催化学报 ›› 2021, Vol. 42 ›› Issue (4): 637-647.DOI: 10.1016/S1872-2067(20)63686-5

• 论文 • 上一篇    下一篇

具有高效析氧催化性能的铁基双元金属有机框架纳米棒研究

吴楚楚a,b,c, 张晓明a,b, 李焕巧a,b, 夏章讯a,b, 于陕升d, 王素力a,b,*(), 孙公权a,b,#()   

  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)燃料电池研究部, 辽宁大连116023
    b中国科学院大连化学物理研究所, 醇类燃料电池及复合电能源研究中心, 辽宁大连116023
    c中国科学院大学, 北京100049
    d吉林大学材料科学系, 吉林长春130012
  • 收稿日期:2020-05-17 接受日期:2020-06-23 出版日期:2021-04-18 发布日期:2021-01-22
  • 通讯作者: 王素力,孙公权
  • 基金资助:
    中国科学院战略先导专项(XDA21090300);国家自然科学基金(91834301);大连化物所科研创新基金项目(DICP ZZBS201705)

Iron-based binary metal-organic framework nanorods as an efficient catalyst for the oxygen evolution reaction

Chuchu Wua,b,c, Xiaoming Zhanga,b, Huanqiao Lia,b, Zhangxun Xiaa,b, Shansheng Yud, Suli Wanga,b,*(), Gongquan Suna,b,#()   

  1. aDivision of Fuel Cells and Battery, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
    bKey Laboratory of Fuel Cells & Hybrid Power Sources, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
    cUniversity of Chinese Academy of Sciences, Beijing 100049, China
    dDepartment of Materials Science, Jilin University, Changchun 130012, Jilin, China
  • Received:2020-05-17 Accepted:2020-06-23 Online:2021-04-18 Published:2021-01-22
  • Contact: Suli Wang,Gongquan Sun
  • About author:#Tel/Fax: +86-411-84379063; E-mail: gqsun@dicp.ac.cn
    *Tel/Fax: +86-411-84762570; E-mail: suliwang@dicp.ac.cn;
  • Supported by:
    Strategic Priority Research Program of the Chinese Academy of Sciences(XDA21090300);National Natural Science Foundation of China(91834301);DICP Grant(DICP ZZBS201705)

摘要:

析氧反应(OER)是电解水制氢的关键步骤,β开发高效、稳定、廉价的OER电催化剂是目前该领域的研究热点.ββ碱性电解液中的OER电催化剂成分以Mn、Fe、Co、Ni等为主,β其中单一组分的Fe基化合物催化活性不高,β但碱性电解液中的痕量铁杂质极易掺入Ni、Co等非Fe基材料的结构中,β极大影响其OER催化性能,β即现有大部分非Fe基化合物无法回避Fe的影响.ββ为探究Fe基多金属电催化剂的活性规律,β本文以结构清晰、组分可控的Fe基金属有机框架材料为基底,β通过掺入Mn、Co、Ni等元素构建双元金属化合物Fe2M-MIL-88B(M = Mn, Co, Ni),β并围绕上述Fe基双金属电催化剂的构效关系展开研究.ββ
扫描电镜、透射电镜、X射线衍射光谱、红外光谱等表征结果表明,β所制备的Fe基双金属材料均为具有MIL-88B构型的纳米棒,β其特征三核金属簇Fe3O中的一个铁原子被第二元金属所替代,β从而形成相应的三核混合金属簇Fe2MO.ββ上述Fe基双金属催化剂的析氧催化活性顺序为: Fe2Ni > Fe2Co > Fe2Mn > Fe (0.1βM KOH电解液).ββ其中,βFe2Ni-MIL-88B电催化剂在10βmA cm-2析氧电流对应的过电位仅需307βmV,β明显低于OER基准电催化剂20 wt% Ir/C(376βmV).ββ
结合材料的元素组成、电化学活性比表面积(ECSA)及金属价态分析发现,β第二元金属的引入会在不同程度上降低Fe的价态,β其中Ni的影响程度最大,βCo次之,βMn的影响最小.ββ借助分子轨道理论对上述实验现象进行了解释.ββ处于低自旋态的Ni2+与邻近桥氧O2-之间存在电子排斥作用,β因此部分电子将从Ni2+经O2-转移至高自旋态的Fe3+,β从而在Ni2+和Fe3+之间形成了较强的电子耦合作用.ββCo2+具有和Ni2+相似的构型,β但影响稍小.ββ而Mn2+和Fe3+同为高自旋态,β对Fe3+的电子结构影响最小,β导致活性改善程度最低.ββ密度泛函理论计算得到的自旋态变化情况印证了上述推测.ββ该系列Fe基双金属材料的催化性能主要受金属活性位点的电子结构影响,βFe与邻近金属间形成的电子耦合作用修饰了金属活性位点的电子结构,β从而提高了材料的OER本征催化活性.

关键词: 析氧反应, 金属有机框架, 电催化, 电子耦合作用, 水氧化

Abstract:

First-row transition metal compounds have been widely explored as oxygen evolution reaction (OER) electrocatalysts due to their impressive performance in this application. However, the activity trends of these electrocatalysts remain elusive due to the effect of inevitable iron impurities in alkaline electrolytes on the OER; the inhomogeneous structure of iron-based (oxy)hydroxides further complicates this situation. Bimetallic metal-organic frameworks (MOFs) have the advantages of well-defined and uniform atomic structures and the tunable coordination environments, allowing the structure-activity relationships of bimetallic sites to be precisely explored. Therefore, we prepared a series of iron-based bimetallic MOFs (denoted as Fe2M-MIL-88B, M = Mn, Co, or Ni) and systematically compared their electrocatalytic performance in the OER in this work. All the bimetallic MOFs exhibited higher OER activity than their monometallic iron-based counterpart, with their activity following the order FeNi > FeCo > FeMn. In an alkaline electrolyte, Fe2Ni-MIL-88B showed the lowest overpotential to achieve a current density of 10 mA cm-2 (307 mV) and the smallest Tafel slope (38 mV dec-1). The experimental and calculated results demonstrated that iron and nickel exhibited the strongest coupling effect in the series, leading to modification of the electronic structure, which is crucial for tuning the electrocatalytic activity.

Key words: Oxygen evolution reaction, Metal-organic frameworks, Electrocatalysis, Electronic coupling effect, Water oxidation