Atomically precise alkynyl-protected Ag20Cu12 nanocluster: Structure analysis and electrocatalytic performance toward nitrate reduction for NH3 synthesis

Electrochemical nitrate reduction reaction (NtrRR) has been emerging as an appealing route for both water treatment and NH 3 synthesis. Herein, we report the structure analysis and electrocatalytic performance of a novel homoleptic alkynyl-protected Ag 20 Cu 12 nanocluster (Ag 20 Cu 12 in short) with atomic precision, which has eight free electrons and displays characteristic absorbance feature. Single crystal X-ray diffraction (SC-XRD) discloses that, it adopts a Ag 14 kernel capped by three Ag 2 Cu 4 (C≡CAr F ) 8 metal–ligand binding motifs in the outer shell. Ag 20 Cu 12 exhibited excellent catalytic performance toward NtrRR, as manifested by the superior NH 3 Faradaic efficiency (FE, 84.6%) and yield rate (0.138 mmol·h −1 ·mg −1 ) than the homoleptic alkynyl-protected Ag 32 nanoclusters. Additionally, it demonstrates good catalytic recycling capability. Density functional theory (DFT) calculations revealed that, the de-ligated Ag 20 Cu 12 cluster can expose the available AgCu bimetallic sites as the efficient active sites for NH 3 formation. In particular, the participation of Cu sites greatly facilitates the initial capture of NO 3 − and simultaneously promotes the selectivity of the final product. This study discovers a novel homoleptic alkynyl-protected AgCu superatom, and offers a great example to elucidate the structure–performance relationship of bimetallic catalyst for NtrRR and other multiple protons/electrons coupled electrocatalytic reactions.