利用扫描电化学显微镜技术研究生物阴极体系的电子传输过程

Bioelectrochemical systems (BESs) are novel technology to remove contaminats and produce clean energy. The cathode is an important limiting factor of the efficiency of the BESs.Although the application of catalysts such as platinum increased the efficiency of oxygen reduction in the cathode, also it incresed the cost of the BESs. The occurrence of biocathode instead of chemical cathode not only decrease the cost of cathode, but also it expands the function of BESs to remove contaminants anodically and cathodically, and combine organics.However, the efficiency of biocathode is presently low. The deep understanding of electron transfer process,which includes electron transfer mechnasim and electron transfer kinetics, is therefore with great significance and necessibility.Scanning electrochemical microscopy(SECM)is an electrochemical technique based on microelectrode, with the advantages of multi-model operation, high resolution, and no destruction of microbial cell structure and no disturbance of microenvironment with the biofilm. Previously there was no report of applying SECM to research the electron transfer mechanism.Therefore this project intends to use SECM as the main meathode, combined with modern chemical analysis, molecular biology, gene knockout technique to clear the electron transport pathway; SECM technique will be applied to analyze the effects of different factors such as temperature, salinity, pH, and potential on electron transfer kinetics of the biocathode,to optimize the operating parameters of the biocathode. The results of this project will provide significant theoretical basis to improve the sewage treatment efficiency,energy output capacity, and function expansion of BESs.

生物电化学体系是一种新型的污染物去除及清洁能源生产技术，阴极性能是其工作效率的关键影响因素。Pt等金属催化剂的应用尽管提高了阴极的氧还原效率，但也增加了构造成本；生物阴极因其氧还原催化功能且造价低、功能丰富而得到广泛关注。近来生物阴极的功能由氧还原催化扩展到污染物去除及有机物合成。然而目前生物阴极的效率较低。因此加深对生物阴极电子传输过程的认识对于提高生物阴极体系的效率和功能的进一步拓展具有重要性和必要性。本项目拟采用具有高时空分辨率的扫描电化学显微镜技术为主要研究手段，结合其他电化学方法、微生物纯培养技术、现代分析化学技术、分子生物学技术确定生物阴极的电子传输途径；分析不同因素如温度、盐度、pH、电位对电子传输动力学的影响。通过对生物阴极电子传输过程的深入研究可为生物阴极产能、污染物去除及电化学合成效率的提高和功能的进一步拓展提供更多理论支持。

针对微生物燃料电池产电性能提高的目标，本研究针对阳极材料、空气阴极隔膜及微生物燃料电池堆等方面开展了研究。以毛巾为原材料进行高温碳化获得了一种具有外向结构的新型三维阳极材料，该材料可有效避免传统三维结构材料经长期运行后导致的生物膜堵塞现象，有效提高微生物燃料电池的产电性能；以混合纤维素酯为空气阴极微生物燃料电池隔膜，结果表明该隔膜具有较好的产电性能与长期稳定性，同时其价格为Nafion材料的1/25，大大降低了微生物燃料电池的构造成本；针对单电池电力输出较低的问题，我们开展了微生物燃料电池堆运行并考察了堆运行模式下阳极电势的变化，结果表明：1. 产电性能较弱的电池阳极容易出现反极化现象，而不是此前报导的与底物浓度有关；2. 在串并联运行模式下，即使单独运行时产电性能较好的电池，只要相较于串联单元中其他电池产电性能弱，该电池阳极也会出现反极化现象；3. 并联运行模式会促进产电性能好的电池的阳极性能，而限制产电性能弱的电池的阳极性能；4.在并串联模式下，并联单元在较大的电流下会发生整体的反极化行为；但反极化行为不会在2个并联单元中同时出现；由于并联单元的反极化行为，所有电池的阳极电势出现较大的波动。该研究为堆运行模式提供了系统优化的理论基础。