Topochemical synthesis and photocatalytic activity of 3D hierarchical BaTiO3 microspheres constructed from crystal-axis-oriented nanosheets

Novel BaTiO3 hierarchical porous microspheres were achieved by using H2Ti2O5·H2O (HTO) hierarchical microspheres as a precursor template via a facile solvothermal method. Interestingly, the BaTiO3 microspheres were constructed with two-dimensional (2D) nanosheets, which were composed of many order nanocrystals with crystal-axis-orientation. The special hierarchical structure, which is both macroporous and mesoporous, exhibits a large specific surface area and a high total pore volume. The photocatalytic performance of BaTiO3 hierarchical microspheres for degradation of methyl orange (MO) under UV-light irradiation was tested, its apparent rate being up to 0.10183 min-1, almost 23 times higher than that for nanoscale BaTiO3 particles. The attractive photocatalytic properties are considered to benefit from the effective features of hierarchical BaTiO3 microspheres, such as the ultrathin thickness of nanosheets and their ordered interconnected macro-mesoporous structure and intrinsic photocatalytic activity. This study offers an in situ topochemical conversion route to synthesis of other titanium-based perovskite hierarchical nanostructures, and thus opening the door for the synthesis of other titanium-based functional materials and expanding their potential application.