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

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.