Dynamically Reconstructed Triple‐Copper‐Vacancy Associates Confined in Cu Nanowires Enabling High‐Rate and Selective CO₂ Electroreduction to C₂₊ Products

Abstract Electrochemically reconstructed Cu‐based catalysts always exhibit enhanced CO₂ electroreduction performance; however, it still remains ambiguous whether the reconstructed Cu vacancies have a substantial impact on CO₂‐to‐C₂₊ reactivity. Herein, Cu vacancies are first constructed through electrochemical reduction of Cu‐based nanowires, in which high‐angle annular dark‐field scanning transmission electron microscopy image manifests the formation of triple‐copper‐vacancy associates with different concentrations, confirmed by positron annihilation lifetime spectroscopy. In situ attenuated total reflection‐surface enhanced infrared absorption spectroscopy discloses the triple‐copper‐vacancy associates favor *CO adsorption and fast *CO dimerization. Moreover, density‐functional‐theory calculations unravel the triple‐copper‐vacancy associates endow the nearby Cu sites with enriched and disparate local charge density, which enhances the *CO adsorption and reduces the CO–CO coupling barrier, affirmed by the decreased *CO dimerization energy barrier by 0.4 eV. As a result, the triple‐copper‐vacancy associates confined in Cu nanowires achieve a high Faradaic efficiency of over 80% for C₂₊ products in a wide current density range of 400–800 mA cm⁻², outperforming most reported Cu‐based electrocatalysts.