【作者】 郑立炎；

【导师】 池毓务；

【作者基本信息】 福州大学 ， 分析化学， 2011， 博士

【摘要】 电致化学发光（Electrochemiluminescence,简称ECL）是在化学发光基础上发展起来的一种新的分析方法，是化学发光与电化学结合的新的技术。它同时具有化学发光与电化学技术的优点，比如灵敏度高、选择性好、背景信号低、线性范围宽，反应可控等特点。本论文的研究主要为了解决目前电致化学发光体系相对较少的问题，研究了一些新材料，主要包括离子液体介质、碳量子点发光体、发光试剂Nafion膜载体、亚锡离子共反应物、氧化亚锡纳米颗粒共反应物等材料在电致化学发光中的应用，开发了一些新的ECL体系并对其ECL机理进行了详细的研究和探讨。本论文分为四个部分，共六章。论文的第一部分，也是第一章，进行文献调研和综述，主要对ECL的发展概况、基本原理、特点、分类及其在分析化学领域中的应用，同时还对本课题的研究目的和意义做了概述。论文的第二部分即第二章，主要是以离子液体作为反应介质，研究了三联吡啶钌/三乙胺电致化学发光体系在这种高粘度、高离子强度的反应介质中的电致化学发光行为。以该反应体系在中性pH缓冲溶液中的电致化学发光行为作为参照。研究发现该体系在离子液体介质中的电化学和电致化学发光行为与其在水溶液中的大不相同，在阳极扫描过程中有两个ECL发光过程，电化学上没有出现明显的催化电流。讨论了该体系在离子液体介质中的反应机理及反应介质的离子强度及粘度对扩散速率、催化效率和电致化学发光强度的影响。论文的第三部分即第三章，通过简单有效的电化学电势扫描方法，在中性水溶液中将具有ECL活性的碳量子点从石墨电极中释放出来。在电解过程中，随着电解时间的增加，电致化学发光信号先逐渐增强后达到稳定值，溶液从无色透明逐渐加深最后变成黄棕色。将电解后的溶液超滤离心分离，可以得到具有荧光和电致化学发光性质的碳量子点。通过透射电镜表征，所制备的碳量子点分散性良好、直径大小为2nm左右球状颗粒。其荧光最大发射波长为455nm左右。对制得的碳量子点的电致化学发光行为进行了研究，发现在-1.5¹.8V电位范围内扫描过程中，它在阳极和阴极过程中都可以产生电致化学发光信号。加入过硫酸根作为共反应物，可以增强碳量子点的阴极电致化学发光信号。同时，其电致化学发光最大发射波长为535nm，相比于荧光最大发射波长有红移现象。我们对碳量子点从石墨上电化学释放机理及碳量子点的电致化学发光机理作了详细的探讨。论文的第四部分（包括了第四、五、六章）主要是发现和研究一些Ru（bpy）₃²⁺新型ECL共反应物。在第四章中，氧气可以作为Nafion/Ru（bpy）₃²⁺修饰电极在中性pH缓冲溶液中的共反应物增强其ECL信号。当修饰电极在+1.5^-1.0V电位范围内扫描过程中，可以观察到3个发光过程，包括两个电位依赖的峰（ECL-1和ECL-2），一个与电位无关的发光（CL-P）。ECL-2产生于扫描电位低于-0.5V的电位范围，这是基于氧气还原产物和Ru（bpy）33+电子转移的发光。在产生ECL-2的过程中，Nafion膜内的疏水性条件在稳定Ru（bpy）33+和氧气自由基负离子（O2·-）方面起着重要的作用。我们讨论了ECL-2的反应机理以及在电化学扫描过程中发光体和共反应物在Nafion膜内浓度分布。和以前大多数ECL的过程不同，ECL-2的发光峰电位跟共反应物溶解氧气的还原电位有关，而与发光体Ru（bpy）₃²⁺的氧化还原电位无关，我们提出了“还原-还原”型ECL机理。ECL技术为探讨电化学反应中的O2还原反应机理及其还原产物的稳定性提供了一种有效的方法。在第五章中研究发现氯化亚锡可以明显增强Ru（bpy）₃²⁺在水溶液中的ECL信号，在循环伏安曲线上，可以观察到明显的催化电流。亚锡离子(Sn²⁺)是第一个被发现可以作为Ru（bpy）₃²⁺ECL共反应物的金属离子。我们以目前最常用的Ru（bpy）₃²⁺/TPrA共反应体系作为研究Ru（bpy）₃²⁺/Sn²⁺性质的参考体系。发现在同一条件下，Ru（bpy）₃²⁺/Sn²⁺所产生的ECL更强更稳定，而且可以在更宽的pH范围内保持优良的ECL活性，还可以在多种电极材料上产生强的ECL信号。同时，我们还对Ru（bpy）₃²⁺/Sn²⁺共反应体系的ECL机理进行了详细的研究，提出了可能的反应机理。新ECL共反应体系的开发对拓展ECL应用范围和寻找其他金属离子类型ECL共反应物有重要的意义。在第六章中我们以多壁碳纳米管作为载体，利用水相共沉淀法制备了氧化亚锡纳米颗粒包裹的碳纳米管复合材料，通过XRD和透射电镜表征，可以观察到氧化亚锡纳米颗粒成功地负载在碳纳米管表面，所合成的氧化亚锡纳米大小为4nm左右。将这种纳米复合材料修饰到玻碳电极表面，发现这种修饰电极可以使联吡啶钌产生很强的ECL信号，说明氧化亚锡纳米颗粒可以作为纳米共反应物，与联吡啶钌之间发生快速电子转移，产生强烈的ECL反应。这种ECL纳米共反应物的发现及研究对拓宽电致化学发光基础理论研究和扩展其在生物传感等领域的应用有重大的意义。更多还原

【Abstract】 Electrochemiluminescence （ECL） analysis is a new analytical method, which isdeveloped based on the combination of electrochemisty （EC） withChemiluminescence （CL）. This method has many advantages of electrochemistry andchemiluminescence, such as high sensitivity, high selectivity, low background signal,wide linear response range, and easy control. In this dissertation, studies were focusedon finding new materials （e.g. ionic liquids, quantum dot luminophores, nanomaterialcoreactants） for ECL, revealing possible new ECL mechanisms, and applyingsensitive, selective and environmentally benign ECL systems in chemosensing andbiosensing.This