Exposed crystal surface-controlled TiO2 nanorods having rutile phase from TiCl3 under hydrothermal conditions

Size-, shape-, and phase structure-controlled synthesis of TiO2 nanocrystallites has long been one of the main themes in TiO2 research. Many synthetic techniques have been utilized in the preparation of TiO2 nanocrystals, among which hydrothermal treatment has been drawing much attention because it directly produces well-crystallized nanocrystallities of a wide range of compositions of crystal phases within a short reaction time. In this study, we carried out hydrothermal growth of rutile TiO2 rods by using aqueous titanium trichloride (TiCl3) solutions containing NaCl. Uniform ultrafine rutile TiO2 particles were obtained, and developed crystal faces were observed by TEM, SEM, XRD, and specific surface area measurements. The obtained rutile fine particles showed high levels of activity for degradation of 2-propanol and acetaldehyde under UV irradiation compared to the activity levels of anatase fine particles (ST-01) developed for environmental clean-up. The surface chemistry of the rutile TiO2 particles was also investigated. From photodeposition of Pt and PbO2, we suggest that the (1 1 0) face provides reductive sites and that the (1 1 1) face provides oxidative sites. These results indicate that the crystal faces facilitate the separation of electrons and holes, resulting in improvement of photocatalytic activity.

The surface chemistry of the rutile TiO2 particles was also investigated. From photodeposition of Pt and PbO2, we suggest that the (1 1 0) face provides reductive sites and that the (1 1 1) face provides oxidative sites. The results suggested that the crystal faces improve the separation of electrons and holes, resulting in improvement of photocatalytic activity. Figure optionsDownload as PowerPoint slide