Interface Modification of Single Atom‐Nanocluster Synergistic Sites to Break the Activity‐Selectivity‐Stability Trade‐Off in Selective Hydrogenations

Synergistic sites (M₁+M_n) integrating single atoms (M₁) and clusters (M_n) exhibit tremendous promise for overcoming linear scaling relationships. However, metal entities spatial segregation within synergistic sites impedes the overall optimization and structure-property analysis, and the support interface of the M₁ and M_n sites critical for intermediate adsorption-transfer kinetics has yet unexplored. Here, for the first time, interfacial modification strategy is proposed to modulate the interface and electronic structure of M₁+M_n sites. This is systematically altered that the interface of Pd₁+Pd_n sites from hydroxyapatite (HAP) to nitrogen-doped carbon-modified HAP (NC/HAP) and pure NC, with all sites maintaining the comparable size and content. In the semi-hydrogenation of alkynes, volcano-type correlations between Pd₁+Pd_n sites with varying interfaces and hydrogenation activities are observed, peaking for those supported on NC/HAP. The obtained Pd₁+Pd_n@NC/HAP exhibits superior activity for alkynol-to-enol conversion, achieving a formation rate up to 3707.7 mol mol_Pd ^-1 h^-1 while maintaining 97.2% selectivity. Comprehensive investigations propose d-band center of Pd₁+Pd_n sites with different interfaces as a descriptor to elucidate the volcano-type correlation for various selective hydrogenation reactions. Interfacial modification of Pd₁+Pd_n sites can optimize their electronic structure, adeptly managing substrates adsorption-desorption kinetic and interface H-spillover between segregated metal sites, thereby breaking ^-the activity-selectivity-stability trade-off.