“…Several studies have reported that the SMSI effect is promoted by different metal oxide supports, such as TiO 2 , − ,, CeO 2 , ,, SiO 2 , ZrO 2 , and Al 2 O 3 . ,, The latter support, mainly in the γ phase (γ-Al 2 O 3 ), is one of the most employed oxides in supported catalysts ,− due to its high specific area, well-defined pore size, stability over a large temperature range and acid/base properties. , The structure of γ-Al 2 O 3 includes octahedral and tetrahedral aluminum cations occupying the interstitial sites between oxygen anions . Theoretical studies have indicated that the metal–support electronic flux depends on the coordination number of the aluminum site at which the metal atom sits. ,− In a DFT study on formaldehyde adsorption on a Pd 4 /γ-Al 2 O 3 model, we showed that the highly coordinated octahedral aluminum cations can donate electron density to the supported Pd 4 cluster . In contrast, tetrahedral aluminum cations have acidic properties and therefore act as electron acceptors.…”