功能化碳点化学发光行为研究及其在环境检测中的应用
文献类型：学位论文
| 作者 | 耿方兰 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 赵利霞 |
| 关键词 | 功能化碳点 Fe 化学发光 modified carbon dots 分析检测 BPEI chemiluminescence analysis iron |
| 其他题名 | Chemiluminescence Behavior of Functional Carbon dots and the Application in Environmental Detection |
| 学位专业 | 环境科学 |
| 中文摘要 | 碳点作为一种尺寸小于 10nm的新型荧光纳米碳材料，自 2004年被发现并分离之日起，就受到了广泛关注。因其表面含有丰富的羟基、羧基以及其它含氧官能团，导致其具有良好的水溶性，同时具有很好的功能化特性，更容易进行表面修饰。而碳点良好的荧光特性以及生物友好性，使其在分析检测、生物标记以及生物成像方面的应用研究成为热点。与传统半导体量子点相比，碳点中不含任何重金属元素，具有环境友好性的巨大优势，因此而受到更多专家学者的关注，具有更好的研究及应用前景。 碳点的化学发光特性是碳点光学特性中十分重要的性质。与已知体系的化学发光机理相似，碳点的化学发光过程一般也存在电子 -空穴复合的氧化还原反应或是高能态中间产物的生成。但是其具体的发光机理目前尚未形成统一结论。化学发光作为一种高灵敏的超痕量检测手段已经被广泛研究，而且形成了许多成熟的化学发光体系，这些体系被广泛应用于自由基、金属离子以及有机物等的分析检测中。但是，碳点作为新型材料，对于其化学发光过程及应用研究相对较少。目前已经报道的碳点的化学发光体系都是向碳点中加入弱化学发光体系或者强氧化剂，而实验室之前的工作报道了碳点在不加任何化学发光体系和强氧化剂，仅仅在强碱存在条件下即可产生化学发光。基于此，本研究对聚乙烯亚胺修饰的功能化碳点的化学发光行为进行了研究。研究主要包括以下两个部分： 1、对文献功能化碳点的合成方法进行了改进，建立了一步式水热反应法合成聚乙烯亚胺修饰的功能化碳点的方法。对所合碳点的形貌、粒径、紫外 -可见吸收和光致发光特性进行了表征。对功能化碳点-NaOH体系的化学发光特性进行了研究，并与乙二胺四乙酸盐热解法合成的裸碳点-NaOH体系进行了对比。发现相同条件下，经修饰的碳点在碱性条件下化学发光强度强于裸碳点。而且，当对水样中存在的金属离子进行筛查时发现，只有 Fe(III)能顾特异性增敏碳点-NaOH体系的化学发光，这种增强作用对修饰后的碳点效果更加明显。在此基础上建立了 Fe(III)的化学发光传感检测体系，检测限可达 6.67×10-8M。应用此体系对三种实际水样进行了加标回收测定，回收率分别为 101%、103%和 93%。对此体系的化学发光机理进行研究，推测发光机理为 Fe(III)作为氧化剂想碳点表面注射空穴，与 NaOH化学还原作用注射的电子放射性复合，产生化学发光。 2、对功能化碳点-Fenton反应体系的化学发光进行了研究。发现所合碳点在酸性Fenton反应体系中表现出化学发光现象，其发光强度是同等条件下裸碳点发光强度的近 1倍。而且化学发光发光强度随 H2O2浓度及 Fe(II)浓度增加而增大，当 Fe(II)浓度大于 5×10-4M时，出现二次发光现象。利用第一次发光现象对苯酚进行检测，初步实验结果显示，苯酚加入到碳点-Fenton体系中可以使体系的化学发光信号降低，但是其信号降低程度有限，尚不能进行实际检测应用，需进一步研究。对其发光机理进行初步研究，两次化学发光光谱显示，两次发光过程均为碳点发光。认为第一次发光现象为(O2)2*生成的共振能量转移过程，第二次发光为 HO•参与的碳点发光过程。 功能化碳点-Fe(III)-NaOH化学发光体系以及功能化碳点-Fenton反应体系， 两个发光体系的发光机理不尽相同，但是都为揭示碳点化学发光机理提供了参考，并且为进一步研究碳点的化学发光过程机理及实际应用提供了理论指导。 |
| 英文摘要 | As a new photoluminescence nano carbon material, whose diameter is smaller than 10 nm, carbon dots have acquired much attention since they are firstly discovered and purified in 2004. For the abundant oxygenic groups, such as carboxyl and hydroxyl in surface, carbon dots have excellent water solubility, which makes it easier to be modified. Carbon dots have been used in many fields such as analytical methods, bio-labeling and bio-imaging for their great photoluminescence quality and biological friendly. Compared to the traditional quantum dots, carbon dots are environmentally friendly and bio-nontoxic, which abstract much attention from the researchers. Chemiluminescence (CL) of carbon dots is a very important optical property. Just as the formal CL, carbon dots can release CL when there is radiative recombination of electrons and holes or there are intermediate products in excited state. Because of the complexity of the mechanism and lack of time in this field, there is no consolidated conclusion yet. But as a high sensitive testing method, CL has been studied for a long time, and there have been a lot of CL systems that have been used in analysis free radicals, metal ions and organics. At the same time, the CL of carbon dots has been studied less than other CL systems. As far as we can see, there are a few of systems studied by some researchers, all of them