Electrochemical growth of hydrous iridium (III) and (IV) oxide on platinum susbtrate

• María Eliana Méndez Universidad de los Andes-Venezuela
• Jairo Márquez Universidad de los Andes-Venezuela
• Richard Briceño Universidad de los Andes-Venezuela

Resumo

It is proposed a novel procedure for the electrochemical growth of iridium (III) and (IV) oxides on platinum substrate from iridium chloride saturated solution at pH 1. Iridium oxides (green and colorless) were obtained with this new technique by cyclic voltammetry in the saturated solution of iridium previously electrodeposited on platinum at constant potential. Unlike other techniques here, the coating fraction (μm2 oxide/ μm2 surface) is measure using a metallic microscope coupled with an image analyzer. The evolution of experimental coating fraction values with time suggested the existence of a progressive nucleation mechanism. Iridium oxides are slowly deposited in a layer by layer mode. The time and coating fraction were correlated to estimate the optimal time for metallic iridium deposition as well as the optimal time for iridium oxidation. This values were 5000 s and 50 cycles (40 mV/s between ”“250 mV and 1450 mV), respectively. The electrocatalytic activity on the oxygen reduction was observed during the iridium oxidation process. Future studies must be focused on proving this property.