradation efficiency was still 99.6–99.9% even after 5 cycles.

Linkers and coordinated solvent molecules; the two effective factors on formation of zinc oxide nanoparticles from metal–organic frameworks

The host and the apohost frameworks of Zn2(ndc)2(DMF)2∙(H2O)4 (1∙DMF∙H2O) and Zn2(bdc)2(H2O)2∙(DMF)2 (2·H2O·DMF), (H2ndc=2,6-naphthalene dicarboxylic acid, H2bdc=benzene-1,4-dicarboxylic acid and DMF=N,N-Dimethylformamide), were synthesized, characterized and subsequently used for preparing of ZnO nanoparticles. The morphology of initial precursors has direct influence on agglomeration tendency of resulting ZnO nanoparticles. Linkers and coordinated solvent molecules are the two effective factors on the formation of zinc oxide nanoparticles from these metal–organic frameworks.

Perlite as a potential support for nickel catalyst in the process of sunflower oil hydrogenation

Investigation was conducted in order to elucidate the possibility of using perlite as support for preparation of nickel based precursor catalyst, potentially applicable in vegetable oil hydrogenation process. On three differently prepared expanded perlite, nickel catalyst precursors with identical Ni/SiO2 = 1.1 and Ni/Mg = 10/1 ratios were synthesized by precipitation-deposition method. Different techniques, SEM micrography, He-pycnometry, calcimetry, Hg-porosimetry, N2-physisorption, H2-chemisorption and temperature programmed reduction, were used for characterization of obtained samples. Determining the precursor texture, morphology and reducibility shows a successfully deposited nickel phase on perlite support with promising properties for vegetable oil hydrogenation. Chosen precursor was reduced and passivated in paraffin oil and the obtained catalyst showed significant catalytic activity in the test of sunflower oil hydrogenation.

Synthesis and characterization of manganese-rich transition metal carbonate precursor in the presence of ethanol

Manganese-rich transition metal carbonate precursors (Ni0.15Co0.15Mn0.7CO3) have been synthesized by the carbonate precipitation in the presence of ethanol. The physical properties of the precursors with different concentration of ethanol have been examined by XRD and SEM. The XRD results show that the precursors prepared by this method are typical hexagonal structure. The SEM results show that the particles of the precursors with the presence of ethanol display more spherical and dispersed than those prepared without using ethanol. Galvanostatic charge–discharge experiments demonstrate that the initial discharge capacity of the cathode material (Li1.2Ni0.12Co0.12Mn0.56O2) is improved by the addition of ethanol. In addition, the effects of reaction temperature, the molar ratio of precipitant/total-cations on the morphology of the resultant precursors and the electrochemical properties of the prepared powders are also investigated. Among the synthesized materials, the sample prepared with 10vol% ethanol and a fixed concentration ratio ([CO32−]/[M2+]=10) at 65°C exhibits not only a relatively high discharge capacity of 272.1mAhg−1, but also excellent rate performance and good cycling performance.

Chlorine Incorporation for Enhanced Performance of Planar Perovskite Solar Cell Based on Lead Acetate Precursor.

We show the effects of chlorine incorporation in the crystallization process of perovskite film based on a lead acetate precursor. We demonstrate a fabrication process for fast grain growth with highly preferred {110} orientation upon only 5 min of annealing at 100 °C. By studying the correlation between precursor composition and morphology, the growth dynamic of perovskite film in the current system is discussed. In particular, we found that both lead acetate precursor and Cl incorporation are beneficial to perovskite growth. While lead acetate allows fast crystallization process, Cl improves perovskite crystallinity. Planar perovskite solar cells with optimized parameters deliver a best power conversion efficiency of 15.0% and average efficiency of 14.0% with remarkable reproducibility and good stability.

Preparation of fibrous nickel powder by precipitation transformation coupled with thermal decomposition

Fibrous particulate precursor was obtained by precipitation transformation in the ternary solution system of ammonium oxalate, nickel chloride and ammonia. The composition and morphology of precursor were characterized by XRD, SEM, IR and DTA/TGA analyses. The results show that the chemical composition and morphology of precursor precipitates at pH=8.4–8.8 are different from those of precursor precipitates at pH=6.0, and the mechanisms of the thermal decomposition of the precursors are different. The effects of various conditions in the process of thermal decomposition, including precursor morphology, atmosphere, temperature and time on the morphology and dispersion degree of obtained nickel powders were studied in detail. The final product inherits the morphology of precursor when the thermal decomposition is conducted under a weakly reducing atmosphere at temperature range of 400–440 °C for 30 min. Fibrous nickel powder can be produced with good dispersion, and its shape changes from smooth, straight and compact fiber into loose and curved fiber with rough surface.

