A systematic study on hydrothermal treatment of titania recording the changes of morphologies of titanate nanostructures was performed by subtly controlled termination of reaction and capture of intermediates. During the hydrothermal process, rapid coalescence of nanoparticles first occurred, followed by exfoliation of large aggregated moieties in their peripheries into nanosheets. The nanosheets were then rolled up to form short nanotubes. Afterwards, the nanotubes transformed into long ones, which eventually assembled into nanowires. This is a stepwise evolution process common for alkaline hydrothermal transitions. The oriented attachment (OA) model plays a vital role here, and the Oswald ripening (OR) mechanism appears to be effective as well.
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