are systems with weak CL systems or strong oxidants in carbon dots solution. Our lab have studied the CL behavior of carbon dots before. In our previous work, we have found a surprising CL behavior of fluorescent carbon dots in the presence of strong alkaline, such as NaOH and KOH. Based on the above, this work is focused on the CL behavior of modified carbon dots. It contains two parts: 1. We have improved the method for the synthesis of branched polyethyleneimine(BPEI) modified carbon dots (BPEI-CDs), and established an easier hydrothermal method for the BPEI-CDs. We used HRTEM, FT-IR, Fluorescence spectrophotometer and XPS to characterize the new material. We have studied the CL behavior of BPEI-CDs in NaOH solution, and compared the CL intensity with the naked carbon dots, which are synthesized through thermal decomposition of EDTA-Na2, in same NaOH solution. The CL intensity of BPEI-CDs is much stronger than the naked carbon dots. When we added different mental ions in the two above carbon dots-NaOH systems, the signal are enlarged very much, and the CL intensity of system with BPEI-CDs have been enlarged more than naked carbon dots. We established an analytical system for the Fe (III) detection. The lowest detection limit(LOD) is 6.67×10-8M. The method is determined by standard addition recovery, for the three water samples, the recovery rate are 101%、103%和 93%. A possible CL mechanism was studied by UV-vis, fluorescence, CL, FT-IR, XPS and EPR spectroscopy. We verified the CL characteristics of the carbon dots and the CL could be attributed to the various surface energy traps in the carbon dots. The radiative recombination of the injected electrons by “chemical reduction” and the injected holes by oxidation of Fe (III) caused the CL phenomenon of carbon dots. 2. We have studied the CL behavior of BPEI-CDs—Fenton system. The results showed that BPEI-CDs showed CL phenomenon in Fenton system, CL intensity of BPEI-CDs is about 10 times stronger than that of naked carbon dots. Meanwhile, The CL intensity increased with the increasing of the H2O2 and Fe (II). When the concentration of Fe (II) was greater than5×10-4M, a second CL appeared. When we added phenol into this CL system, the CL intensity reduced with the increasing of phenol. But there are more work needed to be done for the system used for phenol detection. The mechanism was preliminary explored. The first CL is probably due to the (O2)2*, which causes a resonance energy transfer, and the second CL is probably due to the HO• generated from the Fenton reaction. The mechanisms of the BPEI-CDs—Fe(III)—NaOH system and BPEI-CDs—Fenton system are not same, but they all provided consult for the revelation of the CL mechanism of carbon dots. Further, they provided theoretical guidance for the actual use of the CL of carbon dots. |
| 公开日期 | 2015-06-12 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/13457]  |
| 专题 | 生态环境研究中心_环境化学与生态毒理学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 耿方兰. 功能化碳点化学发光行为研究及其在环境检测中的应用[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：生态环境研究中心
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