Poly(ionic liquid)-based bimetallic tandem catalysts for highly efficient carbon dioxide electroreduction

Poly(ionic liquid)-metal (PIL-metal) hybrids were developed as a platform for facilely constructing tandem catalysts to reach highly efficient electrocatalytic reduction of CO₂ (CO₂RR). By introducing extra metal with distinct CO₂RR response to Cu-PIL hybrids, Cu@PIL@Ag and Cu@PIL@Bi were obtained. Remarkably, Cu@PIL@Ag exhibits an excellent C₂₊ Faradaic efficiency (FE_C2+) of 83.2% with a high partial current density (j_C2+) of 416.1 mA cm^–2 in 3 M KOH and an even higher j_C2+ (708.9 mA cm^–2) in 1 M KOH, while Cu@PIL@Bi possesses high FE_C1 (> 60%) and low FE_C2+ (< 5%) in a wide potential range. Mechanistic studies demonstrate the output of such a tandem system, either synergistic or maladjusted, depends on not only CO₂RR response of Ag and Bi but also specific Cu-Ag and Cu-Bi interactions. Besides, the PIL layer could adjust the reactivity by promoting the dispersion and availability of active sites and enriching the local key intermediates.