Ghazaleh Allaedini

Study of influential factors in synthesis and characterization of cobalt oxide nanoparticles

This study has investigated the different factors in obtaining cobalt oxide nanoparticles. The factors that have been studied are the effect of pH, synthesis temperature, capping agent, annealing temperature, and different usage of cobalt salts. Cobalt oxide nanoparticles were characterized by scanning electron microscopy, energy dispersive X- ray spectroscopy, UV, Fourier transform infrared spectroscopy, and X-ray diffraction. In order to find the effects of various factors, the optimum pH was achieved in the first experiment by the precipitation method; after finding out that in experiments with pH 8 to 9, the particles are homogeneous in shape and regular. The other experiments were repeated with the same pH but changing the factors. In the second experiment, the effect of synthesis temperature at 40?C, 60?C, 80?C, and 100?C was investigated. To find out the effect of capping agent, two experiments were done, one using the oleic acid and the other using 2-(dodecyloxy) acetic acid. In the case of investigating the annealing temperature, the black cobalt oxides were annealed at 400?C, 500?C, and 600?C. The last one was done using two different cobalt salts, cobalt nitrate and cobalt sulfate. Finally, cobalt oxide nanoparticles were characterized.

Synthesis of Fe—Ni—Ce trimetallic catalyst nanoparticles via impregnation and co-precipitation and their application to dye degradation

In this study, trimetallic catalysts were prepared via the co-precipitation and impregnation methods. In order to investigate the effect of impregnation on the catalytic activity and crystallite size, a trimetallic catalyst, Fe—Ni—Ce, was prepared through the co-precipitation method in one set of experiments, and cerium was impregnated with the Ni—Fe mixture in the final stage of the preparation in another set. Fourier transform infrared spectroscopy was employed to confirm the formation of trimetallic catalysts and the success of the impregnation method. The Brunauer-Emmett-Teller nitrogen adsorption isotherm exhibits a high specific surface area (approximately 39 m2 g−1) for the nanoparticles obtained by the impregnation method. The crystallography and morphology of the trimetallic catalysts thus prepared were characterised by X-ray diffraction and scanning electron microscopy. UV-VIS spectroscopy and methylene blue dye degradation tests were also performed to investigate the catalytic activity of the synthesised catalysts. The crystalline size was found to be smaller for the catalysts prepared by the impregnation method. In addition, the samples synthesised using the cerium impregnation method showed superior activity in the methylene blue dye degradation test. The effect of the catalyst dosage on dye degradation, as well as the effect of the initial dye concentration on the catalyst activity, was also studied for both methods.

The effects of cerium doping concentration on the properties and photocatalytic activity of bimetallic Mo/Ce catalyst

In this study, the characterization and photocatalytic activity of MoO3 nanoparticles doped with various doping concentrations of cerium have been investigated. The Fourier transform infrared (FT-IR) spectra of the prepared catalysts confirmed that MoO3 particles have been successfully doped by cerium. Field emission scanning electron microscopy (FESEM) was performed to visualize the surface morphology of the obtained catalysts. The XRD patterns suggested that the crystallinity of the sample with the lowest doping concentration of 15 mol % was higher in comparison with samples of higher doping concentrations. The volume-averaged crystal sizes of the obtained catalysts were calculated to be 25, 28, and 32 nm for 15, 35, and 60 mol % samples, respectively. The photocatalytic activity along with the reaction kinetics of Ce-doped MoO3 nanoparticles have also been investigated through the dye degradation of methyl orange. The synthesized Ce-doped MoO3 particles with the lowest dopant concentration of 15 mol % exhibited the highest photocatalytic activity for methyl orange dye degradation. It was observed that photo-degradation activity decreased with an increase in the doping concentration of cerium. The predicted rate constants for samples with 15, 35, and 60 mol % doping concentrations were found to be 0.0432, 0.035, and 0.029 min–1, respectively.

