Application of channel flow double electrode to the study on platinum dissolution during potential cycling in sulfuric acid solution

Abstract

The applicability of a channel flow double electrode (CFDE) as an in situ monitoring method of Pt dissolution during potential cycling in 0.5M H2SO4 solution at 25°C was investigated. In the CFDE, Pt ions (Ptn+) dissolved from a platinum working electrode were detected by reducing them to Pt on a gold collector electrode which was placed at the downstream. The detection of the Pt dissolution by the collector current was confirmed by EPMA analysis of the collector electrode surface. In anodic scan, a rise of the collector current above 1.05V clearly indicated the platinum dissolution. The collector current showed two different rates of dissolution, i.e. a lower rate from 1.05 to 1.3V where only one layer of oxide (PtO) is formed and the higher rate from 1.3 to 1.46V where two layers of oxides (probably PtO/PtO2) are formed. The collector current, in the cathodic scan, clearly showed two different reduction peaks due to the Pt deposition, which was confirmed by EPMA analysis. On the basis of collector current, the rate and potential range of the Pt dissolution are discussed.