Catalysis Today, 2018,
The preparation of materials with aligned porosity in the nanometer range is of technological importance for a wide range of applications in molecular filtration, biomaterials and catalysis. Herein we present the advantages offered by cryo – lyophilisation technique as a smart and green non-standard concept to produce dense regular polyhedral nanocavities inside the 2D TiO2 nanosheets. Hierarchical morphologies of nanocavities start to appear at temperature higher than 800 °C and are strongly influenced by polymorph TiO2 evolution competing reactions. The small angle X-ray scattering (SAXS) analysis confirms self-assembled 3D nanocavities with size range from 5 to 10 nm in both length and width, and depth ˜3.6 nm formed after realising of the confined ice-water. It was found that nanocavities enhance significantly the absorption properties of TiO2 in the UV region, thereby providing a new approach to increase the photoreactivity of 2D TiO2 nanosheets. The annealed precursors containing aqueous solution of peroxo polytitanic acid (PPTA) at 800 °C exhibited the highest photoactivity in degrading bisphenol A (BPA) due to evenly distributed nanocavities inside single anatase TiO2 nanocrystals interconnected and aligned onto the 2D TiO2 nanosheet arrays.