El-Toni Ahmed Mohamed, Yin Shu, Sato Tsugio
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan.
J Colloid Interface Sci. 2006 Aug 1;300(1):123-30. doi: 10.1016/j.jcis.2006.03.073. Epub 2006 May 11.
Titania is of potential interest as an ultraviolet (UV) radiation blocking material in personal care products because of its excellent UV light absorption properties. Its high photocatalytic activity, however, facilitates the generation of reactive oxygen species, which can oxidize and degrade other ingredients during its formulation, raising safety concerns. Dense coating of titania nanoparticles with a silica layer could help in depression of their photocatalytic activity by disturbing the formation of radicals produced by the reaction of oxygen and/or water with the electron-hole pair. Depression of the high photocatalytic activity of titania necessitates that the silica shell has to be thick, with minimum microporosity. Coating parameters were optimized to attain greater amounts of precipitated silica and thicker shells with lower microporosity, which in turn resulted in great depression of photocatalytic activity. Silica-coated titania nanoparticles were characterized by TEM, XPS, FT-IR, EDX, and microporosity measurements. The photocatalytic activity was evaluated for the coated powder to investigate the efficiency of the silica coating as well.
由于其优异的紫外线吸收特性，二氧化钛作为个人护理产品中的紫外线阻隔材料具有潜在的吸引力。然而，其高光催化活性促进了活性氧的产生，在配方过程中活性氧会氧化和降解其他成分，这引发了安全问题。用二氧化硅层对二氧化钛纳米颗粒进行致密包覆，通过干扰氧气和/或水与电子 - 空穴对反应产生的自由基的形成，有助于降低其光催化活性。要降低二氧化钛的高光催化活性，二氧化硅壳必须足够厚且微孔率最低。对包覆参数进行了优化，以获得更多沉淀二氧化硅和更厚且微孔率更低的壳，这反过来又极大地降低了光催化活性。通过透射电子显微镜（TEM）、X射线光电子能谱（XPS）、傅里叶变换红外光谱（FT - IR）、能量散射X射线光谱（EDX）和微孔率测量对二氧化硅包覆的二氧化钛纳米颗粒进行了表征。还对包覆粉末的光催化活性进行了评估，以研究二氧化硅包覆的效率。
