【作者】 郝远强；

【导师】 刘又年；

【作者基本信息】 中南大学 ， 应用化学， 2014， 博士

【摘要】 摘要：光电活性材料包括有机染料及荧光分子、过渡金属复合物、半导体氧化物、量子点(QDs)等。其优良的物理化学性质使其在光电转换、光催化以及分析检测方面具有广泛的应用。染料敏化太阳能电池(DSSCs)制作成本较低、环境友好是一类被广泛关注的新型太阳能电池。目前实验室得到的DSSCs的最高效率为13%,但与传统的硅基太阳能电池的效率(约30%)还有较大差距。在DSSCs中,电解质氧化还原电对电位与氧化态染料分子能级之间的不匹配是造成电池开路电压和总体效率中偏低的主要原因。而TiO2中光电子与氧化态电解质的复合,阻碍了DSSCs中具有较高电势电解质的使用。针对这问题,在本研究中使用硅烷化处理的有序一维TiO2纳米线阵列作为DSSCs的光阳极,这种开放的结构更有利于形成规则的聚硅氧烷修饰层来阻止光电子的复合,从而为DSSCs中使用高电势电解质成为潜在可能。QDs具有独特的光电性质,已被广泛应用于构建无机离子及生物分子传感器。但这些基于QDs的传感器中,大部分需要进行繁琐的表面修饰和功能化处理。借助化学修饰方法研究基于QDs的简易传感器有很重要的意义。比色检测方法具有操作便利、结果直观等特点,得到了广泛的应用。设计合成新型有效的比色法探针也是研究的热点。本论文设计合成了几种新型光电活性物质,并将它们应用于了DSSCs与分析检测中。主要内容包括：(1)用水热法制备了一维有序结构的TiO2纳米线,在吸附染料后通过硅烷化处理得到的光阳极中,光电子与高活性电解质(Fc+/Fc)间的复合被有效地阻止了。红外光谱证实了聚硅氧烷层的形成。TiO2纳米线阵列为表面修饰提供一种更开放和便于操作的结构,X射线散射能谱显示Si在TiO2纳米线为均匀分布状态。电池性能测试结果表明,硅烷化处理后,在Fc+/Fc电解质中,电池的开路电压及效率都显著地提高了,光阳极中电子的寿命也呈指数关系地增长了。该电极的设计为DSSCs中使用与光敏剂能级更加匹配的电解质提供了可能。(2)引入化学还原方法(还原剂为抗坏血酸,AA),使Cu2+能快速地还原成一价铜并以Cu2S的形式沉积在CdS量子点表面。通过观测CdS量子点在650nm处荧光强度的变化,可在1nM至1μM范围内实现对Cu2+的快速专一检测,检测限为0.5nM,与传统的基于量子点的方法相比低了2至3个数量级。对水样和人脑脊液实际样品中Cu2+含量进行了测试,得到了与标准ICP-MS检测类似的结果,说明该方法有较高的可行性。(3)通过层层组装的方法得到了CdS量子点固载的光电化学电极,将CdS量子点表面富集S2-后电极能产生将强的光电流响应。而电极用半胱氨酸处理后,由于Cys能取代CdS量子点表面的S2-,使得光电流信号下降。实现了对Cys的灵敏检测,检测线性范围为1-100nM,检测限为0.4nM。该方法成功应用于了血清样品中Cys的检测。(4)根据Cys和N3染料竞争对Hg2+结合,利用Hg2+-N3复合物实现了对Cys的比色法检测。首先,由于N3染料分子中SCN基团与Hg2十的配位作用,形成得到Hg2+-N3复合物,对应溶液颜色由红色变为黄色。在Cys的存在下,Cys的巯基与Hg2+具有更强的结合作用,从而将Hg2+-N3复合物中的Hg2+置换,N3染料分子被释放,溶液颜色恢复至红色。基于上述原理实现了对Cys的定量检测,其检测范围为0.5-25μM,检测限57nM。在此基础上,通过在配体联吡啶环上引入磷酸基团,得到了全水溶性的含钌染料。利用该染料分子实现了对水溶液体系中Hg2+的检测。(5)将水杨醛单元与萘酰亚胺重氮盐偶联反应得到了基于萘酰亚胺的偶氮苯染料分子探针1。在探针1中,水杨醛为CN-的识别基团,萘酰亚胺偶氮苯为检测信号基团。与CN-反应后,探针1溶液显示出了从黄到红的显著颜色变化,对应光谱吸收峰位置从408nm移置497nm。在优选的H2O/DMSO (7/3, v/v)混合溶剂体系中,探针1.能实现对CN-的比值式检测,检测范围为2-45μM,检测限为0.4μM。而且该方法具有很高的特异性。另外,利用探针1制备了CN-检测试纸,可目测出浓度大于20μM的CN-溶液。更多还原

