Influence Of Synthesis Parameters Research Articles

Microstructure and thermoelectric properties of porous CaMnO3/CaMn2O4 composite prepared by spray solution combustion synthesis

Oxides are attractive and promising compounds for application as thermoelectric materials owing to thermal and chemical stability, cost-effectiveness, and environmental safety. In this work, CaMnO3 perovskite hollow spheres were synthesized by spray solution combustion synthesis. The effect of the fuel glycine on the phase composition, morphology, and microstructure of CaMnO3 was studied, and the influence of synthesis parameters on the characteristics of the sintered materials was investigated. The porous CaMnO3 (porosity 10–20%) forms by pressureless sintering at 1473 K, which is accompanied by the precipitation of marokite CaMn2O4. It is possible to alter the porosity level as well as marokite and pore size in the CaMnO3/CaMn2O4 composite by tailoring the fuel amount, which, in turn, affects the thermoelectric properties. The zT value of 0.13 at 1073 K, to the best of our knowledge, is the highest zT reported for the undoped CaMnO3 material.

High solid content waterborne polyurethane with high foaming rate to artificial leather: Synthesis and characterization

A type of high solid content waterborne polyurethane (HSWPU) dispersions applied to foamed artificial leathers were designed and prepared by prepolymer method. The solid content of the waterborne polyurethane dispersions could reach 53 %, and the foaming ratio could reach an astonishing 2.50 by adjusting the parameters. The influence of synthesis parameters, including R value (molar ratio of -NCO/-OH), D value (hydrophilic group content), trimethylol propane (TMP) content (degree of crosslinking) and ethylenediamine (EDA) content (it was chain extender) on foaming ratio were investigated. Meanwhile, a series of properties of HSWPU dispersions, films and foamed artificial leathers were introduced in detail. The results demonstrated that R value, TMP content, D value and EDA content synergistically decided the foaming properties of HSWPU dispersions in three aspects: three-dimensional structure, surface tension and polarity, respectively. With optimized parameters of R = 2.0, TMP = 0.4 wt%, DMPA = 3.0 wt% and EDA = 60 wt%, the HSWPU dispersions had good appearance and stability, and the latex particles exhibited excellent water, acid and alkali resistance after films formation. The HSWPU dispersions with high foaming rate without collapsing in the foam-forming process and created uniformly bubble pores. In terms of application properties, the prepared foamed artificial leathers showed admirable air permeability and water vapor transmissions. All results distinctly demonstrate a feasible yet promising paradigm for applying the HSWPU on foamed artificial leathers had great potential applications.

Construction of the mosaic aluminophosphate zeotypes based on nonclassical crystallization and in situ selective etching strategies

Owing to short diffusion lengths and more accessible active sites, hierarchical zeolitic materials can substantially improve catalytic activities and lifetimes compared to the conventional counterparts. Here we develop a straightforward and mesopore-template-free strategy to prepare aluminophosphate-based LTA zeotypes with mosaic architectures and hierarchical porosities. The influence of synthesis parameters and time-dependent study on the crystallization process were studied comprehensively using multiple techniques. The results demonstrate that the mosaic architectures were formed based on nonclassical crystallization, i.e., phase transformation of a lamellar phase to aligned crystalline AlPO4-42 nanoparticles followed by crystal fusion, and in situ selective etching of grain boundaries and defects. Meanwhile, heteroatom-substituted AlPO4-42 zeotypes with the mosaic morphologies can also be synthesized, which show enhanced ideal adsorbed solution theory (IAST) selectivities and efficient dynamic separation performances in the CO2/N2 mixture. This work not only provides a novel mesoporogen-free strategy for the preparation of hierarchical zeotypes, but also sheds new insight into the crystallization pathway.

The influence of synthesis parameters and thermal treatment on the optical and structural properties of zinc oxide-based nanomaterials

The influence of synthesis parameters and thermal treatment on the optical and structural properties of zinc oxide-based nanomaterials

Hybrid mesoporous silica materials templated with surfactant polyion complex (SPIC) micelles for pH-triggered drug release

