微生物燃料电池空气阴极催化剂的制备及其产电性能研究

发布时间：2018-01-11 14:14

  本文关键词：微生物燃料电池空气阴极催化剂的制备及其产电性能研究　出处：《江西师范大学》2014年硕士论文　论文类型：学位论文

  更多相关文章： 微生物燃料电池 空气阴极 催化剂 掺杂 纤维素 氧气还原

【摘要】：微生物燃料电池（MFC）是一种绿色能源新技术。它利用微生物的新陈代谢，氧化有机物将化学能转化为电能，在废水处理方面具有巨大的应用潜力。空气阴极式MFC直接以氧气为电子受体，，是公认的最有应用前景的构型之一。空气阴极材料，特别是氧气还原（ORR）催化剂，成为MFC应用的关键因素之一。 目前MFC的空气阴极催化剂存在价格昂贵、制备过程复杂以及长期稳定性差等问题，制约了其规模化应用。本文基于可再生的纤维素基材料，采用简单易行的方法制备了三种高效廉价的碳基ORR催化剂，以推动MFC在废水处理领域的应用。本文研究内容包括以下三部分： （1）以天然植物稻草秸秆为原料，采用直接碳化的方法制备ORR催化剂。采用辊压法制备空气阴极，考察了催化层粘结剂用量对电池性能的影响，并和炭黑催化剂对比。实验结果表明，植物源ORR碳催化剂的空气阴极电化学性能比炭黑更优。催化层中粘结剂的用量对空气阴极的性能影响较大，当催化剂和粘结剂PTFE的质量比为4时，MFC的产电性能最佳。其电压输出最高达0.558V，最大功率密度为1058mW/m2。增大粘结剂PTFE的用量，如空气阴极3#，最大功率密度降至790mW/m2。因为，过多的粘结剂一方面会覆盖部分ORR催化剂活性位点、阻碍质子传递等；另一方面，增大电极内阻。但是粘结剂用量过少，电极易出现脱落现象。因此，最优粘结剂用量为：催化剂和PTFE质量比为4。 （2）以商业化的磷酸纤维素为原料，采用直接碳化的方法制备磷掺杂碳ORR催化剂。在上一章节已优化的辊压工艺参数下，将磷掺杂碳ORR催化剂制备成空气阴极，研究了其在MFC的性能，并对制备的催化剂做了一系列材料学表征。空气阴极线性伏安扫描结果表明，与未掺杂碳相比，磷掺杂碳催化剂能够明显地提高空气阴极电化学性能。电池性能测试结果显示，1000℃条件下制备的催化剂性能最优，电池稳定电压输出达0.6V，最大功率密度达1312mW/m2，是未掺杂催化剂的近3倍，也高于同体系下的Pt催化剂（1226mW/m2）。杂原子磷在碳催化剂骨架中的成功掺杂，极大地提高了MFC的产电性能。这是首次通过直接碳化的方式制备磷掺杂碳，具有无毒、成本低、易放大等优点，作为MFC催化剂具有巨大的潜力。 （3）以天然可再生的纤维素为碳源，以廉价无毒的无机盐(NH4)3PO4为氮源和磷源，成功地制备了一种新型的氮磷共掺杂的碳材料（PNC）。将其作为ORR催化剂制备成空气阴极，构建MFC，研究MFC的产电性能。线性伏安扫描结果表明，PNC具有优异的ORR催化性能。900℃下制备的PNC-900的MFC电压输出达0.636V，最大功率密度达2288mW/m2，比同体系下含Pt/C催化剂（1661mW/m2）更高。同时与氮掺杂或磷掺杂的碳材料相比，氮磷共掺杂具有更优的ORR催化性能。催化剂的XPS表征显示，N、P原子成功的掺杂入碳骨架中，氮磷共掺杂的协同效应更进一步挺高了碳材料的ORR催化性能。
[Abstract]:Microbial fuel cell (MFC) is a new green energy technology that uses microbial metabolism to oxidize organic matter to convert chemical energy into electricity. Air cathode type MFC is considered as one of the most promising configurations with oxygen as its electron acceptor. Air cathode materials are widely used in wastewater treatment. In particular, oxygen reduction catalyst has become one of the key factors in the application of MFC. At present, the air cathode catalyst of MFC has some problems, such as high price, complex preparation process and poor long-term stability, which restrict its large-scale application. This paper based on renewable cellulosic materials. In order to promote the application of MFC in wastewater treatment, three kinds of carbon-based ORR catalysts with high efficiency and low cost were prepared by a simple and easy method. The ORR catalyst was prepared by direct carbonization and the air cathode was prepared by roller pressing method. The effect of binder content of catalyst layer on the performance of the battery was investigated. 1) using natural straw straw as raw material, the direct carbonization method was used to prepare ORR catalyst and the air cathode was prepared by roller pressing method. Compared with carbon black catalyst, the experimental results show that the electrochemical performance of ORR carbon catalyst is better than that of carbon black, and the amount of binder in catalyst layer has great influence on the performance of air cathode. When the mass ratio of catalyst to binder PTFE is 4:00, the electrical performance is the best, and the output voltage is up to 0.558 V. The maximum power density is 1058mW / m2. By increasing the amount of binder PTFE, such as the air cathode 3#, the maximum power density drops to 790mW / m2. On the one hand, too much binder will cover some active sites of ORR catalyst and block proton transfer. On the other hand, the internal resistance of the electrode is increased. However, if the amount of binder is too small, the electricity will fall off easily. Therefore, the optimal amount of binder is: the mass ratio of catalyst to PTFE is 4. (2) Phosphorus-doped carbon (ORR) catalysts were prepared from commercial cellulose phosphate by direct carbonization under the optimized roll pressing process parameters in the previous chapter. Phosphorus-doped carbon (ORR) catalysts were prepared into air cathodes and their properties in MFC were studied. A series of material characterization was carried out. The results of linear voltammetry showed that the air cathodes were linear. Compared with undoped carbon, phosphorus-doped carbon catalyst can obviously improve the electrochemical performance of air cathode. The results of battery performance test show that the catalyst prepared at 1000 鈩

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