How thermal stability of ionic liquids leads to more efficient TiO₂-based nanophotocatalysts: Theoretical and...

Ionic liquids (ILs) containing distinct nitrogen-bearing organic cations (pyridinium, pyrrolidinium, imidazolium, ammonium, morpholinium) were first used for the preparation of 23 IL-TiO₂ types of composites by ionic liquid assisted solvothermal synthesis. These 23 optimal ILs structures (i.e. compounds exhibiting an optimal combination of specific properties, functionality, and safety) for synthesis and experimental validation were selected by computational high-throughput screening from a combinatorically created library containing 836 ILs theoretically designed and characterized candidates. Then, selected IL-TiO₂ structures with potential photocatalytic activity were synthesized with the use of solvothermal reaction. Then, the decomposition level, the role of the individual IL cation structure on the morphology, thermal stability, surface and photocatalytic properties of the IL-TiO₂ microparticles were determined experimentally. The chemoinformatic analysis of the relationship between the structure of the ionic liquid, its thermal stability under the conditions of synthesis and photocatalytic activity was applied for the first time. The results presented here are the first step in the development of methodology (combined experimental and theoretical) that may simplify the procedure of designing safer and more efficient TiO₂-based photocatalyst. The developed computational methodology makes it possible to predict properties of newly synthesized IL-TiO₂ materials before synthesis and identifies structural features of ILs that influence the efficiency of IL-TiO₂ system. The presented approach reduces the number and cost of necessary experiments, as well as increases the success ratio of efficient TiO₂-based photocatalyst design by a selection of optimal IL structures (i.e. ionic liquid characterized by a combination of most promising physicochemical features).