Mechanochemical synthesis of cobalt oxide nanoparticles (original) (raw)

Synthesis and characterization of cobalt oxide nanoparticles by thermal treatment process

Inorganica Chimica Acta, 2009

The simple preparation of Co 3 O 4 nanoparticles from a solid organometallic molecular precursor N-N 0bis(salicylaldehyde)-1,2-phenylenediimino cobalt(II); Co(salophen) has been achieved via two simple steps: firstly, the Co(salophen) precursor was precipitated from the reaction of cobalt(II) acetate and N-N 0 -bis(salicylaldehyde)-1,2-phenylenediimino; H 2 salophen; in propanol under nitrogen condition; then, cubic phase Co 3 O 4 nanoparticles with the size of mostly 30-50 nm could be produced by thermal treatment of the Co(salophen) in air at 773 K for 5 h. The as-synthesized products were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and scanning electronic microscopy (SEM). These results confirm that the resulting oxide was pure single-crystalline Co 3 O 4 nanoparticles. The optical property test indicates that the absorption peak of the nanoparticles shifts towards short wavelength, and the blue shift phenomenon might be ascribed to the quantum effect. The hysteresis loops of the obtained samples reveal the ferromagnetic behaviors the enhanced coercivity (H c ) and decreased saturation magnetization (M s ) in contrast to their respective bulk materials.

Characterization of Cobalt Oxide Nanoparticles Prepared by the Thermal Decomposition

Acta Chimica Slovenica, 2016

In this work, thermal decomposition of the [Co(NH 3) 5 (H 2 O)](NO 3) 3 precursor complex was investigated under solid state conditions. Thermal analysis (TG/DTA) showed that the complex was easily decomposed into the Co 3 O 4 nanoparticles at low temperature (175 °C) without using any expensive and toxic solvent or a complicated equipment. The obtained product was identified by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). Optical and magnetic properties of the products were studied by UV-visible spectroscopy and a vibrating sample magnetometer (VSM), respectively. FT-IR, XRD and EDX analyses confirmed the formation of highly pure spinel-type Co 3 O 4 phase with cubic structure. SEM and TEM images showed that the Co 3 O 4 nanoparticles have a sphere-like morphology with an average size of 17.5 nm. The optical absorption spectrum of the Co 3 O 4 nanoparticles showed two band gaps of 2.20 and 3.45 eV, which in turn confirmed the semiconducting properties. The magnetic measurement showed a weak ferromagnetic order at room temperature. Photocatalytic degradation of methylene blue (MB) demonstrated that the as-prepared Co 3 O 4 nanoparticles have good photocatalytic activity under visible-light irradiation.

Effect of Solvents on Synthesis and Characterization of Cobalt Oxide ( Co 3 O 4 ) Nanoparticles

We report characteristic of cobalt oxide (Co3O4) nanoparticles prepared by thermal decomposition of Co (Ac)2·4H2O using oleic acid capping agent and NaBH4 reducing agent. Variable in this study is types of solvent: acetone (S1), hexane (S2), and xylene (S3). Physical and chemical properties of the as-prepared Co3O4 samples were investigated by TGA, TEM, BET, XRD, and FT-IR. The form of colloidal suspension using xylene and hexane were well observed. Adding NaBH4 solution, consequently, the pinkviolet solution using these two solvents turned into black due to the oxidation reaction. From XRD result, crystalline structure of Co3O4 nanoparticles prepared by using the three solvent types show the same result indicated as cubic structure with Fd-3m symmetry group and space lattice of 8.06 Å. The particle size of 82.29, 26.83 and 20.59 nm and specific surface area of 7.04, 21.28, and 32.07 m 2 /g were observed for S1, S2, and S3 sample, respectively. In addition, secondary phases were als...

Cobalt oxide nanoparticles by solid-state thermal decomposition: Synthesis and characterization

2019

In this study, mononuclear octahedral cobalt(III) Schiff base complex [CoL3], L = (5-bromo-2-hydroxybenzyl-2-furylmethyl)imine, was synthesized from the reaction of Co(NO3)2•6H2O and the Schiff base ligand L in methanol as solvent. It used as a new precursor to prepare spinel type cobalt oxide nanoparticles by a facile solid-state thermal decomposition. Controlling the temperature and time, Co3O4 nanoparticles were obtained in air at 550oC within 3.5 h. The Co3O4 nanoparticles was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These results confirm that the resulting cobalt oxide products were pure single-phases. Using the present method, Co3O4 nanoparticles can be produced without using any expensive organic solvent and complicated equipment. TEM result showed the products are almost flat with the size of about 10-50 nm. It has potential to be applied as a general method for preparation of other transi...

Mechanochemical route to synthesize Co3O4/CuO composite nanopowders

Co 3 O 4 /CuO composite nanopowders have been successfully synthesized by heating the precursor obtained via a mechanochemical reaction. The precursor and the nanopowders were characterized using thermogravimetric (TG), X-ray diffraction (XRD) and transmission electron spectroscopy (TEM). Subsequent thermal treatment of the precursor at 550-700 °C in air for 2 h resulted in the formation of Co 3 O 4 /CuO nanopowders with an average crystal size of about 25-50 nm, varying with the calcination temperature. The mechanism of nanocrystallite growth is primarily investigated. The morphology of the synthesized Co 3 O 4 /CuO nanopowders is in irregular polyhedron shape and the mechanism of NaCl used as diluent have been analyzed. The mechanochemical route is a novel, cheap and convenient technique suitable for large-scale synthesis of composite nanomaterials.

Preparation and characterization of cobalt oxide nanoparticles via solution combustion method

Nano Science and Nano Technology An Indian Journal, 2009

The spherical shaped Co3O4 nanoparticles have interesting properties and potential applications in coatings, catalysis, sensors, anode materials in rechargeable batteries, solar energy absorbers, magnetism, etc. Inorganic nanoparticles with controlled size and shape are technologically important due to the strong correlation between these parameters and their properties. We have successfully prepared Co3O4 using a solution combustion method. The phase and purity of the synthesized product was examined by X-ray diffraction (XRD) pattern. Infrared spectroscopy studies were performed aiming to ascertain the metal oxygen bonding and nature of the synthesized cobalt oxide nanoparticles. SEM (Scanning electron microscope images show that the nanoparticles are nearly spherical in morphology and are in the range of 100 to 200 nm.Magnetic property and thermal behavior of the synthesized Co3O4 nanoparticles were studied by magnetic hysteresis loop tracer.

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

Journal of Nanostructure in Chemistry, 2013

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, characterization, scale-up and catalytic behaviour of Co3O4 nanoparticles

Bulletin of Materials Science, 2015

Highly uniform cobalt oxide (Co 3 O 4) nanoparticles were synthesized via thermal decomposition of cobalt hydroxy carbonates with particle size around 16 ± 1 nm. The process gives reproducible results in batches of 1-5 kg. The particles show good catalytic activity for the oxidation of oxalic acid and benzaldehyde under mild temperature conditions. The characterization was performed by X-ray diffractometry (XRD), Transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectrum and Nuclear magnetic resonance (NMR). The XRD measurements show cubic spinel phase and Debye-Scherrer relation was used to measure average particle size. The convenience of the production of catalyst can be exploited for its large-scale production and use in laboratories, R&Ds and industries.