碳纳米材料修饰电极强化微生物燃料电池产电特性与机理

发布时间：2019-05-24 18:55

【摘要】：环境与能源问题已然成为影响人类生存与发展的核心问题。近些年，微生物燃料电池（Microbial fuel cell, MFC）能够利用微生物催化直接将燃料的化学能转化为电能，是一种能实现污水净化同时产电的新技术，因此受到了广泛关注。现阶段MFC输出功率密度偏低和构建成本过高限制了其在工程中的实际应用。随着反应器结构材料的优化，源于电极表面微生物催化反应的活化内阻逐渐成为制约MFC功率提升的关键；构建成本则主要来源于阴极用于催化氧气还原的贵金属，寻找廉价高效的化学催化剂，或者利用微生物代替化学催化剂形成生物阴极可以有效降低MFC的构建成本。针对以上存在问题，本论文通过简单的方法实现对阳极电极的表面改性，提高微生物与阳极电极之间的电子转移速率，改善阳极性能；在阴极，开发出廉价高效的氧气还原复合催化剂用以替代贵金属Pt，或者采用生物阴极取代贵金属催化剂，筛选出廉价高效的适合生物阴极的电极材料以及利用简单高效方法修饰生物阴极材料，降低构建成本的同时提高MFC的性能，从而在材料制备和应用方面为实现MFC的大规模实际应用提供有价值的参考数据和切实可行的实施方案。得到如下主要结果与结论：（1）通过层层自组装法制备了介孔碳修饰的碳纸电极，循环伏安法(Cyclicvoltammetry，CV)与电化学阻抗法（Electrochemical impedance spectroscopy，EIS）表明，相比于未经介孔碳修饰的碳纸，其具有更好的稳定的电化学性能,如增大了反应活化面积和电子转移速率，适宜应用于MFC阳极。以介孔碳修饰的碳纸作为阳极的MFC获得了237mW m-2功率密度，为未经介孔碳修饰的碳纸作为阳极的1.9倍（128mW m-2），同时期启动时间也缩短了68%，阳极极化损失也大大降低。（2）原位合成的二氧化锰碳纳米管复合催化剂（‘in-situ MnO2/CNTs’），在中性缓冲溶液中对氧气有很好的还原催化活性。扫描电镜（Scanning electron microscope，SEM）显示MnO2充分均匀的修饰于CNTs表面，且在高强度超声后仍能稳定的附着在CNTs管壁。将‘in-situ MnO2/CNTs’修饰于碳纸电极上，应用于MFC阴极，最大输出功率密度达到了210mW m2，与Pt/C相当（229mW m2），表明‘in-situ MnO2/CNTs’可以作为一种廉价高效的氧气还原催化剂替代Pt/C而应用于MFC阴极。（3）阴极材料的选择对生物阴极型MFC极为重要。主要探究了常用的几种材料石墨毡（Graphite felt，GF）、碳纸（Carbon paper）和不锈钢网（Stainless steel mesh，，SSM）在MFC生物阴极中的应用比较，GF-MFC的电流密度和最大功率密度分别为350mA m2和109.5mW m2，高于CP-MFC（210mA m2and32.7mW m2）和SSM-MFC（18mA m2and3.1mW m2）。三种材料对应的MFC均获得了较高的COD去除率，GF-MFC获得了最大的库伦效率11.7%。三种材料中，石墨毡最适合于应用于双室型生物MFC中的阴极中。（4）通过简单可扩大化的方法制得了CNTs修饰SSM电极CNTs-SSM。SEM显示CNTs均匀的分布在不锈钢网表面，形成了一个三维网状结构，其表面积也随之提高。经过高强度的超声，修饰在不锈钢网表面的CNTs也不会脱落，说明CNTs与不锈钢网的结合非常稳固。CNTs-SSM-MFC的最大功率密度达到147mW m2，是SSM-MFC（3mW m2）的49倍之多。CV测试证明生物阴极上的生物膜可以催化还原氧气，且CNTs-SSM生物阴极表现出氧气催化还原效率远远高于SSM生物阴极。SSM在生产过程中可以极为方面的调整期纤维直径、孔隙，这可以为其在MFC的实际应用提供进一步的优化。此外，SSM易折易弯曲的特性可以使得在MFC实际应用中根据需要构建相应结构形状的CNTs-SSM生物阴极，如立方形、圆柱形或者条状。
[Abstract]:The problem of environment and energy has become a core problem that affects the survival and development of human beings. In recent years, the microbial fuel cell (MFC) can directly convert the chemical energy of the fuel into electric energy by using the microbial catalysis, and is a new technology which can realize the simultaneous electricity generation of the sewage purification, so that the microbial fuel cell (MFC) is widely concerned. At present, the output power density of MFC and the construction cost are too high to limit the actual application of MFC in the project With the optimization of the material of the reactor structure, the activation internal resistance of the microbial catalytic reaction from the surface of the electrode gradually becomes the key to the improvement of the MFC power; the construction cost is mainly derived from the noble metal used for catalyzing the oxygen reduction by the cathode, and the low-cost and high-efficiency chemical catalysis is found the preparation of the biological cathode by using the microorganism in place of the chemical catalyst can effectively reduce the construction of the MFC, According to the above problems, the surface modification of the anode electrode is realized by a simple method, the electron transfer rate between the microorganism and the anode electrode is improved, and the anode performance is improved; and at the cathode, the cheap and high-efficiency oxygen reduction composite catalyst is developed to replace the noble gold. Belongs to the field of Pt, or adopts a biological cathode to replace the noble metal catalyst, and the cheap and high-efficiency electrode material suitable for the biological cathode is screened, the biological cathode material is modified by a simple and high-efficiency method, the construction cost is reduced, and the MFC is improved. And provides valuable reference data and practical real-time practical application in material