Polymer‐Halogen Pockets Steering *CO Adsorption Configurations for Highly Selective CO2 Electroreduction

Abstract The selective CO 2 electroreduction (CO 2 R) toward specific C 2 products represents a critical challenge for practical applicability, requiring precise control over * CO intermediates. Herein, a “polymer‐halogen” pocketed Cu catalyst is proposed, wherein the adjustable concentration of Iodide ion (I − ) within the pocket enables continuous modulation of * CO adsorption configurations on the Cu, thereby enabling tailored CO 2 R toward ethylene or ethanol production. A perfluorosulfonic acid (PFSA)‐modified CuI catalyst is constructed, where I − is in situ leaching from CuI and subsequently confined by PFSA as an anion shielding layer to form polymer‐halogen pockets. By tuning the thickness of PFSA shell, the amount of I − in the pocket can be controlled. The surface‐enhanced in situ Raman spectroscopy demonstrates that the coverage of * CO intermediates on Cu surface increases and tends to adsorb at low coordination Cu sites in catalyst granule for dimerization reaction as the I − concentration in the pocket increases. Furthermore, the coordination environment exhibits distinct product selectivity. * CO at medium‐coordinated sites favor ethanol production, while those at low‐coordinated sites are conducive to ethylene formation. This strategy enables wide modulation of ethylene‐to‐ethanol ratios from 0.65 to 3.96, achieving peak Faradaic efficiencies (FE) of 60.3 ± 2.1% for ethylene and 48.3 ± 1.3% for ethanol.