【作者】 刘馨琳；

【导师】 姚冠新；

【作者基本信息】 江苏大学 ， 材料学， 2014， 博士

【摘要】 纳米半导体材料由于其独特的光、磁、电等特性,在化工、医药、电子和环境保护等领域得到广泛的应用,成为目前最热门的研究材料之一,其中以硒化镉(CdSe).硫化镉(CdS)、二氧化钛(TiO2)为代表的光催化材料研究居多。但是由于CdS、CdSe极易光腐蚀,光稳定性差；而TiO2的光吸收阈值局限在紫外光区,太阳光利用率低,这些不足极大地限制了它们性能的发挥,针对以上问题,对CdSe、CdS和TiO2进行有目的的改性,以提高其稳定性及光催化性能显得尤为重要。本文分别利用负载、复合、掺杂及表面修饰等多种手段对纳米半导体材料(CdSe、CdS、TiO2)改性,制备了各种CdSe、CdS、TiO2复合光催化剂,结合X-射线衍射仪(XRD)、固体紫外可见漫反射(UV-vis DRS)、傅立叶红外光谱仪(FT-IR)、透射电子显微镜(TEM)、X-光电子能谱分析(XPS)、光致发射光谱分析(PL)、电子扫描显微镜(SEM)、拉曼光谱分析(Raman)、热重分析(TG)等多种表征,系统的考查了复合光催化剂的结构、形貌、晶相、吸光特性等理化性能。成功构建了CdSe、CdS、TiO2复合光催化剂光催化降解抗生素的体系,并阐述了可能的降解机理和构效关系。本工作主要包括以下三个方面的内容：1、硒化镉及其复合光催化剂的制备及其对抗生素废水的光降解行为和机理的研究(1)以3-巯基丙酸为稳定剂采用水热法合成结晶度良好的CdSe量子点光催化剂。通过XRD、UV-vis DRS、FT-IR、TEM和XPS等表征手段对CdSe量子点的结构、形貌等进行表征。通过TEM照片知,合成的CdSe量子点颗粒大小均一,分散性好,它们的直径大约在5nm左右。并以头孢氨苄抗生素溶液为模拟废水进行光催化降解实验,探究了各种条件对光催化降解效果的影响,结果表明：当Se/Cd的摩尔比为5/4,以氯化镉为镉源合成的CdSe量子点具有较高的光催化活性。在最优条件下经紫外光照射,CdSe量子点对头孢氨苄废水的降解率达到70.34%。(2)以CdSe量子点为敏化剂,采用多步水热法合成了量子点敏化的硒化镉-钨酸铋(CdSe-Bi2WO6)复合光催化剂。利用XRD、SEM、PL、UV-vis DRS等手段对制备的光催化剂进行表征；通过PL分析可知,CdSe-Bi2WO6复合光催化剂的荧光强度比纯Bi2WO6有所减弱,这预示着CdSe-Bi2WO6复合光催化剂的光催化活性将有所提高。实验中以四环素废水为研究对象,考查了复合光催化剂的光催化活性,研究结果表明CdSe的负载量对CdSe-Bi2WO6复合光催化剂的光催化活性有一定的影响,光催化性能随CdSe负载量的增加先增强后减弱,当CdSe的负载量为15%时达到最佳效果。光催化再生实验表明,经量子点敏化的CdSe-Bi2WO6复合光催化剂具有良好的稳定性,5次循环实验后仍保持较高的光催化活性。2、硫化镉量子点复合光催化剂的制备及其对抗生素废水的降解效率研究(1)以碳纳米管(CNTs)为载体,采用水热法合成了碳纳米管表面负载CdS量子点的复合光催化剂CdS/CNTs。利用XRD、TEM、Raman、UV-vis DRS、PL等手段对制备的光催化剂的形貌、结构进行了表征；考查了不同条件如催化剂中CNTs的含量对CdS/CNTs复合光催化剂光催化降解四环素模拟废水活性的影响,并深入讨论了光催化降解的动力学行为。结果表明,95%-CdS-5%-CNTs复合光催化剂具有较高的光催化活性,降解率达到81.2%。且降解过程符合一级动力学行为。(2)采用水热法将CdS量子点与三氧化钨(WO3)半导体材料复合,构建能带交错的异质结复合光催化剂CdS-WO3,通过XRD、SEM、STEM、TEM、 UV-vis DRS、PL等手段对光催化剂的形貌、结构进行表征。以环丙沙星抗生素水溶液为模拟废水进行光催化降解实验,考查了催化剂中CdS的复合量对光催化降解环丙沙星活性的影响。结果显示,30%-CdS-70%-WO3的光催化剂对环丙沙星废水的降解率最高,为88.85%,其活性是相同实验条件下纯W03对环丙沙星废水降解率的3倍。3、二氧化钛复合光催化剂的制备及其对抗生素废水的降解行为和选择性研究(1)选取氯化钠(NaCl)为氯源,采用固相合成法合成了氯掺杂的Ti02复合光催化剂。通过XRD、SEM、TEM、XPS、UV-vis DRS等对催化剂的晶相、表面结构、形貌、掺杂及吸光特性进行了表征,结合降解实验考查了不同氯源和不同煅烧温度对合成复合光催化剂光催化降解环丙沙星抗生素废水活性的影响。结果表明,以NaCl为氯源掺杂TiO2的复合光催化活性最高,对环丙沙星抗生素废水的降解率达到87.71%。(2)以环丙沙星(CIP)为模板分子,以丙烯酰胺(AM)、三羟甲基丙烷丙烯酸酯(TMPTA)、偶氮二异丁腈(AIBN)分别为功能单体、交联剂和引发剂,采用光引发的方式合成了表面分子印迹氯掺杂TiO2光催化剂。利用XRD、SEM、TEM、FT-IR、TG、UV-vis DRS等对制备的表面分子印迹光催化剂的结构、形貌进行表征。考查了不同功能单体、以及不同模板分子与功能单体的摩尔比对表面分子印迹光催化剂降解环丙沙星模拟废水活性的影响。结果显示：当以AM为功能单体,模板分子、功能单体、交联剂三者的摩尔比为1：2：6时,表面分子印迹光催化剂在可见光下对环丙沙星的降解效果最佳,降解率为70.9%。同时结合对不同目标物的对比降解实验,说明了制备的分子印迹光催化剂对环丙沙星具有较好的选择性降解能力。(3)以四环素(TC)为模板分子,分别以4-乙烯基吡啶(4-VP)、TMPTA、 AIBN和甲苯作为功能单体、交联剂、引发剂和溶剂,采用微波加热方式合成了表面分子印迹氯掺杂TiO2光催化剂。利用XRD、SEM、TEM、FT-IR、UV-vis DRS等对制备的表面分子印迹光催化剂进行表征,利用降解实验考查了不同溶剂、反应时间以及模板分子与功能单体的不同比例对所制备的表面分子印迹光催化剂光催化降解TC模拟废水活性的影响。结果表明,当模板分子、功能单体、交联剂三者的摩尔比等于1：4：6,微波加热功率为600W,加热时间为90min时得到的表面分子印迹光催化剂对15mg/L的TC溶液的降解达到最佳效果,降解率为72.35%。对不同污染物的降解对比实验表明,表面分子印迹光催化剂对目标污染物TC具有较好的选择性降解能力；并用液质联用等手段阐述了四环素的光催化降解过程。更多还原

