Developing novel hybrid ionic liquid/porous material/co-solvent absorbents with the confinement effect is essential for CO₂ separation. In this study, CO₂ solubilities in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/titanium dioxide/polyethylene glycol ([Hmim][Tf₂N]/TiO₂-PEG200) with different ratios of [Hmim][Tf₂N]/TiO₂ and various roughnesses of TiO₂ (P25 and T500) were measured and described with the Henry's law. Furthermore, the contribution of the confinement effect on the CO₂ solubility was quantified, and the relationship between the surface roughness and molecular parameters was established for predicting its contribution to the confinement effect. In addition, the hybrid absorbent was recycled by a multi-cycle experiment. The results show that the contribution of confinement effect on CO₂ absorption capacity (on mass basis) and Gibbs free energy occupy around 24.5 % and 8.12 % in [Hmim][NTf₂]/T500-PEG200 (w_{[Hmim][NTf2]/T500} = 2.88 wt%) at 308.2 K, respectively. The surface roughness can double the confinement effect. Based on the CO₂ absorption capacity and enthalpy, [Hmim][NTf₂]/T500-PEG200 (w_{[Hmim][NTf2]/T500} = 2.88 wt%) is a promising hybrid absorbent for CO₂ separation.