In Situ Analysis of Chloride Effect on Platinum Dissolution by a Channel-Flow Multi-Electrode System

The effect of Cl- on Pt dissolution under both potentiostatic and potential cycling conditions is reported, using a channel-flow multi-electrode (CFME) as an in situ detection method. To avoid the contamination of the entire CFME system by Cl-, a liquid-phase chloride ion gun is placed upstream of the double electrode. Under potentiostatic conditions, Cl- enhances Pt dissolution by forming PtCl42- at potentials below 1.0 V and PtCl62- above 1.2 V. Under potential cycling conditions, Cl- accelerates Pt dissolution above 1.2 V by the enhanced formation of both PtCl62- and PtCl42-. The cathodic dissolution of Pt2+ during PtO2 reduction is also increased in the presence of Cl-. A mechanism for the effect of Cl- on Pt dissolution is proposed. (C) 2014 The Electrochemical Society. All rights reserved.