New Surfactant PolyIon Complex (SPIC) micelles were assembled by electrostatic complexation of an antibacterial cationic surfactant, cetylpyridinium chloride (CPC), and a double hydrophilic block copolymer (DHBC) containing a neutral comb block of poly(oligo(ethylene glycol)) methyl ether acrylate (PEOGA) and a weak polyacid block of poly(acrylic acid) (PAA). The corresponding SPIC micelles, with a CPC/PAA core and a PEOGA corona, were successfully used as structure directing and functionalizing agents in a soft and sustainable sol-gel strategy, yielding hybrid mesoporous silica (MS) materials with a monomodal pore size distribution centred at 2.8 nm. The influence of synthesis parameters, including the pH, concentrations and ratios of components, was systematically investigated. The obtained hybrid MS materials were intrinsically functional, with PEOGA blocks anchored in silica walls via H-bonding, while weak polyacid blocks, complexed with CPC, were confined within the mesopores. The response of the materials to pH changes (pH 7.4, 4.2 and 3) indicated remarkable stability of the anchored DHBC, while CPC was selectively released under the acidic conditions typical of orodental biofilm microenvironments. This result is noteworthy, since the release of encapsulated amphiphilic drugs into water is less favorable than that of hydrophilic drugs. Owing to the control of their pore and functionality properties, ordered hybrid silica materials templated and functionalized with SPIC systems will be materials of choice for developing pH-responsive biomedical devices using wet processing techniques.

Preparation and characterization of high catalytic performance supported TS-2 zeolites for phenol hydroxylation

Good inter-grown TS-2 zeolites layer is successfully prepared on the outer surface of porous millimeter α-Al2O3 sphere by secondary hydrothermal synthesis. The supported TS-2 zeolites are loaded into a fixed-bed catalytic reactor for catalyzing phenol hydroxylation by hydrogen peroxide, which could efficiently avoid the fussy separation process. Influences of synthesis parameters on Ti active micro-environment, crystal morphology and catalytic performance of the supported TS-2 zeolites are investigated in this work, medium isopropanol content is necessary for preparing fine and homogenous TS-2 zeolites layer on the porous α-Al2O3 sphere. Besides, formation process of the supported TS-2 zeolites is studied in this study, which divided into three stages, dissolution of seed crystals, formation of novel nuclei, growth and aggregation of TS-2 zeolites layer. When the titanium source, isopropanol/SiO2 and TiO2/SiO2 molar ratio of the initial synthesis gel are tetrabutyl titanate, 1.0 and 0.035, tetra-coordinated titanium containing and compact TS-2 zeolites layer are fully covered on the α-Al2O3 sphere, the optimum phenol conversion and dihydroxybenzene selectivity of the zeolites are 40.07% and 98.52% at 65 °C.

Effects of activation temperature and time on porosity features of activated carbons derived from lemon peel and preliminary hydrogen adsorption tests

Lemon peels, a common biomass waste, have an interesting composition in terms of cellulose and mineral salts that makes them good precursors for activated carbon production processes. From a circular economy perspective, this work highlights the possibility of turning a waste material into a new resource. The resulting nanostructures show interesting performance in terms of specific surface area and total pore volume, with excellent grade of microporosity, that make them suitable for various applications ranging from supercapacitors, sensors, gases separation and storage, etc. The last, and in particular hydrogen storage, represents the most interesting one. In this study the development of activated carbon through pyrolysis method, consisting of carbonization in inert ambient and subsequent physical activation in oxidizing atmosphere is reported. Influence of synthesis parameters on the porosity formation was investigated with the aim of textural properties optimization. All produced samples were initially characterized both morphologically and crystallographycally. Then, textural and adsorption properties were evaluated through volumetric apparatus. The experimental results show improvement of both textural and adsorption properties as function of synthesis parameters, developing adsorbent materials with high fraction of micropores (≃84 %), specific surface area (≃500 m2/g) and hydrogen uptake of 0.93 wt% at 77 K and 1 bar.

Anti-corrosion Behavior of Al<sub>2</sub>O<sub>3</sub>@SiO<sub>2</sub> Composite Electrokinetic Nanoparticles on Reinforced Concrete

Electromigration of electrokinetic nanoparticles in concrete structures is an effective approach to enhancing pore structure and retarding the transportation rate of chloride ions. However, there is limited research on the impact of stable positively charged electrokinetic nanoparticles on the corrosion behavior of reinforced concrete. In this paper, the structure of reinforced concrete was optimized by controllably Al2O3@SiO2 composite electrokinetic nanoparticles driven by a direct current electric field, and the influence of synthesis parameters, such as reaction time and temperature, on the modified silica sol was discussed. After 14 days of electromigration, spherical nanoparticles were found at depths of 5 to 10 mm inside the concrete. The porosity of the concrete reduced from 26.2% to 9.9%, with the most desirable pore size decreasing from 96.3 nm to 40.3 nm. After 9 months of dry and wet cycling, the electrokinetic nanoparticle-treated samples demonstrated a higher corrosion potential and a lower corrosion current density. Electromigration of electrokinetic nanoparticles slowed the transportation rate of chloride ions and significantly reduced their content in the concrete. Additionally, the Al2O3@SiO2 layer coating on the steel further enhanced its anti-corrosion ability, effectively inhibiting the corrosion of the reinforcement in concrete.

