Channel flow double electrode study on palladium dissolution during potential cycling in sulfuric acid solution

Channel flow double electrode (CFDE) was applied to study palladium dissolution during potential cycling in 0.5 M H2SO4 solution at 25 °C. In the CFDE, Pd ions (Pdn+) dissolved from a Pd working electrode were detected by reducing them to Pd on a gold collector electrode, which was placed at the downstream. The detection of the Pd dissolution by the collector current was confirmed by (Electron Probe Micro Analyzer) EPMA analysis of the collector electrode surface. In anodic scan, gradual rise of the collector current till 0.7 V indicated Pd dissolution. The dissolution was confirmed by EPMA. Anodic as well as cathodic dissolution was confirmed when potential cycling was done till 0.8 V. Dissolution of palladium was found to increase anodically as well as cathodically when upper limit of polarization was increased. From collector current and the results of EPMA, the dissolution mechanism is proposed.

► Pd dissolution confirmed when potential was cycled from 0.4 V to 0.7 V.
► Anodic as well as cathodic dissolution confirmed when upper potential limit of potential cycling was 0.8 V or above.
► Anodic as well as cathodic dissolution increases with increase in upper potential limit.
► When Pd was polarized till or above 1.4 V anodically, electrochemical as well as chemical dissolution occurred during the cathodic scan.
► Palladium ions also got produced chemically with the reduction of palladium oxide.