Lewis-base ligand-reshaped interfacial hydrogen-bond network boosts CO 2 electrolysis.

Both the catalyst and electrolyte strongly impact the performance of CO 2 electrolysis. Despite substantial progress in catalysts, it remains highly challenging to tailor electrolyte compositions and understand their functions at the catalyst interface. Here, we report that the ethylenediaminetetraacetic acid (EDTA) and its analogs, featuring strong Lewis acid-base interaction with metal cations, are selected as electrolyte additives to reshape the catalyst-electrolyte interface for promoting CO 2 electrolysis. Mechanistic studies reveal that EDTA molecules are dynamically assembled toward interface regions in response to bias potential due to strong Lewis acid-base interaction of EDTA 4- -K + . As a result, the original hydrogen-bond network among interfacial H 2 O is disrupted, and a hydrogen-bond gap layer at the electrified interface is established. The EDTA-reshaped K + solvation structure promotes the protonation of *CO 2 to *COOH and suppressing *H 2 O dissociation to *H, thereby boosting the co-electrolysis of CO 2 and H 2 O toward carbon-based products. In particular, when 5 mM of EDTA is added into the electrolytes, the Faradaic efficiency of CO on the commercial Ag nanoparticle catalyst is increased from 57.0% to 90.0% at an industry-relevant current density of 500 mA cm -2 . More importantly, the Lewis-base ligand-reshaped interface allows a range of catalysts (Ag, Zn, Pd, Bi, Sn, and Cu) to deliver substantially increased selectivity of carbon-based products in both H-type and flow-type electrolysis cells.