Reactivation of passive titanium: the enhancement of O-2 evolution after potentiodynamic cyclings

Titanium oxide films were grown potentiodynamically at 50 mV s(-1) from -1. 1 up to 10.0 V, at room temperature (23 +/- 1 degrees C) in H3PO4/ NaH2PO4 aqueous solutions of ionic strength 0.5 mol L-1 and pH 3.0. After the oxide growth, the passive electrode was subjected to different repetitive potent iodynamic cycles at 50 mV s(-1) between pre-set cathodic (E-s,E-c) an;anodi c (E-s,E-a) switching potentials. The changes in the electrochemical behavi our of the passive electrode, specially that of the O-2 evolution reaction, were followed as a function of the number of cycles and of the limiting ne gative potential value used, E-s,E-c. The enhancement of the oxygen reactio n rate occurring with the repetitive potential sweeps might be due to an in crease of both the oxide conductivity and the porous-oxide surface area, (C ) 2000 Elsevier Science S.A. All rights reserved.