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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 | Year: 2015

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.

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
Optik | Year: 2015

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.

Fadhalaoui A.,University of Carthage | Dhaouadi H.,Laboratoire Materiaux Traitement et Analyse | Marouani H.,University of Carthage | Kouki A.,L3M | And 2 more authors.
Materials Research Bulletin | Year: 2016

CrxCe1-xPO4 (x = 0.00-0.20) nanorods were synthesized using the hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), infrared absorption spectroscopy (IR) and transmission electron microscopy (TEM). The XRD results revealed the formation of a pure CePO4 hexagonal phase. TEM images confirmed the nano-size character of the as-prepared samples. Impedance spectroscopy analysis was used to analyze the electrical behavior of samples as a function of frequency at different temperatures. The increase of Cr-amount led to an increase in the total conductivities and decreased the activation energies (Ea (x = 0.00) = 1.08 eV to Ea (x = 0.20) = 0.80 eV). The optical properties of CrxCe1-xPO4 nanomaterials were investigated using UV-vis spectroscopy. The band-gap energy values decreased with increasing Cr-content showing a red-shift trend. The improvement of the electrical conductivity and optical properties makes the CrxCe1-xPO4 nanomaterials possible candidates to be used as electrolytes in solid oxide fuel cells, in photocatalytic and photovoltaic applications. © 2015 Elsevier Ltd.

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