Influence Of Synthesis Conditions Research Articles

ChemInform Abstract: Nonfunctionalized Gold Nanoparticles: Synthetic Routes and Synthesis Condition Dependence

AbstractReview: some of the most relevant synthetic procedures reported up to date, with a special focus on synthetic routes to nonfunctionalized gold nanoparticle in aqueous media, influence of synthesis conditions on the shape, stability, and reactivity of the nanoparticles; 92 refs.

The Influence of Synthesis Conditions on the Structure of Mg-Al Layered Double Hydroxide

In this paper, the influence of synthetic conditions (the molar ratio of Mg2+ and Al3+; the concentration of cationic; the aging temperature and time) on the grain size and crystallinity of Mg-Al layered double hydroxide (LDH) has been investigated systematically based on the orthogonal experiment. Mg-Al LDH was prepared using magnesite through chemical precipitation and hydrothermal methods. The samples were characterized by X-ray diffraction (XRD). The grain size which along a and c axis were calculated through Scherrer formula. The experimental results showed that the grain size along a axis increased with the rise of synthesis temperature, while the grain size along c axis reduced. It was also found that the aging temperature and time had a great influence on the crystallinity of Mg-Al LDH.

Influence of synthesis conditions on the performance of chitosan–Heteropolyacid complexes as membranes for low temperature H2–O2 fuel cell

Flat, free-standing chitosan/phosphotungstic acid (PTA) polyelectrolyte membranes were prepared by in-situ ionotropic gelation process at room temperature on porous alumina support firstly impregnated by H3PW12O40. Scanning electron microscopy revealed the formation of compact and homogeneous membranes, whose thickness resulted to be dependent on chitosan concentration and reticulation time. X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) evidenced the formation of almost amorphous membrane without appreciable concentration of not protonated NH2 groups and PTA3− ions with preserved Keggin structure. Membranes were tested as proton conductor in low temperature H2–O2 fuel cell allowing to get peak power densities up to 300 mW cm−2. Electrochemical impedance measurements allowed to estimate polyelectrolytes' conductivity up to 28 mS cm−1 at room temperature.

A Novel Titanate As Anode Material for Sodium Ion Batteries

The concern regarding the availability and cost of lithium is raised owing to the fast growth of the markets for lithium ion battery (LIB) and other Li-chemistry based energy storage technologies, such as Li-Air and Li-S systems. Sodium ion battery (SIB) is considered as an alternative technology, due to the potentially low cost and abundance of sodium[1]. Yet many key components of SIBs, including cathode, anode, electrolyte, still require further improvement. Here we report a new titanate compound as a promising anode material for sodium ion batteries. The compound was synthesized through solid state reaction. Powder X-ray diffraction (XRD) and refinement were applied to investigate the crystal structure. Electron microscopy was used to study the morphology. The electrochemical tests showed high first discharge capacity of >200 mAh/g and ~80 mAh/g reversible capacity in following cycles with good retention, as shown in Figure 1. Ex situ XRD was also performed for fully and partially discharged/charged samples to discover the cycling mechanism and possible reasons for the capacity decay of this material. The influence of synthesis conditions, including temperature, ball mill rate and carbon coating amount were also systematically investigated. Figure 1

Influence of potassium permanganate on the anisotropic growth and enhanced UV emission of ZnO nanostructures using hydrothermal process for optoelectronic applications

The effect of in situ addition of potassium permanganate (KMnO4) in controlling morphology, composition, structural and optical properties of the ZnO nanostructures prepared by hydrothermal technique has been investigated. The influence of synthesis conditions on the growth of ZnO nanorods was meticulously studied by field-emission scanning electron microscope, X-ray diffractometer, transmission electron microscopy (TEM) and high-resolution TEM. It is demonstrated that the KMnO4 concentration has great influence on the morphology and on the alignment of ZnO nanorods. Further the optical properties of nanostructures were investigated by photoluminescence (PL) spectroscopy and ultraviolet–visible diffuse reflectance spectroscopy. The PL spectrum divulged a continuous suppression of defect-related broadband emission by increasing the concentration of the KMnO4, which produced the quenching of surface defects present in the nanorods. The intensity ratio of the peaks corresponding to near-band emission (NBE) to that of deep-level emission of the KMnO4-modified ZnO nanorods was found to increase by eightfold of magnitude. Further it must be noted that nearly 17-fold enhancement in the PL emission of the peak corresponding to NBE was observed in KMnO4-modified ZnO compared to the ZnO grown without any additive. The I–V plot showed dependence of current values under dark and illumination over the amount of KMnO4 added during the growth stage.

