Photocatalytic properties of exposed crystal surface-controlled rutile TiO2 nanorod assembled microspheres.

The photocatalytic activity of TiO 2 is correlated with its exposed crystal surface, phase composition, morphology, and crystallite size. In this study, TiO 2 microspheres with exposed crystal surface-controlled rutile TiO 2 nanorods were fabricated by employing a simple hydrothermal reaction in the presence of NaCl solution. The crystal phase, morphology, and size of the as-obtained materials were significantly dependent on the NaCl concentration. The exposed crystal surface of TiO 2 nanorods could be tailored by adjusting the NaCl concentration. With increasing NaCl concentration, the exposed area of the (1 1 1) crystal surface gradually decreased, whereas the area of the newly exposed (0 0 1) surface gradually increased. Characterization results indicated that the crystal phase of the TiO 2 microspheres was the only rutile structure in the system and no brookite phase was found. The diameter of the microspheres can be changed from 3.5 μm to 2 μm by tuning the NaCl concentration. Photocatalytic degradation of papermaking wastewater using the synthesized materials showed that the photocatalytic activities of the samples are affected by the exposed (0 0 1) crystal surface of TiO 2 , which can induce the separation of electrons and holes, thereby resulting in improved photocatalytic activity. [ABSTRACT FROM AUTHOR]