pohan, lemeyonouin aliou guillaume université de cocody - laboratoire de chimie physique, ufr ssmt, Côte d’Ivoire , ouattara, lassiné université félix houphouët-boigny de cocody - laboratoire de chimie physique, ufr ssmt, Côte d’Ivoire

ELECTROCHEMICAL BEHAVIOUR IN A SLIGHTLY HEATED ACIDIC SUPPORTING ELECTROLYTE OF THE THERMALLY PREPARED BULK IRIDIUM DIOXIDE ELECTRODE

31455

A bulk iridium dioxide electrode was prepared thermally on a titanium substrate. Its morphology was characterized by a scanning electron microscope and its surface presents a ‘’cracked mud’’ structure with aggregate of IrO2 particles distributed over the coating layer. The prepared electrode was studied in perchloric acid heated slightly at 25°C, 30°C and 39,4°C. The IrO2 surface does not change in morphology when it is used in the slightly heated perchloric acid electrolyte. The electrolyte temperature increase led to the increase of the total, external and internal voltammetric charge about 45%, 72,8% and 20,22% respectively. The temperature effect is much more pronounced for the external charge than the internal charge. The activation energies were determined and they were about 4,0 kJ/mol and 3,2 kJ/mol for the low and the high potential scan rates respectively. The Tafel slopes determined for the oxygen evolution reaction are almost the same, around 43 mV/decade and they are independent of the temperature. That indicated that the slight temperature increase does not change the rate determining step in the oxygen evolution reaction. That electrode, even after being used in slightly heated acidic electrolytes possesses its electrochemical characteristic towards a simple redox couple such as potassium ferri/ferrocyanide.

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Iridium dioxide , voltammetry , differential capacitance , Tafel slope , temperature

Revue Ivoirienne des Sciences et Technologie

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