小分子化合物，电化学活性菌及纳米材料间的电子传递机制及应用拓展

发布时间：2018-08-19 12:47

【摘要】：由于全球的能源危机和污染控制,可再生洁净能源是人类未来可持续发展的最佳选择。因此本论文对电化学活性菌(EAB)和可见光驱动的光催化光解水制氢体系进行研究。EAB是环境中普遍存在的,并在生物地球化学,环境修复以及生物能源产电等领域起到重要作用。进二十年来,对于EAB的胞外电子传递(EET)机制方面有大量研究,到目前为止,普遍认为EAB将胞外电子传递到胞外的固体电子受体有三种可能的途径：(a)直接接触的电子传递；(b)胞外可溶性电子媒介；(c)导电纳米线或者导电鞭毛。通过对于EAB胞外电子传递机制的研究和阐明,对于检测和定量EAB的胞外电子转移能力有明确的指导作用,并对增强EAB在环境领域中的应用提供理论基础。本论文对EAB、纳米材料以及小分子化合物间的电子和能量传递过程,开展了一系列工作,主要研究内容和结果如下。 1.通过对EAB与可溶性媒介类荧光探针核黄素小分子之间的电子转移的研究,建立了一种快速、原位和高灵敏的荧光方法来检测EAB,并量化EAB的胞外电子传递能力。此方法被成功用于定量两株模式EAB的平均胞外电子传递能力(Shewanella oneidensis MR-1,1.32±0.04fA; Geobacter sulfurreducens DL-1,9.08±0.23fA)。此方法也通过定量并比较Shewanella野生型和突变株的平均胞外电子传递能力,从分子生物学水平上快速的鉴定了与胞外电子传递相关的基因。 2.碳材料被广泛的用于生物电化学体系中的电极材料,但是在长期连续的运行过程中,微生物趋向于粘附在碳材料电极表面上并形成厚并且致密的生物膜,这将限制电子和营养物在微生物-电极界面的传质。通过采用修饰W03纳米棒的碳纸电极作为微生物燃料电池的阳极,Shewanella oneidensis MR-1作为阳极接种产电微生物,这种新型的电极材料能够完全抑制Shewanella oneidensis MR-1生物膜的生长,并且展现出优越的电化学性能和对电子媒介核黄素的强的电化学响应。这两个因素结合起来能促成这种新型电极材料对于悬浮的Shewanella oneidensis MR-1胞外的电子的连续稳定的摄取。这导致在长期运行过程当中以修饰W03纳米捧的碳纸电极为阳极的微生物燃料电池比纯碳纸电极以及修饰W03纳米颗粒的碳纸电极的微生物燃料电池展现出更稳定的性能。此项工作表明W03纳米棒在实际生物电化学领域的新型抗生物污染材料中有广泛的应用前景。 3.有研究表明通过自组装方法在金电极上修饰羧基终端的烷硫醇单分子层能够有效的提高EAB与电极表面的电子转移,但是这种增强机制仍然很难弄清楚。本工作通过自组装方式在真空溅射金电极表面修饰巯基乙酸与巯基乙氨单分子层,获得Au-COOH以及Au-NH2。并在微生物电解池(MEC)体系里以Geobacter sulfurreducens DL-1为阳极产电微生物,分别以Au-COOH, Au-NH2以及Au作为的阳极对电解池的性能进行比较。此外,三种电极的电化学性能和电极表面与细菌之间的相互作用也进行了研究。结果表明,Au-NH2具有最优越的电化学性能,MEC体系里,Au-COOH都产生了比Au高的电流密度。Au-NH2表Au-COOH面形成的生物膜比Au表面的更稠密,然而表面形成的生物膜比Au表Au-NH2面的更厚。这些都表明直接电子传递在这个过程中起到的重要作用。这项工作表明羧基和氨基官能团能够通过加速EAB与电极之间的直接EET以提升电极的性能。4.光解水制氢气这种洁净能源的需求推动了高效的光催化系统的快速发展。本工作报道了一种低成本,易制备,环境友好的可见光催化的光解水制氢系统。此系统包括氧杂蒽染料和无机Ni(Ⅱ)或者Co(Ⅱ)盐的三乙醇胺水溶液。通过加入2-巯基乙醇作为表面活性剂能有效提高系统制氢的效率和稳定性。光催化产氢的结果,透射电镜以及电催化产氢反应测试结果显示此体系的产氢催化中心是原位形成的Ni系或者Co系的纳米颗粒。动态光散射结果表明巯基乙醇增强产氢的机制是通过稳定非均相的Ni系或者Co系纳米颗粒催化剂。
[Abstract]:Because of the global energy crisis and pollution control, renewable clean energy is the best choice for the sustainable development of mankind in the future. Therefore, this paper studies electrochemical active bacteria (EAB) and visible light-driven photocatalytic photolysis system for hydrogen production from water. EAB is ubiquitous in the environment, and exists in biogeochemistry, environmental remediation and bioenergy. Extracellular electron transfer (EET) mechanism of EAB has been studied extensively in the past 20 years. Up to now, it is generally believed that there are three possible ways for EAB to transfer extracellular electrons to extracellular solid electron receptors: (a) direct contact electron transfer; (b) extracellular soluble electron mediators; (c) conduction. Electron nanowires or conductive flagellates. Through the study and elucidation of the mechanism of extracellular electron transfer of EAB, it has a clear guiding role for the detection and quantification of extracellular electron transfer ability of EAB, and provides a theoretical basis for enhancing the application of EAB in the field of environment. This paper will focus on the electrons and energy between EAB, nanomaterials and small molecular compounds. A series of works have been carried out. The main research contents and results are as follows.
1. A rapid, in situ and highly sensitive fluorescence method was developed to detect EAB and quantify the extracellular electron transfer capacity of EAB. This method was successfully used to quantify the average extracellular electron transfer capacity (Shewanella oneid) of two model EABs. By quantifying and comparing the average extracellular electron transport capacity of wild-type and mutant Shewanella strains, the genes related to extracellular electron transport were identified rapidly from the molecular biological level.
