ACMFC氧还原催化反应高效杂环碳催化剂的制备及反应动力学模型

Air-cathode microbial fuel cells (ACMFCs) generate electric energy at the same time when treating waste wastewater, which makes it a promising technology in future. However, high cost and low power output are the two main issues that hinder the ACMFC’s further development. In this project, low-cost non-metallic catalyst will be used to replace the far more expensive Pt/C catalyst which directly leads to high cost of ACMFC. In view that the reaction rate of the oxygen reduction reaction governed by the activity of the catalyst together with the mass transport of the oxygen, is the key to improve the power output of ACMFCs, the recently emerging heteroatom doped carbon (HDC) catalyst of high catalytic activity will be prepared and used in this project, and moreover a three-phase interface reaction kinetic model will be developed and on the basis of which the mass transport of the oxygen will be optimized. Firstly, by the pyrolysis method, nitrogen-, sulfur- or phosphorus- doped carbon catalysts and the more reactive nitrogen-sulfur or nitrogen-phosphorus dual doped carbon catalysts will be prepared. In the preparation, inorganic nitrogen, sulfur or phosphorus is used as precursors, replacing the organic precursors which are prone to have toxic by-product. The key heterocyclic functional groups will be determined and the method for improving these functional groups will be studied. Activity, stability and selectivity will be characterized based electrochemical tests. Secondly, taking account of the detailed structure of the catalytic layer, a reaction kinetic model will be constructed describing the flow of electrolyte, the oxygen transport as well as the oxygen reduction reaction. Then structure parameters of cathode corresponding to the fastest oxygen transport will be found by the optimization analysis based on this model. Finally, both the energy-generation and the wastewater treatment abilities will be studied for the prepared HDC-cathode ACMFCs.

ACMFC兼备水处理与产能，应用前景广阔。成本高、产能低是目前ACMFC存在的主要问题。贵金属Pt/C催化剂的使用是导致成本高的直接原因，本项目制备低成本非金属催化剂代替Pt/C。催化剂活性和氧气传质共同决定了ACMFC氧还原催化反应速率，是提高产能的关键，本项目制备并应用新兴的高催化活性杂环碳催化剂（HDC）并基于三相界面动力学模型对阴极传质进行优化。首先，以无机氮、硫、磷代替易产生毒副产物的有机前驱物，采用热解法制备掺氮、硫、磷碳催化剂以及活性更强的氮硫、氮磷共掺杂碳催化剂；确定关键杂环元素官能团，并研究提高其含量的制备工艺；基于电化学测试表征所制备HDC的催化活性、稳定性和选择性；其次，在考虑催化层细部结构的基础上，建立同时描述电解液流动、阴极各层氧气传质和氧还原反应的动力学模型，并通过优化获得有利于传质的阴极结构参数；最后，考察所制HDC阴极ACMFC的产能和实际废水处理效果。

微生物燃料电池（MFC）兼备水处理与产能,应用前景广阔。成本高、产能低是目前MFC存在的主要问题。 贵金属Pt/C催化剂的使用是导致成本高的直接原因。本项目通过热解法合成了高活性、稳定性好、低成本的氮/硫/微量铁共掺杂的纳米微球催化剂（N/S/FeDC），全面优化了制备催化剂的条件，如氮/硫/铁比、温度、焙烧时间等。发现以N/S/FeDC 为催化剂的MFC的产能比以Pt/C为催化剂的MFC高24%。在分析氮/硫源、碳基体对催化剂活性和微观结构的影响的基础上，深入研究了该催化剂的氧还原催化机理。发现微量铁的不仅能形成Fe-N2/C, Fe-S2/C, and FeC3的催化活性位，还能增加催化C-N\C-S活性位的生成。此外，氧气在阴极的传质被发现是制约MFC产能的另一要素，扩散层作为阴极的重要组成部分，对氧气传质起着举足轻重的作用。本研究发现使扩散层孔隙较大程度的分布在中孔范围内可降低氧气传质造成的极化损失并提高MFC产能。本项目为MFC的放大化和实际应用提供了理论依据。