Impact of growth kinetics on morphology and pore structure of TiO ₂ - One-pot synthesis of macroporous TiO ₂ 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). H ₂O was supplied by an esterification reaction between acetic acid and 2-propanol (denoted as H ₂Oe), and/or by intentionally adding it (denoted as H ₂Oa). It was found that the quantity of H ₂Oa plays a crucial role in the morphology and porous structure of the final TiO ₂ product. Without the addition of H ₂Oa, 1D and porous TiO ₂ was synthesized. With the addition of H ₂Oa, and when the H ₂Oa:TiO ₂ molar ratio was in the range of 1:1 to 60:1, macroporous TiO ₂ microspheres possessing a large surface area and high thermal stability were obtained. When the H ₂Oa:TiO ₂ molar ratio exceeded 60:1, porous TiO ₂ 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.