Channel-flow triple electrode for simultaneous in situ detection of platinum and copper dissolution

A channel -flow triple electrode (CFTE) was constructed for in situ monitoring of the dissolution of Pt-Cu alloys during electrochemical measurements. In the CFTE, Cu2+ ions dissolved from upstream Cu or Pt-Cu alloy electrodes were quantitatively detected by electrochemical reduction of Cu2+ to Cu on the downstream detection electrode. The dissolution behaviors of Cu-rich Pt-Cu alloys in 0.5 M H2SO4 during anodic polarization and potential cycling were investigated using CFTE. The level of Pt dissolution was below the detection limit, and Pt could not be detected during the anodic polarization of Pt-Cu alloys. However, the dissolution of both Pt and Cu was detected under potential cycling for a Pt-75 at% Cu alloy (Pt25Cu75). The dissolution of Cu as Cu2+ from Pt25Cu75 occurred continuously at the pit bottoms through the thick Pt-enriched layer at potentials above 0.7 V vs the standard hydrogen electrode during potential cycling. In contrast, Pt dissolved mainly from the Pt-enriched layer. The potential cycling scan rate did not affect the mechanism of Cu dissolution from Pt25Cu75. The high time-resolution of detection by the CFTE enables dissolution peaks to be distinguished under potential cycling at a high scan rate. The CFTE therefore provides an excellent method for monitoring the dissolution of Pt-Cu alloys.

Automated summary

A channel-flow triple electrode (CFTE) was used to monitor the dissolution of Pt-Cu alloys during electrochemical measurements. It was found that Pt dissolution was below detection limit during anodic polarization, but both Pt and Cu dissolution were detected under potential cycling for a Pt-75 at% Cu alloy. The CFTE provides an excellent method for monitoring the dissolution of Pt-Cu alloys with high time-resolution.