Electrochemical reduction of carbon monoxide (CORR) provides pathways for decarbonizing chemical manufacturing by producing high-value multicarbon (C2+) products, though achieving high activity and selectivity toward a single principal C2+ product remains challenging. Acetate, a critical liquid product, can be metabolized by bacteria to synthesize long-chain carbon compounds. Here, we design a core-shell Cu2O/Cu-2-methylimidazole (CuIM) catalyst with dual Cu sites (Cu+ and Cu0) during the CORR, which shifts the reaction pathway from symmetric *CO-*CO coupling to asymmetric *CH2-*CO coupling, thereby enhancing acetate formation. Ex situ X-ray diffraction spectroscopy (XRD) and in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) analyses reveal that Cu+ remains stable and acts as an active site for generating *CH2 intermediates on the CuIM catalyst. The CuIM electrocatalyst achieves a Faradaic efficiency (FE) of 77.8% for acetate production from CO and a partial current density of 541.3 mA cm-2. These advancements enable high energy efficiency in membrane electrode assemblies and reduced downstream separation costs for liquid products in solid-state electrolyte systems.