The effect of alumina and magnesia supported germanium nanoparticles on the growth of carbon nanotubes in the chemical vapor deposition method

The effect of alumina and magnesia supported germanium (Ge) nanoparticles on the synthesis of carbon nanotubes (CNTs) using the chemical vapor deposition (CVD) method in atmospheric pressure was investigated. The TEM micrographs confirmed the formation of carbon nanotubes, and the field emission scanning electron microscopy (FESEM) analysis suggested a tip-growth mechanism for the grown carbon nanotubes. The X-ray diffraction (XRD) pattern indicated a graphitic nature of the carbon nanotubes. The obtained CNTs using Ge nanoparticles supported by MgO resulted in a higher degree of graphitization than the CNTs obtained using Ge nanoparticles supported by Al2O3. Raman spectroscopy analysis of the CNTs confirmed the presence of radial breathing modes (RBM), which verified the formation of CNTs. High frequency Raman analysis demonstrated that the degree of graphitization of the synthesized CNTs using magnesia supported Ge nanoparticles is higher than that of the alumina supported Ge nanoparticles with the values of (ID/IG) ratios equal to 0.45 and 0.73, respectively.

Synthesis of graphene through direct decomposition of CO2 with the aid of Ni–Ce–Fe trimetallic catalyst

In this study, few-layered graphene (FLG) has been synthesized using the chemical vapour deposition (CVD) method with the aid of a novel Ni–Ce–Fe trimetallic catalyst. Carbon dioxide was used as the carbon source in the present work. The obtained graphene was characterized by Raman spectroscopy, and the results proved that high-quality graphene sheets were obtained. Scanning electron microscopy, atomic force microscopy and transmission electron microscopy pictures were used to investigate the morphology of the prepared FLG. The energy-dispersive X-ray spectroscopy results confirmed a high yield (∼48%) of the obtained graphene through this method. Ni–Ce–Fe has been shown to be an active catalyst in the production of high-quality graphene via carbon dioxide decomposition. The X-ray photoelectron spectroscopy spectrum was also obtained to confirm the formation of graphene.

Chemical Vapor Deposition of Methane in the Presence of Cu/Si Nanoparticles as a Facile Method for Graphene Production

This study reports on a facile, scalable, and economical method for the synthesis of graphene sheets via catalytic decomposition of methane. The catalyst was prepared by a simple sol–gel method. In this method, copper was doped by a silicon dioxide substrate to prepare a novel catalyst to be used in the chemical vapor deposition (CVD) process. The CVD method has a remarkably high capacity as well as efficiency potentials in terms of high-yield graphene production with superior morphology. Few-layered graphene (FLG) sheets were produced successfully under atmospheric pressure. The X-ray crystallography patterns confirmed the formation of graphene sheets. The obtained graphene was characterized by Raman spectroscopy, and the results proved that high quality graphene sheets with an ID/IG ratio of 0.7 were obtained. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) micrographs were also used to investigate the shape and the morphology of the prepared FLG. The average thickness of the obtained graphene sheets was found to be equal to ˜8 nm using transmission electron microscopy (TEM). XRD, FTIR and XPS spectra were also obtained to confirm the formation of graphene and its nature.

Structural properties and optical characterization of flower-like Mg doped NiO

In this study, un-doped and Mg doped NiO nanoparticles have been synthesized through a simple sol-gel method. To investigate the effect of Mg-doping on the structure of NiO, the obtained nanoparticles were characterized using scanning electron microscopy (SEM). Flower/star like morphology was clearly observed in the SEM micrographs. The BET (Brunauer-Emmett-Teller) nitrogen absorption isotherm exhibits high specific surface area (∼37 m2 /g) for the Mg doped NiO nanoparticles. X-Ray diffraction (XRD) of the prepared Mg-NiO nanoparticles showed a face-centered cubic (f.c.c) structure, and the average particle size was estimated to be 32 nm using Scherrer’s formula. Energy Dispersive X-Ray (EDX) confirms that the NiO particles are successfully doped with Mg. Photoluminescence (PL) and UV-Vis optical absorption characteristics of the prepared nanoparticles have also been investigated in this study. The PL emission response showed a blue shift when NiO was doped with Mg, which is indicative of interstitial oxy...

Comparative Study on the Microstructure and Photoluminescence Properties of SnO2 Nano Particles Prepared by Different Methods

This study presents comparisons between the morphologies and photoluminescence properties of tin oxide (SnO2) nanoparticles prepared by two methods, namely the sol gel and the co-precipitation methods. The characteristics of the particles were analyzed using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The particles prepared using the sol-gel method have a finer particle size and more spherical shape. However, no significant difference was observed in terms of morphology and homogeneity in the samples produced by either the co-precipitation or sol-gel methods. In contrast, the photoluminescence study shows that the emission peak for powder prepared using the sol-gel method was higher than that of the co-precipitation method.