The influence of synthesis conditions on the surface state of detonation nanodiamonds

The paper addresses thermal desorption of volatile products from the surface of detonation nanodiamonds modified in the process of synthesis. Their possible doping is shown to have a slight effect on the behavior and temperature range of evolution of atomic oxygen, water, carbon monoxide and dioxide. The atomic oxygen spectrum has two peaks (at 250–300 and 550–650°C), emission of water has three peaks (at 50–80, 220–260, and 550–600°C), the evolution of CO has a single peak at 600–760°C, and that of CO2 has two peaks (at 200–270 and 520–660°C). Phosphorus-containing detonation nanodiamonds have been found to evolve phosphine over the entire temperature range of nanodiamond treatment.

Preparation, characterization and application of molecularly imprinted monolithic column for hesperetin

The molecularly imprinted solid-phase extraction (MISPE) monolithic column coupled with high-performance liquid chromatography (HPLC) was firstly developed for the extraction of hesperetin in the flesh of Citrus reticulata cv. Chachiensis, which is a traditional Chinese medicine (TCM). The molecularly imprinted polymers (MIPs) have been prepared by a thermal polymerization method using hesperetin as the template, acrylamide (AM) as functional monomer and ethylene glycol dimethacrylamide (EGDMA) as cross-linker in the mixed porogen of methanol, toluene and dodecanol. The prepared MIPs were characterized in detail by SEM and FTIR. The results confirmed the uniform and open structure of network skeleton with large flow-through pores. The influence of synthesis conditions on the specific recognition properties of hesperetin MIPs were also investigated systematically. The results showed that high adsorption capacity and good selectivity of MIPs were achieved when using non-imprinted polymer monolith (NIP) and structure similarly compound rutin as references. Furthermore, several parameters of the MISPE method have been optimized, and then it was successfully applied to the extraction of hesperetin from the flesh of Citrus reticulata cv. Chachiensis. Good gathering and impurity removing ability of prepared MIP were demonstrated. The MISPE method was proven to be a potentially competitive technique for separation and cleanup of hesperetin in complex TCM with satisfied recovery (90.8±3.2%) and good precision (RSD=6.48%).

Influence of synthesis conditions on composition of alkyl (meth)acrylate–vinyl alkyl ether copolimers

Synthesis of methyl methacrylate copolymers with vinyl butyl ether has been carried out from the monomer mixture by compensate polymerization method. Analysis of their composition has shown that, respectively, either a conversion nonuniform copolymer is formed with methyl methacrylate units for the most part, or a copolymer nearing equimolar composition. By the example of monomer couple butyl acrylate–vinyl alkyl ether it has been shown that in order to get the structurally uniform copolymer, it is possible to use both classical radical initiators and binary alkylborane–oxygen initiators.

Influence of synthesis conditions on the structure and phase formation during the SHS hydration of titanium

SHS hydrogenation of titanium sponge in various modes of hydrogen deficiency and excess is investigated. According to data of the time-of-flight mass spectroscopy, a nonuniform H+ distribution is found over the sponge bulk during the synthesis in the H2 deficiency mode and a uniform one is found in the H2 excess mode. The surface structure of the Ti sponge before and after SHS hydrogenation is compared by SEM. An increase in structure lamination compared with the initial sponge is found for the hydrogenated sponge irrespective of the H2 content. Layers acquire a regular geometric shape and are arranged in a definite order with a repeated motif. Distances between the layers vary from the micron to nanometer sizes. The phase formation mechanism during the hydrogenation of titanium is investigated by time-resolved X-ray diffraction. The final product is formed through a series of intermediate phases according to the solid-phase mechanism: α-Ti → α-Ti[H] → β-Ti[H] → TiH2.

