Structural Transformation of Monocrystalline Platinum Electrodes upon Electro-oxidation and Electro-dissolution

Abstract

Atomic-level understanding of the degradation of Pt materials is important for the rational design of nanoscopic Pt electrocatalysts for fuel cells. We report on the dissolution and structural transformation of spherical, monocrystalline, polyoriented Pt (Pt(spherical)) in 0.50 M aqueous H2SO4 upon potential cycling in the surface oxide formation–reduction region. The potential cycling is performed in the EL–EU range (EL = 0.07 V and 0.90 ≤ EU ≤ 1.50 V) to correlate dissolution and morphology data to EU. The amount of dissolved Pt is monitored using flow injection coupled to inductively coupled plasma mass spectrometry (ICPMS), and structural changes, which modify cyclic voltammetry profiles, are examined using scanning electron microscopy (SEM). In the case of EU ≤ 1.20 V, there is minor dissolution of the (100) and (110) facets, while the (111) facet remains stable. In the case of EU ≥ 1.30 V, all facets undergo significant dissolution. Changes in the surface morphology of Pt(spherical) upon repetitive ...