Channel-Flow Double-Electrode Study on the Dissolution and Deposition Potentials of Platinum under Potential Cycles

Abstract

A channel-flow double-electrode system has been employed to determine the potential regions of Pt dissolution and redeposition during a cyclic voltammetry (CV) measurement in 0.5 M H 2 SO 4 solution at 25°C. The double-electrode system consists of a Pt plate as a working electrode (WE) placed upstream and a Au plate as a collector electrode (CE) placed downstream with a separation gap of 0.1 mm. Pt ions dissolved at the WE during CV have been detected at the CE by employing an appropriate reduction potential and have been analyzed by using an electron probe microanalyzer (EPMA). The EPMA results show that the deposition of Pt from hydrated Pt ions occurs below 0.60 V vs the standard hydrogen electrode. When CV is carried out between 0.0 and 1.4 or 1.6 V, dissolution of Pt occurs during both the anodic and cathodic scans of the CV. When CV is carried out between 0.0 V and an upper potential limit of 1.2 V, the dissolution of Pt could be observed only in the anodic scan. The dissolution mechanism of Pt during CV is proposed. © 2009 The Electrochemical Society.