DataSheet1_Mechanochemical Synthesis of Fluorine-Containing Co-Doped Zeolitic Imidazolate Frameworks for Producing Electrocatalysts.docx

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 (Zn0.9Co0.1(CF3-Im)2). Time-resolved in situ X-ray diffraction studies of the mechanochemical formation revealed a direct conversion of starting materials to the products. Both polymorphs of Zn0.9Co0.1(CF3-Im)2 were pyrolyzed, yielding Co-N-F containing carbons, which are active toward electrochemical ORR.

由金属有机框架（metal organic frameworks, MOFs）热解得到的催化剂，是替代质子交换膜燃料电池中常用的昂贵稀缺铂基电催化剂的极具潜力的候选材料。MOFs具备金属中心与有机配体间的有序连接结构，可通过热解转化为金属氮共掺杂碳材料，该类材料对氧还原反应（oxygen reduction reaction, ORR）展现出电催化活性。此外，无金属杂原子掺杂碳材料（如N-F掺杂碳）同样具备优异电催化活性。因此，兼具Co-N-F掺杂的碳材料有望成为更具前景的ORR电催化剂。本研究报道了两种晶型沸石咪唑酯骨架（zeolitic imidazole framework）的机械化学合成方法：钴掺杂2-三氟甲基-1H-咪唑锌（Zn₀.₉Co₀.₁(CF₃-Im)₂）。对该机械化学合成过程的时间分辨原位X射线衍射研究表明，原料可直接转化为目标产物。将上述两种Zn₀.₉Co₀.₁(CF₃-Im)₂晶型分别进行热解处理，均可得到含Co-N-F掺杂的碳材料，该材料对电化学ORR具有催化活性。