| Autor: |
Khaldeev, G. V., Petukhov, I. V., Shcherban’, M. G. |
| Zdroj: |
Russian Journal of Electrochemistry; September 2000, Vol. 36 Issue: 9 p934-941, 8p |
| Abstrakt: |
Anodic oxidation of sodium hypophosphite on smooth Pd and Pd/Pt electrodes and a Pd membrane is studied. Theivs.Ecurves for the Pd electrode exhibit two anodic current peaks. One is caused by oxidation of H2PO2-, and the other, by simultaneous ionization of Pd and oxidation of H2PO2-. The hypophosphite ion adsorbed on the Pd surface hinders the formation of the passive film. This brings about a rapid dissolution of Pd in the oxygen region and its subsequent deposition with the formation of palladium black. The oxidation probably includes a slow heterogeneous chemical reaction, specifically, a cleavage of the P-H bond of the hypophosphite ion. The change in the reaction stoichiometry following an increase in solution pH and in anodic polarization is probably due to changing conditions of the H2PO2-adsorption and the number of adsorption sites occupied by H2PO2-on the surface. Following an increase in polarization, the phosphite ion may undergo oxidation to phosphate. |
| Databáze: |
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