Polypyrrole-derived mesoporous nitrogen-doped carbons with intrinsic catalytic activity in the oxygen reduction reaction
Polypyrrole-derived mesoporous nitrogen-doped carbons with intrinsic catalytic activity in the oxygen reduction reaction
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DOI：
10.1039/c3ra41719k
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发表时间：
2013-01-01
期刊：
影响因子：
3.9
通讯作者：
Titirici, Maria-Magdalena
中科院分区：
文献类型：
--
作者：
Sevilla, Marta;Yu, Linghui;Titirici, Maria-Magdalena
使用纳米铸造技术成功制备了含有少量石墨碳的氮掺杂介孔碳。使用聚吡咯作为N-掺杂剂碳前体，使用SBA-15或二氧化硅干凝胶作为模板。石墨碳域提供高达 0.33 S cm(-1) 的良好电子电导率，这是电化学应用的必要特性，而介孔结构则减少了传质限制。这些特性进一步与高氮含量（3.55-5.45 wt%）相结合。因此，所制备的材料对氧还原反应（ORR）表现出增强的固有电催化活性。它们表现出与 Ag/AgCl 类似的 90 至 -70 mV 的起始电位，并且在较低电位范围内的电流密度超过了碱性介质中商用铂催化剂的电流密度。它们的性能优于 Vulcan XC72R 碳纤维。此外，与商业铂催化剂不同，它们不受甲醇交叉效应的影响。研究发现，石墨含量必须保持良好平衡，因为一方面，它可以增强电导率，但另一方面，它会选择性地催化不利的 2e(-) 过程。
N-doped mesoporous carbons containing small amounts of graphitic carbon have been successfully prepared using the nanocasting technique. Polypyrrole was used as N-dopant carbon precursor and SBA-15 or silica xerogel as templates. Graphitic carbon domains provide a good electronic conductivity of up to 0.33 S cm(-1), a necessary property for electrochemical applications, while a mesoporous structure reduces mass transport limitations. These characteristics are further combined with a high N content (3.55-5.45 wt%). As a result, the as-prepared materials exhibit an enhanced intrinsic electrocatalytic activity towards the oxygen reduction reaction (ORR). They exhibit an onset potential of similar to-90 to -70 mV vs. Ag/AgCl and a current density in the lower potential regime that exceeds that of a commercial platinum catalyst in a basic medium. Their behavior is superior to that of Vulcan XC72R carbon. Furthermore, unlike commercial Pt catalysts, they are unaffected by the methanol cross-over effect. It was found that the graphitic content must be well-balanced as, on the one hand, it enhances conductivity but, on the other hand, it selectively catalyses an unfavorable 2e(-) process.