Transformation of brookite-type TiO2 nanocrystals to rutile:: correlation between microstructure and photoactivity
Transformation of brookite-type TiO2 nanocrystals to rutile:: correlation between microstructure and photoactivity
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DOI：
10.1039/b514632a
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发表时间：
2006-01-01
影响因子：
--
通讯作者：
Petrova, N
中科院分区：
文献类型：
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作者：
Bakardjieva, S;Stengl, V;Petrova, N
以二氧化钛粉末、盐酸、尿素和聚乙二醇10000为原料，采用改进的热分解法制备了纯板钛矿型二氧化钛纳米粒子。在105℃下获得了平均直径约为400-450 nm的独特的花状沸石团聚体，其平均直径约为4-5 nm。研究了钛铁矿-金红石的转变，得到了在不同温度(200-800℃)下具有不同晶型的锐钛矿型、钛铁矿和金红石型二氧化钛混合物。用高分辨电子显微镜(HRTEM)、电子衍射图和BET/BJH分析表征了纯钛铁矿/二氧化钛混合物的物相组成、微晶尺寸和孔容。为了了解亚稳态二氧化钛的相变过程，对其进行了X射线粉末衍射分析。通过光催化降解水溶液中的4-氯苯酚，考察了不同组成的钛铁矿-锐钛矿-金红石和锐钛矿-金红石晶型的纯钛铁矿和不同组成的二氧化钛粉末的光催化活性。具有最高催化活性的二氧化钛样品在500℃时得到，其含量为：钛铁矿3.2%，锐钛矿42.9%，金红石53.9%，记为TiO[B])/500。
Nanometric particles of pure brookite TiO2 were synthesized by modified thermolysis of reactant solutions containing titania powder, HCl, urea and PEG 10000. Unique flower-like brookite agglomerates with an average diameter of similar to 400-450 nm composed of single brookite nanocrystals of similar to 4-5 nm were obtained at 105 degrees C. The brookite -> rutile transformation has been studied and TiO2 mixtures with variable amount of anatase, brookite and rutile polymorphs at different temperatures (from 200 to 800 degrees C) were obtained. High resolution transmission electron microscopy (HRTEM), electron diffraction pattern and BET/BJH analyses were used to characterize the phase assemblages, crystallite size and pore volume of the pure-phase brookite and TiO2 mixtures. In order to understand the metastable-stable TiO2 phase transformation X-ray powder diffraction (XRD) was performed. The photoactivity of pure brookite and TiO2 powders with different compositions of the brookite-anatase-rutile and anatase-rutile polymorphs obtained during the transitions was examined by photocatalyzed degradation of 4-chlorophenols in aqueous solution. The titania sample having the highest catalytic activity was obtained at 500 degrees C, contained 3.2% brookite, 42.9% anatase and 53.9% rutile and is referred to as TiO[B])/500.