Tailoring Metal–Support Interaction in Pt/γ-Al₂O₃ Single-Atom Catalyst via Surface Hydroxylation Implicated by DFT Calculations

Pt/γ-Al2O3 single-atom catalysts (Pt/γ-Al2O3 SACs) are among the most important SACs. The diverse physicochemical properties and tunable acid–base properties of γ-Al2O3 offer a versatile platform while also complicating the metal–support interaction (MSI) and call for extensive study of MSI in the SACs, which can heavily influence the behavior of the Pt atom. In this work, density functional theory (DFT) calculations were conducted to investigate the MSI between Pt and γ-Al2O3(110) at four coverages of surface hydroxyl groups (0.0/2.99/5.98/8.97 OH nm–2) to mimic the surface morphology at high (dehydrated or low coverage) and low (medium and saturated coverage) temperatures. The results indicate that Pt shows high propensity to bind at the sites of Lewis acid–base pairs constituted of Al and bridging O atoms, and low and medium levels of hydroxylation (2.99 and 5.98 OH nm–2) can enhance the binding of Pt on the surface with the maximal MSI up to −3.51 eV without sacrificing the coordination sites of Pt atoms (CN ≤ 3), thus maintaining their activity in catalysis. Such enhancement fades away at high hydroxyl coverage (8.98 OH nm–2) due to steric hindrance and weakened electrostatic interaction. The tailoring of MSI was analyzed in terms of geometry, coordination environments, surface-to-metal charge transfer, and nature and strength of Pt binding to provide insights into the forces governing the dispersion of Pt atoms on γ-alumina and to implicate the improvement of the catalyst’s activity, longevity, and resistance to sintering. This study enriches our understanding of the intricate metal–support interactions in Pt/γ-alumina SACs and contributes to catalyst optimization to enable the development of more efficient, selective, and stable catalytic systems.