Facile synthesis of anatase TiO2 mesocrystal sheets with dominant {001} facets based on topochemical conversion

Abstract

Uniform anatase TiO₂ mesocrystal sheets with dominant {001} facets were synthesized via a self-assembly and self-etching surfactant-free solvothermal process. The formation of well-faceted square sheets can be ascribed to the highly oriented assemblies of building blocks, while the etching agent HF also plays an important role in the tailored synthesis. During the topochemical conversion from NH₄TiOF₃ to TiO₂, a shrinkage void was generated, and the reason proposed is based on the crystal structural differences. Calcination leads to a more observable porous structure but the original shape is well retained. Smaller sheets can be simply obtained by substituting ethanol with 2-propanol which behaves as a synergistic capping agent.