Regulating electrochemical CO2RR selectivity at industrial current densities by structuring copper@poly(ionic liquid) interface.

[Display omitted] • Copper@poly ionic liquid (Cu@PIL) hybrid is prepared via in-situ polymerization method. • Multi-electron CO 2 reduction (> 2e–) with industrial current density (≥300 mA cm−2) is realized on this novel Cu@PIL system. • The outer layer of PIL enriches local CO 2 concentration by adsorption CO 2 molecules with cationic fragment. • The structurally induced interfacial electric field at Cu@PIL interface stabilizes polarized intermediates, wherein the anions at the inner PIL layer regulate the current density and product selectivity by different electron donation ability. Ionic liquid-based electrocatalytic CO 2 reduction faces the challenge of achieving high selectivity toward value-added C 2+ products at high reaction rate (≥ 100 mA cm−2). Herein, novel copper@poly(ionic liquid) (Cu@PIL) hybrids demonstrate multi-electron reduction (> 2e–) with current densities ≥ 300 mA cm−2. Remarkably, Cu@PIL with F– anion exhibits high C 2+ faradaic efficiency of 58 % with a high partial current density of 174 mA cm−2. Further, a highest C 2+ partial current density of 233 mA cm−2 was also achieved. Experimental combined theoretical investigations reveal that the "individual" ionic pairs in the outer PIL layer enrich local CO 2 concentration, thereby promoting the CO 2 supply. Besides, an interfacial electric field is induced by the unbonded imidazolium moieties at Cu-PIL interface, which stabilize intermediates. Anions, differing in the electron-donating number to the imidazolium moieties, influence both the enrichment of CO 2 and the stabilization of intermediates, thus regulating current density and product selectivity. [ABSTRACT FROM AUTHOR]