From Peripheral Ag Sites to an Ag-Based Framework: Regulating CO2 Electroreduction Selectivity and Stability in V-Ag...

Atomically precise heterometallic nanoclusters offer molecular platforms for correlating metal-site organization with electrocatalytic behavior, yet how structural architecture simultaneously controls reaction pathways and catalyst durability remains unclear. Herein, we demonstrate a divergent assembly of two V-Ag nanoclusters with contrasting framework organizations, enabled by polyoxovanadate-supported Ag+ coordination and thiacalix[4]arene-directed assembly. V18Ag8 contains peripheral Ag+ sites anchored on a polyoxovanadate scaffold, whereas Ag22V8 features an integrated Ag-based framework incorporating vanadium-oxo units. V18Ag8 strongly favors CO formation, reaching a maximum CO Faradaic efficiency of 94.51% at -1.0 V versus RHE, but undergoes pronounced deactivation during prolonged electrolysis, accompanied by loss of CO selectivity and increasing H2 evolution. In contrast, Ag22V8 markedly enhances the competing formate pathway, delivering formate Faradaic efficiencies above 20% and a maximum of approximately 30%. Mass spectrometry and postelectrolysis characterizations attribute these differences to the lability of surface-anchored Ag sites in V18Ag8 and the greater integrity of the integrated Ag framework in Ag22V8. In situ infrared spectroscopy and DFT calculations further reveal that V18Ag8 predominantly follows the *COOH-*CO pathway, whereas Ag22V8 enables concurrent *COOH- and *OCHO-mediated routes. These results highlight framework-level Ag-site organization as an important structural parameter for jointly regulating CO2RR selectivity and catalytic durability.