X-ray photoelectron spectroscopy and rotating disk electrode measurements of smooth sputtered Fe-N-C films
X-ray photoelectron spectroscopy and rotating disk electrode measurements of smooth sputtered Fe-N-C films
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DOI：
10.1016/j.apsusc.2020.146012
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发表时间：
2020-06
影响因子：
6.7
通讯作者：
Yun Xu;Michael J. Dzara;Sadia Kabir;S. Pylypenko;K. Neyerlin;A. Zakutayev
中科院分区：
文献类型：
--
作者：
Yun Xu;Michael J. Dzara;Sadia Kabir;S. Pylypenko;K. Neyerlin;A. Zakutayev
基于碳基质中铁和氮的络合物(Fe-N-C)的氧还原反应(ORR)电催化剂是聚合物电解质膜(PEM)燃料电池中替代铂族金属(PGM)的一种有前途的催化剂。Fe-N-C催化剂的进一步改进将得益于对催化中心活性和稳定性的模型薄膜研究，但Fe-N-C模型薄膜的合成是具有挑战性的。本文报道了在反应性氮气气氛中，在可拆卸的玻碳转盘电极(RDE)尖端上共溅射铁和碳制备的Fe-N-C薄膜的合成和表征。扫描电子显微镜(SEM)测量表明，高温下沉积的Fe-N-C薄膜比高温下热处理的薄膜更平整。两种高温样品在Fe-N-C薄膜上测得的电催化活性均大于室温样品。从X射线光电子能谱(XPS)数据分析可知，高温使Fe-N-C薄膜中碳的石墨化程度增加，并增加了石墨化和氢化氮物种的相对数量。总体而言，本研究的结果证明了薄膜模型系统方法用于研究无PGM催化剂中活性中心的可行性。
Electrocatalysts for the oxygen reduction reaction (ORR) based on complexes of iron and nitrogen in a carbon matrix (Fe-N-C) are a promising alternative to platinum group metal (PGM) based catalysts in polymer electrolyte membrane (PEM) fuel cells. Further improvements of Fe-N-C catalysts would benefit from model thin film studies of activity and stability of catalytic sites, but synthesis of Fe-N-C model thin films is challenging. Here we report on synthesis and characterization of Fe-N-C thin films produced by co-sputtering iron and carbon in a reactive nitrogen atmosphere onto removable glassy carbon rotating disk electrode (RDE) tips. Scanning electron microscopy (SEM) measurements indicate that the Fe-N-C films deposited at high temperature are smoother than the films annealed at high temperature. Electrocatalytic activity measured on the thin Fe-N-C films is greater for both high-temperature samples than for the room-temperature sample. From the analysis of X-ray photoelectron spectroscopy (XPS) data, exposure of the films to high temperatures results in increased graphitization of the carbon within the Fe-N-C films, and increased relative amount of graphitic and hydrogenated nitrogen species. Overall, the results of this study demonstrate the feasibility of a thin film model system approach for studying active sites in PGM-free catalysts.