Iron and nitrogen-doped double gyroid mesoporous carbons for oxygen reduction in acidic environments
Iron and nitrogen-doped double gyroid mesoporous carbons for oxygen reduction in acidic environments
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DOI：
10.1088/2515-7655/abc31a
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发表时间：
2020-11
期刊：
影响因子：
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通讯作者：
F. Matsuoka;Kevin E. Fritz;P. Beaucage;Fei Yu;Jin Suntivich;U. Wiesner
中科院分区：
文献类型：
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作者：
F. Matsuoka;Kevin E. Fritz;P. Beaucage;Fei Yu;Jin Suntivich;U. Wiesner
铁和氮掺杂的碳（Fe-N-C）代表了一类有前途的替代贵金属的电催化剂，用于酸性环境中的氧还原反应（ORR）。为了使Fe-N-C具有活性，最关键的参数之一是微孔性，必须控制微孔性以使活性位点密度最大化。然而，微孔的使用必须针对高通量质量传输的要求进行优化。在这里，我们合成并展示了具有微孔孔壁的螺旋状介孔Fe-N-C作为联合收割机在高通量下将高活性中心密度与有利的质量传输相结合的途径。尽管具有中孔特征，但回旋状中孔Fe-N-C催化剂具有与纯微孔构型中获得的ORR活性相当的竞争性重量和体积ORR活性。我们的研究结果表明，微孔Fe-N-C电催化剂的ORR活性可以通过使用具有微孔孔壁的介孔Fe-N-C与介孔相结合。我们进一步研究了氮掺入方法对介孔氮掺杂碳电催化剂的影响。我们发现，尽管具有0.2 ×更高的N浓度，但通过NH3的氮掺入产生与通过化学添加剂的掺入相似的ORR活性，我们将这一发现归因于吡啶和季铵N在ORR中的作用。
Iron- and nitrogen-doped carbon (Fe-N-C) represents a promising class of alternative electrocatalysts to noble metals for the oxygen reduction reaction (ORR) in acidic environments. To make Fe-N-C active, one of the most critical parameters is microporosity, which must be controlled to maximize the active site density. However, the use of microporosity must be optimized for the requirement of high-flux mass transport. Here, we synthesized and demonstrated gyroidal mesoporous Fe-N-C with microporous pore walls as an avenue to combine a high active-site density with favorable mass transport at high flux. The gyroidal mesoporous Fe-N-C catalysts have competitive gravimetric and volumetric ORR activities, comparable to the ORR activity obtained in purely microporous configurations despite having mesoporous features. Our result suggests that the ORR activity of microporous Fe-N-C electrocatalysts can be combined with mesoporosity through the use of mesoporous Fe-N-C with microporous pore walls. We further investigate effects of the nitrogen incorporation method on mesoporous N-doped carbon electrocatalysts. We find that despite having ∼2 × higher N concentration, nitrogen incorporation via NH3 yields similar ORR activity to incorporation via a chemical additive, a finding we attribute to the role of pyridinic and quaternary N in the ORR.