Synthesis, characterisation, adsorption ability and activity of Cu,ZnO@UiO-66 in methanol synthesis

Metal–organic framework UiO–66 was synthesised by solvothermal method. The influence of synthesis conditions on the quality of UiO–66 was studied. The obtained material was characterised by XRD, IR, TGA, SEM, TEM, AAS and nitrogen physisorption measurements (BET). Physisorption measurement of different gases (CO2, H2, CH4 and CO2/CH4) was carried out using a high pressure volumetric analyser. Synthesised UiO–66 in the form of ball shaped crystals possessed high surface areas of up to 1041 m2.g−1, micropore volume of 0.913 cm3.g−1, pore radius of 15 and thermal stability of up to 423C. According to experimental results, at 30 bar, CO2 storage capacity of the synthesised UiO–66 is nine times higher than that of H2 and four times higher than that of CH4. The [email protected]–66 and Cu,[email protected]–66 catalysts were prepared and tested in the hydrogenation of CO and CO2. As it followed from investigation, Cu,[email protected]–66 catalyst has been shown to be the best one with the yield of methanol reaching 229.04 μmol.g−1.h−1 and 153.93 μmol.g−1.h−1in the hydrogenation of CO and CO2, respectively.

Influence of synthesis conditions on formation of core–shell titanate–ferrite particles and processing of composite ceramics

Strontium titanate–nickel ferrite (SrTiO3–NiFe2O4) composite and core–shell particles have been prepared by the combination of sol–gel and co-precipitation route. Modifications of the synthesis procedure (pH value, functionalization of core and shell particles) have been carried out in order to maximize the electrostatic forces between the phases and thus optimize the core–shell morphology of the synthesized powder. It was found that the synthesis pH has considerable influence on the morphology of as-synthesized particles as well as their phase composition. Prepared powders were processed into dense composite ceramics by conventional sintering in air and/or by spark plasma sintering. Particle morphology and thus particle synthesis procedure has proven to have a direct impact on the density, homogeneity and phase composition of the sintered ceramics.

New Insights into the Mechanism of ZnO Formation from Aqueous Solutions of Zinc Acetate and Zinc Nitrate

The controlled synthesis of ZnO at the micro- and nanoscale has been the focus of significant research due to its importance in electrical and optoelectronic applications, and the potential of tuning its properties at the crystal formation stage. We present a detailed study of ZnO growth processes which supports and consolidates previous findings and gives a clearer understanding of the mechanism of ZnO formation. The influence of synthesis conditions on ZnO formation was investigated by comparison of two different growth routes (Zn(CH3COO)2–NH3 and Zn(NO3)2·6H2O−HMTA) both known to result in the formation of wurtzite structured, twinned hexagonal rods of ZnO. The identities of the solid phases formed and supernatants were confirmed by data from SEM, XRD, FTIR, XPS, TGA, and ICP-OES analysis; giving insight into the involvement of multistep pathways. In both cases, reaction takes place via intermediates known as layered basic zinc salts (LBZs) which only later transform to the oxide phase. In the ZnAc2–NH...

Study on crystallinity and morphology controlling of titania using acrylamide gel method and their photocatalytic properties

In this study, polyacrylamide gel method was used for preparation of pure and mixed phase TiO2 nanoparticles. The influence of synthesis conditions on the physicochemical properties of products was investigated. It was found that the type of acid, which was used for acidifying the precursor solution together with calcination temperature can affect the phase structure, crystalline size, morphology and thereby photocatalytic activity of obtained TiO2 nanoparticles. Different trends were observed during the phase transformation, particle growth, shift in energy of band gap with the change in tensile strain to compressive strain of the prepared TiO2 nanomaterial. X-ray diffraction (XRD) showed that prepared nanocrystals, which were calcined at 450°C have pure anatase and anatase–rutile mixed structures. The prepared samples having crystallite size between 5nm and 60nm were observed at different calcination temperatures. In addition, the photocatalytic activities of the prepared samples were evaluated by monitoring the degradation of Cresol Red (CR). The results show that the photocatalyst (TECI), exhibits the highest photocatalytic efficiency where 94.7% of CR can be decomposed after UV exposure for 75min.

Radiation Copolymerization of Styrene/Acrylic Acid Grafted to Silica Surface For separation and purification purposes: I. Characterization and sorption of some organic compounds and Metals.

Highly porous and interconnected styrene/acrylic-based porous materials were prepared by radiation-induced graft copolymerization of styrene/acrylic acid monomers onto surface of silica prepared from rice husk ash. The influence of synthesis conditions; such as irradiation dose, monomer concentrations and different solvents; were studied. It was found that the nature of the solvent had profound influence on the copolymerization reaction and water /ethanol mixture was selected as a suitable solvent for copolymerization processes. Graft copolymers of styrene/ acrylic onto silica surface was verified through Fourier Transform Infrared (FTIR) spectroscopy and Eenergy Dispersive Spectroscopy (EDX) was used to investigate the surface profile of representative copolymers by viewing the distribution of elemental nitrogen. ThermoGravimetric Analysis (TGA) and differential Thermal Analysis (DTA) of the copolymers were investigated. From the characterization of the prepared copolymer it was found that: copolymers of (styrene/acrylic)/silica are considerably different from each other, (styrene/acrylic)/silica based copolymers exhibited relatively more homogenous surface compared to (styrene/acrylic) copolymers. Water uptake percent increases as silica ratio increases to reach 24174 (mol/gm) and this prepared copolymer has a considerable capacity for adsorption of organic compounds and metals.

