Effect Of Synthesis Method Research Articles

The Effect of Na2ZrO3 Synthesis Method on the CO2 Sorption Kinetics at High Temperature

Sodium zirconate (Na2ZrO3) can capture CO2 at high temperature with high efficiency. In this study, Na2ZrO3 sorbents were synthesized by wet-mixing and sol-gel methods. Both heated-drying and freeze-drying were applied for drying the solutions to form different porous structures in the prepared samples. The material characterization and cyclic sorption test were carried out, and the effects of synthesis methods and drying methods on the sorption properties of Na2ZrO3 were studied. The experimental results showed that Na2ZrO3 sorbents prepared by sol-gel mixing and freeze-drying possessed a more porous structure and smaller crystals, which favored the initial sorption rate of the materials. But sol-gel method and freeze-drying method could also reduce the content of monoclinic crystal in the sorbent, which limited the sorption of Na2ZrO3 in the later stage. Wet-mixing followed by heated-drying was unfavorable to porous structure, but the sample prepared via wet-mixing and heated-drying was the richest in monoclinic phase. Even though it captured CO2 at the slowest rate in the initial minute, the CO2 sorption by this sorbent was much more sustainable and the CO2 capacity was the highest over all the cycles. The findings in this study indicated that the content of monoclinic crystal form was the most important determinant of sorption performance. Seeking for highly porous property of Na2ZrO3 is not necessary.

Effect of Synthesis Methods on the Catalytic Reforming of Kerosene

Effect of Synthesis Methods on the Catalytic Reforming of Kerosene

Effect of Synthesis Methods on Properties of Copper Oxide Doped Titanium Dioxide Photocatalyst in Dye Photodegradation of Rhodamine B

Copper modified titanium dioxide photocatalysts have been widely reported for their excellent performance in the wastewater treatment. However, there is lack of information on the effect of different synthesis methods towards the properties and catalytic activity of the photocatalyst. In this research, a series of copper-doped titanium dioxide (Cu-TiO2) photocatalysts were synthesized via three different methods of sonochemical, impregnation and physical mixing. Cu-TiO2 with varied molar ratios of Cu dopant to TiO2 TR595 (100:0, 99:1, 98:2, 97:3 and 96:4) were prepared. Comparison of physical-chemical properties and photocatalytic activity among the synthesized samples were made. X-ray diffraction analysis depicted the formation of TiO2 rutile phase in all samples. Besides, diffuse reflectance UV-visible analysis proved that the synthesized samples were active under visible light region. According to the Tauc plot and photoluminescence spectra, the band gap energies and recombination rate of electron-hole pairs of Cu-TiO2 samples decreased upon loading of Cu. Moreover, EDX analysis confirmed the existence of Ti and Cu in all the samples. The photocatalytic efficiencies of the synthesized samples were discovered through photodegradation of Rhodamine B organic dye under 6 hours of visible light irradiation. Amongst, Cu-TiO2 photocatalysts synthesized via sonochemical method with molar ratio of 98:2 produced the highest photocatalytic activity of 64.8% which attributed to the lowest recombination rate of photogenerated charge carriers and availability of large number of reactive oxidative species.

The Effect of the Synthesis Method on Physicochemical Properties of Selective Granular Polymer Sorbents

Investigation of the effect of the polymer synthesis method on physicochemical properties of sorbents is one of the topical problems in the chemistry of macromolecular compounds that has high scientific and practical interest. Determination of the optimal synthesis method will make it possible to create sorbents with physicochemical properties that led to the realization of effective sorption. In this work, we investigated the effect of synthesis methods (Pickering emulsion polymerization and precipitation polymerization in solution) of granular polymers based on 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate on physicochemical and sorption properties. The synthesis by Pickering emulsion polymerization led to improvement of the n-propyl alcohol diffusion into the polymer network and to the formation of more homogeneous and structurally stable polymer networks. Creating selective polymer networks by Pickering emulsion polymerization compared to precipitation polymerization in solution led to an increase in porosity, creation of more segregated surface of granules, improvement of binding sites availability at the temperature of 37 °C, and formation of the homogeneous sorption surface with high affinity to target molecules at 25 °C and 37 °C. Selective polymers synthesized by both polymerization methods had the largest values of available sorption surfaces areas for target molecules at 37 °C.

