Metal-Support Interactions of Platinum Nanoparticles Decorated N-Doped Carbon Nanofibers for the Oxygen Reduction Reaction
Metal-Support Interactions of Platinum Nanoparticles Decorated N-Doped Carbon Nanofibers for the Oxygen Reduction Reaction
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DOI：
10.1021/acsami.5b06225
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发表时间：
2016-01-13
影响因子：
9.5
通讯作者：
Roth, Christina
中科院分区：
文献类型：
--
作者：
Melke, Julia;Peter, Benedikt;Roth, Christina
讨论了氮掺杂碳材料作为燃料电池中电化学氧还原反应（ORR）的催化剂载体。这项工作涉及从聚苯胺纳米纤维 (PANI NF) 前体制备负载在氮掺杂碳纳米纤维 (N-CNF) 上的 Pt 纳米颗粒 (NP)，并研究所生产材料的 ORR 活性。最初，Pt NP 沉积在 PANI NF 上。 PANI NF 前驱体通过近边缘 X 射线吸收精细结构 (NEXAFS) 和透射电子显微镜 (TEM) 测量进行表征。结果表明，在 PANI NF 前体材料中，来自 Pt 的电子正在向芳环的 π 共轭体系转移。 Pt 原子与 PANI 的这种强烈相互作用解释了 Pt NP 在 PANI NF 上的高度分散。随后，PANI NF 前体在不同的热处理条件下碳化，产生结构不同的 N-CNF，并通过 NEXAFS、X 射线光电子能谱 (XPS) 和 TEM 测量进行表征。结果表明，所有研究的 N-CNF 中都存在 N 基团和 Pt NP 之间的相互作用。然而，N-CNF 的不同之处在于 N 物质的组成和 Pt NP 的分散性。具有窄尺寸分布的小平均 Pt NP 尺寸归因于 N-CNF 中吡啶 N 基团的存在，而对于主要具有石墨和吡咯 N 基团的 N-CNF，发现具有宽尺寸分布的平均 Pt NP 尺寸增加。通过旋转盘电极测量的 Koutecky-Levich 分析研究的碱性介质中的 ORR 活性表明，与传统的 Pt/C 催化剂相比，ORR 活性大大增强。
N-doped carbon materials are discussed as catalyst supports for the electrochemical oxygen reduction reaction (ORR) in fuel cells. This work deals with the preparation of Pt nanoparticles (NPs) supported on N-doped carbon nanofibers (N-CNF) from a polyaniline nanofiber (PANI NF) precursor, and investigates the ORR activity of the produced materials. Initially, Pt NPs are deposited on PANI NFs. The PANI NF precursors are characterized by near-edge X-ray absorption fine structure (NEXAFS) and transmission electron microscopy (TEM) measurements. It is shown, that in the PANI NF precursor materials electrons from the Pt are being transferred toward the pi-conjugated systems of the aromatic ring. This strong interaction of Pt atoms with PANI explains the high dispersion of Pt NPs on the PANI NF. Subsequently, the PANI NF precursors are carbonized at different heat-treatment conditions resulting in structurally different N-CNFs which are characterized by NEXAFS, X-ray photoelectron spectroscopy (XPS) ,and TEM measurements. It is shown that an interaction between N-groups and Pt NPs exists in all investigated N-CNFs. However, the N-CNFs differ in the composition of the N-species and the dispersion of the Pt NPs. A small mean Pt NP size with a narrow size distribution is attributed to the presence of pyrdinic N-groups in the N-CNFs, whereas, for the N-CNFs with mainly graphitic and pyrrolic N-groups, an increase in the average Pt NP size with a broad size distribution is found. The ORR activity in alkaline media investigated by Koutecky-Levich analysis of rotating disk electrode measurements showed a largely enhanced ORR activity in comparison to a conventional Pt/C catalyst.