dissertation consists of four parts, or six chapters. Chapter1is also the firstpart. In this chapter, the general introduction, the mechanisms of ECL, the historicalperspective and classificationss of ECL, developing direction of ECL and the pruposeand signification of this disserataion were described based on the investigation ofliteratures in the field of ECL.The second part is chapter2. In this part, the ECL behaviors of Ru（bpy）₃²⁺/TEA in1-butyl-3-methylimidazolium hexafluorophosphate （BMIPF6） ionic liquid wereinvestigated and compared with those in aqueous solution （pH7.0PBS） at a goldelectrode. The electrochemical and ECL behaviors of Ru（bpy）₃²⁺/TEA were muchdifferent with those in aqueous solution. It was found that the Ru（bpy）₃²⁺/TEA systemgave rise to one small and one large peak ECL peak at anodic process and thecatalytic current of Ru（bpy）₃²⁺/TEA system was disappeared in ionic liquid. Theeffects of viscosity and ionic strength of ionic liquid on diffusion coefficients,catalytic efficiency, and ECL intensity were investigated and discussed to reveal theECL mechanism of Ru（bpy）₃²⁺/TEA system in the ionic liquid of BMIPF6.The third part is chapter3. In this part, a simple and effective method for preparingwater-soluble carbon nanocrystals （CNCs） with ECL activity by applying a scanningpotential at graphite rods were reported, and the ECL behaviors of the as-preparedCNCs were observed and studied in detail. The cathodic ECL intensity increased withthe number of potential cycles before reaching a constant value after30cycles. With increasing the electrolysis time, the color of the electrolyte solution changed fromcolorless to yellow and finally dark brown. A colorless CNC solution was obtained byultrafiltering the dark brown solution with10k Da molecular weight cutoff （MWCO）membrane. High-resolution transmission electron microscopy （HRTEM） indicatedthat the obtained CNCs were monodispersed, spherical-shaped particles with averagesize of2.0nm. The maximum PL emission wavelength of CNCs is455nm. Bothanodic and cathodic ECL emission of the CNCs werer observed when the potentialwas cycled between+1.8and-1.5V. Additionally, in the presence of peroxydisulfate（S2O82-）, the ECL intensity of CNCs in the presence of S2O82-was greatly enhanced.The maximum ECL emission wavelength （535nm） was substantially red-shifted fromPL maximum. The ECL emission of CNCs was attributed to the formation of excitedstate CNCs （R*） via electron transfer between negatively charged CNCs （R·-） andpositively charged CNCs （R·+） or SO·-4.The fourth part includes chapters4-6. In this part, some new efficient coreactants ofRu（bpy）₃²⁺were found, and their ECL behaviors and ECL reaction were stuied indetail. In chapter4, O2was found to act as a new coreactant for