Effects of synthesis method, feedstock type, and pyrolysis temperature on physicochemical properties of biochar nanoparticles

Effects of synthesis method, feedstock type, and pyrolysis temperature on physicochemical properties of biochar nanoparticles

Effect of Synthesis Methods on Conductivity and Luminescence Properties for La3+ and Ho 3+ Co-Doped Ceo2

Effect of Synthesis Methods on Conductivity and Luminescence Properties for La3+ and Ho 3+ Co-Doped Ceo2

Effect of synthesis method on structural, ferroelectric and conduction relaxation in Pb1-xLaxTiO3, where x = 0.25 ceramics

The structural, ferroelectric, dielectric and conduction mechanism of Pb0.75La0.25TiO3 ceramics synthesized using solid state reaction route & Auto Combustion method have been reported. X-ray diffraction data reveals that prepared ceramics using both the methods crystallizes into tetragonal phase whereas ferroelectric loop confirms the presence ferroelectric ordering. Frequency dependent ε′ and ε″ at different temperature shows the Cole-Cole relaxation behaviour. The Jonscher’s power law fitted parameter ‘n’ vs. temperature explains the conduction mechanism in prepared ceramics.

Thermochemical study of the structural stability of low-silicate CHA zeolite crystals

In this study, the effect of synthesis method on the structural stability of low-silica CHA zeolite crystals were investigated. For this purpose, template-free CHA crystals with similar chemical compositions were synthesized using seeded secondary growth and inter-zeolite transformation approaches. The stability performance of as-synthesized crystals was studied at temperatures, steam flow in a closed system, and acidic media. The results were analyzed using XRD, FTIR, DLS and FESEM. It was found both methods have similar structural stability behavior. The thermal stability investigation proved they have maintained their crystalline structure against heating, up to 800 °C, and at higher temperatures, the amorphous phase prevailed. The CHA crystals synthesized via both methods are stable in terms of hydrothermal stability up to 200 °C. Moreover, the results of chemical resistance showed CHA crystals exhibit excellent resistance to weak acidic medium, but against stronger acids, it has completely lost its crystallinity after 72 h.

The Effect of Synthesis Methods on the Yield and Quality of Ti3c2tx-Mxene

The Effect of Synthesis Methods on the Yield and Quality of Ti3c2tx-Mxene

Effects of Synthesis Methods on the Structural and Magnetic Properties of Double Perovskite Sr2crreo6 Oxide Powders

Effects of Synthesis Methods on the Structural and Magnetic Properties of Double Perovskite Sr2crreo6 Oxide Powders

The electrochemical performance of manganese oxoborate cathodes for lithium-ion batteries: Effect of synthesis method

Cathodes for lithium-ion batteries (LIBs) present stability and performance issues; therefore, searching for alternative novel electrode materials or modifications of known ones is one of the main issues. Warwickite-type Mn 2 OBO 3 samples synthesized by hydrothermal (HT), solid-state (SS), and solution combustion (SC) methods were investigated for the first time as cathode materials for LIBs. The prepared Mn 2 OBO 3 electrodes were analyzed using scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques in order to correlate the surface properties and electrochemical behaviour. X-ray photoelectron spectroscopy (XPS) revealed the existence of +2 and + 3 oxidation states of Mn in the electrodes. The band gaps (E g ) for all electrodes were calculated between 1.75 and 2.04 eV. The electrochemical performance of the Mn 2 OBO 3 electrodes (E) prepared with the SC method was significantly improved. The E-SC electrode showed the highest initial discharge capacity of about 155 mAhg -1 and found to be more stable at a current density of 30 mAg -1 . The results presented here provide a new approach to the utilization of manganese oxoborate compounds as promising cathode materials for high-performance energy storage systems and emphasize that homogeneously structured cathode electrodes with a high surface area are desirable for LIBs.

ZSM-5@Sil-1 core shell: Effect of synthesis method over textural and catalytic properties

A modified technique of epitaxial growth employed to produce “core-shell” catalysts coating microporous ZSM-5 with a layer of Silicalite-1 is presented in this paper. The aim was to passivate surface acidity of a ZSM-5 zeolite, in the view of potential limitation of surface effect generally responsible for coke formation. Core-shell catalysts have been synthesized starting from a ZSM-5 core with Si/Al = 25. Two different hydrothermal Silicalite-1 synthesis were performed: one using the ZSM-5 as made-form and the second using the ZSM-5H+-form as core. This allowed to investigate the effect of the organic template, filling the pores of the core, on the shell growth mechanism. Coating procedure lasted 24 h and it was repeated twice to increase Silicalite-1 thickness. All catalysts were tested for the reaction of methanol dehydration to DME in an atmospheric system at 180–240° and time on stream tests were carried out to analyse the stability of the samples. Considering the catalytic performances in terms of methanol conversion, DME selectivity and deactivation, core-shell catalysts, synthetized using an as-made form core, exhibited interesting performances, resulting from a more controlled growth of the passivating layer. These materials could constitute valid option for hybrid (Metal-Zeolite) catalyst, where the reduction of surface acidity could better stabilize the metallic function.

