Impact of growth kinetics on morphology and pore structure of TiO2-one-pot synthesis of macroporous TiO2 microspheres.

Titanium dioxide was synthesized by the hydrolysis of titanium tetraisopropoxide (TTIP) in the presence of acetic acid, 2-propanol, and organic amines (octylamine, aniline, and isobutylamine). H2O was supplied by an esterification reaction between acetic acid and 2-propanol (denoted as H2Oe), and/or by intentionally adding it (denoted as H2Oa). It was found that the quantity of H2Oa plays a crucial role in the morphology and porous structure of the final TiO2 product. Without the addition of H2Oa, 1D and porous TiO2 was synthesized. With the addition of H2Oa, and when the H2Oa:TiO2 molar ratio was in the range of 1:1 to 60:1, macroporous TiO2 microspheres possessing a large surface area and high thermal stability were obtained. When the H2Oa:TiO2 molar ratio exceeded 60:1, porous TiO2 with an irregular shape was formed. The variation in the morphology and porous structure is attributed to the manipulation of the growth kinetics by the addition of water.