白金電極上での次亜リン酸イオンの酸化反応

抄録

The anodic oxidation of reductant H₂PO₂^- related to electroless nickel plating was studied at various pH, reductant concentrations, temperatures, and additives using electrochemical methods. The oxidation rate of H₂PO₂^- decreases with the decrease in pH and, when pH is in the range of 4-6, the oxidation rate can be increased by adding malic acid. Malic acid decreases the reaction order of H₂PO₂^- from 0.54 to 0.19. The existence of free Ni²⁺ in the solution decreases the H₂PO₂^- oxidation rate because insoluble materials are formed between free Ni²⁺ and HPO₃²⁺ coming from the oxidation product of H₂PO₂^-. The detrimental effect of free Ni²⁺ can be eliminated by the addition of malic acid through the complex reaction between free Ni²⁺ and malic acid. Experimental results are better explained by the electroless reaction presented by Van Der Meerakker.