Influence of synthesis conditions on the adsorption and catalytic properties of mordenite zeolite

The effect of the preliminary holding of the BS-100 “white soot” at 150–155°C for 6 to 7 h and the crystallization conditions on both the characteristics of powdered MOR zeolite samples (degree of crystallinity, composition, particle size composition, and adsorption of C6H6 molecules) and their catalytic properties in the α-methylstyrene dimerization reaction has been studied.

A facile novel synthesis of delafossite CuFeO2 powders

P-type transparent conducting oxides copper delafossite CuFeO2 powders have been successfully synthesized by using hydrothermal method. The influence of synthesis conditions on the crystal structure, morphology, optical and magnetic properties was systematically studied using X-ray diffraction, scanning electron microscope (SEM), UV–Vis–NIR scanning spectrophotometer and vibrating sample magnetometer. The results indicated the precipitated precursor at pH value of 12 using 1 M NaOH as a base in the presence of hydrazine hydrate as a reducing agent hydrothermally treated at 280 °C for 96 h was transformed to pure rhombohedral 3R delafossite phase. SEM observations of these powders confirmed their hexagonal like structure. The transmittance of the sample was around 65 %. The optical band gap of delafossite–CuFeO2 sample prepared was 3.5 eV as a visible transparent material. Furthermore, magnetic properties behavior was identified and paramagnetism property was found at a room temperature. The saturation magnetization and coercive force for the pure sample were 1.2 emu/g and 58.35 Oe, respectively.

Influence of synthesis conditions on the surface passivation and electrochemical behavior of layered cathode materials

The surface reconstruction of NMC materials is influenced by the synthesis conditions and the electrochemical cycling history.

Si-based nanocomposites derived from layered CaSi2: influence of synthesis conditions on the composition and anode performance in Li ion batteries

A novel fabrication method and Si-based nanocomposite anode materials, containing CaxSi2 and nickel silicide, with tunable capacity and electrical conductivity.

Influences of synthesis conditions on chemical composition of Cu2ZnSnS4 nanocrystals prepared by one pot route

In present work, the Cu2ZnSnS4 (CZTS) nanocrystals (NCs) were successfully synthesized via a rapid and simple one pot route. The influences of the reaction temperature and time on the chemical composition were first investigated in detail by energy dispersive X-ray spectroscopy. Meanwhile, the variations of the structural, morphological and optical properties of the as-synthesized CZTS NCs were analyzed by combining with the changes of the chemical composition via x-ray diffraction, field emission scanning electron microscopy (FE-SEM) and UV–Vis–IR spectrophotometer, respectively. It was found that the reaction temperature and time had significant impacts on the element composition, especially for the variations of Zn and Sn; and the variations of structure, morphology and band gap energy were closely linked with the changes of Zn and Sn. The characterization results of the as-synthesized CZTS NCs, under the optimal synthesis condition (250 °C, 1 h), were shown as following: the compositional ration was near stoichiometric (Zn/Sn = 0.81, Cu/(Zn + Sn) = 0.97, S/(Cu + Zn + Sn) = 1.07), the average size of NCs was 19.98 nm, the size of aggregation nanoparticles was in the range of 200–500 nm, and the band gap energy was 1.5 eV. All results suggested that the as-synthesized CZTS NCs were good light absorption layer material for thin film solar cell.

Influence of synthesis conditions on the shape and size characteristics of TiO2 nanocrystals

Nanocrystals of TiO2 of various shapes have been obtained by the solvothermal synthesis technique. It is found that the morphology of TiO2 particles is determined by the type of solvent, while their crystallinity and the sizes of particles depend on the temperature and duration of the synthesis. The conditions needed for nanocrystals of anatase to be formed in the shape of spherical particles with a diameter of 10–15 nm, cubic particles with ribs of 25–30 nm, and nanowires with diameters of 50–100 nm and lengths of more than 100 μm are determined. The structural and geometric parameters of synthesis products are determined with the help of the PEM technique.