Effect of synthesis method on the oxygen reduction performance of Co–N–C catalyst

In recent years, Co, N co-doped carbon (Co–N–C) materials as oxygen reduction reaction (ORR) catalysts have attracted great attention because of their good ORR stability as well as decent activity. Co-doped zeolitic imidazolate framework-8 (Co@ZIF-8) as the precursor for synthesizing Co–N–C has attracted great interest recently. Co@ZIF-8 synthesis method may affect the properties of the as-synthesized Co@ZIF-8 precursors, which will surely affect the properties and ORR performance of Co@ZIF-8-derived Co–N–C catalysts. Herein, three methods, viz. room-temperature stirring method, reflux method, and hydrothermal method, were used to synthesize Co@ZIF-8 precursors. Physical characterization shows that the synthesis method has a great influence on the textural properties, composition, and graphitization degree of the as-synthesized Co–N–C catalysts. Electrochemical characterization shows that Co–N–C-R synthesized with reflux method exhibits an onset potential (Eonset) of 0.905 V, a half-wave potential (E1/2) of 0.792 V and a limiting current density (JL) of 5.85 mA cm−2 in acidic media, which are higher than those of Co–N–C–S (Eonset = 0.870 V, E1/2 = 0.770 V, JL = 4.71 mA cm−2) and Co–N–C–H (Eonset = 0.892 V, E1/2 = 0.785 V, JL = 4.68 mA cm−2) synthesized with room-temperature stirring method and hydrothermal method, respectively. The better ORR activity observed on Co–N–C-R can be attributed to its larger graphitization degree and larger mesopore volume. Catalytic stability test shows that Co–N–C-R has negligible activity loss after 5000 potential cycles. This work demonstrates that reflux method is a more suitable method for synthesizing Co–N–C catalysts for ORR.

Effect of Synthesis Method on Properties of Layered Double Hydroxides Containing Ni(III)

Unstable oxidation state +3 of nickel can be stabilized in the structure of layered double hydroxides, the resulting crystallinity and properties being dependent on the synthesis method. Three different wet chemical methods (co-precipitation at variable pH, co-precipitation followed by hydrothermal treatment, co-precipitation with microwave treatment) were used to synthesize Mg/Ni–Al layered double hydroxides containing triply charged nickel cations. Lattice parameters of the samples synthesized by various methods were found to differ from each other by about 1.5%. The most crystallized sample was obtained by hydrothermal synthesis. The oxidation state of nickel in the LDH samples was confirmed by XPS. TEM mapping gave evidence of the uniform distribution of nickel in all the samples. The LDHs’ reduction with hydrogen and thermal transformations of the phase composition and morphology of LDHs were studied in detail. The properties of the samples synthesized by the different methods were shown to be quite similar.

MOF-derived CeO2 supported Ag catalysts for toluene oxidation: The effect of synthesis method

Volatile organic compounds (VOCs), such as toluene, have aroused wide concerns its emissions growth and harmfulness. Catalytic oxidation has been considered as one of the most efficient technologies for toluene degradation. In this work, MOF-derived CeO2 supported Ag catalysts were prepared by different synthesis method. Toluene oxidation test found that Ag-Ce-BTC-C synthesized by one-pot and calcination at 500 °C under Ar and O2 atmosphere exhibited the better catalytic performance for toluene oxidation (T90 = 226 °C). H2 temperature programmed reduction and X-ray photoelectron spectroscopic results exhibited that the preparation method had a great influence on the physicochemical properties of the supported Ag catalysts. The better catalytic performance was attributed to the better reducibility, more active oxygen species and oxygen vacancies, higher molar ratio of Oads/Olat, Ce3+/Ce4+ and Ag0/Agδ+. This work has a certain guiding significance for the preparation of highly active MOF-derived supported catalysts.

Towards efficient Cu/ZnO catalysts for ester hydrogenolysis: The role of synthesis method

Cu/ZnO catalysts represent an environmentally friendly alternative to Adkins catalysts used for ester hydrogenolysis. Cu/ZnO are mostly synthesized by co-precipitation (COP); however, other synthesis methods may help to obtain small highly dispersed Cu crystallites advantageous for catalyst activity. A comparative study on the effect of synthesis method on Cu/ZnO catalysts properties and activity is missing. Thus, we synthesized 8 wt% Cu/ZnO catalysts by five methods (COP, deposition-precipitation (DP), chemisorption-hydrolysis (CH), incipient wetness (IWI) and wet impregnation (WI)), characterized and tested them in dimethyl adipate hydrogenolysis. The CH-prepared catalyst was prone to Cu sintering, which impaired its performance. IWI led to large Cu nanoparticles, pore blocking and poor catalytic performance. COP and DP resulted in the smallest Cu nanoparticles (13−14 nm), largest Cu surface area (3.9–4.2 m2 gcat−1) and specific surface area (40−43 m2 gcat−1) reflected in their superior catalytic activity making DP a good alternative to COP to prepare active Cu/ZnO catalysts.

