The electrochemical reduction of CO2 (eCO2RR) that exclusively produces one product at industrial current density is crucial for the substantial storage of renewable energy. Modulating the electronic structure of atomically dispersed catalysts can effectively regulate the adsorption of rate-determining-step intermediates to achieve the desired products. Here, the study constructs a hybrid catalyst consisting of single Ag atoms and Ag atomic clusters supported on nitrogen-doped multi-walled carbon nanotubes that can effectively regulate the important intermediate structure of *COOH. The X-ray photoelectron and X-ray absorption near-edge spectroscopies demonstrate that turning Ag single atoms into Ag clusters can weaken the electron transfer between Ag–N and present a relatively rich electron state. Thus, the rate-determining step of *COOH massive formation is significantly accelerated, as proven by in situ synchrotron infrared spectroscopy and density functional theory calculations. Using this strategy, a CO Faradaic efficiency outperforming 99% from −0.3 to −0.8 V (vs reversible hydrogen electrode) with current densities above 200 mA cm−2 and a half-cell energetic efficiency of 86% is achieved. This work highlights a promising approach to advancing synergistic catalysts for achieving more controllable and efficient eCO2RR.
