新型可见光敏化中空多壳层核壳结构制备的微界面结构调控及其在水体修复中的协同作用机理研究

In an effort to greatly enhance visible light utilization efficiency in photocatalytic wastewater remediation, a non-conventional template is firstly applied to synthetize CdS hollow nanospheres via hydrothermal synthesis method, which is visible light photosensitive and resistant to light corrosion. And then this research explores the preparation of homogeneous size and controllable nano graphene layer by chemical stripping method and the modification of its interfacial properties. Next, self-assembly of core-shell structure of graphene coated CdS hollow nanospheres in liquid environment is intensively investigated. The preferred combination method of hollow core-shell nanocomposite particles with functional activated carbon fiber and their interfacial interaction mechanism are studied in this research. With modifying the microstructure of core-shell structure and investigating its water remediation behaviors, it focuses on inspections of interaction mechanisms between micro-reaction interface and pollutants and synergistic effect of composites in various multilayer nano structure. One objective is to deeply understand dynamic self-assembly mechanism of multiple level hierarchical ordered nano core-shell structure. And other objective is to reveal the microcosmic reaction mechanism of visible light sensitization and the interactions and synergistic effects of core-shell materials and support in water treatment. In general, with exploring the controllable preparation method of hollow multi-shell core-shell structure, this research can provide theoretical and technical basis for the practicality of visible light photocatalyst for environmental friendly wastewater remediation.

为大幅提高可见光催化修复水体的光利用效率，研究采用非常规模板剂，通过水热合成法，探索制备具有可见光敏化特征且免受光源腐蚀的中空CdS纳米微球、化学剥离法制备尺度均一可控的石墨烯片层及其界面性能调控方法、在液相环境下石墨烯包覆中空CdS纳米微球的核壳自组装制备方法以及多壳层中空核壳结构的制备和调控方法。研究中空多壳层核壳表面改性与功能活性炭纤维的有机复合方法及界面间相互作用机制。通过对核壳结构界面间的微结构调控，结合水体修复研究，探索纳米材料间的微反应界面与污染物分子的相互作用，纳米复合粒子各种不同层次界面间的相互作用机理；深刻认识动态组装生成多级多层次有序纳米核壳功能结构材料的自组装作用原理；揭示可见光光敏化的微观作用机理及其在水体修复中载体、核壳之间相互作用方式和协同作用机理。探索中空多壳层核壳结构制备的规律性方法，为可见光催化剂的实用化和水体无害化修复提供理论依据和技术基础。

纳米核壳结构特别是双壳层中空核壳纳米结构材料的制备与机理探索对大幅提高光利用率，光高效快速降解有机污染物具有重要的理论意义与现实意义。通过对核壳结构材料及其光催化降解机理的系统研究和理论探索获得的主要结论如下：.1. 采用超声化学法成功地合成了易于调控、结构完好的PS@CdS核壳结构纳米球。核的平均粒径约260 nm，CdS壳层厚度在10~30 nm之间。其载流子浓度和可见光催化降解活性获得大幅提升。.2. 采用比较法合成了球状及树枝状两种PS@CdS@TiO2中空双壳层纳米材料。树枝形CdS@TiO2 HDNPs具有更高的光催化活性。球形CdS@TiO2 HDNPs其在五次重复实验中展现出更好的光催化稳定性。.3. 通过静电自组装的过程，将带负电的氧化石墨烯与带正电荷的中空CdS@SiO2结合后水合肼还原，获得中空CdS@SiO2@GR。去内核后制备出以中空CdS为内核，GR为外壳且内核与外壳之前存在独立的纳米间隔层的中空夹层型中空CdS@@GR复合光催化剂。.4. 研究表明，中空化后有利于光的多次折射利用和比表面积增加。偶联剂（PVP）是合成核壳型复合纳米材料的必备材料，水解是整个反应的限速步骤，较少的催化剂缺陷能抑制光生电子-空穴对的复合。核壳电子-空穴具有双重激发作用，可强化有机污染物的降解。快速产生和高度累积的羟基自由基是光催化降解过程中的主要活性物种，可以把包括RhB、MB和MO等有机污染物氧化降解为更小、无毒的物质。中空CdS@@GR表现出极为优异的吸附能力和光催化活性，特别适合处理浓度低、毒性高、降解难度大的有机染料废水。