【Abstract】 Semiconductor nano materials have been widely used in chemical, pharmaceutical, electronics, military, aerospace and other fields due to its unique electric, optical, magnetic properties, which have been one of the most popular research materials at present. Among the semiconductor materials, CdSe, CdS, TiO2are the most in-depth study because of the excellent photoelectric properties. But, the CdSe and CdS photocatalysts are easily photocorrosion during the process of photodegradation, and the TiO2is limited by the visible light, so it is need to modified the photocatalysts to improve the photocatalytic activity.In this paper, the CdSe, CdS and TiO2were modified by loading, compositing, etc to construct the composite photocatalyst to increase the photocatalytic activity. The samples were characterized with XRD, UV-vis DRS, FT-IR, TEM, XPS, SEM and PL.This paper mainly includes the following three aspects:1. Preparation and research on the mechanism and photodegradation of antibiotic with CdSe and their composite photocatalysts.(1) CdSe nanocrystals were synthesized with3-Mercaptopropionic acid as a stabilizer by hydrothermal method. The structure and properties of CdSe quantum dot will be characterized by XRD, UV-vis DRS, FT-IR, TEM and XPS data. According to the photocatalytic degradation of Cefalexin wastewater, the effect and mechanism of various conditions were discussed. The results show that:theCdSe quantum dots with cadmium chloride as the Cd source, in the molar ratio of Se/Cd to5/4have the highest photocatalytic activity and the degradation ratio of Cefalexin wastewater reached70.34%under the UV light.(2) The CdSe-Bi2WO6composite photocatalyst was synthesized by multi-step hydrothermal method via selecting the CdSe nanocrystals as a sensitizer, which is applied to the research on photocatalytic degradation of Ttetracycline wastewater under visible light. The prepared photocatalyst was characterized by XRD, SEM, PL and UV-vis DRS. The content of CdSe has certain effect on the photocatalytic activity of CdSe-Bi2WO6composite photocatalysts. When the load of CdSe was15%, the photocatalytic activity was highest. The CdSe-Bi2WO6composite photocatalyst has good stability and keep high activity after5times of repeated experiments.2. Preparation and Research on the photodegradation of antibiotic with CdS composite photocatalyst.(1) Carbon nanotubes (CNTs) as a carrier, the CdS/CNTs composite photocatalyst were synthesized by hydrothermal method. The structure and performance of photocatalysts were characterized by XRD, TEM, Raman, UV-vis, DRS, PL etc, and discussed the activity and kinetics of photodegradation. From the results,95%-CdS-5%-CNTs conposite photocatalyst has high photocatalytic activity, the degradation ratio of Tetracycline is81.2%. Moreover, the process of degradation adhere to the first-order kinetic.