Highly porous TiO_2 nanofibres with a fractal structure

摘要

TiO_2 nanofibres were prepared using a templating method with tetraisopropylorthotitanate (TiPT) as a precursor. The preparation comprises liquid phase deposition on cellulose fibres followed by thermal removal of the cellulose template. The obtained TiO_2 fibrous substance consists of micron-size fibres with a microstructure of nanofibres. It was demonstrated that nanofibres are basically formed through the aggregation of TiO_2 nanoparticles and nanorods into chain structures during the thermal treatment process. The measured surface area of the TiO_2 fibres was about 250 m~2 g~(-1). It was shown that the pore size distribution is multi-scale and a fractal morphology was demonstrated with two fractal regimes with dimensions of 1.78 and 2.97 for sizes below and above 7.5 nm, respectively. The crystalline phase of the TiO_2 nanofibres, as well as the nanoparticles in the solution, could be controlled by the pH of the solution. A pH of 1.2 resulted in rutile phase, while a pH of 1.8 resulted in anatase phase.