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

Abstract

We report the fabrication of homoleptic alkynyl-protected Ag₁₅ (C≡C-^t Bu)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 the 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 ca. 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 (DFT) calculations disclosed that Ag₁₅ (C≡C-^t Bu)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.

Keywords: Ag15(C≡C-tBu)12+ nanocluster; CO2 adsorption; CO2 reduction reaction; DFT calculations.