固体氧化物燃料电池中CaO，Pt，Pd修饰对氧还原反应的增强效应

发布时间：2018-01-13 19:38

本文关键词：固体氧化物燃料电池中CaO，Pt，，Pd修饰对氧还原反应的增强效应　出处：《中国科学技术大学》2017年硕士论文　论文类型：学位论文

【摘要】：能源短缺和环境污染是全世界在可持续发展道路中所面临的重大问题,因此找到一种高效清洁的能源生产方式迫在眉睫。固体氧化物燃料电池(SOFC)是一种电化学转换装置,能高效地将碳氢燃料或者氢燃料转化成电能,且几乎无污染物的排放。而发生在阴极的氧还原反应(ORR)是影响SOFC性能的主要因素。本论文从提高阴极性能的角度出发,第一部分研究和分析了 CaO修饰对La0.6Sr0.4Co0.2Fe0.8O3-δ(LSCF)阴极上氧还原反应速率的影响;第二部分研究贵金属Pt和Pd修饰对La0.7Sr0.3Mn03(LSM)薄膜不同晶面取向上表面交换反应过程的影响。以下是本文研究的具体内容:第二章中采用离子浸渍法制备CaO修饰的LSCF阴极,探究CaO修饰对LSCF阴极性能的影响。首先通过向LSCF(LSCF-SDC)电极中浸渍硝酸钙溶液,800 ℃C热处理1h后分解得到CaO纳米颗粒修饰的LSCF(LSCF-SDC)电极。通过交流阻抗谱分析可知,CaO纳米颗粒的修饰可以有效地减小LSCF电极的极化阻抗,且CaO浸渍量为5.18 wt.%时,电极性能最佳。修饰后的CaO-LSCF/SDC/CaO-LSCF对称电池在空气气氛下650 ℃时的极化阻抗为0.310Ω·cm2,小于未经修饰的0.510 Ω·cm2。并用弛豫时间分布(DRT)的方法分析交流阻抗谱,发现通过CaO的浸渍,中频区对应的电荷转移过程明显加快。通过电导弛豫法测得CaO修饰后LSCF表面交换系数有一个数量级的增大,当0.07 mg·cm-2 的 CaO 涂覆在 LSCF 条子表面时,700℃ 下,Kchem从1.80×10-5cm·s-1增大至2.81×10-4 cm·s-1,表明CaO可促进LSCF表面的氧表面交换动力学过程。同时浸渍电极的单电池上也显示了良好的性能输出,湿润H2气氛下,NiO-SDC/SDC/CaO-LSCF单电池在650℃时的最大功率密度可达800 mWcm-2,大于 NiO-SDC/SDC/LSCF 的 600 mWcm-2。第三章中采用不同取向的致密LSM单晶薄膜作为研究对象,经Pt和Pd纳米颗粒修饰后,探究贵金属修饰对不同取向的LSM薄膜上的氧表面交换反应的影响。首先采用脉冲激光沉积(PLD)法制备出(001),(110)和(111)取向的LSM薄膜,然后用蒸镀法制得Pd和Pt纳米颗粒修饰的LSM薄膜上。通过电导弛豫法测得修饰Pt和Pd修饰前后不同取向的LSM薄膜的表面交换系数,Kchem,测试温度区间为500℃到650℃。发现未经修饰的LSM薄膜,不同晶面取向上的Kchem值不同,且(110)取向在三个晶面中Kchem值最小,表明三个晶面上的表面交换动力学过程是不同的。经Pd和Pt纳米颗粒修饰后,LSM三个晶面上的Kchem值都增大,表明Pd和Pt对氧表面交换反应动力学都有促进作用。且Pd和Pt的促进作用不同,其在不同晶面上的提升因子也不相同,且都在(110)取向上最大。Pt修饰的(110)取向的LSM薄膜,其表面交换速率的提升因子高达129,是Pd修饰的(110)取向的5倍。
[Abstract]:Energy shortage and environmental pollution is a major problem facing the world in the road of sustainable development in an imminent, so to find efficient and clean energy production. The solid oxide fuel cell (SOFC) is an electrochemical conversion device, can efficiently be hydrocarbon fuel or hydrogen fuel into electricity, and almost no pollution and the occurrence of emissions. At the cathode oxygen reduction reaction (ORR) is the main factor affecting the performance of SOFC. This paper focuses on improving the cathode performance point of view, the first part of the research and analysis of CaO modification on La0.6Sr0.4Co0.2Fe0.8O3- 6 (LSCF) on cathodic oxygen reduction reaction rate influence; the second part of the noble metal Pt and Pd modified La0.7Sr0.3Mn03 (LSM) thin films with different crystal orientations on the impact of the surface exchange reaction. The following is the main content of this paper: by ion impregnation method in the second chapter, the preparation of CaO repair LSCF cathode decoration, explore the effects of CaO modification on LSCF cathode performance. Firstly, through to the LSCF (LSCF-SDC) calcium nitrate impregnation solution electrode, LSCF C 800 degrees of heat treatment after 1h decomposition of CaO nanoparticles modified electrode (LSCF-SDC). The AC impedance spectrum analysis shows that the polarization resistance of modified CaO nano particles can be effectively reduce the LSCF electrode, and CaO impregnation was 5.18 wt.%, the best performance. The electrode polarization impedance of CaO-LSCF/SDC/CaO-LSCF symmetric cell modified in the atmosphere at 650 C for 0.310. Cm2, less than the unmodified 0.510. Cm2. and the relaxation time distribution (DRT) method for the analysis of communication impedance spectroscopy, found by CaO impregnation, if the charge transfer process was accelerated. By conductivity relaxation measured by CaO modified LSCF surface exchange coefficient has a magnitude increases, when coated with CaO 0.07 mg - cm-2 Note on LSCF surface, 700 DEG C, from 1.80 Kchem * 10-5cm S-1 * 10-4 cm increased to 2.81 s-1, indicating that CaO can enhance the oxygen surface LSCF surface exchange kinetics. At the same time, single cell immersed electrodes also showed a good performance output, wet H2 atmosphere, NiO-SDC/SDC/ CaO-LSCF in single cell 650 degrees the maximum power density can reach 800 mWcm-2, more than NiO-SDC/SDC/LSCF 600 mWcm-2. in the third chapter, the dense LSM single crystal films with different orientation as the research object, by Pt and Pd nanoparticles modified on noble metal modified effect on oxygen surface exchange reaction of LSM thin films with different orientation. The first by pulsed laser deposition (PLD) was prepared by (001), (110) and (111) oriented LSM films, LSM films and evaporation method of Pd and Pt nanoparticles modified by conductivity relaxation measured by modified Pt and modified Pd not The surface of LSM films with the orientation of the exchange coefficient, Kchem, test the temperature range of 500 C to 650 C. Found that without LSM film modified by different crystal orientations on different Kchem values, and (110) orientation of Kchem in the three planes in the minimum value, show that the surface of the three planes on the exchange the dynamic process is different. The results of Pd and Pt nanoparticles modified LSM three surface Kchem value increased, indicating that Pd and Pt exchange reaction kinetics of oxygen surface have stimulative effect. And the Pd and Pt to promote the role of different, the different crystal on the surface of the lifting factor is not the same. And in the orientation of maximum (110) modified.Pt (110) LSM film orientation, enhance the factor of its surface exchange rate as high as 129, is modified by Pd (110) 5 times the orientation.

【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM911.4

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