PDF(Pubmed)
Abstract：
\"Core/shell\" composites are based on a ferrite core coated by two layers with different properties, one of them is an isolator, SiO2, and the other is a semiconductor, TiO2. These composites are attracting interest because of their structure, photocatalytic activity, and magnetic properties. Nanocomposites of the \"core/shell\" МFe2O4/SiO2/TiO2 (М = Zn(II), Co(II)) type are synthesized with a core of MFe2O4 produced by two different methods, namely the sol-gel method (SG) using propylene oxide as a gelling agent and the hydrothermal method (HT). SiO2 and TiO2 layer coating is performed by means of tetraethylorthosilicate, TEOS, Ti(IV) tetrabutoxide, and Ti(OBu)4, respectively. A combination of different experimental techniques is required to prove the structure and phase composition, such as XRD, UV-Vis, TEM with EDS, photoluminescence, and XPS. By Rietveld analysis of the XRD data unit cell parameters, the crystallite size and weight fraction of the polymorphs anatase and rutile of the shell TiO2 and of the ferrite core are determined. The magnetic properties of the samples, and their activity for the photodegradation of the synthetic industrial dyes Malachite Green and Rhodamine B are measured in model water solutions under UV light irradiation and simulated solar irradiation. The influence of the water matrix on the photocatalytic activity is determined using artificial seawater in addition to ultrapure water. The rate constants of the photocatalytic process are obtained along with the reaction mechanism, established using radical scavengers where the role of the radicals is elucidated.
摘要：
“芯/壳”复合材料基于铁氧体芯，由两层具有不同性能的涂层，其中一个是隔离器，SiO2，另一种是半导体，TiO2。这些复合材料由于其结构而引起人们的兴趣，光催化活性，和磁性。“核/壳”的纳米复合材料SPAFe2O4/SiO2/TiO2(SPA=Zn(II),Co（II））型是用两种不同方法生产的MFe2O4核合成的，即使用环氧丙烷作为胶凝剂的溶胶-凝胶法(SG)和水热法(HT)。SiO2和TiO2涂层通过正硅酸乙酯进行，TEOS,钛（IV）四丁醇，和Ti(OBu)4。需要结合不同的实验技术来证明结构和相组成，如XRD，UV-Vis,带EDS的TEM,光致发光，和XPS。通过Rietveld分析XRD数据的晶胞参数,确定了TiO2壳和铁氧体核的多晶型锐钛矿和金红石的微晶尺寸和重量分数。样品的磁性，在紫外光照射和模拟太阳照射下，在模型水溶液中测量了它们对合成工业染料孔雀石绿和罗丹明B的光降解活性。除超纯水外，还使用人工海水确定水基质对光催化活性的影响。获得了光催化过程的速率常数以及反应机理，使用自由基清除剂建立，其中自由基的作用被阐明。
