Photocatalytic CO2 reduction co‐catalyzed by ionic liquids

Efficiently generating C1 building blocks from environmentally friendly carbon sources, such as through photocatalytic CO2 reduction, is essential for fostering a sustainable circular economy. The pursuit of gentle catalytic activation methods has yielded powerful catalysts that can be synergistically employed alongside various reaction media to enhance overall performance. Herein, we elucidate the influence of diverse imidazolium‐based ionic liquids as additives for visible‐light‐driven CO2reduction with ruthenium(II)‐ and rhenium(I)‐bipyridine complexes. Our investigation reveals that incorporating ionic liquids into traditional solvents at concentrations below 10% can markedly boost CO production while suppressing H2 generation. The best results were obtained for the highly basic ionic liquid [C2mim][OAc], resulting in a substantial rise in CO formation from 0.3 µmol/h to 5.4 µmol/h and an increase in turnover number from 3 to 59. This study underscores the cooperative influence of imidazolium‐based ionic liquids on CO2 photoreduction while circumventing their use as primary solvents, thus offering a promising avenue for sustainable chemical synthesis.