The high‐rate electrochemical CO2 conversion to ethanol with high partial current density is attractive but challenging, which requires competing with other reduction products as well as hydrogen evolution. This work demonstrates the in situ reconstruction of KCuF3 perovskite under CO2 electroreduction conditions to fabricate a surface fluorine‐bonded, single‐potassium‐atom‐modified Cu(111) nanocrystal (K–F–Cu–CO2). Density functional theory calculations reveal that the co‐modification of both F and K atoms on the Cu(111) surface can promote the ethanol pathway via stabilization of the CO bond and selective hydrogenation of the CC bond in the CH2CHO* intermediate, while the single modification of either F or K is less effective. The K–F–Cu–CO2 electrocatalyst exhibits an outstanding CO2‐to‐ethanol partial current density of 423 ± 30 mA cm−2 with the corresponding Faradaic efficiency of 52.9 ± 3.7%, and a high electrochemical stability at large current densities, thus suggesting an attractive means of surface co‐modification of halide anions and alkali‐metal cations on Cu catalysts for high‐rate CO2‐to‐ethanol electrosynthesis.

The high‐rate ethanol electrosynthesis from CO2 is challenging due to the low selectivity and poor activity, which requires the competition with other reduction products and H2. Here, the electrochemical reconstruction of Cs3Cu2Cl5 perovskite to form surface Cl‐bonded, low‐coordinated Cs modified Cu(200) nanocubes (CuClCs), is demonstrated. Density functional theory calculations reveal that the CuClCs structure possesses low Bader charges and a large coordination capacity; and thus, can promote the CO2‐to‐ethanol pathway via stabilizing C−O bond in oxygenate intermediates. The CuClCs catalyst exhibits outstanding partial current densities for producing ethanol (up to 2124 ± 54 mA cm−2) as one of the highest reported values in the electrochemical CO2 or CO reduction. This work suggests an attractive strategy with surface alkali‐metal cations for ampere‐level CO2‐to‐ethanol electrosynthesis.

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The electrochemical CO2 reduction to CH4 has been extensively demonstrated, but still suffers from relatively poor activity and requires high overpotentials especially at large electrolysis rates. Perovskite oxides (AxByO) are one type of promising electrocatalyst for the CO2 reduction due to their tunable electronic structures. In this work, a Ca2CuO3 perovskite oxide catalyst is developed with alkaline‐earth A‐sites, featuring an inherently strong basic strengthand outstanding capability for CO2 adsorption, as well as the undercoordinated Cu sites generated through partial surface Ca2+ cation leaching. The Ca2CuO3 catalyst exhibitsa high partial current density of 517 ± 23 mA cm−2 for producing CH4 at a low applied potential of −0.30 V versus reversible hydrogen electrode, which further reached to a peak value of 1452 ± 156 mA cm−2. Density functional calculations show that the undercoordinated Cu sites allowed to promote the hydrogenation of *CO and subsequent *CHO intermediates, thus leading to the high CH4 activity. This work suggests an attractive design strategy for tuning the A‐sites in perovskite oxides to realize high‐rate CO2‐to‐CH4 electrosynthesis with low overpotentials.