Влияние параметров вакуумно-дугового синтеза на структурные и магнитные свойства наночастиц NiO

NiO nanoparticles were synthesized using the vacuum arc sputtering method. The influence of synthesis parameters on the structural and magnetic properties of the samples was studied. X-ray diffraction analysis confirms the polycrystalline nature of the resulting nanoparticles under all deposition conditions, but the preferred crystallite orientation depends on the deposition conditions. Magnetic behavior correlates with the crystallite size of NiO nanoparticles. Condensates with particle sizes in the range of 4–6 nm exhibit superparamagnetic behavior, which changes to antiferromagnetic behavior as the particle size increases.

Copper Ferrite Nanoparticles Synthesized Using Anion-Exchange Resin: Influence of Synthesis Parameters on the Cubic Phase Stability

Copper ferrite is of great interest to researchers as a material with unique magnetic, optical, catalytic, and structural properties. In particular, the magnetic properties of this material are structurally sensitive and can be tuned by changing the distribution of Cu and Fe cations in octahedral and tetrahedral positions by controlling the synthesis parameters. In this study, we propose a new, simple, and convenient method for the synthesis of copper ferrite nanoparticles using a strongly basic anion-exchange resin in the OH form. The effect and possible mechanism of polysaccharide addition on the elemental composition, yield, and particle size of CuFe2O4 are investigated and discussed. It is shown that anion-exchange resin precipitation leads to a mixture of unstable cubic (c-CuFe2O4) phases at standard temperature and stable tetragonal (t-CuFe2O4) phases. The effect of reaction conditions on the stability of c-CuFe2O4 is studied by temperature-dependent XRD measurements and discussed in terms of cation distribution, cooperative Jahn-Teller distortion, and Cu2+ and oxygen vacancies in the copper ferrite lattice. The observed differences in the values of the saturation magnetization and coercivity of the prepared samples are explained in terms of variations in the particle size and structural properties of copper ferrite.

A One‐Step Synthesis of Dispersed Bismuth Orthogermanate Powder and its Performance for Alpha‐ and Gamma‐Radiation Detection

AbstractBismuth orthogermanate Bi4Ge3O12 (BGO) powder with morphology suitable for production of cheap new generation detectors was obtained in a one‐step room temperature co‐precipitation process. The influence of synthesis parameters on the phase composition and morphology of the product was systematically studied via powder diffraction and scanning electron microscopy methods. The obtained BGO powder was shown to have ∼50 % decreased flash time compared to a single crystal in the case of both α‐ and γ‐produced scintillation. For α‐produced scintillation share of the slow luminescent component decreased from 35 to 10 %, too. Such improved spectral‐kinetic characteristics provide better time and space detectors resolution and allows one to reduce radiation exposure for tomography patients.

Room temperature synthesis of lead-free FASnI3 perovskite nanocrystals with improved stability by SnF2 additive

Tin halide perovskites are among the candidates for replacing lead-based ones for less toxicity and comparable optical properties. However, stability remains a challenge due to the easier oxidation of Sn2+ than Pb2+. Here, for the first time, we applied the ligand-assisted reprecipitation method to synthesize CH(NH2)2SnI3 (FASnI3) orthorhombic perovskite nanocrystals with an average diameter of 7.7 nm and a photoluminescence emission at 825 ± 2 nm (1.5 eV). The influence of synthesis parameters, including precursor solvent, precipitation media, temperature, and time on optical properties of nanocrystals, was studied. By incorporating SnF2, the stability of the nanocrystals was improved, and the oxidation from FASnI3 to FA2SnI6 was significantly delayed, which was quantitively demonstrated and confirmed by observing the characteristic diffraction peaks of the perovskite phase using x-ray diffraction at various exposure time to air. The addition of SnF2 is optimized to be 6%. The FASnI3 nanocrystals stayed stable for at least 265 days under N2 storage at room temperature and relative humidity of 20%.

