我們以水熱法製備氧化鈦奈米管Dnt，並以原子吸收光譜(AAS)、熱重分析(TGA)、X射線繞射光譜(XRD)、拉曼光譜、高解析穿透式電子顯微鏡(HRTEM)、N2等溫吸附脫附，以及擴散反射式紫外線-可見光光譜(UV-vis)等工具鑑定。 N2等溫吸附脫附實驗顯示Dnt具有極高的表面積(385 m2/g)，遠高於起始二氧化鈦Degussa P25 (50 m2/g)。根據HRTEM觀察，奈米管外徑約8至10 nm，而內徑約6至8 nm。XRD及拉曼光譜指出Dnt的晶型與P25極為不同，並非anatase及rutile。 本研究探討煅燒條件對Dnt的影響─隨著煅燒溫度的提升，Dnt表面積會逐漸地下降，而形態則是會由奈米管狀逐漸變成顆粒狀。Dnt的晶型轉變成anatase發生在300至400 oC間。 Dnt的光催化活性是以亞甲基藍脫色反應評估。Dnt雖然不如P25，但可藉由煅燒而有顯著的提升。這結果顯示其光催化活性是由晶型所支配而非表面積。 我們以初溼含浸法與直接水熱法製備氧化鈦奈米管擔體銀觸媒。NO的程溫脫附實驗顯示水熱法所製備的樣品具有極高的NO吸附能力，並且能將NO分解產生N2。 Titania nanotubes were prepared by hydrothermal method and characterized by atomic absorption spectroscopy (AAS), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), Raman spectroscopy, high resolution transmission electron microscopy (HRTEM), N2 adsorption/desorption iso- therm and diffuse reflectance ultraviolet- visible spectroscopy (UV-vis). The N2 adsorption/desorption isotherm experiment indicated that Dnt exhibits high surface area (385 m2/g), which is much higher than that of the raw TiO2 Degussa P25 (50 m2/g). The diameter of nanotubes was about 8 to 10 nm with the inner diameter of ca. 6 to 8 nm from HRTEM observation. XRD and Raman spectroscopy indicated that the crystal phase of Dnt is very different from Degussa P25, which is neither the anatase nor the rutile. The effects of calcination condition of the TiO2-nanotubes were studied in this research. The surface area reduced progressively and the morphology changed from nanotube-shaped to particle form along with the increase of calcination temperature. The crystal phase of Dnt was changed to anatase after calcination between 300 and 400 oC. The photocatalytic activity of Dnt was evaluated by photobleaching of methylene blue. The activity of the Dnt is poorer than that of the Degussa P25, but being improved significantly by calcination. The results suggested that the photocatalytic activity is dominated by the crystal phase and not the surface phase. TiO2-nanotube supported Ag catalysts were prepared by incipient-wetness impregnation and direct hydrothermal method. Temperature-programmed desorption of NO (NO-TPD) indicated that the hydrothermal sample exhibits higher capability for NO adsorption and decomposition of NO to N2.