2. Carbon materials are widely used as electrode materials in bioelectrochemical systems. However, during long-term continuous operation, microorganisms tend to adhere to the surface of carbon electrode and form thick and dense biofilm, which will limit the mass transfer of electrons and nutrients at the microbial-electrode interface. Carbon modified W03 nanorods are used. Shewanella oneidensis MR-1 as the anode of microbial fuel cell and Shewanella oneidensis MR-1 as the anode inoculated with electricity-producing microorganisms, this new electrode material can completely inhibit the growth of Shewanella oneidensis MR-1 biofilm, and exhibit excellent electrochemical performance and strong electrochemical response to electron-mediated riboflavin. The combination of elements contributes to the continuous and stable uptake of electrons from suspended Schwanella oneidensis MR-1 cells by this novel electrode material, which results in the long-term operation of microbial fuel cells using modified W03 nano-sized carbon paper electrode as anode compared with pure carbon paper electrode and modified W03 nano-particle carbon paper electrode. Microbial fuel cells exhibit more stable performance. This work shows that W03 nanorods have a wide range of applications in the field of bioelectrochemistry as novel anti-biofouling materials.
3. It has been shown that the modification of carboxyl terminal alkanethiol monolayer on gold electrode by self-assembly method can effectively improve the electron transfer between EAB and electrode surface, but the enhancement mechanism is still difficult to clarify. Au-COOH and Au-NH2 were obtained. The electrochemical performance of the three electrodes and the interaction between the electrode surface and bacteria were compared in the microbial electrolytic cell (MEC) system using Geobacter sulfurreducens DL-1 as anode and Au-COOH, Au-NH2 and Au as anode respectively. The results show that Au-NH2 has the best electrochemical performance. In MEC system, Au-COOH produces a higher current density than Au. The Au-COOH surface of Au-NH2 forms a denser biofilm than Au surface, whereas the biofilm formed on the surface is thicker than Au-NH2 surface. This work shows that carboxyl and amino groups can improve the performance of electrodes by accelerating the direct EET between EAB and electrodes. 4. The need for clean energy such as water photolysis to produce hydrogen promotes the rapid development of efficient photocatalytic systems.
A low-cost, easy-to-prepare and environmentally friendly visible-light photocatalytic system for hydrogen production from water by photolysis is reported. The system consists of aqueous triethanolamine solutions of oxanthracene dyes and inorganic Ni (II) or Co (II) salts. The efficiency and stability of hydrogen production can be effectively improved by adding 2-mercaptoethanol as a surfactant. The results of transmission electron microscopy and electrocatalytic hydrogen production showed that the catalytic center of the system was in-situ Ni-based or Co-based nanoparticles.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：O641;TB383.1

【共引文献】