高等学校化学学报 ›› 2012, Vol. 33 ›› Issue (07): 1534-1539.doi: 10.3969/j.issn.0251-0790.2012.07.031

• 物理化学 • 上一篇    下一篇

高温处理对碳载吡啶钴催化氧还原性能的影响

徐莉1, 林瑞2, 丁蕾1, 戴先峰1, 乔锦丽1   

  1. 1. 东华大学环境科学与工程学院 上海 201620;
    2. 同济大学新能源汽车工程中心, 上海 201804
  • 收稿日期:2011-11-03 出版日期:2012-07-10 发布日期:2012-07-10
  • 通讯作者: 乔锦丽, 女, 博士, 教授, 主要从事固体高分子膜燃料电池关键材料研究与开发, E-mail: qiaojl@dhu.edu.cn E-mail:qiaojl@dhu.edu.cn
  • 基金资助:

    国家自然科学基金(批准号: 21173039)、 高等学校博士学科点专项科研基金(批准号: 20110075110001)和国家环境保护纺织工业污染防治工程技术中心项目资助.

Effect of Heat-treated Temperature on the Carbon-supported Cobalt Pyridine Electrocatalysts for Oxygen Reduction

XU Li1, LIN Rui2, DING Lei1, DAI Xian-Feng1, QIAO Jin-Li1   

  1. 1. College of Environmental Science and Engineering, Donghua University, Shanghai 201620, China;
    2. Clean Energy Automotive Engineering Center, Tongji University, Shanghai 201804, China
  • Received:2011-11-03 Online:2012-07-10 Published:2012-07-10

摘要: 利用碳黑(Vulcan XC-72R) 中加入硫酸钴和吡啶(Py)作为催化剂前躯体, 经溶剂分散热处理构建了一类新型的高效氧还原CoPy/C复合催化剂. 运用循环伏安法和旋转圆盘电极(RDE)技术研究了不同温度(600~900 ℃)处理CoPy/C催化剂在碱性介质中对氧还原的电催化性能. 结果表明, 热处理能显著提高CoPy/C的催化活性, 活性次序为800 ℃>900 ℃>600 ℃>未处理. 其中800 ℃处理的15%Co25%Py/C(质量分数)复合催化剂表现出最佳的氧还原催化性能, 以其制备的气体扩散电极在3.0 mol/L KOH 电解质溶液(O2气氛)中的半波电位为-0.069 V(相对于标准可逆氢电极), 起峰电位为0.026 V, 同时表现出明显的极限扩散电流. 利用透射电镜、 能谱分析和X射线衍射技术对催化剂的微观形貌、 颗粒大小和活性位结构的研究结果表明, 所制备的碳黑负载吡啶钴催化剂(15%Co25%Py/C)平均粒径为17 nm, 经800 ℃处理后吡啶结构发生了坍塌, 形成了其它价态的钴氧化合物、 硫化物和单质钴, 并协同吡啶中的氮对氧起催化还原作用. RDE结果表明, O2在CoPy/C催化剂上的反应动力学主要通过4e-过程还原成H2O.

关键词: 碳载吡啶钴催化剂, 热处理, 循环伏安, 旋转圆盘电极, 碱性燃料电池, 氧还原反应

Abstract: CoPy/C catalysts for the oxygen reduction reaction(ORR) were prepared with 40/60(mass ratio)(15%Co25%Py/C) using cobalt sulfate hepathydrate(CoSO4·7H2O) and pyridine(Py) as the Co and N precursors supported on Vulcan XC-72R followed by heat treatment in an inert atmosphere at different temperatures ranging from 600 ℃ to 900 ℃. The catalysts were characterized by TEM, XRD and SEM-EDS anlaysis. Their ORR activities as the function of heat treatment temperatures for catalyst synthesis were evaluated by cyclic voltammograms(CVs) and rotating disk electrode(RDE) measurements. The results show that high temperature treatment can greatly improve the ORR activity of CoPy/C catalyst, for which the catalyst synthesized at 800 ℃ exhibits the best ORR activity. The nanoparticles of the catalyst as-prepared, with a diameter of 17 nm, uniformly dispersed on Vulcan carbon(Vulcan XC-72R). XRD and EDS anlaysis indicate that the structure of CoPy/C is destroyed after high temperature pyrolysis, and changed as the different valence cobalt oxide and cobalt sulfide, which are with N and S as the active sites for ORR. In 3.0 mol/L KOH, 15%Co25%Py/C(in O2) can produce the obvious ORR current, giving the onset potential at 0.026 V(vs. SCE) with a half-wave potential of -0.069 V. RDE results further reveal that 15%Co25%Py/C catalysts in 3.0 mol/L KOH solution catalyze the ORR via four-electron pathway, through which the molecular oxygen is directly reduced to H2O.

Key words: CoPy/C catalyst, Heat-treatment, Cyclic voltammogram, Rotating disk electrode(RDE), Alkaline fuel cell, Oxygen reduction reaction

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