催化学报 ›› 2017, Vol. 38 ›› Issue (10): 1668-1679.DOI: 10.1016/S1872-2067(17)62885-7

• 论文 • 上一篇    下一篇

一步热解核黄素制备高性能氧还原反应电催化剂

邓玉潇, 皇甫海新, 唐水花, 李杰   

  1. 西南石油大学材料科学与工程学院油气藏地质与开发国家重点实验室, 四川成都 610500
  • 收稿日期:2017-05-04 修回日期:2017-07-03 出版日期:2017-10-18 发布日期:2017-10-28
  • 通讯作者: 唐水花
  • 基金资助:

    催化基础国家重点实验室开放项目(N-14-1);教育部海外留学归国人员科研启动项目;成都科技局国际合作项目。

High performance ORR electrocatalysts prepared via one-step pyrolysis of riboflavin

Yuxiao Deng, Haixin Huangfu, Shuihua Tang, Jie Li   

  1. State Key Laboratory of Oil and Gas Reservoir Geology & Exploitation, School of Materials Science and Engineering, Southwest Petroleum University, Chengdu 610500, Sichuan, China
  • Received:2017-05-04 Revised:2017-07-03 Online:2017-10-18 Published:2017-10-28
  • Contact: 10.1016/S1872-2067(17)62885-7
  • Supported by:

    This work was supported by Open Project from State Key Laboratory of Catalysis (N-14-1), Scientific Research Foundation for Returned Scholars, Ministry of Education of China, and International Technology Collaboration of Chengdu Science and Technology Division.

摘要:

质子交换膜燃料电池具有零污染、能量密度高、操作温度低和超静低音等优点,因而广泛应用于新能源汽车动力电源.然而质子交换膜燃料电池阴极氧还原反应(ORR)过程缓慢且复杂,因此需要大量的高性能ORR电催化剂.商品铂基催化剂是目前最为广泛使用的ORR催化剂,然而其高昂的价格阻碍了燃料电池汽车的商业化进程.因此,近年来人们致力于研发高性能的非贵金属ORR催化剂,并成功获得了具有高ORR活性及优异稳定性的催化剂.然而开发贵金属替代催化剂还存在制备过程较为复杂、单体有毒等缺点.
核黄素具有成本低廉、无毒、氮含量高等优点,本文将其直接作为碳源和氮源,以无水氯化铁为铁前驱体,通过简单的一步热解法制备了高性能的Fe-N-C催化剂.表征结果表明,合成的催化剂表面由于氮的掺杂导致石墨烯存在较多的缺陷,其比表面积为301 m2 g-1且孔径分布主要位于45 nm处;催化剂由很薄、卷曲的石墨烯片层和一些颗粒组成,其中的碳材料高度石墨化且存在Fe2O3晶体.结合X射线光电子能谱和催化剂的ORR活性,推导出石墨化氮为ORR的主要活性位,铁在ORR反应中也起着重要作用.在氧气饱和的0.1 mol L-1 KOH溶液中,Fe-N-C催化剂的ORR活性达到4.16 mA cm-2,与商品Pt/C催化剂相当(4.46 mA cm-2).采用计时电流法在0.66 V(相对于RHE电位)下运行3 h后,Fe-N-C催化剂电流仅下降了3%,而Pt/C催化剂下降了40%,表明Fe-N-C催化剂与Pt/C催化剂具有相近的ORR活性,但稳定性比Pt/C催化剂更出色.测试结果表明,Fe-N-C催化剂的抗甲醇毒化性能远优于Pt/C催化剂.在酸性介质中,Fe-N-C催化剂的ORR活性比Pt/C催化剂低,但稳定性更高.总之,该Fe-N-C催化剂在碱性介质中有较高的活性和稳定性,在酸性介质中有较高的稳定性.因此,我们采用廉价、无毒的核黄素作为碳氮源,通过简单的一步热解法制备出的Fe-N-C催化剂能较好地满足燃料电池ORR催化剂高性能和低成本的要求,具有很好的应用前景.

关键词: 核黄素, 热解, 氧气还原反应, 氯化铁, 电催化剂

Abstract:

Efficient, cost-effective electrocatalysts for an oxygen reduction reaction (ORR) are currently required for fuel cells. In the present work, riboflavin was used as a cheap, nontoxic carbon and nitrogen precursor to prepare Fe-N-C catalysts via one-step pyrolysis in the presence of anhydrous iron chloride. Raman spectroscopy indicated that the catalyst containing nitrogen created a great quantity of defects in the carbon structures, while nitrogen adsorption-desorption isotherms showed that the catalyst was mesoporous. Transmission electron microscopy demonstrated that the Fe-N-C catalyst was composed of very thin, curved and porous graphene layers together with some Fe2O3 nanoparticles, and X-ray diffraction patterns confirmed that the carbon in the catalyst was highly graphitized. X-ray photoelectron spectroscopy indicated that the active sites for the ORR were primarily composed of graphitic nitrogen, although Fe sites also played an important role. The ORR activity of the Fe-N-C catalyst reached a maximum of 4.16 mA cm-2, and its chronoamperometric response was found to decrease by only 3% after operating for 3 h at 0.66 V (vs RHE) in an O2-saturated 0.1 mol L-1 KOH solution. In contrast, a commercial 40 wt% Pt/C catalyst with a loading of 0.2 mgPt cm-2 exhibited an activity of 4.46 mA cm-2 and a 40% loss of response. The electrochemical performance of this new Fe-N-C catalyst was therefore comparable to that of the Pt/C catalyst while showing significantly better stability.

Key words: Riboflavin, Pyrolysis, Oxygen reduction reaction, FeCl3, Electrocatalyst