具有磁性的表面等离子体复合光催化剂的构建及其对PAHs降解机理研究

Polycyclic aromatic hydrocarbons (PAHs), a class of typical persistent organic pollutants, widely exist in water bodies of China, which results in an urgent need to explore the efficient degradation technology. The aims of this investigation are to fabricate magnetic plasmonic composite photocatalysts for effective photodegradation of PAHs in water under visible light. Fe3O4 composites with g-C3N4 or GO single layer will be fabricated by a combining method. Then, one-dimensional silver based semiconductors such as Ag2CrO4 and Ag2S further are self-assembled on the surface of Fe3O4/g-C3N4 or Fe3O4/GO to form magnetic plasmonic composite photocatalysts, which can achieve the visible light degradation of PHAs in water. The magnetic plasmonic composite photocatalysts can be quickly separated from the water with assistance of the outside magnetic field, taking advantage of the superparamagnetism of Fe3O4, so that the processes of separation and regeneration for the catalysts are simple and repeatable. According to comparison and selection of the catalyst preparation methods and influence factors, optimal preparation methods and conditions for the magnetic plasmonic composite photocatalysts will be obtained. Taking the typical PAHs such as naphthalene, phenanthrene and pyrene as the targeted compounds, the degradation kinetics and main influencing factors will be studied and a dynamic model of catalytic degradation of the target compounds will be established. Through identifying the degradation products of target compounds, and combining with the active sites of the theoretical calculation data, the degradation pathway of the target compounds will be discussed in details. Furthermore, the structure-activity relationship between microstructure and performance of photocatalysts will be proposed. By the implementation of this project, the experimental and theoretical foundation will be investigated throughout for the novel photocatalysts which will be applicable to degrade and remove PAHs in water under visible light irradiation. The results will promote the application of magnetic plasma composite photocatalysts on the purification and pollution control of water environment.

本项目拟以我国水体中广泛存在的持久性有机污染物多环芳烃（PAHs）为目标物，将四氧化三铁(Fe3O4)纳米颗粒与单层类石墨相氮化碳(g-C3N4)或氧化石墨烯(GO)纳米片复合，制备出磁载的Fe3O4/g-C3N4或Fe3O4/GO，再在其表面自组装一维银基半导体形成磁性等离子体复合光催化剂，实现其对水体中PAHs的可见光降解。利用Fe3O4的超顺磁性，实现在外磁场辅助下将光催化剂迅速分离，以重复利用。通过催化剂制备方法与影响因素的比选,确定最优制备方法与条件；以典型PAHs(萘、菲、芘等)为目标物，研究其降解动力学及主要影响因素，建立其降解动力学模型；鉴定降解产物，并结合活性点位的理论计算数据，以探讨目标物的降解途径，揭示光催化剂的微结构与性能之间的构效关系。为设计该类光催化剂应用于水体中PAHs降解及去除奠定实验及理论基础，推动磁性等离子体复合光催化剂在水环境净化和污染治理方面的应用。

多环芳烃类化合物（PAHs）是典型的持久性有机污染物（POPs），被列为优先控制污染物的一类，主要来源于燃料的不完全燃烧，也有一些PAHs是化工原料，如萘、菲与蒽等，我国许多水体乃至饮用水源都受到了PAHs的污染。因此，有必要开发应用于水中微量PAHs的去除技术，从而降低其对生态环境和人类健康的潜在风险。.本研究首次合成了具有表面等离子体共振效应的多元p-n结或等离子体共振的纳米催化剂（如 Co3O4/Bi2O2CO3、n-BiVO4@p-MoS2、g-C3N4/Bi4Ti3O12、h-BN Bi4O5Br、Bi4O5Br2、 Ag/Ag2CO3/BiVO4、Cu2O/Bi2MoO6 等），开展了新型磁性光催化剂（Ag/Ag2S/h-RGO、Fe3O4/C3N4/Co3O4等）研究，以建立了一种新型、可回收利用的可见光催化材料的方法。利用多种表征手段，对材料的结构组成和光学性质进行分析，研究其对光催化活性的影响，探讨目标化合物的降解速率与光催化剂电子和晶体结构之间的构效关系。引入外加磁场，考察所制备磁性复合光催化材料在实际应用过程中的分离和回收效率，实现光催化剂的简便回收。利用计算模拟探究新型材料模型及其能带和电子结构，探索Ag纳米粒子引起的SPR效应的FDTD模拟方法，从分子、原子水平阐明复合光催化剂电子和能带结构变化及载流子迁移机理，并将实验得到的数据与模拟计算结果相互验证。探究PAHs的高效检测方法，建立PAHs及其衍生物可见光催化的降解动力学模型。利用高斯软件模拟，确定PAHs（萘与萘酚）分子结构中易被攻击的反应位点。通过GC-MS，LC-MS等谱学手段鉴定PAHs及其衍生物降解过程的中间产物。利用自由基捕获及电子顺磁波谱（EPR）鉴定光催化反应过程中发挥主要作用的活性物种。结合以上各种实验结果，推导这类光催化材料高效光催化降解PAHs的反应机理。在完成既定任务的同时，课题也开展了新型异质结可见光光催化材料降解水中PCPPs的研究，并取得了较好的效果。.课题完成了预定的目标任务，并做了相关扩展工作。已发表SCI收录论文18篇，其中2篇为ESI高引论文，发表中文核心期刊论文3篇，另有几篇论文待发表。研究成果将为新型可见光催化剂的合成与调控提供科学依据，为去除水中PAHs等有毒有害有机物去除提供新型、高效的方法和技术。