Electrochemical Measurements on Enhanced Dissolution of Pd from Pd−Zn Alloys in Hydrochloric Acid

Anodic behaviors of Pd − Zn alloys in hydrochloric acid have been observed by channel flow double electrode to examine dissolution of Pd enhanced by alloying. The measurements on Pd − 40%Zn, Pd − 60%Zn and Pd − 78%Zn show that the enhancement of Pd dissolution depends strongly on the alloy compositions. A linear sweep voltammogram with a Pd − 78%Zn electrode indicates that Pd dissolved from the alloy at unusually low potentials, and this might be explained by a dissolution of unstable Pd clusters transiently formed through preferential dissolution of Zn. On the other hand, potentiostatic measurements show that Pd dissolves from Pd − 60%Zn at a higher rate than from the two other alloys. Dissolution characteristics of the alloys are discussed by considering their potential dependency and the morphological changes of the dissolving surface.