Hollow Square RodLike Microtubes Composed of Anatase Nanocuboids with Coexposed {100}, {010}, and {001} Facets for Improved Photocatalytic Performance.

In this study, hollow square rodlike microtubes composed of anatase nanocuboids with coexposed {100}, {010}, and {001} facets were successfully synthesized via a mild hydrothermal treatment method in the presence of NHF by using layered HTiO ribbons as the precursor. The precursor HTiO ribbons were prepared from H/Na ion-exchanged NaTiO. The suspension solution of protonated HTiO ribbons was adjusted to desired pH values (0.5-13.0) prior to hydrothermal treatment. The elongated direction of the microtubes is along the axis, according to the profile of the HTiO ribbons. The transformation from staggered [TiO] sheets to hollow square rodlike microtubes contained the formation and recombination of the dispersed octahedral [Ti(OH)(OH)] monomers, the formation and growth of the initial anatase nuclei, and the reassembly of the anatase nanocuboids along the -axis direction during the continuous hydrothermal process. The degradation rate of pH 0.5-TiO was the highest at 1.66 × 10 min, which was 1.3, 1.5, 2.0, 2.3, and 18.4 folds higher than that of pH 3.0-TiO (1.27 × 10 min), pH 7.0-TiO (1.11 × 10 min), pH 5.0-TiO (0.83 × 10 min), P25-TiO (0.73 × 10 min), and the blank sample (0.09 × 10 min), respectively. Compared with P25-TiO and the other anatase TiO samples, pH 0.5-TiO exhibited the best photocatalytic activity, which was mainly attributed to its larger proportion of {010} (or {100}) facets, smaller crystalline size, higher band gap, and larger specific surface area.