Selective CO2 Fixation Mediated by Ferricyanide SCILLs: A “Catch-andRelease” Catalytic Approach

The chemical fixation of CO₂ into cyclic carbonates represents an attractive strategy for sustainable chemical production. This work reports the synthesis of the ferricyanide-based ionic liquid [BMIm]₃·[Fe(CN)₆], immobilized on SiO₂ to produce supported catalytic ionic liquid layers (SCILLs). Molecular dynamics simulations revealed an anisotropic ion-pair organization that promotes efficient CO₂ activation under nanoconfinement. The catalyst exhibited excellent performance under mild conditions (70–100 °C, 1–2 bar), achieving turnover numbers up to 729 with 99% selectivity toward cyclic carbonates. In situ ¹³C NMR spectroscopy identified the formation of the NHC–CO₂ intermediate, demonstrating that the imidazolium cation actively participates in catalysis through carbene generation rather than acting solely as a hydrogen-bond donor. Although partial ionic liquid leaching reduced recyclability, the results provide new mechanistic insights into nanoconfined catalytic systems and offer promising perspectives for designing efficient materials for sustainable CO₂ utilization.