Hydrothermal conversion of self-assembled titanate nanotubes into nanowires in a revolving autoclave

Titanate nanowires were synthesized through the hydrothermal synthesis route (10 M NaOH, 130 degrees C) from anatase in a rotating autoclave. A combined TEM, SEM, XRD, FT-Raman, and N-2 adsorption investigation of the reaction products as a function of time revealed that the 60-150 nm wide and similar to 5 mu m long nanowires are in fact formed by the merging of self-assembled nanotube bundles. The nanowires are able to further self-assemble into similar to 5 mu m wide and longer than 30 mu m long, dense "superbundles" if the reaction is allowed to run long enough. We propose that the spontaneous nanotube arrangement could be caused by the rotation-assisted oriented attachment of the tubes.