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

Abstract

Ionic liquid-based electrocatalytic CO2 reduction faces the challenge of achieving high selectivity toward value-added C2+ 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 C2+ faradaic efficiency of 58 % with a high partial current density of 174 mA cm−2. Further, a highest C2+ 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 CO2 concentration, thereby promoting the CO2 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 CO2 and the stabilization of intermediates, thus regulating current density and product selectivity.