The oxygen and chlorine evolution reactions at titanium oxide electrodes modified with platinum

MARIANA ISABEL ROJAS; MARÍA JOSÉ ESPLANDIÚ; LUCÍA BERNARDITA AVALLE; EZEQUIEL PEDRO MARCOS LEIVA; VICENTE ANTONIO MACAGNO

ELECTROCHIMICA ACTA

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1998 vol. 43 p. 1785 - 1794

0013-4686

The oxygen (OER) and chlorine evolution reactions were used as probes to test the electronic properties of modified electrodes (Ti/TiO2-Pt). Both reactions were studied in acidic solutions by means of current-potential (j-E) and impedance measurements under steady state conditions. The effect of dopant concentration, TiO2 thickness, and concentration of the electroactive species in the solution was analyzed. A disminution of the electron transfer current with titanium oxide thickness was obtained whereas an increase of the current was found on augmenting the Pt amount. At low titanium oxide thickness both inner-sphere reactions behave in the same way as in case of pure Pt, indicating that platinum site are the active ones. However, at higher titanium oxide thickness, the platinum sites become less active and the valve metal oxide (TiO2) begins to block OER and CLER reactions. The electrochemical impedance spectroscopy results are compared with those of the current-potential measurements and a good correction is found between them.