PREPARATION OF NICKEL - COBALT SPINEL OXIDES NixCO3-xO4.COMPARISON OF TWO PHYSICAL PROPERTIES STEMMING FROM FOUR DIFFERENT PREPARATION METHODS AND USING CARBON PASTE ELECTRODE

A comparative study of two electro-physical properties (porosity and electrical conductivity) of binary nickel cobalt oxides electrodes with spinels mixed oxides NixCo3-xO4 as active matter, was carried out. Four different routes were used to prepare spinel-type NixCo3-xO4 (0 ≤ x ≤ 2.5) compounds in order to link these properties with the preparation method. The substitution of Ni for Co increases the conductivity and the porosity of the electrode till a certain ratio of nickel. X-ray diffraction patterns showed that the oxides crystallize in a cubic spinel phase. Electrical conductivity as well as porosity depends on the preparation route. KEY WORDS: Nickel cobalt spinel oxides, Porosity, Electrical conductivity, Mixed oxides electrodes, Carbon paste electrode, Pechini sol-gel method Bull. Chem. Soc. Ethiop. 2007, 21(2), 255-262

SYNTHESIS AND CHARACTERIZATION OF Ni0.4Co2.6O4 SPINEL MIXED OXIDES POWDER: STUDY OF ITS SURFACE PROPERTIES BY VOLTAMMETRY, X-RAY, FTIR, UV-VIS-NIR SPECTROSCOPY AND SCANNING ELECTRON MICROSCOPY

Electrochemical studies were carried out on Ni0.4Co2.6O4 powders prepared by sol-gel via propionic acid method using cyclic and steady state voltammetries. The oxide surface was characterized by scanning electron microscopy (SEM), X-ray diffraction, UV-vis-NIR and FTIR spectroscopies. The results showed that the formation of homogeneous oxide with a single spinel phase occurred at 350°C. The surface redox couple NiOOH/Ni(OH)2 is confined on the surface material l. KEY WORDS: Ni0.4Co2.6O4 spinel mixed oxides powder, Sol-gel process, Surface properties Bull. Chem. Soc. Ethiop. 2005, 19(2), 213-220

<b>Synthesis and characterization of Ni0.4Co2.6O4 spinel mixed oxides powder: study of its surface properties by voltammetry, x-ray, ftir, UV-VIS-NIR spectroscopy and scanning electron microscopy</b>

Electrochemical studies were carried out on Ni_0.4Co_2.6O₄ powders prepared by sol-gel via propionic acid method using cyclic and steady state voltammetries. The oxide surface was characterized by scanning electron microscopy (SEM), X-ray diffraction, UV-vis-NIR and FTIR spectroscopies. The results showed that the formation of homogeneous oxide with a single spinel phase occurred at 350^°C. The surface redox couple NiOOH/Ni(OH)₂ is confined on the surface material l