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 PtCl 4 2− at potentials below 1.0 V and PtCl 6 2− above 1.2 V. Under potential cycling conditions, Cl − accelerates Pt dissolution above 1.2 V by the enhanced formation of both PtCl 6 2− and PtCl 4 2− . The cathodic dissolution of Pt 2+ during PtO 2 reduction is also increased in the presence of Cl − . A mechanism for the effect of Cl − on Pt dissolution is proposed.