Mesoporous N-Doped Carbons Prepared with Thermally Removable Nanoparticle Templates: An Efficient Electrocatalyst for Oxygen Reduction Reaction
Mesoporous N-Doped Carbons Prepared with Thermally Removable Nanoparticle Templates: An Efficient Electrocatalyst for Oxygen Reduction Reaction
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DOI：
10.1021/jacs.5b02027
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发表时间：
2015-04-29
影响因子：
15
通讯作者：
Chen, Shaowei
中科院分区：
文献类型：
--
作者：
Niu, Wenhan;Li, Ligui;Chen, Shaowei
利用热移除纳米粒子模板制备了含微量Fe的自支撑N掺杂介孔碳（Fe-N/C）。实验上，采用一锅法水热合成含有大量FeO（OH）纳米棒的聚2-氟苯胺（P2 FANI），并将其均匀分布在聚合物基体中，通过热解制备Fe-N/C。FeO（OH）纳米晶充当刚性模板以防止P2 FANI在碳化过程中坍塌，其中形成介孔骨架，具有约400 m2/g的中比表面积。随后的高温热处理导致FeO（OH）纳米晶的分解和蒸发，并形成介孔碳，其比表面积显著增加至934.8 m2/g。电化学测试表明，所得的介孔碳对氧还原反应（ORR）表现出明显的电催化活性，在800 ℃下制备的介孔碳对氧还原反应（ORR）表现出明显的电催化活性。其中Fe-N/C-800的启动电位最高，（+0.98 V vs RHE），更高的扩散限制电流，更高的选择性（在+0.75 V对RHE下电子转移数n > 3.95），高得多的稳定性，并且在0.1M KOH溶液中比商业Pt/C催化剂对甲醇渗透具有更强的耐受性。显著的ORR性能归因于高表面积和电催化活性位点的充分暴露，所述电催化活性位点主要来自N掺杂的碳，含Fe物质的贡献较小。
Thermally removable nanoparticle templates were used for the fabrication of self-supported N-doped mesoporous carbons with a trace amount of Fe (Fe-N/C). Experimentally Fe-N/C was prepared by pyrolysis of poly(2-fluoroaniline) (P2FANI) containing a number of FeO(OH) nanorods that were prepared by a one-pot hydrothermal synthesis and homogeneously distributed within the polymer matrix. The FeO(OH) nanocrystals acted as rigid templates to prevent the collapse of P2FANI during the carbonization process, where a mesoporous skeleton was formed with a medium surface area of about 400 m(2)/g. Subsequent thermal treatments at elevated temperatures led to the decomposition and evaporation of the FeO(OH) nanocrystals and the formation of mesoporous carbons with the surface area markedly enhanced to 934.8 m(2)/g. Electrochemical measurements revealed that the resulting mesoporous carbons exhibited apparent electrocatalytic activity for oxygen reduction reactions (ORR), and the one prepared at 800 degrees C (Fe-N/C-800) was the best among the series, with a more positive onset potential (+0.98 V vs RHE), higher diffusion-limited current, higher selectivity (number of electron transfer n > 3.95 at +0.75 V vs RHE), much higher stability, and stronger tolerance against methanol crossover than commercial Pt/C catalysts in a 0.1 M KOH solution. The remarkable ORR performance was attributed to the high surface area and sufficient exposure of electrocatalytically active sites that arose primarily from N-doped carbons with minor contributions from Fe-containing species.