Core/Shell Metal Oxides@MIL-53(Al) Nanoparticles as Catalyst for the Selective Hydrogenation of Cinnamaldehyde

Abstract

Metal oxides@metal–organic framework (MOFs)-based core/shell nanostructures demonstrate promising potential in catalytic hydrogenations. However, the direct nucleation and growth of MOFs on the topologically diverse surfaces of metal oxides face significant challenges due to the high interfacial energy resulting from topological mismatches. Herein, we present a facile in situ growth strategy for directly assembling an MIL-53(Al) layer on the surface of CeO₂ nanospheres at low temperatures by mixing and stirring CeO₂ nanospheres and MIL-53(Al) precursors without requiring sacrificial templates or additional surface modifications. Moreover, key factors such as reaction time, temperature, and the types of aluminum salts and ligands are systematically explored to comprehensively understand the nucleation behavior of MOFs shells. Notably, when active Pt nanoparticles are sandwiched between the CeO₂ core and the MIL-53(Al) shell, the MIL-53(Al) effectively stabilizes the Pt nanoparticles and enhances the selectivity of hydrocinnamaldehyde in cinnamaldehyde hydrogenation. CeO₂/Pt@MIL-53(Al) achieved more than twice the selectivity for HCAL compared to CeO₂/Pt and even outperformed Pt/MIL-53(Al). Undoubtedly, this study provides distinctive insights into the nucleation and growth mechanisms of MOFs on metal oxides, expands the strategies for fabricating metal oxides@MOFs core/shell nanostructure, and proposes innovative ideas and possibilities for broadening the application domains of MOFs-based materials.