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首页> 美国卫生研究院文献>Nanomaterials >The Structure and Chemical Composition of the Cr and Fe Pyrolytic Coatings on the MWCNTs’ Surface According to NEXAFS and XPS Spectroscopy
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The Structure and Chemical Composition of the Cr and Fe Pyrolytic Coatings on the MWCNTs’ Surface According to NEXAFS and XPS Spectroscopy

机译：NEXAFS和XPS光谱分析MWCNTs表面的Cr和Fe热解涂层的结构和化学成分

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The paper is devoted to the structure and properties of the composite material based on multi-walled carbon nanotubes (MWCNTs) covered with pyrolytic iron and chromium. Fe/MWCNTs and Cr/MWCNTs nanocomposites have been prepared by the metal organic chemical vapor deposition (MOCVD) growth technique using iron pentacarbonyl and bis(arene)chromium compounds, respectively. Composites structures and morphologies preliminary study were performed using X-ray diffraction, scanning and transmission electron microscopy and Raman scattering. The atomic and chemical composition of the MWCNTs’ surface, Fe-coating and Cr-coating and interface—(MWCNTs surface)/(metal coating) were studied by total electron yield method in the region of near-edge X-ray absorption fine structure (NEXAFS) C1s, Fe2p and Cr2p absorption edges using synchrotron radiation of the Russian-German dipole beamline (RGBL) at BESSY-II and the X-ray photoelectron spectroscopy (XPS) method using the ESCALAB 250 Xi spectrometer and charge compensation system. The absorption cross sections in the NEXAFS C1s edge of the nanocomposites and MWCNTs were measured using the developed approach of suppressing and estimating the contributions of the non-monochromatic background and multiple reflection orders radiation from the diffraction grating. The efficiency of the method was demonstrated by the example of the Cr/MWCNT nanocomposite, since its Cr2p NEXAFS spectra contain additional C1s NEXAFS in the second diffraction order. The study has shown that the MWCNTs’ top layers in composite have no significant destruction; the MWCNTs’ metal coatings are continuous and consist of Fe O and Cr O . It is shown that the interface between the MWCNTs and pyrolytic Fe and Cr coatings has a multilayer structure: a layer in which carbon atoms along with epoxy –C–O–C– bonds form bonds with oxygen and metal atoms from the coating layer is formed on the outer surface of the MWCNT, a monolayer of metal carbide above it and an oxide layer on top. The iron oxide and chromium oxide adhesion is provided by single, double and epoxy chemical binding formation between carbon atoms of the MWCNT top layer and the oxygen atoms of the coating, as well as the formation of bonds with metal atoms.
机译：本文专门研究了基于热解铁和铬覆盖的多壁碳纳米管（MWCNT）的复合材料的结构和性能。通过金属有机化学气相沉积（MOCVD）生长技术分别使用五羰基铁和双（芳烃）铬化合物制备了Fe / MWCNTs和Cr / MWCNTs纳米复合材料。使用X射线衍射，扫描和透射电子显微镜以及拉曼散射对复合材料的结构和形态进行了初步研究。通过全电子产率方法研究了近边缘X射线吸收精细结构区域中MWCNTs表面，Fe涂层和Cr涂层以及界面-（MWCNTs表面）/（金属涂层）的原子和化学组成。 （NEXAFS）使用俄罗斯-德国偶极子束线（RGBL）在BESSY-II上的同步加速辐射以及使用ESCALAB 250 Xi光谱仪和电荷补偿系统的X射线光电子能谱（XPS）方法对C1，Fe2p和Cr2p吸收边缘进行分析。纳米复合材料和MWCNTs在NEXAFS C1s边缘的吸收截面是使用已开发的抑制和估计非单色背景和来自衍射光栅的多反射阶次辐射的贡献的方法来测量的。通过Cr / MWCNT纳米复合材料的实例证明了该方法的效率，因为其Cr2p NEXAFS光谱在第二衍射级包含了额外的Cls NEXAFS。研究表明，复合材料中的MWCNTs顶层没有明显的破坏。 MWCNT的金属涂层是连续的，由Fe O和Cr O组成。结果表明，多壁碳纳米管与热解铁和铬涂层之间的界面具有多层结构：在该层中，碳原子与环氧-C-OC-C-键形成了氧，形成了涂层中的金属原子在MWCNT的外表面上，其上方是金属碳化物的单层，顶部是氧化层。通过在MWCNT顶层的碳原子与涂层的氧原子之间进行单，双和环氧化学键合形成以及与金属原子的键合，可以提供氧化铁和氧化铬的粘附力。

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