Noble-Metal-Free Fe-N/C Catalyst for Highly Efficient Oxygen Reduction Reaction under Both Alkaline and Acidic Conditions
Noble-Metal-Free Fe-N/C Catalyst for Highly Efficient Oxygen Reduction Reaction under Both Alkaline and Acidic Conditions
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DOI：
10.1021/ja504696r
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发表时间：
2014-08-06
影响因子：
15
通讯作者：
Xu, An-Wu
中科院分区：
文献类型：
--
作者：
Lin, Ling;Zhu, Qing;Xu, An-Wu
在这项工作中，我们报道了一种新的非贵金属氧还原反应(ORR)催化剂的合成和评价，该催化剂是由一种在碱性和酸性介质中都表现出优异活性的铁配合物裂解而成的。以11，11‘-双(联吡啶并[3，2-a：2’，3‘-c]吩嗪)(Bippz)为配体，合成了一种富氮铁配位聚合物(Fe-bippz)，通过热解形成了高密度氮、铁掺杂的自担载催化剂。800℃热解催化剂(Fe-N/C-800)在0.1M KOH中表现出最高的ORR活性，起始电位和半波电位分别为923 mV和809 mV，与相同催化剂负载量下的铂/C催化剂(半波电位818 mV vs RHE)相当。此外，Fe-N/C-800催化剂在0.1M高氯酸溶液中具有良好的ORR活性，起始电位和半波电位分别比铂/C催化剂低38 mV和59 mV。最优的Fe-N/C-800催化剂表现出比铂/C催化剂更高的甲醇耐久性和耐受性。我们认为，Fe-N/C-800催化剂具有相当高的表面活性中心密度，这是因为Fe-N/C-800具有良好的ORR活性，但其比表面积不是那么高。电化学测试表明，Fe-N/C-800催化剂在氢氧化钾和高氯酸中遵循有效的四电子转移途径。
In this work, we report the synthesis and assessment of a new non-precious-metal oxygen reduction reaction (ORR) catalyst from pyrolysis of an iron-coordinated complex which manifests superior activity in both alkaline and acidic media. 11,11'-bis ( dipyrido [3,2-a:2',3'-c]phenazinyl) (bidppz) was selected as a ligand for the formation of a nitrogen-rich iron-coordinated coordination polymer (Fe-bidppz) which forms a self-supporting catalyst containing high densities of nitrogen and iron doping by pyrolysis. The catalyst pyrolyzed at 800 degrees C (Fe-N/C-800) shows the highest ORR activity with onset and half-wave potentials of 923 and 809 mV in 0.1 M KOH, respectively, which are comparable to those of Pt/C (half-wave potential 818 mV vs RHE) at the same catalyst loading. Besides, the Fe-N/C-800 catalyst has an excellent ORR activity with onset and half-wave potentials only 38 and 59 mV less than those of the Pt/C catalyst in 0.1 M HClO4. The optimal Fe-N/C-800 catalyst displays much greater durability and tolerance of methanol than Pt/C. We propose that the Fe-N/C-800 catalyst has a considerably high density of surface active sites because Fe-N/C-800 possesses excellent ORR activity while its specific surface area is not so high. Electrochemical measurements show that the Fe-N/C-800 catalyst in KOH and HClO4 follows the effective four-electron-transfer pathway.