Synthesis by soft chemistry of size-controlled zinc oxide (ZnO) nanocrystals for antimicrobial applications

This work focuses on the synthesis of ZnO nanoparticles (NPs) by the sol-gel method for antimicrobial applications. The influence of synthesis parameters on the size of NPs is discussed. The addition of water and an alcoholamine (Monoethanolamine MEA) during the synthesis made possible the crystallization of ZnO at low temperature (<110°C). Our experiments have also shown that these reagents exert an influence on the size of the NPs. The NPs after precipitation are recovered in the form of powders then characterized by different techniques: X-ray diffraction (XRD) and Raman spectroscopy. The crystalline domain size are calculated from Scherrer’s formula. The antimicrobial potential of these NPs has been studied. The technique applied for this evaluation consists in estimating the minimum inhibitory concentration (MIC) of the NPs by measuring the evolution of the optical density of the bacteria over time. The results showed that the synthesized ZnO NPs show efficacy on the Escherichia coli bacteria.

A Self-Matting Waterborne Polyurethane Coating for PVC Artificial Leather

A type of polyester-based self-matting waterborne polyurethane (ESMWPU) with an excellent matte effect of 0.8° and transmittance of 78.5% for PVC artificial leather was synthesized. The influence of synthesis parameters, including R value, crosslinking and hydrophilic group content, on coating gloss and transmittance was investigated. Meanwhile, the properties necessary for applying water-based resins to plasticized PVC were detailed. The results demonstrated that R value, crosslinking degree and hydrophilic group content synergistically decided the morphological changes of latex particles during their film-forming process in three aspects: particle stiffness, three-dimensional structure and particle size, respectively. With optimized parameters of R = 1.9, TMP = 2 wt% and DMPA = 1.75 wt%, ESMWPU latex particles stabilized their spherical shapes without collapsing in the film-forming process and created a rough surface, resulting in a matte effect. In terms of application performance, good wetting and adhesion for ESMWPU to a plasticized PVC surface was achieved with a 2 wt% leveling agent load. Moreover, due to the high cohesion energy of ester bonds and intermolecular hydrogen bonds, this type of polyester-based ESMWPU also depicted admirable thermal adhesion resistance. All aforementioned results distinctly demonstrate a feasible yet promising paradigm for applying ESMWPU on PVC artificial leather.

Influence of Synthesis Parameters and Polymerization Methods on the Selective and Adsorptive Performance of Bio-Inspired Ion Imprinted Polymers

Ion-imprinted polymers (IIPs) have been widely used in different fields of Analytical Sciences due to their intrinsic selective properties. However, the success of chemical imprinting in terms of selectivity, as well as the stability, specific surface area, and absence of swelling effect depends on fully understanding the preparation process. Therefore, the proposal of this review is to describe the influence of relevant parameters on the production processes of ion-imprinted polymers, including the nature (organic, inorganic, or hybrid materials), structure, properties of the salt (source of the metal ion), ligand, crosslinking agent, porogenic solvent, and initiator. Additionally, different polymerization methods are discussed, the classification of IIPs as well as the applications of these adsorbent materials in the last years (2017–2022).

Synthesis, potential of hydrogen activity, biological and chemical stability of zinc oxide nanoparticle preparation by sol–gel: A review

Zinc oxide nanoparticles (ZnO NPs) have received wide attention due to their various applications in manufacturing. Extensive research is going on for the development of nanoproducts throughout the world. Due to their unique properties, NPs have gained considerable importance compared to bulk counterparts for their utilisation in gas sensors, biosensors, cosmetics and drug-delivery systems. Sol-gel technology is widely adopted to produce ZnO NPs due to its easy, low-cost and highly controllable features. This review summarises the basic chemical methods for preparing the gel solution of ZnO NPs and focuses on their chemical and physical factors that directly affect their structural properties. ZnO NP synthesis involves four major steps: (1) dissolution, (2) hydrolysis, (3) polymerisation and (4) conversion to ZnO. The sol–gel method effectively controls the homogenous formation and interaction of materials with minimal effort. The efficacy of these steps and the influence of synthesis parameters on ZnO NPs are also discussed in this review.In the next part of this review, we will evaluate the differences and similarities among ZnO NPs synthesised using different techniques and address the challenges and prospects of this compound.

