Unique Role of Anchoring Penta-Coordinated Al3+ Sites in the Sintering of γ-Al2O3-Supported Pt Catalysts

γ-Al2O3-supported Pt group catalysts are widely used in many industrially important catalytic processes. However, γ-Al2O3-supported Pt catalysts are prone to deactivation via metal sintering at high temperatures, in oxidative reaction environments, or both. Using a combination of experimental HRTEM and EXAFS measurements and theoretical DFT calculations, we find that pentacoordinated Al3+ sites (Alp) on the γ-Al2O3(100) surface can inhibit Pt sintering both thermodynamically and kinetically because of their strong interactions with atomic Pt or Pt oxide species. The present work suggests a promising approach for stabilizing the size and morphology of supported catalytically active phases.