Photocatalytic reduction of CO2 to produce chemical fuels is considered a green approach, as it can address the environmental and social issues caused by rising CO2 concentrations while also mitigating the energy crisis. Ionic liquids (ILs) have been widely used in CO2 capture. Surface modification of TiO2 nanotubes (TNTs) with ILs promises simultaneous CO2 capture and reduction to chemicals. This study first optimized the anodization process of TNTs by adjusting the water content, achieving a tubular array microstructure with optimal photocatalytic performance. Subsequently, the ILs with the best CO2 enrichment performance were selected to modify the surface of the TNTs. The resulting nanocomposite achieved a photocatalytic reduction of CO2 to acetic acid under simulated sunlight, with an acetic acid yield of 17.4 μmol gcat⁻1 h⁻1. After five cycles, there was no significant decline in acetic acid production. The surface modification of the ILs facilitated the enrichment and activation of CO2 from the water solution onto the catalyst surface. The presence of a large amount of activated CO2 and single-C intermediates on the catalyst surface increased the probability of C-C coupling, thereby promoting the formation of the two-carbon product, acetic acid.