Fe-N-modified multi-walled carbon nanotubes for oxygen reduction reaction in acid
Fe-N-modified multi-walled carbon nanotubes for oxygen reduction reaction in acid
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DOI：
10.1039/c1cp23029h
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发表时间：
2011-01-01
影响因子：
3.3
通讯作者：
Shao-Horn, Yang
中科院分区：
文献类型：
--
作者：
Byon, Hye Ryung;Suntivich, Jin;Shao-Horn, Yang
报道了一种基于多壁碳纳米管（MWCNTs）表面功能化的Fe-N-C催化剂的合成方法，该催化剂在酸性条件下对氧还原反应（ORR）具有高活性和稳定性。Fe-N-MWCNT催化剂的ORR质量活性可以根据Fe前体的选择而变化3-4倍，被发现具有比N-改性的MWCNT（N-MWCNT）高得多的ORR质量活性和更高的稳定性。具有主要Fe-N-x部分的Fe-N-MWCNT催化剂（其中x近似为4）和表面Fe/C比近似为0.004的催化剂在酸中表现出最高的ORR质量活性。（类似于0.7 mA mg（-1）Fe-N-MWCNT，0.8 V vs. RHE），其中其它Fe-N-MWCNT催化剂的较低质量活性可归因于较低的Fe/C比和Fe-N-x部分X射线光电子能谱（XPS）和扩展X射线吸收精细结构（EXAFS）光谱显示，此外，与N-MWCNTs相比，Fe-N-MWCNTs的增强的稳定性可以归因于在ORR期间较少的H2 O2产生，如从旋转环盘电极（RRDE）测量所确定的，以及通过旋转盘电极（RDE）测量的H2 O2电还原的较高活性。Fe-N-MWCNTs具有较大的表面Fe/C比和Fe-N-x结构，对应于较高的ORR活性和稳定性，表明表面功能化有助于在碳纳米结构上接枝活性催化位点，并有助于深入了解质子交换膜燃料电池（PEMFC）非贵金属催化剂（NNMC）的ORR机理。
We report a facile synthesis of Fe-N-C catalysts based on the surface functionalization of multi-walled carbon nanotubes (MWCNTs), which show high activity and stability for oxygen reduction reaction (ORR) in acid. Fe-N-MWCNT catalysts, whose ORR mass activities could vary by 3-4 times depending on the choice of Fe precursors, were found to have considerably higher ORR mass activity and higher stability than N-modified MWCNTs (N-MWCNTs). The Fe-N-MWCNT catalyst with a dominant Fe-N-x moiety (with x approximate to 4) and a surface Fe/C ratio of similar to 0.004 exhibits the highest ORR mass activity in acid (similar to 0.7 mA mg(-1) Fe-N-MWCNT at 0.8 V vs. RHE), where the lower mass activity of other Fe-N-MWCNT catalysts can be attributed to lower Fe/C ratios and Fe-N-x moieties (with x smaller than 4) as revealed from X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) spectroscopy. Moreover, the enhanced stability of Fe-N-MWCNTs in comparison to N-MWCNTs can be attributed to less H2O2 production during ORR as determined from rotating ring disk electrode (RRDE) measurements, and higher activity for H2O2 electro-reduction by rotating disk electrode (RDE) measurements. The large surface Fe/C ratio and Fe-N-x moiety corresponding to high ORR activity and stability of Fe-N-MWCNTs demonstrate that surface functionalization can be very helpful to graft active catalytic sites onto carbon nanostructures, and to provide insights into the ORR mechanism of non-noble metal catalysts (NNMCs) for proton exchange membrane fuel cells (PEMFCs).