Low-Temperature Synthesis and HRTEM Analysis of Ordered Mesoporous Anatase with Tunable Crystallite Size and Pore Shape

A new direct synthesis methodology for the preparation of mesoporous titania with hexagonal mesostructure and with walls of tunable crystallinity and crystallite size has been developed. As the crystallites grow they eventually reach a point where they are too big to fit within the pore walls, the mesoorder becomes distorted and is finally lost. It is run at an unprecedented low temperature of 40 degrees C without the need for an autoclave or high-temperature post-treatment procedures and is thus compatible with low temperature stable substrates. High-resolution transmission electron microscopy and electron diffraction reveal that the pore walls of the mesoordered material consists of anatase TiO2 nanoparticles. The method allows for a wide choice of synthesis time during which the anatase crystallites grow slowly within the range of 2-5 nm in size but needs to be kept such that the crystallites have not yet grown too large for them to be coassembled into an ordered mesostructure.