Sn-based redox cycle mediated microenvironment regulation of Cu sites on poly(ionic liquid) enhance electrocatalytic CO-to-C₂₊ conversion

Electrocatalytic CO reduction provides a sustainable route for high-value CO utilization. To promote the selectivity of C₂₊ products (FE_C2+) at high reaction rates, the electronic structure and the microenvironment of Cu sites in Cu@PIL were regulated by introducing a Sn-mediated redox cycle. The obtained Cu@PIL@Sn-x hybrids provided high FE_C2+ (> 70%) within a wide current density (j) range from –100 to −700 mA cm^–2. Particularly, an excellent FE_C2+ of 96.8 % with a high j_C2+ of −484.2 mA cm^–2 was obtained on Cu@PIL@Sn-1.0. Besides, it exhibited high tolerance of diluted CO gas at −250.0 mA cm^–2. Mechanistic studies demonstrated the rich high-valence Cu species and the adjacent Sn-Cl species at the Cu@PIL@Sn-x hybrids jointly account for the local enrichment of oxygen-containing species on Cu surface during the electrolysis of CO, even at high overpotentials, which enables the C–C coupling at high reaction rates.