It is highly desired yet challenging to strategically steer CO 2 electroreduction reaction (CO 2 ER) toward ethanol with high selectivity, to which the evolution of reaction intermediates on catalytically active sites holds the key. Herein, we report that K doping in Cu 2 Se nanosheets array on Cu foam serves as a versatile knob for tuning the interaction between Cu sites and reaction intermediates in CO 2 ER, enabling highly selective production of ethanol. As revealed by characterization and simulation, the electron transfer from K to Se can stabilize Cu(I) species which facilitate the adsorption of linear *CO L and bridge *CO B intermediates to synergistically promote C-C coupling during CO 2 ER. As a result, the optimized K 11.2% -Cu 2 Se nanosheets array can catalyze CO 2 ER to ethanol as a single liquid product with high selectivity in a potential area from -0.6 to -1.2 V. Notably, it offers a Faradaic efficiency of 70.3% for ethanol production at -0.8 V with an extraordinary stability for 130 h.