| Popis: |
The electrochemical reduction of the thick oxide film formed on Pt electrode by severe preanodization has been studied in LiOH, NaOH and KOH solutions of different concentrations (0.001 ∼ 1.0 M) using a galvanostatic technique. An outermost monolayer oxide and an inner multilayer oxide of the thick oxide film exhibit different potential behaviors in the cathodic reduction. In dilute solution, both the oxides are completely reduced in a potential range of 0.6-0.4 V ( vs rhe in the test solution) in a single step. As the concentration is increased, however, the reduction potential of the inner oxide only shifts rapidly into a H-electrosorption potential region and the amount of the oxide reduced at this potential decreases. The remaining oxide is slowly reduced at H 2 -evolution potential. The retardation of the reduction of the inner oxide is related to cations adsorbed on Pt electrode. This retardation effect increases in the order, K + + + . |
