Effect of an Ammonia Treatment on Structure, Composition, and Oxygen Reduction Reaction Activity of Fe–N–C Catalysts
Effect of an Ammonia Treatment on Structure, Composition, and Oxygen Reduction Reaction Activity of Fe–N–C Catalysts
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DOI：
10.1021/jp207417y
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发表时间：
2011-11
影响因子：
3.7
通讯作者：
U. Kramm;I. Herrmann-Geppert;P. Bogdanoff;S. Fiechter
中科院分区：
文献类型：
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作者：
U. Kramm;I. Herrmann-Geppert;P. Bogdanoff;S. Fiechter
首次详细研究了草酸负载热解三铁四甲基苯基卟啉（Fe(TMPP)Cl）制备的Fe - n - c催化剂在氨中二次热处理对其结构和组成的影响。采用旋转环盘电极（RRDE）测定了酸性溶液中氧还原反应（ORR）的活性。为了评估观察到的ORR活性增加的来源，进行了体元素分析，57Fe穆斯堡尔光谱，n2吸收测量和x射线衍射。氨水二次热处理对Fe-N-C催化剂的ORR活性有显著影响；NH3处理诱导的催化剂均含氮化铁；氮化物形成越多，对ORR活性的影响越明显。通过随后的酸浸完全去除氮化物是可能的，但会略微降低ORR活性。根据这些结果，我们得出结论，氮化物本身不可能是导致主要…
For the first time, the effect on structure and composition by a second heat treatment in ammonia was studied in detail for Fe–N–C catalysts prepared by oxalate-supported pyrolysis of chloroirontetrametoxyphenylporphyrin (Fe(TMPP)Cl). The oxygen reduction reaction (ORR) activity was determined by rotating ring-disk electrode (RRDE) measurements in acidic solution. To evaluate the origin of the observed increase in ORR activity, bulk elemental analysis 57Fe Mossbauer spectroscopy, N2-sorption measurements, and X-ray diffraction were performed. A second heat treatment in ammonia was found to affect the ORR activity of Fe–N–C catalysts significantly; induced by NH3 treatment, all catalysts contained iron nitride; as more nitride was formed, the effect on ORR activity was more pronounced. A complete removal of the nitride by a subsequent acid leaching was possible but decreased the ORR activity slightly. On basis of these results, we conclude that the nitride itself cannot be the site responsible for the main...