SYNTHESIS AND CHARACTERIZATION OF (Ba1-хSrx)7Nb4MoO20 POWDERS FOR PROTON-CONDUCTING SOLID OXIDE FUEL CELLS

This work reports on the preparation and characterization of Sr2+-doped Ba7Nb4MoO20 powders prepared by a solid-state synthesis as promising materials for solid oxide fuel cells. The influence of synthesis parameters and strontium content (x = 0; 0.05; 0.10; 0.15; 0.20) on the phase composition and properties of (Ba1-xSrx)7Nb4MoO20 powders was studied. The results of the phase analysis show that (Ba1-xSrx)7Nb4MoO20 (x = 0; 0.05; 0.10) powders with a minimum amount of secondary phases can be obtained after at least three repeated synthesis cycles at 1060–1080 оС for 10 h. According to the laser diffraction analysis, the synthesized powders comprise particles with a polydisperse size distribution spreading from 0.05 μm to 12 μm and average particle size of 2.1 μm. Electron microscopy observations support these findings and demonstrate that the particles and their aggregates have rounded irregular shape. Moreover, it was found that the morphology and particle size of the powder does not depend on the strontium content. Doping (Ba1-xSrx)7Nb4MoO20 with 15 mol.% and 20 mol.% Sr2+ leads to the formation of a significant amount of secondary phases due to exceeding the solubility limit of strontium, thus making these compositions unsuitable for use in solid oxide fuel cells.

Novel Synthetic Dopamine Analogues: Carbon-13/Nitrogen-15 Isotopic Labeling and Fluorescence Properties

Dopamine (DA) and its analogues are compounds of interest in polymer science where their properties provide a multitude of applications. However, in elucidating polydopamine structure, there are ambiguities related to the types of bonds, the structure of monomeric units, their ratio, and influence of synthesis parameters. In order to minimize these variables, isotopic labeling presents an optimal alternative. In the diversification and understanding of these polymers, we aim to investigate analogues that by selective isotopic labeling provide possibilities for structure elucidation both of the polymerized analogues as well as polydopamine. In the present paper we report the synthesis of three new dopamine derivatives, labeled *CL ((Z)-3-(3,4-bis(benzyloxy)phenyl)-2-cyano-2-propenamide) and both labeled and unlabeled DL/*DL (2-aminomethyl-3-(3,4-dihydroxyphenyl)propionamide). The labeled *CL and *DL compounds contain selective 13C and 15N labeling in the alkyl chain. For these new compounds, NMR, FT-IR and fluorescence characterization, including by time-resolved laser spectroscopy, are reported.

Part I: NiMoO4 Nanostructures Synthesized by the Solution Combustion Method: A Parametric Study on the Influence of Synthesis Parameters on the Materials' Physicochemical, Structural, and Morphological Properties.

The impact of process conditions on the synthesis of NiMoO4 nanostructures using a solution combustion synthesis (SCS) method, in which agar powder and Ni(NO3)2 were utilized as fuel and as the oxidant, respectively, was thoroughly studied. The results show that the calcination temperature had a significant implication on the specific surface area, phase composition, particle size, band gap, and crystallite size. The influence of calcination time on the resulting physicochemical/structural/morphological properties of NiMoO4 nanostructures was found to be a major effect during the first 20 min, beyond which these properties varied to a lesser extent. The increase in the Ni/Mo atomic ratio in the oxide impacted the combustion dynamics of the system, which led to the formation of higher surface area materials, with the prevalence of the β-phase in Ni-rich samples. Likewise, the change in the pH of the precursor solution showed that the combustion reaction is more intense in the high-pH region, entailing major implications on the physicochemical properties and phase composition of the samples. The change in the fuel content showed that the presence of agar is important, as it endows the sample with a fluffy, porous texture and is also vital for the preponderance of the β-phase.

Open-tubular capillary electrochromatography with hydroxypropyl-β-cyclodextrin imprinted polymers: hybrid polyhedral oligomeric silsesquioxane as a coating for enantioseparation.

A hydroxypropyl-β-cyclodextrin (HP-β-CD) imprinted coating based on polyhedral oligomeric silsesquioxane (POSS) for open tubular electrochromatography was prepared. The mixture of methacryl-POSS (MA0735), HP-β-CD (template), methacrylic acid (MAA, monomer), N,N′-methylenebisacrylamide (MBA, crosslinker) and toluene-dimethyl sulfoxide (porogen) was used to synthesize the chiral selective coating. The influence of synthesis parameters on the imprinting effect and separation performance, including the amount of HP-β-CD, POSS, and MAA, was investigated systemically. The optimum polymerization was prepared by mixing HP-β-CD, MA0735, MAA, and MBA with the molar ratio of 1 : 1.87 : 1.60 : 1.60. Five racemates were separated by the modified capillary columns using aqueous buffer. Column efficiency on the POSS-based MIPs coating column was greater than 22 000 plates/m. MIPs-POSS hybrid coating capillaries had improved resolution (3.36 times) and the greatest resolution was up to 6.15 within 10 min.