preparation and application to realize the large-scale practical application of the MFC. Application programme. The following main results are obtained The results are as follows: (1) The mesoporous carbon-modified carbon paper electrode, the cyclic voltammetry (CV) and the electrochemical impedance method (EIS) are prepared by layer-by-layer self-assembly method, which shows that the mesoporous carbon-modified carbon paper electrode, the cyclic voltammetry (CV) and the electrochemical impedance method (EIS) show that the mesoporous carbon-modified carbon paper electrode, the cyclic voltammetry (CV) and the electrochemical impedance method (EIS) show that the mesoporous carbon-modified carbon paper electrode, the cyclic voltammetry (CV) and the electrochemical impedance method (EIS) show that the mesoporous carbon the modified carbon paper has better stable electrochemical performance, such as increasing the reaction activation area and the electron transfer rate, The carbon paper modified with mesoporous carbon was used as the MFC of the anode to obtain 237 mW m-2 power density, which is 1.9 times (128 mW m-2) of the non-mesoporous carbon-modified carbon paper as the anode, and the starting time of the same period is also shortened by 68%, and the polarization loss of the anode and (2) in-situ synthesized manganese dioxide carbon nano-tube composite catalyst (in-situ MnO2/ CNTs'), the oxygen in the neutral buffer solution is very good, Scanning electron microscopy (SEM) showed that the MnO2 is well and uniformly modified on the surface of CNTs, and can still be attached stably after high-intensity ultrasound On the carbon paper electrode, the maximum output power density was 210 mW and the maximum output power density was 210 mW/ m2, which was equivalent to that of Pt/ C (229 mW m2), indicating that the "in-situ MnO2/ CNTs' could be used as an inexpensive and efficient oxygen reduction catalyst instead of Pt/ C." for MFC cathodes. (3) Selection of cathode materials for biological yin The current density and the maximum power density of GF-MFC were 350 mA and 109.5 mW, respectively, and higher than that of CP-MFC (210 mA m2and32.7 mW) and SSM-MFC (18 mA m2an). The corresponding MFC of the three materials obtained higher COD removal rate, and the GF-MFC was the largest. The coulomb efficiency is 11.7%. In the three materials, the graphite felt is most suitable for the two-chamber type In the cathode of MFC, CNTs-SSM (CNTs-SSM) modified by CNTs were prepared by simply and expansively. The SEM showed that CNTs were uniformly distributed on the surface of stainless steel mesh and a three-dimensional mesh junction was formed. The surface area of the structure is also improved, and the CNTs modified on the surface of the stainless steel mesh do not fall off after the high-strength ultrasonic wave, and the CNTs are explained. The combination of the stainless steel mesh is very stable. The maximum power density of the CNTs-SSM-MFC reaches 147 mW m2, which is the SSM-MFC (3 The results of the CV test show that the biofilms on the biological cathode can be used to catalyze the reduction of oxygen, and the CNTs-SSM biocathodes show the efficiency of the oxygen catalytic reduction. It is far higher than the SSM biological cathode. The SSM can adjust the fiber diameter and pore diameter during the production process, which can be the real time of the MFC. in addition, the characteristics of the easy-to-bend of the SSM can make it possible to construct the CNTs-SSM biological cathode of the corresponding structure shape according to the needs in the practical application of the MFC, such as
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：X703;TM911.45

【共引文献】