Institut für Technische Chemie, Gottfried Wilhelm Leibniz Universität Hannover Callinstr.3, D-30167 Hannover, Germany.
ACS Appl Mater Interfaces. 2014 Feb 26;6(4):2270-8. doi: 10.1021/am4051876. Epub 2014 Feb 10.
Transparent layers containing TiO2 have been intensively studied because of their interesting application potential including photocatalytically active and self-cleaning surfaces. In the present work, transparent TiO2-ZnO thin films on a SiO2 interlayer were successfully deposited on the surface of polycarbonate to provide polymeric sheets with a self-cleaning, superhydrophilic, and photocatalytically active surface layer. To ensure a good adhesion of the SiO2 interlayer, the polycarbonate sheets were first modified by irradiation with UV(C) light. The prepared films were characterized by UV/vis spectrophotometry, SEM, XRD, Raman spectroscopy, ellipsometry, and water contact-angle measurements. All prepared films are transparent, have thicknesses in the range between 120 and 250 nm, and possess superhydrophilic properties. Moreover, they exhibit good adhesion qualities as defined quantitatively by cross-cut tests. However, their mechanical strengths, checked by felt-abrasion tests, differ by changing the molar TiO2-ZnO ratio. The photocatalytic activity, expressed as photonic efficiency, of the coated surfaces was estimated from the kinetics of the photocatalytic degradation of methylene blue and methyl stearate. The combination between superhydrophilic properties and photocatalytic activity was determined by studying the change of water contact angle during the storage of the prepared films in the dark under an ambient atmosphere and under an atmosphere containing either acetone or isopropanol followed by UV(A) irradiation. In addition, self-cleaning properties were examined by determining the changes in the contact angle during the irradiation time after applying oleic acid to the surface. The results show that increasing the molar ratio of ZnO in TiO2 coatings up to 5% yields maximum photonic efficiency values of 0.023%, as assessed by the photocatalytic degradation of methylene blue. Moreover, the superhydrophilic coating with a molar TiO2-ZnO ratio of 1:0.05 exhibits the best self-cleaning properties combined with a good mechanical stability and a very good stability against UV irradiation.
透明层含有 TiO2 已被深入研究，因为他们有趣的应用潜力，包括光催化活性和自清洁表面。在目前的工作中，透明 TiO2-ZnO 薄膜上的 SiO2 中间层成功地沉积在聚碳酸酯的表面提供聚合物片具有自清洁，超亲水，和光催化活性表面层。为了确保 SiO2 中间层的良好的附着力，聚碳酸酯片首先用 UV（C）光照射进行改性。制备的薄膜的特征在于紫外可见分光光度法，SEM，XRD，拉曼光谱，椭圆光度法和水接触角测量。所有制备的薄膜都是透明的，具有 120 到 250nm 的厚度，并具有超亲水性能。此外，它们表现出良好的附着力质量，通过十字切割试验定量定义。然而，它们的机械强度，通过毛毡磨损试验检查，通过改变 TiO2-ZnO 的摩尔比而不同。光催化活性，用光子效率表示，由亚甲基蓝和硬脂酸甲酯的光催化降解动力学来估计。在黑暗条件下，在环境气氛中和在含有丙酮或异丙醇的气氛下，通过研究制备的薄膜在储存过程中光催化活性的变化来确定超亲水性和光催化活性之间的组合。此外，通过测定表面涂覆的油酸后的接触角在照射时间内的变化来检查自清洁性能。结果表明，在 TiO2 涂层中 ZnO 的摩尔比增加到 5%，可以获得最大的光子效率值 0.023%，通过亚甲基蓝的光催化降解来评估。此外，具有摩尔比 TiO2-ZnO 为 1:0.05 的超亲水涂层具有最佳的自清洁性能，结合良好的机械稳定性和对紫外线辐射的非常好的稳定性。
