Rautenberg Max, Gernhard Marius, Radnik Jörg, Witt Julia, Roth Christina, Emmerling Franziska
BAM Federal Institute of Materials Research and Testing, Berlin, Germany.
Department of Chemistry, Humboldt-Universität zu Berlin, Berlin, Germany.
Front Chem. 2022 Mar 14;10:840758. doi: 10.3389/fchem.2022.840758. eCollection 2022.
Catalysts derived from pyrolysis of metal organic frameworks (MOFs) are promising candidates to replace expensive and scarce platinum-based electrocatalysts commonly used in polymer electrolyte membrane fuel cells. MOFs contain ordered connections between metal centers and organic ligands. They can be pyrolyzed into metal- and nitrogen-doped carbons, which show electrocatalytic activity toward the oxygen reduction reaction (ORR). Furthermore, metal-free heteroatom-doped carbons, such as N-F-Cs, are known for being active as well. Thus, a carbon material with Co-N-F doping could possibly be even more promising as ORR electrocatalyst. Herein, we report the mechanochemical synthesis of two polymorphs of a zeolitic imidazole framework, Co-doped zinc 2-trifluoromethyl-1H-imidazolate (ZnCo(CF-Im)). Time-resolved X-ray diffraction studies of the mechanochemical formation revealed a direct conversion of starting materials to the products. Both polymorphs of ZnCo(CF-Im) were pyrolyzed, yielding Co-N-F containing carbons, which are active toward electrochemical ORR.
由金属有机框架（MOF）热解衍生的催化剂有望替代聚合物电解质膜燃料电池中常用的昂贵且稀缺的铂基电催化剂。MOF包含金属中心与有机配体之间的有序连接。它们可以热解为金属和氮掺杂的碳，这些碳对氧还原反应（ORR）表现出电催化活性。此外，无金属的杂原子掺杂碳，如N-F-C，也已知具有活性。因此，具有Co-N-F掺杂的碳材料作为ORR电催化剂可能更具前景。在此，我们报道了两种沸石咪唑框架多晶型物的机械化学合成，即钴掺杂的锌2-三氟甲基-1H-咪唑盐（ZnCo(CF-Im)）。对机械化学形成过程的时间分辨X射线衍射研究表明，起始材料直接转化为产物。ZnCo(CF-Im)的两种多晶型物都进行了热解，生成了对电化学ORR有活性的含Co-N-F的碳。
