Crystal Phase-Dependent Electronic Metal-Support Interactions Enable Chemoselective Hydrogenation of α, β-Unsaturated Aldehydes

Abstract Electronic metal-support interactions (EMSI) provide an effective means of tuning the electronic structure of supported metal catalysts and thereby modulating their catalytic properties. However, how the crystal phase of supports governs EMSI and in turn influences the selective hydrogenation remains largely unexplored. Here, we report a crystal-phase engineering strategy to precisely regulate EMSI in ultrafine Ir nanoclusters (NCs) supported on polymorphic Nb2O5. Comprehensive spectroscopic characterization reveals that the orthorhombic Nb2O5-T phase forms a distinctive socketed metal-support interface that strongly anchors Ir NCs and induces substantial electron transfer from the support to the metal. Distinct from classical strong metal-support interactions that often compromise active-site accessibility, this socketed interfacial configuration simultaneously enhances EMSI, stabilizes the Ir NCs, and preserves abundant exposed active sites. The resulting electron-rich Ir species facilitates H2 activation and interfacial hydrogen spillover while favoring preferential adsorption of the carbonyl group over the C=C bond in α, β-unsaturated aldehydes. Consequently, Ir@Nb2O5-T exhibits high activity, selectivity, and durability for the selective hydrogenation to unsaturated alcohols under mild conditions, overcoming the typical activity–selectivity trade-off. This work establishes a direct crystal phase–EMSI–reactivity relationship and highlights crystal-phase engineering as a powerful strategy for manipulating metal–support interfaces toward highly selective heterogeneous catalysis.