Photocatalytic CO2-to-ethanol conversion via multiple enrichment effects in porous liquids.

Photocatalytic CO2 reduction to multi-carbon products like ethanol remains challenging. We report a porous liquid (PL) system, PL(Cu-Cu2O@NU), driving selective CO2-to-ethanol conversion. It features Cu0/Cu+ dual sites in NH2-UiO-66 (NU) hybridized with a methoxypolyethylene glycol-functionalized imidazolium ionic liquid (IL). This system facilitates C-C coupling via a triple enrichment mechanism: IL and NU synergistically enrich CO2, IL enriches electrons at Cu sites, and confined pores enrich intermediates. Consequently, PL(Cu-Cu2O@NU) achieves an 83.3 μmol·g-1·h-1 ethanol yield with 95.2% selectivity, outperforming Cu-Cu2O@NU by 4.7-fold. Control experiments (showing no ethanol over isolated NU, IL, or Cu-Cu2O) directly validate this mechanism. Supplemental computations substantiate these findings: molecular dynamics confirm confined pores reduce *CO diffusion for enrichment, while density functional theory reveals lowered C-C coupling barriers. Furthermore, d-band upshifts enhance CO2-Cu overlap, and Cu0/Cu+ sites mediate the critical *CO → *COCO transition. These integrated observations firmly establish PLs as robust confinement-driven platforms for selective CO2-to-C2+ conversion.