以具有抗积碳与氧还原活性的氮掺杂银/氮化铁/晶态碳为阴极的微生物燃料电池产电机制

在单室微生物燃料电池（MFC）处理污水过程中，异养微生物会在阴极形成生物膜（积碳），成为O2竞争体，使O2还原反应（ORR）效率降低。本项目以三聚氰胺为碳（氮）源，引入石墨化助剂（Fex+）和功能性组分（Ag+），通过强化原位氮掺杂促进碳化铁向氮化铁转化而同步碳热还原合成银/氮化铁/晶态碳（Ag/FexN/NGC）材料，利用其抗积碳与高效O2还原的协同作用，改善ORR的不利限制而提高MFC功率输出；以抑制细菌呼吸酶活性和破坏细胞结构为目标，分析活性氧对生物膜生成的拮抗作用，阐明Ag/FexN/NGC的组成与结构对抗积碳性能的影响；基于对Ag/FexN/NGC的ORR催化性能与途径分析，阐释FexN和Ag之间协同作用对ORR催化活性与电子转移能力的增强机理；将Ag/FexN/NGC阴极表面抗生物积碳的活性氧消耗过程与催化剂活性中心ORR过程有机结合，揭示此ORR性能强化的MFC的产电机制。

In the wastewater treatment process, the heterotrophic microorganisms (biocarbon) in single–chamber microbial fuel cell (MFC) can make use of the substrates to form biofilm on the cathode surface, which will change it into a strong O2 competitor. The biocarbon may also inhibit the proton migration and the anode’s electron transfer, which results in the decrease of O2 reduction reaction (ORR) efficiency and catalytic activity of cathode catalysts. In this project, melamine with polar functional groups is selected as carbon (nitrogen) source, and based on the charge matching principle, the graphitized assitant (Fex+) and functional ingredients (Ag+) are added to the synthesis system. By using the method of carbothermal reduction with enhanced in situ nitrogen doping, nitrogen–doped silver/iron nitride/partily–graphitized carbon (Ag/FexN/NGC) composites can be simutaneously synthesized through converting Fe3C to FexN. This study aims to prepare the cathode catalyst with the characteristics of bio–carbon inhibition and high ORR efficiencies, which can change the unfavorable restrictions of the surface ORR on cathode, thereby improving the MFC power output. By restraining the activity of the respiratory enzyme of bactria and damaging the bacterial structure, effect of the generated reactive oxygen (ROS) on property of bio–carbon inhibition is discussed. Influence of the crystalline type and structure of Ag/FexN/NGC on property of bio–carbon inhibition is also explored. Based on the analysis of catalytic activity and pathway for ORR by using Ag/FexN/NGC, mechanism for the enhancement of catalytic reduction activity and electron transport by using the synergistic effect between Ag and FexN is investigated. By combining the process of ROS consumation (by bio–carbon inhibition) with the process of ORR on active centers of the catalyst, electricity generation mechanism for MFC with ORR–enhanced Ag/FexN/NGC cathodes can be revealed.