超声波作用下的钛醇盐水解法制备纳米TiO2

近十几年来, 有关二氧化钛光催化性能的研究已引起人们的浓厚兴趣, 在此方面进行了大量研究. 目前, 纳米二氧化钛的制备方法主要有化学沉淀法、溶胶-凝胶法、气相法和水热法等1,2]. 超声化学是近年来新兴的一门边缘交叉学科, 已被应用于制备具有特殊结构和性能的纳米材料, 如金属3]、碳化物4]、氮化物5]、氧化物6]、合金7]以及生物材料8]等, 但对于超声作用在纳米粒子晶型转变方面的研究报道较少.

Sonochemical Synthesis of Nanocrystalline TiO2 by Hydrolysis of Titanium Alkoxides

Nanocrystalline TiO₂ has been studied extensively in recent years as photocatalysts to deal with environmental pollutions, such as water purification, wastewater treatment and air purification. Here a novel sonochemical method for directly preparing anatase nanocrystalline TiO₂ has been established. Nanocrystalline TiO₂ were synthesized by the hydrolysis of titanium tetrabutyl in the presence of water and ethanol under a high-intensity ultrasonic irradiation(20 kHz, 100 W/cm²) at 363 Kfor 3 h. The structure and particle sizes of the product were dependent upon the reaction temperature, the acidity of the medium and the reaction time. Characterization was accomplished by using various different techniques, such as powder X-ray diffraction(XRD), transmission electron microscopy(TEM), thermogravimetry differential thermal analysis(TG-DTA) and Fourier transform infrared(FTIR) spectroscopy. The TEMimages showed that the particles of TiO₂ were columnar in shape and the average sizes were ca. 3 nm×7 nm. The formation mechanism of nanocrystalline TiO₂ under a high intensity ultrasonic irradiation was also investigated. The hydrolytic species of titanium tetrabutyl in water condensed to form a large number of tiny gel nuclei which aggregated to form larger clusters. Ultrasound irradiation generated a lot of local hot spots within the gel and the crystal structural unit was formed near the hot spots with the decrease of the gel nuclei, which lead to form nanocrystal particles.