Kind Of Synthesis Method Research Articles

Co–FeOOH thin nanosheets derived from 2D ZIF-L for efficient oxygen evolution reaction

The complicated reaction pathway and slow electron-transfer kinetics of the oxygen evolution reaction (OER) have been identified as a critical bottleneck that restricts the overall performance of electrochemical water splitting. Metal oxyhydroxides have emerged as viable alternative catalysts as compared to the precious metal-based commercial benchmarks. Yet, the activity may be compromised by the instability of the layered structures. Herein, a simple two-step method is developed for the synthesis of Co–FeOOH electrocatalysts by thermal treatment of cobalt-containing zeolitic imidazolate framework (ZIF-L) deposited on the skeleton of NF (nickel foam) in the presence of FeSO4 and urea. Co–FeOOH/NF, the thin nanosheet arrays exhibit a high specific surface area and high hydrophobicity. The addition of Co regulates the electronic environment around the Fe center, which optimizes the adsorption energy of intermediates and enhances the inherent OER activity of active sites. The Co–FeOOH nanoarrays show excellent OER performance and 99.7% Faradaic efficiency (FE). At current densities of 10 and 100 mA cm−2, there is a low overpotential of 208 and 249 mV, respectively at 1 M KOH. This kind of synthesis method will provide a promising approach for the construction of catalysts featuring stable structures for alkaline water oxidation.

A sensing approach for manganese ion detection by carbon dots nanocomposite thin film-based surface plasmon resonance sensor

Although plenty of carbon dots have been synthesized by many kinds of synthesis methods, their potential in metal sensing applications is still limited. Herein, the application of carbon dots-cellulose nanocrystals (CDs-CNC) thin film towards manganese ions sensing was demonstrated experimentally using surface plasmon resonance (SPR) sensor. The experimental results showed that the CDs-CNC thin film-based SPR sensor provides the detection of parts per billion concentrations of Mn2+ in an aqueous solution with high sensitivity response of 0.0534° ppb-1. The thickness and refractive index of thin films were then determined by fitting the experimental SPR spectra using the WinSpall simulation program. The proposed CDs-CNC thin film-based SPR sensor exhibit better sensing performance in comparison to the previous film-based sensor, suggesting the suitable technology candidate for environmental monitoring applications.

Design and application of ionic covalent organic frameworks

Ionic covalent organic frameworks (iCOFs) are an emerging type of crystalline organic polymers that consist of the ionic skeleton and corresponding counterions. As a joint subgroup of porous ionic polymers (PiPs) and COFs, iCOFs can combine the benefits of both PiPs and COFs. Thus, iCOFs demonstrate great potential in many application fields such as ion conduction, life science, adsorption, separation, catalysis, and sensing. In this context, this review straightens the thread of thought toward this seductive material. A comprehensive introduction was expanded in all kinds of synthesis methods, classification features, and application potential. Finally, the opportunities and challenges of iCOFs were analyzed in detail to understand the future developing prospects deeply.

Effects of plasma conditions on sulfurization of MoO3 thin films and surface evolution for formation of MoS2 at low temperatures

Recently, two-dimensional (2D) MoS2 with the superior properties has been extensively investigated as a next-generation semiconductor channel material to electronic and optoelectronic devices. In order to apply MoS2 thin films to the industrial application, it is important not only to secure excellent properties but also to develop a suitable process for their large area synthesis. Among the various kinds of synthesis methods, the plasma sulfurization of transition metals or oxides has been considered a promising way to form 2D transition metal sulfides at low temperatures. However, there have been an insufficient number of systematic studies of surface phenomena during the plasma sulfurization. Therefore, this study examined the effects of the plasma conditions on the sulfurization process to form uniform MoS2 thin films. It was discovered that the introduction of hydrogen to the H2S gas during the plasma period and the thickness of the initially formed MoO3 thin films had important effects on the obtaining of continuous MoS2 thin films. Furthermore, a model of the surface evolution occurring during the plasma sulfurization process was proposed based on the observations. The results of this work could inspire other researchers and assist in the study of the sulfurization of various other oxides films.

