Dissolution of Pt–M (M: Cu, Co, Ni, Fe) binary alloys in sulfuric acid solution

Abstract

The dissolution behavior of equimolar Pt–M (M: Cu, Co, Ni, Fe) alloys has been studied under conditions of immersion, potentiostatic polarization, and potential cycling in 0.5 M H 2SO 4 solution at 25 °C. The quantity of dissolved ions under these conditions has been determined with inductively coupled plasma mass spectrometry (ICP-MS). In 3-h immersion tests, selective dissolution of M atoms occurs immediately after immersion and is quickly suppressed. The rest potential shifts rapidly in the noble direction and approaches that for pure Pt. The general features of cyclic voltammograms of the alloys are very similar to those for pure Pt, although the current is considerably larger for the Pt–Fe alloy. These results indicate that the surfaces of these alloys are covered with a Pt-enriched layer because of preferential dissolution of M atoms. The resulting suppression of dissolution is reversed by potentiostatic polarization at 1.4 V. The enhancement at 1.4 V is more remarkable under the condition of potential cycling.