The influence of the anion electrolyte on the electro-oxidation of hypophosphite in strong acid media

The electrocatalytic oxidation of hypophosphite was studied in strong acid medium, at a nickel electrode, in the presence of different electrolytes (H 3PO4. H2SO4, HNO3, and HClO4). A correlation was found between the effects of the anion electrolyte on the Ni catalytic activity and on the metal diss olution. These phenomena were explained in terms of the competitive adsorpt ion between the anions electrolyte and H3PO2 species. The comparison of the Ni2+ amount in electrolyzed solutions containing hypophosphite and hypopho sphite-free solutions showed that depending on the anion electrolyte, the p resence of H3PO2 may accelerate or hinder the dissolution of the nickel ele ctrode. Thr dependence of the Ni2+ amount on the hypophosphite concentratio n reveals that the H3PO2 species participate in the Ni dissolution. The eff ect of the electrolyte composition on the Ni catalytic activity was also an alyzed in terms of pH medium in strong acid pH range. (C) 2000 The Electroc hemical Society. S0013-4651(99)10-098-3. All rights reserved.