氧阴极催化剂的制备及其电化学性能研究

发布时间：2018-01-14 14:47

本文关键词：氧阴极催化剂的制备及其电化学性能研究　出处：《天津大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着碱性金属-空气电池和燃料电池日益广泛的应用，对空气阴极上发生的氧化还原反应(ORR)的催化剂材料需求越来越紧迫。因此研究ORR催化剂材料具有重要意义。本文通过对比实验在回流法制备的碳球（CMs）、水热法制备的碳球（CS）和氧化石墨（GO）三种碳材料中选择最佳催化剂载体。用相同的浸渍煅烧法制备不同载体相同锰氧化物含量的复合物催化剂，，通过稳态极化曲线的测试选择了CMs和CS。再通过循环伏安和交流阻抗测试最终选择CMs作本文的催化剂载体。本文还探索了不同蔗糖浓度、不同硫酸浓度和不同反应时间对形成CMs的影响。通过浸渍煅烧法制备了一系列不同MnOx含量的催化剂，对比发现MnOx质量分数为7.32%的催化剂ORR活性最好。7.32%MnOx/CMs比表面积为1278m2·g-1。通过XRD、TEM研究表明锰氧化物均匀地分布在碳球的表面。稳态极化曲线、Tafel曲线、循环伏安和交流阻抗等电化学测试研究结果表明：复合物催化剂7.32%MnOx/CMs在碱性介质中有着较大的表观电流密度0.649mA·cm-2和较正的还原电位-0.4Vvs.Hg/HgO，具有较好的电化学催化活性；发生在7.32%MnOx/CMs催化剂上的ORR反应过程为2-电子过程。通过浸渍煅烧法制备了一种高效ORR催化剂CeOx-MnOx/CMs。通过TEM、SEM、EDX和元素分布图发现CeOx-MnOx成功地附着在了碳球表面且分布均匀。稳态极化曲线表明CeOx-MnOx/CMs具有较低的过电位和较高的ORR还原电流，表观电流密度为2.17mA·cm-2。通过循环伏安测试可知该电极的还原峰值电位为-0.28V vs. Hg/HgO。根据Koutecky Levich测试计算结果，发生该复合物上的ORR过程为2-电子还原过程。通过铝-空气电池性能测试发现CeOx-MnOx/CMs为阴极的铝空气电池最大功率密度为266mW·cm-2。
[Abstract]:With the increasing application of alkaline metal-air battery and fuel cell. The demand for the catalyst materials for the redox reaction on the air cathode is becoming more and more urgent, so it is of great significance to study the ORR catalyst materials. In this paper, the carbon spheres (CMS) prepared by reflux method were compared with each other. Among the three carbon materials prepared by hydrothermal method, the best catalyst support was chosen, and the complex catalyst with the same content of manganese oxide was prepared by the same impregnation calcination method. CMs and CSS were selected by the measurement of steady state polarization curve. Finally, CMs was selected as catalyst carrier by cyclic voltammetry and AC impedance test. Different sucrose concentrations were also explored in this paper. The effect of different sulfuric acid concentration and reaction time on the formation of CMs. A series of catalysts with different MnOx content were prepared by impregnation and calcination. It was found that the catalyst with MnOx content of 7.32% had the best ORR activity. The specific surface area of MnO2 / CMs was 1278 m ~ 2 路g ~ (-1) through XRD. TEM results show that manganese oxides are uniformly distributed on the surface of the carbon sphere, and the steady-state polarization curve is the Tafel curve. The results of electrochemical measurements such as cyclic voltammetry and AC impedance show that:. The complex catalyst 7.32MnOxr / Ms has a large apparent current density of 0.649mA 路cm-2 and a positive reduction potential of -0.4Vvs.Hgr HgO in alkaline medium. . It has good electrochemical catalytic activity. The process of ORR reaction on the catalyst of 7.32 MNO _ x / CMs is a 2-electron process. An efficient ORR catalyst CeOx-MnOx-CMs. was prepared by impregnation and calcination. EDX and elemental distribution diagram showed that CeOx-MnOx was successfully attached to the surface of carbon sphere and distributed uniformly. The steady-state polarization curve showed that CeOx-MnOx/CMs had lower overpotential and higher distribution. ORR reduction current. The apparent current density is 2.17mA 路cm-2.The peak reduction potential of the electrode is -0.28V vs. HgP / HgO by cyclic voltammetry. Levich test results. The ORR process on the complex is a 2-electron reduction process. The maximum power density of aluminum air cell with CeOx-MnOx/CMs cathode is 266MW 路cm ~ (-2).
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM911.4;O643.36

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