Synthesis, structure anatomy, and catalytic properties of Ag14Cu2 nanoclusters co-protected by alkynyl and phosphine ligands

Abstract

We report the synthesis, structure anatomy, and catalytic properties of Ag₁₄Cu₂(CCAr^F)₁₄(PPh₃)₄ (CCAr^F: 3,5-bis(trifluoromethyl)phenylacetylene) nanoclusters, denoted as Ag₁₄Cu₂. Ag₁₄Cu₂ has a robust electronic structure with two free valence electrons, and it has a distinctive absorbance feature. Single-crystal X-ray diffraction (SC-XRD) disclosed that Ag₁₄Cu₂ possesses an octahedral Ag₆ metal kernel capped by two Ag₄Cu₁(CCAr^F)₇(PPh₃)₂ metal–ligand units. Remarkably, it exhibits excellent bifunctional catalytic performance for 4-nitrophenol reduction and the electrochemical CO₂ reduction reaction (eCO₂RR). In 4-nitrophenol reduction, it adopts first-order reaction kinetics with a rate constant of 0.137 min⁻¹, while in the eCO₂RR, it shows a CO faradaic efficiency (FE_CO) of 83.71% and a high current density of 92.65 mA cm⁻² at −1.6 V vs. RHE. Moreover, Ag₁₄Cu₂ showed robust long-term stability with no significant decay in current density and FE_CO over 10 h of continuous operation in the eCO₂RR. This study not only enriches the potpourri of alkynyl-protected bimetallic AgCu nanoclusters, but also demonstrates the great potential of employing metal nanoclusters for bifunctional catalytic applications.