Size effects of alkylimidazolium cations on the interfacial properties and CO2 uptake capacity in layered organic–inorganic imidazolium–TiO2 hybrids

Abstract

Layered inorganic–organic TiO₂–ILs hybrids with tunable basal spacing were fabricated through electrostatic interaction between 2D inorganic nanosheets and organic imidazolium-based ILs. Imidazolium cations with various sizes were intercalated into lamellar titanate nanosheets, forming layered structures with slabs turbostratic restacking. The effects of cation sizes on the interfacial properties of hybrids were comprehensively investigated by XRD, SEM, TEM, AFM, FT-IR, Raman and TG techniques. The results confirmed that the ratio of interlayer imidazolium cations declined with increasing carbon chain length. A CO₂ absorption experiment was conducted and TiO₂–ILs compounds displayed enhanced CO₂ absorption capacity with the increase of alkyl chain length, which could be attributed to the synergistic interfacial effects induced by diverse interactions between ILs and inorganic nanosheets. An absorption mechanism was proposed on account of ion-exchangeable characteristic of these layered hybrids and the intercalated H₂O molecules were found to play a crucial role in CO₂ uptake.