Tuning solution chemistry for morphology control of lithium-ion battery precursor particles

Many battery materials are synthesized via calcination of precursor particle powders with a lithium source. The precursor particles frequently are made via coprecipitation reactions, and a number of combinations of coprecipitation agents have been demonstrated previously. Detailed control over the morphology of precursor particles and the resulting final electrode materials would be highly desirable, but currently detailed understanding of the impact of synthesis conditions on precursor morphology are lacking. Herein, tunable monodisperse MnCO3 particles for Li-ion battery precursors of varying size and shape were synthesized through batch coprecipitation. The effect of solution chemistry on final particle morphology was confirmed via scanning electron microscopy and considered in the context of solution equilibrium calculations and nucleation and growth of precipitate crystals. The tunability of MnCO3 particle morphology with reagent concentration was demonstrated with transitions from rhombohedra to cubes to spheres to smaller spheres with regards to overall secondary particle structures. Other experimental factors were also examined to further understand the processes resulting in the transitions in MnCO3 morphology. Precursor particles were calcined to form LiMn2O4 to verify the ability to maintain the tunable morphology in the final battery materials and to confirm suitability for battery cathodes.

Hydrothermal synthesis of hexagonal CeO2 nanosheets and their room temperature ferromagnetism

Hexagonal CeO2 nanosheets of 40–50 nm in thickness and 300–400 nm in side-length have been successfully synthesized via controlling the morphology of CeCO3OH precursors by a facile hydrothermal technique using CeCl3·7H2O as cerium source, ammonium hydrogen carbonate as precipitants, and ethylenediamine as complexant. The reaction time and the amount of CeCl3·7H2O and ethylenediamine were systematically investigated. The as-synthesized hexagonal CeO2 nanosheets were examined by XRD, SEM, TEM, XPS, Raman scattering and magnetization measurements. It is found that the amount of CeCl3·7H2O and ethylenediamine are key parameters for controlling the final morphology. The hexagonal CeO2 nanosheets have a fluorite cubic structure and there are Ce3+ ions and oxygen vacancies in surface of samples. The synthesized CeO2 shows excellent room temperature optical properties. M–H curve exhibits excellent room-temperature ferromagnetism (RTFM) with saturation magnetization (Ms) of 3.02 × 10−2 emu/g, residual magnetization (Mr) of 0.68 × 10−2 emu/g and coercivity (Hc) of 210 Oe, which is likely attributed to the effects of the Ce3+ ions and oxygen vacancies.

Chemical deposition of selenium layers for selenization of sputtered and electrodeposited Cu–Zn–Sn metallic layers for photovoltaic application

One of the key steps for high efficiency kesterite based solar cells is the control of the growth conditions of the kesterite phase from precursors. In this work, chemical deposition was used to introduce the selenium needed for Cu–Zn–Sn selenization and Cu2ZnSnSe4 (CZTSe) synthesis. The influence of annealing time and precursor morphology based on deposition techniques (electrodeposition or sputtering) on the reaction path and kinetics of growth and degradation of kesterite phase was studied using scanning electron microscopy, X-ray diffraction and Raman characterizations. Important differences were detected between porous electrodeposited precursors and dense sputtered precursors. It was suggested that this difference comes from the morphology of the precursors, and that a control of the morphology is critical for the control of the annealing processes in CZTSe synthesis.

Studies of thermal decomposition kinetics and temperature dependence of thermodynamic functions of the new precursor LiNiPO4·3H2O for the synthesis of olivine LiNiPO4

The olivine LiNiPO4 was synthesized via the calcination of the new precursor LiNiPO4·3H2O at 600 °C. The precursor was obtained from low-temperature (50 °C) wet chemical reaction. The results from XRD, FTIR, AAS/AES and TG/DTG/DTA techniques confirmed the formula of the title compounds. The SEM results indicated the morphologies of the hydrate precursor as thin plate particles and the calcined product as small bead particles. The BET surface area of the final calcined product at 600 °C is much higher (5.807 m2 g−1) than that reported in the literature (0.25 m2 g−1). The kinetic triplet [activation energy, E, pre-exponential factor, A, and the most probable mechanism function, g(α)] and the thermodynamic functions of activated complexes (ΔS ≠, ΔH ≠ and ΔG ≠) for the dehydration step of LiNiPO4·3H2O were determined and discussed. The mechanism of the dehydration process is the single-step A3/2 (assumed random nucleation and its subsequent growth). New information, namely the isobaric molar heat capacity, experimental entropy, enthalpy and Gibbs energy changes as function of temperature (K) of LiNiPO4·3H2O and LiNiPO4, was evaluated from the DSC data by third-order polynomial fitting and reported for the first time. The calculated corresponding thermodynamic functions from kinetic parameters are compared and discussed.