Abstract
The integration of organometallic motifs with metal nanoclusters offers a powerful strategy for constructing hybrid catalysts with precisely tunable active sites. Here, we report the synthesis of a 20-silver nanocluster, Ag(20)-Fc, via cooperative coordination between thiacalix[4]arene (TC4A) and ferrocenylacetylene ligands. The cluster adopts a distinctive sandwich-like architecture, featuring two Ag(5)@TC4A units flanking a ferrocenyl-stabilized Ag(10) core, and exhibits excellent structural tunability. Ligand engineering allows replacement of the ferrocenylacetylene units with methoxyphenylacetylene (Ag(20)-OPh) or phenylacetylene (Ag(20)-Ph), while preserving the core framework. Electrospray ionization mass spectrometry reveals dynamic structural reorganization in solution, where Ag(5)@TC4A fragments are capable of capturing Ag-alkyne species and reassembling into sandwich-type clusters-a process substantiated by the structural features of Ag(24), Ag(12), and Cu(2)Ag(11). Ag(20)-Fc generates a locally electron-rich environment and conjugated ethynyl bridges that facilitate directional charge transfer, delivering outstanding electrocatalytic CO(2) reduction. It achieves over 98% faradaic efficiency for CO across a wide potential range (-1.0 to -1.8 V vs. RHE) and maintains operational stability for 24 h, significantly outperforming Ag(20)-OPh and Ag(20)-Ph. Density functional theory calculations uncover a dual enhancement mechanism in which orbital hybridization between ferrocenyl groups and silver atoms tunes the electronic structure at active sites, resulting in a 0.28 eV reduction in the energy barrier for *COOH intermediate formation compared to Ag(20)-Ph.