Homoleptic Alkynyl-protected Ag15 Nanocluster with Atomic Precision: Structural Analysis and Electrocatalytic Performance toward CO2 Reduction

Atomically precise Ag nanoclusters provide an ideal platform to correlate the structure and electrocatalytic performance at the atomic level. Herein, we report the fabrication of homoleptic alkynyl-protected Ag15(C≡CtBu)12+ (abbreviated as Ag15) nanocluster and its electrocatalytic properties toward CO2 reduction reaction. Crystal structure analysis reveals that, Ag15 possesses a body-centered-cubic (BCC) structure with an Ag@Ag8@Ag6 metal core configuration. Interestingly, we found that, Ag15 can adsorb CO2 in air and spontaneously self-assembled into one-dimensional linear material during the crystal growth process. Furthermore, Ag15 can convert CO2 into CO with a faradaic efficiency of ~95.0% at -0.6 V and a maximal turnover frequency of 6.37 s-1 at -1.1 V along with excellent long-term stability. Finally, density functional theory calculations disclosed that, Ag15(C≡CtBu)11+ with one alkynyl ligand stripping off from the intact cluster can expose the uncoordinated Ag atom as the catalytically active site for CO formation.