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

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 H2SO4 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.

► The quantity of dissolved ions from Pt alloys was determined with ICP-MS. ► The Pt–Fe exhibits a larger dissolution rate than Pt–Cu, Pt–Co and Pt–Ni. ► The monitoring of the Erest values showed the formation of the Pt-enriched layer. ► The Pt-enriched layers of the Pt–Cu, Pt–Co and Pt–Ni suppress further dissolution.