微流体污染物氨硝燃料电池层流界面膜功能特性研究

A device of ammonia-nitrate fuel cell is developed to achieve self-produced electricity simultaneously with nitrogen removal, which is a promising technology in the field of nitrogen-rich wastewater treatment. However, a big gap exists between the power output and the theoretical value due to the separator problem, for example, high internal resistance, permeability and diffusion etc. Thus, in this project, a new microfluidic ammonia-nitrate fuel cell system is established to resolve the separator problem. By comparison of experiment including different microchannel types and sizes, different electrode placement, flow pressure and rate, an optimized microfluidic cell system is established. A 3D-graphene aerogel porous electrode loading bimetal catalyst is prepared and the catalyzed mechanism is investigated. Using isotope labeling N to record the material sign in the electrode and the microchannel, the products trajectory can be inferred. Using chromatography for determination of diffusion rate or penetration rate can make clear that the laminar interfacial film functions in the process of mass transfer performance. With the analysis of thermal imaging analyzer, fluorescence microscope, thermal infrared microscope, and other optical instruments, combined with power output performance, information that concentration difference, pH gradient and temperature, is how to impact on the microfluidic laminar interfacial film performance can be found out. By constructing a mathematical model of ammonia-nitrate fuel cell to simulate the electrode surface species, the concentration distribution in microchannel and diffusion process, the deep mechanism of energy loss from the mass transfer can be revealed.

氨硝燃料电池应用于含氮污染物的脱氮处理效果良好，预示它在含氮废水处理领域广阔的应用前景，但受限于膜内阻及膜渗透、扩散等原因导致电量输出不理想。所以本课题构建微流体氨硝燃料电池体系，通过研究不同的微通道类型与尺寸、电极放置方式、通道内流体压力与流速等因素优化微流体电池体系，在石墨烯气溶胶基材上修饰双金属优化三维多孔电极并明晰其催化机理及催化反应的微观过程；采用同位素标记N来记录物质在电极和层流界面膜上的运动轨迹，借助色谱仪测定扩散速率或渗透速率以明确层流界面膜在物质传递过程中的隔膜功能性能。借助热成像分析仪、荧光显微镜、热红外显微镜等光学仪器、结合电池电能输出明晰层流界面膜间的电势差、浓度差、酸碱度和酸碱梯度以及反应温度等微观因素是如何对微流体层流界面膜功能特性产生影响，构建数学模型论证电池运行时电化学过程物质在电极表面、微通道内的浓度分布与扩散过程，揭示实验难以进行的传质能量损耗机理。

氨硝燃料电池展现了良好的脱氮效果，预示它在含氮废水处理领域大有可为，但受限于电极活性、膜界面功能不稳定等原因阻碍了其深入发展。本项目通过物理表征、电化学技术表征手段和DFT理论分析明晰了NiCu纳米催化电极中Cu掺杂Ni的作用机理，确定催化氨活性物质是NiCu羟基氧化物，进一步构建了硫化结合原位电化学调控两级重构高效的二维NiCu-S-T/CP和三维NiCu@NiCuOOH-NF核壳纳米结构的催化电极，筛选出最优的NiCu氨催化阳极；构建了flow-over型和flow-through型的氨微流体燃料电池体系，挖掘出了层流界面膜功能特性的宏观影响因素，探明了电极构型、电极尺寸、流体流速、氨初始浓度、电解质浓度梯度、温度梯度等对电池产电性能的影响，揭示了这些宏观影响因素对层流界面膜的影响机制以及对氨微流体燃料电池产电性能的作用规律，发现了微流体膜界面功能稳定运行的传质能量损耗因素，掌握了有效的提高氨硝燃料电池产电脱氮效能的控制方法。本项目研究成果拓展了对氨硝燃料电池更为全面的认知，攻克了污染物产电应用基础研究的理论与技术难关，推进了氨硝燃料电池产电在氨硝脱氮技术领域的深入发展。