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Abstract

Al–Pt compounds have been systematically studied as electrocatalysts for the oxygen evolution reaction (OER). Considering the harsh oxidative conditions of the OER, all Al–Pt compounds undergo modifications during electrochemical experiments. However, the degree of changes strongly depends on the composition and crystal structure of a compound. In contrast to Al-rich compounds (Al₄Pt and Al₂₁Pt₈), which reveal strong leaching of aluminum, changes in other compounds (Al₂Pt, Al₃Pt₂, rt-AlPt, Al₃Pt₅, and rt-AlPt₃) take place only on the surface or in the near-surface region. Furthermore, surface modification leads to a change in the electronic structure of Pt, giving rise to the in situ formation of catalytically more active surfaces, which are composed of intermetallic compounds, Pt-rich Al_xPt_1−x phases and Pt oxides. Forming a compromise between sufficient OER activity and stability, Al₂Pt and Al₃Pt₂ can be considered as precursors for OER electrocatalysts.