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In this study, we present an investigation aimed at characterizing and understanding the synergistic interactions in encapsulated catalytic structures between the metal core ( i.e. , Pd) and oxide shell ( i.e. , TiO 2 , ZrO 2 , and CeO 2 ). Encapsulated catalysts were synthesized using a two-step procedure involving the initial colloidal synthesis of Pd nanoparticles (NPs) capped by various ligands and subsequent sol–gel encapsulation of the NPs with porous MO 2 (M = Ti, Zr, Ce) shells. The encapsulated catalytic systems displayed higher activity than the Pd/MO 2 supported structures due to unique physicochemical properties at the Pd–MO 2 interface. Pd@ZrO 2 exhibited the highest catalytic activity for CO oxidation. Results also suggested that the active sites in Pd encapsulated by an amorphous ZrO 2 shell structure were significantly more active than the crystalline oxide encapsulated structures at low temperatures. Furthermore, CO DRIFTS studies showed that Pd redispersion occurred under CO oxidation reaction conditions and as a function of the oxide shell composition, being observed in Pd@TiO 2 systems only, with potential formation of smaller NPs and oxide-supported Pd clusters after reaction. This investigation demonstrated that metal oxide composition and (in some cases) crystallinity play major roles in catalyst activity for encapsulated catalytic systems. 

Co₂C, an emerging catalyst for the conversion of syngas to oxygenates, shows support‐sensitive behavior that has not yet been fully explained. Here, we characterize Co catalysts modified with ZnO atomic layer deposition on SiO₂, carbon, CeO₂, and Al₂O₃supports. We find that under syngas conditions, ZnO‐promoted Co transforms into Co₂C on SiO₂, carbon, and CeO₂, but not on Al₂O₃. Moreover, the support affects the extent of carburization: while the SiO₂‐supported catalyst carburizes completely, carbon‐ and CeO₂‐supported catalysts show incomplete conversion of Co to Co₂C. These three catalysts also exhibit different oxygenate selectivities. In contrast, the modified Al₂O₃‐supported catalyst retains the Fischer‐Tropsch catalytic properties of metallic Co. By depositing increasing amounts of Al₂O₃by ALD on the SiO₂support, decreasing Co₂C formation and oxygenate selectivity occurs.In‐situXANES reveals that Al₂O₃prevents Co₂C formation by enabling the ZnO to restructure into ZnAl₂O₄during reduction. Thus, in addition to modifying the active catalyst phase, the promoter can also strongly interact with the support, significantly impacting catalyst performance.