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

Abstract

• In situ method for monitoring dissolution of Pt–Cu alloys was developed. • Established method enables Pt and Cu detection with high time resolution. • Pt and Cu dissolved independently from Pt–75 at% Cu alloy under potential cycling. • The dissolution behavior of Pt–75 at% Cu was unaffected by the scan rate. 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, Cu 2+ ions dissolved from upstream Cu or Pt–Cu alloy electrodes were quantitatively detected by electrochemical reduction of Cu 2+ to Cu on the downstream detection electrode. The dissolution behaviors of Cu-rich Pt–Cu alloys in 0.5 M H 2 SO 4 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 (Pt 25 Cu 75 ). The dissolution of Cu as Cu 2+ from Pt 25 Cu 75 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 Pt 25 Cu 75 . 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.