Time filter

Source Type

Barkaoui S.,Laboratoire des Materiaux Utiles | Haddaoui M.,Tunis el Manar University | Dhaouadi H.,Laboratoire Materiaux Traitement et Analyse | Raouafi N.,Tunis el Manar University | Touati F.,Laboratoire Materiaux Traitement et Analyse
Journal of Solid State Chemistry

Nanostructured tricobalt tetraoxide, Co3O4, was hydrothermally synthesized starting from cobalt dichloride hexahydrate (CoCl2·6H2O) and urea (H2NCONH2) as precursor and polyethylene glycol-400 (PEG-400) as a structure-directing agent. Uniform urchin-like nanostructures were hydrothermally obtained at 150°C for 16 h, and the Co3O4 morphology did not collapse after a subsequent calcination at 300°C for 2 h. XRD measurements indicated that the average sizes of Co3O4 particles prior and after heating at 300°C are 64 and 44 nm, respectively. This material has been successfully used for the nanostructuration of screen-printed carbon electrodes (SPCEs) which were used for the sensitive electrochemical detection of hydrogen peroxide (H2O2). The sensor is endowed with a large dynamic range (0.1 to 50 μM) and a limit of detection of 0.145 μM. The as obtained results show that the Co3O4 nanomaterial could be a candidate to be used as sensors for the detection of analytes. © 2015 Published by Elsevier Inc. Source

Gmati N.,University of Monastir | Boughzala K.,University of Monastir | Abdellaoui M.,Laboratoire des Materiaux Utiles | Bouzouita K.,University of Monastir
Comptes Rendus Chimie

The britholites have gained a great interest thanks to their potential applications as matrices for the confinement of the byproducts in the nuclear industry such as minor actinides and long-lived fission products. However, the preparation of britholites requires high temperatures, above 1200 °C. In this work, we strive to prepare these kinds of compounds by a mechanochemical synthesis at room temperature from the starting materials SrF 2, SrCO 3, Sr 2P 2O 7, La 2O 3 and SiO 2 using a planetary ball mill. The obtained results showed that the prepared products were carbonated apatites and the corresponding powders contained some unreacted silica and lanthana. To obtain pure britholites, a heat-treatment at 1100 °C was required. The mechanism involved in the different steps of the reaction is discussed in this paper. The obtained results suggest that the use of raw materials containing no carbonate is expected to directly lead to pure britholites by appropriate milling at room temperature. © 2011 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved. Source

Dhaouadi H.,Laboratoire des Materiaux Utiles | Touati F.,Laboratoire des Materiaux Utiles
Materials Letters

Cobalt-manganese pyrophosphate nanostructures with formula Co xMn 2 - xP 2O 7 (x = 0, 0.25, 0.5, and 1) were successfully prepared via two different methods: the precipitation and the hydrothermal at 150 °C using poly-ethylene-glycol-5000 (PEG-5000), with further calcinations at 500 °C. The Rietveld refinement of the XRD data confirms that Co xMn 2 - xP 2O 7 nanoparticles crystallize in the monoclinic system with space group C2/m. The crystallite size obtained from X-ray line broadening was found to be 41 nm for the Mn 2P 2O 7 compound. The grain size of Co xMn 2 - xP 2O 7 varies when increasing the degree of substitution. IR and Raman studies show characteristic bands of the P 2O 7 4- anion. A correlation between the partial replacement of Mn by Co and the dependent lattice parameters, the microstructure and the spectroscopic properties was observed. An effort has been made to explain the observed correlation with a qualitative model. © 2012 Elsevier B.V. All rights reserved. Source

Barkaoui S.,Laboratoire des Materiaux Utiles | Dhaouadi H.,Laboratoire Materiaux Traitement et Analyse | Kouass S.,Laboratoire des Materiaux Utiles | Touati F.,Laboratoire Materiaux Traitement et Analyse

Copper cobaltite oxides of formula CuxCo3-xO4 (x = 0.0; 0.1; 0.2; 0.4 and 0.6) were synthesized by hydrothermal conditions using polyethylene-glycol-400 (PEG-400) as surfactant. The as-prepared samples are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Rietveld fitted patterns confirm the formation of cubic spinel structure with Fd-3m space group. Particle size was determined from the XRD peak broadening analysis. The Cu-doping effect on the structural and optical properties of the copper cobaltite oxides was investigated. Phase purity of CuxCo3-xO4 was confirmed by X-ray diffraction studies. XRD results reveal that the lattice parameters and the theoretical density (dth) were found to increase with Cu-substitution. The direct and indirect band gap energies were found to decrease with increasing Cu-content from 1.72 eV (x = 0) to 1.39 eV (x = 0.6) and from 1.75 eV for x = 0 (Co3O4) to 1.40 eV for x = 0.6 (Cu0.6Co2.4O4) respectively, indicating a red shift trend when the Cu-content increases. © 2015 Elsevier GmbH. All rights reserved. Source

Janene F.,Laboratoire des Materiaux Utiles | Dhaouadi H.,Laboratoire des Materiaux Utiles | Etteyeb N.,University of Tunis | Touati F.,Laboratoire des Materiaux Utiles

Flower-like nanocrystalline (Cu2O) was prepared via a hydrothermal process using paraphenylenediamine which acts as a reducing and structure-directing agent. The morphology, the structure, the crystallinity, and the composition were studied through X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. It was found that the hydrothermal reaction time had a little effect on the morphology of Cu2O nanocrystals, but influenced the nanocrystal dispersibility. The optical properties of the as-synthesized Cu2O nanomaterials were studied by UV-visible diffuse reflection spectra and room temperature photoluminescence. The values of the band gap for Cu2O nanorods and nanoflowers were found to be 2.43 and 2.34 eV, respectively. A cyclic voltammetric study of the Cu2O nanoflowers revealed a reversible redox behavior with charge-discharge cycling corresponding to the reversible lithium intercalation/deintercalation process in the crystal lattice. Thus, Cu2O is a promising candidate for many applications such as an electrode material for a lithium ion battery. © 2014, Springer-Verlag Berlin Heidelberg. Source

Discover hidden collaborations