Hierarchically Dual-Mesoporous TiO₂ Microspheres for Enhanced Photocatalytic Properties and Lithium Storage

Hierarchically dual-mesoporous TiO₂ microspheres have been synthesized by a solvothermal process in the presence of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF₄ ]) and diethylenetriamine (DETA) as co-templates. Secondary mesostructured defects in the hierarchical TiO₂ microspheres produce oxygen vacancies, which not only significantly enhance photocatalytic activity in the degradation of methylene blue (1.7 times that with P25) and acetone (2.9 times that with P25), but are also beneficial for lithium storage. Moreover, we propose a mechanism to rationalize the role of this dual mesoporosity of the TiO₂ microspheres in enhancing molecular diffusion, ion transportation, and electronic transitions.