In the present study, a Fe₃O₄‐TiO₂ (FT) core‐shell and a core‐multishell structure of Fe₃O₄‐SiO₂‐TiO₂ (FST) were synthesized, and their bactericidal capability was investigated on Escherichia coli (E. coli). Scanning electron microscopy (SEM), ultraviolet–visible spectroscopy (UV–vis), X‐ray diffraction, Brunauer–Emmett–Teller, zeta potential, and fluorimetry were carried out to characterize properties of synthesized nanoparticles. An efficiency of 98% adsorption and harsh bacterial damage was observed when E. coli was put in contact with FST. Weaker adsorption of bacteria in contact with FT demonstrated that heterojunction has destructive effects on nanostructure. Further investigation proved that more OH were produced on the surface of FST, which is a sign of its longer lifetime. Moreover, results revealed that the presence of SiO₂ in the structure caused enhanced coverage, surface area, and porosity in TiO₂ outer layer, all of which have positive effects on adsorption. However, UV–vis showed smaller band gap for FT. It suggests that although photoactivity of FST is less influenced by light absorption, it possesses more e/h lifetime for generation of reactive oxygen species. Results point to the importance of SiO₂ as an obstacle of heterojunction on both adsorption and photoactivity. It was also proposed that increasing band gap in FST can be attributed to the porosity of SiO₂ that causes suppression of TiO₂ nanocrystallite growth.

中文翻译：

---

Fe3 O4 -SiO2 -TiO2 核-多壳纳米粒子对大肠杆菌光催化活性增强的吸附动力学和机理研究。

在本研究中，合成了 Fe ₃ O ₄ -TiO ₂ (FT) 核壳结构和 Fe ₃ O ₄ -SiO ₂ -TiO ₂ (FST)核-多壳结构，并研究了它们对大肠杆菌的杀菌能力。大肠杆菌（大肠杆菌）。使用扫描电子显微镜 (SEM)、紫外-可见光谱 (UV-vis)、X 射线衍射、Brunauer-Emmett-Teller、zeta 电位和荧光法来表征合成纳米粒子的性质。观察到 98% 的吸附效率和严重的细菌损伤。与 FST 取得了联系。与 FT 接触的细菌吸附较弱表明异质结对纳米结构具有破坏性影响。进一步的研究证明，在 FST 表面产生了更多的 OH，这是其寿命更长的标志。此外，结果表明，结构中 SiO ₂的存在导致 TiO ₂外层的覆盖率、表面积和孔隙率增加，所有这些都对吸附产生积极影响。然而，UV-vis 显示出更小的 FT 带隙。这表明虽然 FST 的光活性受光吸收的影响较小，但它具有更长的 e/h 寿命来产生活性氧。结果表明 SiO ₂的重要性作为异质结对吸附和光活性的障碍。也有人提出，FST 中带隙的增加可归因于 SiO ₂的孔隙率，其导致抑制 TiO ₂纳米微晶的生长。