CARBON QUANTUM DOTS (CQDS) from RAMBUTAN and PANDAN LEAVES for CU2+ DETECTION

A facile and eco-friendly process for the synthesis of carbon quantum dots (CQDs) was carried out via hydrothermal and microwave treatment using Rambutan and Pandan leaves as carbon sources. The effects of synthesis methods on the optical and physical properties of CQDs, and the sensing activity of CQDs through Cu 2+ detection are presented in this study. From the analysis, the band-gap energies of CQDs are found to be ranging from 2.52 to 3.51 eV. The CQDs solutions exhibit significant fluorescence property, in which bright cyan fluorescence can be detected under Ultraviolet (UV) light irradiation at wavelength of around 405 nm. The CQDs synthesized from Pandan and Rambutan leaves using hydrothermal method show quantum yield (QY) values at around 2.46% and 2.70%, respectively. The FT-IR analysis recorded existing functional groups on the surface of CQDs to be of hydroxyl and carbonyl groups, which can serve as adsorption sites for the detection of Cu 2+ . Furthermore, this study indicates that CQDs emission from Pandan and Rambutan leaves using hydrothermal method shows the best turn-off behavior when detecting the presence of Cu 2+ with minimum limit of detection (LoD) as low as 123 µM.

Effect of synthesis methods on dielectric performance of ZnO nanoparticles

ABSTRACT Zinc oxide (ZnO) nanoparticles are widely studied for the application of dye-sensitised solar cells (DSSCs). The control of nanoscale morphology and microstructural properties of ZnO is critical for DSSCs performance. The current study provides an insight about the effect of synthesis methods (i.e. co-precipitation and sol–gel) on structural, optical and electrical properties of ZnO nanoparticles. The formation of hexagonal wurtzite phase with space group P63mc was confirmed by Rietveld fitted X-ray diffraction and Raman spectroscopy. The variation in morphology due to different synthesis methods was confirmed by Scanning electron microscopy. Functional groups were identified by Fourier transform infrared spectroscopy. The presence of defects led to the narrowing of band gap of ZnO nanoparticles, and was confirmed by diffuse reflectance spectroscopy. The frequency-dependent dielectric behaviour was explained by means of Maxwell–Wagner–Sillars model. The current study paves the way of potential application of ZnO nanoparticles in DSSCs.

Effect of synthesis method on the ultimate properties of copper-based catalysts supported on KIT-6 for direct CO2 hydrogenation to methanol

The effect of synthesis method on the ultimate properties of copper-based catalysts supported on KIT-6 was investigated. A series of catalysts with 0.60Cu/0.15ZnO/0.05MnO/1.0KIT-6 mole ratio was synthesized using three methods, i.e. citric acid impregnation (CA), wet impregnation (WI), and deposition-precipitation (DP). Characterization study shows the catalyst synthesized using CA method had relatively high metal-support interactions and preserved the structures of preshaped KIT-6 support the best. The CA catalyst was also characterized with low mesopore plugging, high porosity, along with the formation of small copper crystallites and large copper surface areas. The presence of abundant accessible active sites in CA catalyst is strongly supported by temperature-programmed desorption results. After reaction, X-ray diffraction analysis indicates CA catalyst had greatest resistance to copper crystallite growth. In direct CO2 hydrogenation reaction, the CA catalyst led to remarkably high methanol production rate (3.94 kg/kgcat·h), i.e. 34%–164% higher than the others, including a commercial catalyst.

Effect of synthesis methods on the acetone sensing behaviour of fluorescent carbon dots

Carbon dots (CDs) are an emerging family of nanostructures due to their unique optical properties, high chemical stability, biocompatibility, and low toxicity, they have been able to attract a lot of attention and cause significant changes in various scientific fields. In this study, the green synthesis of stable CDs by hydrothermal and pyrolysis methods (H-CDs and P-CDs) is performed from Nigella sativa seeds as a natural precursor. Using these methods, the formation and the surface passivation of the CDs are done simultaneously, resulting in the intrinsic fluorescence emission. The as-prepared CDs are characterised by UV–vis spectroscopy, fluorescence spectroscopy, elemental analysis, dynamic light scattering, Fourier transform infrared spectroscopy, and transmission electron microscopy, from which their structural information and property are interpreted. The fluorescence intensity graph of H-CDs and P-CDs, with excitation wavelengths in 360 nm, shows the highest emissions at 430 and 410 nm, respectively. Particle size distribution was obtained at about 4 nm. The fluorescent quantum yield (QY) of H-CDs and P-CDs was measured to be 7% and 2%, respectively. The synthesised CDs showed good photoluminescence (PL) responses to acetone solution. Acetone had a different effect on the PL properties of CDs obtained from pyrolysis and hydrothermal methods so that in P-CDs, it increased the intensity of PL, and in H-CDs; it decreased the intensity of PL.