催化学报 ›› 2016, Vol. 37 ›› Issue (7): 1127-1133.DOI: 10.1016/S1872-2067(15)61104-4

• 论文 • 上一篇    下一篇

以金属有机骨架为前驱体的高活性氧还原非贵金属催化剂制备

白杨芝a,b, 衣宝廉a, 李佳c, 蒋尚峰a, 张洪杰a, 邵志刚a, 宋玉江c   

  1. a. 中国科学院大连化学物理研究所, 洁净能源国家实验室(筹), 辽宁 大连 116023;
    b. 中国科学院大学, 北京 100049;
    c. 大连理工大学化工系, 精细化工国家重点实验室, 辽宁 大连 116024
  • 收稿日期:2016-03-15 修回日期:2016-04-12 出版日期:2016-06-17 发布日期:2016-06-17
  • 通讯作者: Zhigang Shao, Yujiang Song
  • 基金资助:

    国家重点基础研究发展计划(973计划,2015CB932304);国家自然科学基金(21436003).

A high performance non-noble metal electrocatalyst for the oxygen reduction reaction derived from a metal organic framework

Yangzhi Baia,b, Baolian Yia, Jia Lic, Shangfeng Jianga, Hongjie Zhanga, Zhigang Shaoa, Yujiang Songc   

  1. a. Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China;
    b. University of Chinese Academy of Sciences, Beijing 100049, China;
    c. State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China
  • Received:2016-03-15 Revised:2016-04-12 Online:2016-06-17 Published:2016-06-17
  • Contact: Zhigang Shao, Yujiang Song
  • Supported by:

    This work was supported by the National Basic Research Program of China (973 Program, 2015CB932304) and the National Natural Science Foundation of China (21436003).

摘要:

燃料电池具有能量转化效率高、功率密度高、低温操作、无污染等优点,因而在电动汽车动力源、移动式电源及分散电站等领域具有广阔的应用前景.Pt/C催化剂是目前使用最广泛的燃料电池阴极氧还原反应(ORR)的催化剂,然而其有限的储量、较低的稳定性、易CO中毒等缺点限制了燃料电池的大规模商业化,因此研制高活性和稳定性的非贵金属催化剂以代替Pt/C催化剂显得至关重要.金属有机骨架(MOFs)是由金属阳离子和有机配体配位而成的结构可调的空间三维材料,其作为前驱体制备非贵金属ORR催化剂具有独特的优势:(1)MOFs的三维晶体结构可以提供高的活性位点密度;(2)有机配体可以在热解的过程中转化为碳支撑体,使得活性金属物质和碳支撑体可以同时生成;(3)可以调节形成MOFs的金属离子和有机配体来设计一定特性的MOFs结构,从而制备结构和功能可调的催化剂;(4)MOFs具有可调控的孔径尺寸及可修饰的孔道表面,其较大的比表面积和不同孔隙分布有利于吸附反应物氧气分子,而且可以得到不同元素和金属掺杂的多孔碳材料.因此,本文选择MOF材料ZIF-67作为前驱体,通过在500-900℃高温热处理制备了非贵金属ORR催化剂,在0.1mol/LKOH溶液中进行电化学测试,发现其中600℃热处理得到的催化剂的活性较好.为了进一步提高催化剂的导电性和分散性,对该催化剂进行了BP2000碳载处理.电化学测试发现,该催化剂的ORR活性进一步提高:当载量为1.0mg/cm2时,其ORR起始电位和半波电位分别达1.017和0.857V(vs.RHE),与商业化Pt/C(20μgPt/cm2)的性能相近.透射电镜结果表明,制备的催化剂为单质Co粒子镶嵌的N掺杂的多孔碳材料,其中Co粒子的粒径为10nm左右,其存在可由X射线衍射测试得以确认.X射线光电子能谱表征显示,碳载得到的催化剂中N原子主要以吡啶型存在,后者可能起到一定的ORR活性位点作用,且其比表面积为296m2/g,高于未碳载的268m2/g,也有利于提高其电化学活性.结果还显示,与商业化Pt/C相比,碳载催化剂具有更好的抗甲醇性和稳定性.

关键词: 燃料电池, 氧还原反应, 非贵金属催化剂, 金属有机骨架, 碱性电解液

Abstract:

The development of a non-precious metal electrocatalyst (NPME) with a performance superior to commercial Pt/C for the oxygen reduction reaction (ORR) is important for the commercialization of fuel cells. We report the synthesis of a NPME by heat-treating Co-based metal organic frameworks (ZIF-67) with a small average size of 44 nm. The electrocatalyst pyrolyzed at 600 ℃ showed the best performance and the performance was enhanced when it was supported on BP 2000. The resulting electrocatalyst was composed of 10 nm Co nanoparticles coated by 3-12 layers of N doped graphite layers which as a whole was embedded in a carbon matrix. The ORR performance of the electrocatalyst was tested by rotating disk electrode tests in O2-saturated 0.1 mol/L KOH under ambient conditions. The electrocatalyst (1.0 mg/cm2) showed an onset potential of 1.017 V (vs. RHE) and a half-wave potential of 0.857 V (vs. RHE), which showed it was as good as the commercial Pt/C (20 μgPt/cm2). Furthermore, the electrocatalyst possessed much better stability and resistance to methanol crossover than Pt/C.

Key words: Fuel cell, Oxygen reduction reaction, Non-precious metal catalyst, Metal organic framework, Alkaline condition