【作者】 石锡峰；

【导师】 唐波；

【作者基本信息】 山东师范大学 ， 分析化学， 2014， 博士

【摘要】 人类社会的快速发展所带来的能源环境问题日益严峻，随着人们对半导体材料研究的不断深入，太阳能化学转化与储存研究成为解决当前社会发展面临的环境污染和能源危机问题的根本途径之一。近年来，在光催化降解有机污染物、太阳能燃料电池、光催化分解水制氢、光催化还原二氧化碳等方面得到了较为快速的发展。但是，现有研究结果对太阳光能利用率普遍相对较低，远未达到实际应用的要求。如何提高太阳能的利用率成为目前该领域研究的核心问题。针对上述光催化应用热点领域及光催化材料研究中亟待解决的问题，本文将研究目标定位于通过新型光催化剂的构筑，提高光催化还原二氧化碳以及光分解水产氢的催化反应效率研究。研究方法是基于多通道电子转移、多激子生成、载流子空间分离、延长活性中间体寿命等原理，通过选择廉价、易得，且具有良好的吸光性能和电子储存传输性能的纳米碳材料（碳纳米管及石墨烯），作为基本结构单元，与半导体材料组装，构建出能够实现光生电子的定向传输、有效提高其与空穴分离效率的微纳结构催化剂，用于提高光催化还原二氧化碳及光解水制氢的效率，为光催化反应的实际应用研究提供新的途径。本论文具体内容如下：第一章，简要介绍碳纳米管和石墨烯的制备、修饰、表征及其光催化应用等方面的研究概况。第二章，以碳纳米管（CNT）为电子受体及光催化活性中心，与对可见光响应的FeOOH半导体以及具有染料敏化作用的RuL2Cl22H2O进行共价组装，利用CNT本身的氧化羧基与RuL2Cl22H2O分子中的羧基在合适的环境中可形成氢键作用的性质，通过改变反应体系的溶剂环境，成功构筑了具有三电子转移通道的复合催化剂材料。并选择二氧化碳的光催化羧基化为模型反应对其光催化效果进行了评价，结合理论模拟计算分析，证实了该催化材料在非极性溶剂中三电子转移通道的形成。第三章，以氧化石墨烯（GO）为载体和电子传输体，利用其表面丰富的羧基，与经过氨基化修饰的PbS量子点通过酰胺键连接，构建了ZnO@PbS/GO复合材料。在该结构中，ZnO作为PbS量子点的载体及光电子传输桥梁，结合GO良好的电子传输性质，充分利用了PbS量子点的多激子产生（MEG）性质，有效解决了PbS量子点在光解水制氢体系中状态不稳定及电子传输差的问题，首次实现了PbS量子点的MEG性质在悬浮光解水制氢体系中的应用。实验结果表明，MEG效应可有效提高光催化制氢的效率。第四章，设计构建了ZnO/MOF/GO复合结构的光催化剂。其中，GO作为载体及电子传输体，将ZnO和MOF两种材料通过分步原位组装的方法共同负载在其表面上。在该结构中，ZnO作为良好的半导体材料提供光电子，光生电子通过石墨烯的电子传递作用顺利的传输到相邻的MOF上，与MOF中的氢离子作用产生氢自由基，进而生成氢气分子。该结构通过将活性位点与催化剂本体材料实现空间分离，避免了生成的氢自由基再次被ZnO中的空穴氧化而发生逆反应，另一方面，MOF对氢自由基的稳定作用也提高了其生成氢分子的几率，从而提高光还原水制氢的效率。第五章，分别选取CuCl22H2O、Cu(NO3)22H2O、Cu(OAc)2H2O为原料，利用溶剂热的方法制备了不同的对应产物，对其组成及光催化产氢效果进行了探讨，发现了一种新的配合物光催化产氢材料(Cu-DG)。在此基础上，通过引入GO，构建了(Cu-DG)/GO复合结构光催化剂，有效提高了Cu-DG配合物的光催化产氢效率。本文以碳纳米管和石墨烯为基本结构单元，分别针对增加光电子数目、提高电荷的空间分离效率、延长光催化自由基中间体寿命等几个关键问题，构筑了不同结构的新型光催化剂。通过光催化还原二氧化碳及光分解水制氢反应对其光催化效果进行了评价，结果表明，上述问题的解决有助于提高光催化剂的催化效率，本文的研究将在新型光催化剂的设计方面提供很好的借鉴作用。更多还原

【Abstract】 With the deepening research of semiconductor materials for the serious energy andenvironmental crisis, it has got rapid development on chemical transfer and storage of solarenergy, which is the fundamental way to solve the problem of environmental pollution andenergy crisis in the development of human society. In recent years, the photocatalyticdegradation of organic pollutants, solar fuel cells, photocatalytic splitting of water andphotocatalytic carbon dioxide fixation have been developed rapidly. However, the existingstudies on the utilization of solar energy chemical conversion are very low, far short of therequirements of practical applications. How to improve the utilization of solar energy becomesthe core issue in this research field.Based on the popular research fields and problems need to be solved in photocatalyticapplication as mentioned above, the target of this paper focused on the construction of novelphotocatalysts to improve the photocatalytic efficiency of H2generation and CO2reduction.The strategy is to employ the nanocarbon materials as the basic unit and introduce themechanism of multiple electron transfer channels, multiple exciton generation, spatialseparation of carriers, extending the radical life into the construction of photocatalysts. In thenovel photocatalysts, nanocarbon materials serve as the electron acceptor and active sitesprovider as well as the supporting matrix to anchor nanoparticles, which could improve thephotocatalytic efficiency greatly.In the first section, the basic structure of the catalyst constructed in this paper, carbonnanotubes and graphene oxide were introduced briefly, including their synthesis,characterization, modification and applications.In the second chapter, a dye-sensitized photocatalyst with three electron transitionchannels was constructed, in which FeOOH and photosensitizer RuL2Cl22H2O were employed as the electron donor, carbon nanotubes were served as the electron traps/container. Thecatalytic results for carboxylation reaction of phenol by CO2and TD-DFT calculation resultsindicated the catalyst possessed three electron transition channels assisted by intermolecularhydrogen bonding interaction.In the third chapter, a novel ZnO@PbS/GO photocatalyst was constructed based onmultiple exciton generation effect and applied in hydrogen generation. The presence of multipleexciton generation process, which was confirmed by transient absorption spectrum andphotocurrent measurements, remarkably improves the photocatalytic efficiency of hydrogengeneration.In the fourth chapter, a ZnO/(Cu-BTC)MOF/GO structure was constructed, which realizedthe spatial separation of photoelectron and hydrogen radical for the introduction of(Cu-BTC)MOF. The spatial separation avoided the oxidation of radical by holes in ZnO andextended its life. On the other hand, the MOF effectively stabilized the hydrogen radical andimproved the chances of its generating hydrogen molecules, so as to improve the efficiency ofphotocatalytic hydrogen production.In the last section, the products of different copper salt in diethylene glycol wassynthesized with the existence of GO. And their influence on photocatalytic hydrogengeneration was investigated with the characterization of the products.The results reported in this research paper as mentioned above should be much helpful toconstruct a novel photocatalyst with the synergistic effect of photoelectron generation andseparation for the photocatalytic efficiency improvement.更多还原