Coordinatively unsaturated Al³⁺ centers as binding sites for active catalyst phases of platinum on γ-Al₂O₃

In many heterogeneous catalysts, the interaction of metal particles with their oxide support can alter the electronic properties of the metal and can play a critical role in determining particle morphology and maintaining dispersion. We used a combination of ultrahigh magnetic field, solid-state magic-angle spinning nuclear magnetic resonance spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy coupled with density functional theory calculations to reveal the nature of anchoring sites of a catalytically active phase of platinum on the surface of a γ-Al ₂O₃ catalyst support material. The results obtained show that coordinatively unsaturated pentacoordinate Al³⁺ (AL ³⁺Penta) centers present on the (100) facets of the Y-Al2O3 surface are anchoring Pt. At low loadings, the active catalytic phase is ato mica Hy dispersed on the support surface (Pt/Al³⁺_peta = 1), whereas two-dimensional Pt rafts form at higher coverages.