The role of nanostructure in nitrogen-containing carbon catalysts for the oxygen reduction reaction
The role of nanostructure in nitrogen-containing carbon catalysts for the oxygen reduction reaction
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DOI：
10.1016/j.jcat.2006.01.022
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发表时间：
2006-04-01
影响因子：
7.3
通讯作者：
Ozkan, US
中科院分区：
文献类型：
--
作者：
Matter, PH;Zhang, L;Ozkan, US
用乙腈在Vulcan炭XC-72和浸渍2wt%Fe或2wt%Ni的Vulcan炭上以醋酸盐形式高温热解制备了氧还原反应催化剂。采用BET比表面积分析、BJH孔径分布、电导率测试、透射电子显微镜等手段对催化剂进行了表征。程序升温氧化、热重分析、X射线衍射、X射线光电子能谱和转盘电极半电池测试。在热解前添加Fe的催化剂活性最高，但添加Ni或不添加金属的样品仍表现出比未处理的碳更高的氧还原活性。XPS测试结果表明，活性最高的催化剂中吡啶氮的含量明显较高。已经提出了一种假说来解释这一趋势，该假说基于不同的纳米结构的形成，这取决于用于乙腈分解的载体材料。根据这一提出的解释，具有纳米结构的含氮碳样品会暴露出更多的边缘平面(在其中发现吡啶氮的平面)，对于ORR来说将更加活跃。样本的10张图片有力地支持了这一假设。需要进一步的研究来确定氧还原的活性部位；然而，这个部位很可能位于石油碳边缘平面。(C)2006 Elsevier Inc.保留所有权利。
Catalysts for the oxygen reduction reaction (ORR) were prepared by the high-temperature pyrolysis of acetonitrile over Vulcan carbon XC-72, and Vulcan carbon impregnated with 2 wt% Fe or 2 wt% Ni in the form of an acetate salt. The catalysts were characterized by BET surface area analysis, BJH pore size distribution, electrical conductivity testing, transmission electron microscopy (TEM). temperature-programmed oxidation, thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and rotating disk electrode half-cell testing. The most active catalysts were formed when Fe was added to the support before the pyrolysis; however, samples in which Ni or no metal was added still showed increased activity for oxygen reduction Compared with untreated carbon. The most active catalyst had a significantly higher amount of pyridinic nitrogen, as determined from XPS. A hypothesis has been proposed to explain this trend based on the formation of different nanostructures depending on which support material is used for the acetonitrile decomposition. According to this proposed explanation, nitrogen-containing carbon samples with nanostructures resulting in exposure of more edge planes (the plane in which pyridinic nitrogen is found) will be more active for the ORR. TEN images of the samples strongly support this hypothesis. Further research is needed to positively identify the active site for oxygen reduction; however, this site is likely located oil carbon edge planes. (c) 2006 Elsevier Inc. All rights reserved.