New insights into polymer mediated formation of anatase mesocrystals

Abstract

The reaction between (NH₄)₂TiF₆ and H₃BO₃ in the presence of varying quantities of PEG-6000 was used to form NH₄TiOF₃ mesocrystals (MCs). The amount of PEG-6000, employed as a template, is crucial to the formation of defect free, non-agglomerated NH₄TiOF₃ MCs; high concentrations lead to MC agglomeration, lower ones result in centralized defects. This polymer-mediated formation process may be understood using an analogy with known polymerization reactions. The oxofluorotitanate MCs readily undergo a thermal topotactic transformation to give anatase MCs with photocatalytic activity. The TiO₂ MCs are porous, with highly orientated lamellar crystallites that form part of the larger mesocrystal structure.