Ru（bpy）₃²⁺ECL inNafion film, resulting in a strong ECL light emission. ECL experiments were carriedout at a Ru（bpy）₃²⁺/Nafion film-modified glassy carbon electrode （GCE） immersing inair-saturated phosphate buffer solution （pH7.4）. Scanning in the potential range of+1.5to-1.0V resulted in three luminescent processes, including twopotential-dependent luminescence peaks （ECL-1and ECL-2）, and onepotential-independent persistent luminescence emission （CL-P）. Therein, ECL-2occurring at potential less than-0.5V was demonstrated to be a newchemiluminescent reactions between O2and Ru（bpy）₃²⁺. In ECL-2, Nafion film playsimportant roles in stabilizing Ru（bpy）33+and O2-radical essentially for producing thenew ECL. Unlike previously reported ECL processes, ECL-2peak potential wasdependent on the reduction potential of the coreactant （i.e., O2） rather than the redoxpotentials of the luminopore, Ru（bpy）₃²⁺, which would provide a useful way to probeO2, O2-radical, and their stabilities in electrochemical reactions.In chapter5, we found that stannous chloride could significantly enhance theelectrochemiluminescence （ECL） of tris （2,2’-bipyridyl） ruthenium （II）(Ru（bpy）₃²⁺)in aqueous solution. An obvious electrocatalytic oxidation current of Sn²⁺byRu（bpy）₃²⁺was observed. Sn²⁺was the first reported metal ion that could serve as anexcellent ECL coreactant of Ru（bpy）₃²⁺. ECL properties of Sn²⁺were evaluated by comparison with a common ECL coreactant, tripropylamine （TPrA）. TheRu（bpy）₃²⁺-Sn²⁺ECL coreactant system produces stronger and more stable ECLsignals, can keep its excellent ECL activity in a wider pH range and have morechoices in using electrode materials than Ru（bpy）₃²⁺/TPrA ECL coreactant system.Moreover, the coreactant ECL mechanism between Ru（bpy）₃²⁺and Sn²⁺was alsostudied in detail. This study would be very useful for finding and understaning othermetal ion-based coreatants for Ru（bpy）₃²⁺ECL.In chapter6，the SnO nanoparticles deposited multiwall carbon nanotubes （SnONPs@MCNTs） were synthesised in aqueous solution by hydrolyzing Sn²⁺and usingMCNTs as carriers. The XRD pattern and HRTEM images indicated that SnO NPswith an average size of ca.4.0nm were well coated at MWCNTs. In the experiment, aGC electrode was coated with SnONPs@MCNTs composites, and inserted into anECL cell containing Ru（bpy）₃²⁺solution （pH7.4）. A very strong ECL signal wasobserved when the electrode was applied a potential higher than+1.0V. This strongECL signals indicate there is a highly effective electron transfer process between SnOnanoparticles and Ru（bpy）33+. The high ECL sensitivity, easy labeling, convenientassembly at the electrode and low toxicity, suggest promising application of the nanocoreactant-Ru（bpy）₃²⁺system in sening, and electron transfer probing fornanomaterials.更多还原