Anodic oxidation mechanism of hypophosphorous and phosphorous acid on palladium

Abstract

The mechanism of anodic oxidation of hypophosphorous and phosphorous acid on palladium has been studied. Both acids undergo a catalytic dehydrogenation followed by the ionization of the resulting atomic hydrogen. This process is characterized by a limiting value of the polarizing current. Reaction order and activation energy have been determined for the rate-determining steps. The experimental data suggest that the rate-determining step is the electrochemical hydrogen ionization in the anodic oxidation of hypophosphorous acid and the catalytic dehydrogenation, H₃PO₃→H₂PO₃ + H, for phosphorous acid. Suggestions are made for the anodic deactivation of the palladium electrode in the hypophosphorous acid anodic oxidation.