Dispersibility and Size Control of Silver Nanoparticles with Anti-Algal Potential Based on Coupling Effects of Polyvinylpyrrolidone and Sodium Tripolyphosphate.

In nearly all the cases of biotoxicity studies of silver nanoparticles (AgNPs), AgNPs used often have general dispersibility and wide size distribution, which may inevitably generate imprecise results. Herein, a kind of synthesis method by coupling effects of polyvinylpyrrolidone (PVP) and sodium tripolyphosphate (STPP) was proposed, in order to prepare AgNPs with better dispersibility and a stable size. Based on this, the preparation mechanism of AgNPs and the potential anti-algae toxicity were analyzed. UV-vis analysis showed that the particle size distribution of AgNPs prepared by co-protective agents was more uniform. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and energy dispersive X-ray (EDX) were used to confirm that the obtained nano silver was of a high purity and stable size (~30 nm in diameter). Zeta potential and Fourier transform infrared spectroscopy (FTIR) analysis results indicated the synthesis mechanism of AgNPs by co-protective agents, more precisely, PVP limited the polynegative effect and prevented the linear induction of P3O105− produced by STPP during the growth of silver nuclei. Subsequently, Chlorella and Scenedesmus obliquus were utilized to test the toxicity of AgNPs, confirming that AgNPs synthesized through co-protective agents have potential inhibitory ability on algae, but not severe. This study provides a basic theory for the induction of synthetic AgNPs by various factors in the natural environment and a scientific reference for the environmental risk assessment.

Fascinating Physic-Chemical Properties and Resourceful Applications of Selected Cadmium Nanomaterials

Nanomaterials are the leading edge for the rapid development of fascinating nanotechnology. The design of nanostructures with favoured shape, particle size and structure are the most important and interesting fields of nanoscience. Recently inorganic nanomaterials have attracted much interest for their novel physical, chemical, optical, electrical and magnetic properties etc, and also showed their wide variety of potential applications in nanoscale devices. In the past decade, nano semiconductors of groups II–VI have defined wide interest in many areas of physical, chemical and biochemical sciences etc. They possess high chemical stability, along luminescence life time and offered the possibility of controlling the surface functionality. This review deals with cadmium sulfide and cadmium oxide nanoparticles with different kinds of synthesis methods, crystallinity–morphology–shape, compositions, functional groups and stretching vibrations of CdS and CdO. Owing to its properties cadmium nanoparticles have showed tremendous vibrational applications in photodetectors, sensors, photocatalysts, solar cells etc.

Comparing three methods of simultaneous synthesis and stabilization of Fe3O4 nanoparticles: Changing physicochemical properties of products to improve kinetic and thermodynamic of dye adsorption

Fe3O4 nanoparticles (FNPs) were synthesized by conventional heating (CH), co-precipitation (CP) and microwave heating (MH) methods in presence of pectin crosslinked by β-isopropylglutaric acid (-CP) to stabilize nanoparticles. The role of the cross-linked pectin and kinds of synthesis methods was appeared to increase the effective total surface of FNPs both simultaneously as the synergistic effects and separately. The effective role of the microwave irradiation to decrease FNPs mean size was seen, so that its size in FMH was smaller 21.5% and 38.2% than that of FCP and FCH, and in FMH-CP was smaller 27.2% and 58.9% than that of FCP-CP and FCH-CP, respectively. The various experiments were done on the structures, functional groups, and connection quantities of -CP to FNPs synthesized by CH, CP and MH methods. The different physical properties of the obtained composites containing magnetization, zeta potential and thermal analyses were determined. To study the adsorption of methylene blue (MB) from the aqueous and alkali solution, the role Fe–O− groups of FNPs was evaluated more effective than the role of –COO− and –O− of -CP in the stabilized nanoparticles. Fe3O4 NPs stabilized by -CP using microwave heating showed the highest capacity of MB adsorption due to having the most suitable thermodynamic and kinetic parameters.