【Abstract】 ABSTRACT: Optically and electrically active materials, including organic dyes, fluorescent molecules, metal complexes, quantum dots (QDs) and etc., due to their excellent chemical and physical properties, have wide applications in photoelectric conversion, photocatalysis, and analytical chemistry. Dye-sensitized solar cells (DSSCs), as a type of alternative, renewable energy source, have attracted a great deal of attention because of their low production cost, environmentally friendly fabrication processes. So far, the highest achieved efficiency for DSSCs is13%which is much less that for silicon based solar cell (e. g.30%). The mismatch in the energy between the redox potential and the HOMO level of the sensitizers lowers the open-circuit voltage and consequently the conversion efficiency of the DSSC. And the recombination between electrons injected by excited dyes at the anode with the oxidized redox species prevent using electrolyte with higher energy level, compared with the normally used triiodide/iodide redox shuttle. To surmount this problem, silane-treated (coated) one-dimensional TiO2nanowire arrays as the photoanode of DSSC was proposed. The open and spatially accessible structure of the TiO2nanowire arrays would be favorable for the coating with uniform polysiloxane which could act as effective insulating layers for blocking the recombination reaction while using high-potential redox couple. Owing to their unique electrical and optical properties, QDs have been widely used to construct various sensors for inorganic ions and biomolecules. But most of those QDs-based sensors require sophisticated procedures for surface decoration, so the development of facile sensors using QDs in combination with chemical reactions is noteworthy. Colorimetric method is extremely attractive because of the convenient and direct readout for detection result. The design of novel dyes as effective colorimetric probes for various analytes has attracted enormous attentions.In this thesis, several kinds of optically, electrically active materials were designed. And their applications in DSSCs and analytical chemistry were also explored. The main contents are as follows:(1) Effective blockage of recombination electron transfer of a high reactive redox couple (Fc+/Fc) at TiO2nanowire array electrodes was achieved by silanization of the dye loaded TiO2nanowire array. FT-IR clearly showed the formation of polysiloxane network at fluorine doped tin electrodes covered with TiO2nanowire arrays and the dye molecules. Energy-dispersive X-ray spectroscopy (EDS) also reveals the presence of Si over multiple spots at the cross sections of the silanized TiO2nanowire array electrodes. As a result, a rather high open-cell voltage Voc (0.69V) and an enhanced efficiency (0.749%) for DSSC with the Fc+/Fc couple were obtained. Contrary to the passivated TiO2nanoparticle film electrodes at which a complex, biphasic dependence of electron lifetime on Voc was observed, we recorded a logarithm linear dependence of the lifetime on Voc after the silanization treatment.(2) By reducing free and/or weakly coordinated Cu2+with a Cu2+-reducing agent (ascorbic acid for example) and detecting the photoluminescence peak of Cu2S-covered CdS QDs at650nm, Cu2+concentrations ranging from1nM to1μM can be readily determined. The detection limit of0.5nM was achieved, which is at least2-3orders of magnitude lower than QD-based detection methods. Among a number of metal ions interferences, only Cu2+causes the red shift of the CdS photoluminescence. Analyses of Cu2+in a river water sample and Cu2+coordinated by amino acids and proteins in cerebrospinal fluids were performed.(3) The photoelectrochemical response at electrodes immobilized with CdS quantum dots whose surface were enriched with sulfide ions was found to change when sulfide ions are replaced by thiol-containing compounds. A sensitive photoelectrochemical method was therefore developed for selective detection of Cys. Immersion of the resultant electrode in sample solution containing a sulfhydryl compound allows the sulfide anions to be gradually replaced by the Cys. The adsorption, hence the decrease in photoelectrochemical response (photocurrent) correlates with the concentration of the Cys in solution. The dynamic range is 1-100nM and the detection limit is0.4nM.(4) A novel reversible colorimetric sensor, which based on a competitive ligation of Hg2+by thiols and thiocyanate (SCN) on the N3dye (bis(4,4’-dicarboxy-2,2’-bipyridine) dithiocyanato ruthenium (II)), was developed for the detection of Cys. First, Hg2+ions coordinated to the sulfur atom of the dyes’ SCN groups, and this interaction induces a change in color from red to yellow, owing to the formation of a complex of Hg2+-N3. Then, in the presence of Cys, the red color of N3is recovered concomitantly with the dissociation of the Hg2+-N3complex, due to the extraction of Hg2+by biothiols. The dynamic range of this method is0.5-25μM and the detection limits is57nM. Furthermore, by using phosphate group-incorporated bipyridine liagand, we synthesized a water soluble ruthenium-contaning dye which was successfully used for the colorimetric detection of Hg2+in aqueous solution.(5) A naphthalimide-based azo dye (1) used as a colorimetric and ratiometric probe for the detection of CN-was synthesized by incorporating a salicylaldehyde moiety, which acts as a recognition unit, to the naphthalimido diazonium salt. Upon reacting with CN-, probe1display dramatic color changes rapidly from yellowish to red, corresponding to the absorption bands shift from408nm to497nm. The colorimetric probe allows ratiometric detection of CN-with a linear range of2-45μM and a LOD (limit of detection) of0.4μM. In the optimized H2O/DMSO (7/3, v/v) mixed solvent, probe1displays excellent selectivity for CN-over other anions. In addition,1was successfully employed to prepare the filter paper-based test strips which can be used to monitor CN-conveniently, and the discernible concentration of CN-can be as low as20μM.更多还原