Construction of Atomic-Scale Compressive Strain for Oxime Electrosynthesis

Abstract

Tuning the surface strain is a powerful strategy to enhance the catalytic activity of metal nanocatalysts, yet an atomically precise catalyst with intramolecular strain to unlock the atomic-level strain-structure–activity relationship is still highly desired. Herein, we report the synthesis, structural anatomy, and catalytic performance toward cyclohexanone oxime electrosynthesis of an atomically precise Ag 16 Cu 18 (C≡C-C 6 H 11 ) 24 (Ag 16 Cu 18 ) nanocluster, which has a Cu 6 ring in the center. The Cu–Cu distance in the Cu 6 ring is only 1.616 Å in a single crystal, the shortest Cu–Cu bond in Cu nanomaterials to date. Furthermore, once Ag 16 Cu 18 was loaded onto carbon paper, the ultrashort Cu–Cu bond elongated to ∼2.40 Å, still showing strong intramolecular compressive strain. Ag 16 Cu 18 exhibited excellent catalytic activity toward oxime electrosynthesis, manifested by a maximal Faradaic efficiency, yield, and yield rate of cyclohexanone oxime reaching 47.4%, 95.4%, and 2.66 mmol·h –1 ·cm –2 at –0.35 V, respectively. In-situ attenuated total reflection surface-enhanced infrared spectroscopy revealed that the Cu sites adjacent to the Ag atoms primarily reduce NO and stabilize it at the *NH 2 OH stage, while the Cu sites with compressive strain provide H* for NO reduction and adsorb cyclohexanone to react with *NH 2 OH, forming cyclohexanone oxime simultaneously. Density functional theory calculations confirmed the presence of compressive strain in the Cu 6 ring, which facilitates H* formation and cyclohexanone adsorption, hence significantly contributing to oxime generation. This study not only reports a case of atomically precise clusters with intramolecular compressive strain but also provides an atomic-level understanding for employing bimetallic nanocluster-based catalysts toward the electrosynthesis of valuable organic molecules.

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