(2) CdS-WO3photocatalyst with heterojunction structure were prepared via the hydrothermal method. The structure and properties of the photocatalyst were characterized by XRD, SEM, STEM, TEM, UV-vis, DRS, PL, etc. The photocatalytic degradation experiments on Ciprofloxacin antibiotic solution was tested. Effects on the photocatalytic activity of different concertration of CdS was investigated and the results show that30%-CdS-70%-WO3composite photocatalyst on degradation of Ciprofloxacin waste water reached88.85%, which is3times of pure WO3.3. Preparation and Research on the photodegradation and selection of antibiotic with TiO2composit photocatalyst(1) The Cl doped TiO2composite photocatalyst were prepared via a solid-state method with NaCl as the source of chlorine. The crystal phase, surface structure, morphology, doped and optical properties of the photocatalysts were characterized by XRD, SEM, TEM, XPS, UV-vis, DRS, etc. Through doped with different ion and synthesised with different calcination temperature, we can find that the photocatalytic activity of Cl doped TiO2is highest and the degradation ratio of Ciprofloxacin antibiotic waste water reached87.71%.(2) The surface molecular imprinted Cl doped TiO2photocatalyst was synthesized by surface molecular imprinted technology using Ciprofloxacin (CEP) as the molecular template. The acrylamide (AM), Trimethylolpropaneacrylate (TMPTA), and2,2-azobisisobutyronitrile (AIBN) were considered to functional monomer, cross-linking and initiate, respectively. The structure, morphology and properties of the imprinted photocatalyst were characterized by XRD, SEM, TEM, FT-IR, TG, UV-vis and DRS, etc. Effects of different functional monomers and different ratio on imprinted photocatalyst were investigated. From the results, when the molecular imprinted photocatalyst with the proportion of molecular template and functional monomer was1:2:6and the AM as the functional monomers, the degradation ratio of Ciprofloxacin under visible light reached70.9%. From the photodegradation experiments with different targets, we can find that the photocatalyst prepared by molecular imprinting technique has better selectivity.(3) The Cl doped TiO2imprinted photocatalyst was prepared via surface molecular imprinted technology with a facile microwave-assisted method with Tetracycline (TC) as the molecular template.4-vinyl pyridine (4-VP), Trimethylolpropaneacrylate (TMPTA), and2,2-azobisisobutyronitrile (AIBN) were considered to functional monomer, cross-linking agent and initiate, respectively. The molecular imprinted photocatalyst was characterized by XRD, SEM, TEM, FT-IR, UV-vis, DRS etc. Photocatalytic activity of the surface imprinted photocatalyst with different ratios and different solvents, reaction time, the kind of template molecule and functional monomer is discussed. From the results, we can see that When the template molecule: functional monomer:crosslinking is1:4:6, power of microwave heating is600W, the heating time is90min, the surface imprinted photocatalyst on degradation of TC solution with15mg/L reached to72.35%. At the same time, the mechanism of photocatalytic degradation with surface molecular imprinting Cl doped TiO2photocatalyst were studied.更多还原