Preparation and Characterization of Carbon Nanofibers from the High Temperature Controllable Flame

Carbon nanofiber is a new type of carbon materials and it has wide application prospects. At present, there are many kinds of synthesis methods of carbon nanofibers. Among them, preparation of carbon nanofibers from the controllable flame is a new method. It needs simple laboratory equipments and normal atmosphere pressure in this method. Experimental apparatus is including controllable flame burner, thermocouple, mass flow meter and catalyst preparation system, etc. The key factors of synthesis experiment involving the carbon source, the catalyst and high temperature heat source. Characterization of the carbon nanofibers from the controllable flame is by scanning electron microscope (SEM) and transmission electron microscope (TEM).The experimental results indicated that carbon nanofibers with less impurity can be captured at the temperature from 720 to 880 ̊C when carbon monoxide and iron-based catalyst served as carbon source and the catalyst respectively.

COMPARING AND IMPROVING THE SYNTHESIS OF STATE-BASED SPECIFICATIONS FROM SCENARIO-BASED SPECIFICATIONS

The scenario-based specifications are popularly used to capture user requirements. The state-based specifications are very appropriate to capture system design. Recently, there has been increased research interest in connecting these two kinds of specifications, called synthesis. Synthesis is a way to automatically construct the state-based specifications from the scenario-based specifications. There are two kinds of synthesis methods: global synthesis and local synthesis. Global synthesis means constructing a state-based specification for the whole system from the scenario-based specifications, while local synthesis means constructing a state-based specification for each object in the system. The two different synthesis methods have different uses and need to be systematically compared. The contributions of this paper are twofold. Firstly, we propose an improved method supporting the global and the local synthesis of state machines (a kind of state-based specifications) by using a novel algorithm for state machine execution and an algorithm similar to operator priority analysis method, which can fully automate the process of synthesis. Our synthesis method also satisfies two important properties: completeness and soundness. Secondly, to the best of our knowledge, our work does the first attempt to systematically compare global synthesis with local synthesis, and shows some insightful results of the experimental comparison between the two kinds of synthesis methods, which are valuable for the practitioners to choose an appropriate synthesis method for the analysis and verification of the system.

Elaboration of blue-emitting blue pigments based on Eu 2+/Co 2+ codoped BaMgAl 10O 17 through the heterogeneous distribution of dopants

Photoluminescence and coloring properties of Eu 2+/Co 2+ codoped BaMgAl 10O 17 were investigated to produce inorganic blue-luminescent pigments. Two kinds of synthesis methods were employed for BaMgAl 10O 17:Eu 2+,Co 2+ powders based on a conventional solid-state reaction and a newly developed precipitation method. Powder samples through the solid-state reaction exhibited blue photoluminescence from Eu 2+, which was quenched considerably by codoping with Co 2+ due to the occurrence of a Eu 2+ → Co 2+ energy transfer. The precipitation method was then conceived to separate Eu 2+ and Co 2+ spatially in a BaMgAl 10O 17 particle. Powder samples through the precipitation method could be colored blue by optical absorption of Co 2+ without degrading blue photoluminescence from Eu 2+. The inhomogeneous distribution of the Eu 2+/Co 2+ dopants in the BaMgAl 10O 17 particles was instrumental to the suppression of the Eu 2+ → Co 2+ energy transfer.

Multiple-walled BN nanotubes obtained with a mechanical alloying technique

An experimental method to obtain multiple-walled nanotubes of BN using low energy is presented. The method is based on the use of mechanical alloying techniques with elemental boron powders and nitrogen gas mixed in an autoclave at room temperature. The chemical and structural characteristics of the multiple-walled nanotubes were obtained using different techniques, such as X-ray diffraction, transmission electron microscopy, EELS microanalysis, high-resolution electron microscopy images and theoretical simulations based on the multisliced approach of the electron diffraction theory. This investigation clearly illustrates the production of multiple-wall BN nanotubes at room temperature. These results open up a new kind of synthesis method with low expense and important perspectives for use in large-quantity production.

Influence of regioregularity of photodoped poly(3-alkylthiophenes) on the stability of electrical conductivity

Many kinds of synthesis methods were performed leading to different structure regularities and were studied in relation to their electrical conductivity. The effect of temperature on the degradation of the conductivity have been investigated.