XPS和NEXAFS光谱研究MWCNT表面碳化钨涂层的埋层和界面,Applied Sciences

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XPS和NEXAFS光谱研究MWCNT表面碳化钨涂层的埋层和界面
Applied Sciences ( IF 2.5 ) Pub Date : 2020-07-09 , DOI: 10.3390/app10144736
Danil Sivkov , Sergey Nekipelov , Olga Petrova , Alexander Vinogradov , Alena Mingaleva , Sergey Isaenko , Pavel Makarov , Anatoly Ob’edkov , Boris Kaverin , Sergey Gusev , Ilya Vilkov , Artemiy Aborkin , Viktor Sivkov

当前，X射线光电子能谱（XPS）被广泛用于表征纳米结构材料的表面。在不破坏样品的情况下确定深度的原子分布和化学状态的能力对于研究几纳米厚的涂层的内部结构非常重要，并使XPS成为用于纳米结构体系无损检测的首选工具。在这项工作中，使用超软X射线光谱法研究多壁碳纳米管（MWCNT）表面上热解碳化钨纳米级涂层的隐藏层和界面。XPS测量是使用带有样品电荷补偿功能的实验室光谱仪进行的，近距离X射线吸收精细结构（NEXAFS）的研究使用了BESSY-II处的俄罗斯-德国偶极子束线（RGBL）同步加速器辐射进行。通过扫描和透射电子显微镜，X射线衍射仪，拉曼散射和NEXAFS光谱测试了所研究的样品。结果表明，MWCNT和碳化钨热解涂层之间的界面具有三层结构：（i）由外石墨烯层碳原子组成的界面层，与吸附在MWCNT表面的氧化物的氧原子形成键，以及来自涂层的钨原子；（ii）非化学计量的碳化钨WC 与吸附在MWCNT表面上的氧化物中的氧原子和涂层中的钨原子形成键。（ii）非化学计量的碳化钨WC 与吸附在MWCNT表面上的氧化物中的氧原子和涂层中的钨原子形成键。（ii）非化学计量的碳化钨WC_1-x纳米级颗粒层；（iii）在空气中形成的WC _1-x / MWCNT纳米复合材料外表面上的3.3nm厚的非化学计量的氧化钨WO _3-x层。通过在来自MWCNT上层的碳原子与来自涂层的钨原子之间形成化学键，确保碳化钨纳米级颗粒对纳米管外表面的粘附。

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Studies of Buried Layers and Interfaces of Tungsten Carbide Coatings on the MWCNT Surface by XPS and NEXAFS Spectroscopy

Currently, X-ray photoelectron spectroscopy (XPS) is widely used to characterize the nanostructured material surface. The ability to determine the atom distribution and chemical state with depth without the sample destruction is important for studying the internal structure of the coating layer several nanometers thick, and makes XPS the preferable tool for the non-destructive testing of nanostructured systems. In this work, ultra-soft X-ray spectroscopy methods are used to study hidden layers and interfaces of pyrolytic tungsten carbide nanoscale coatings on the multi-walled carbon nanotube (MWCNT) surfaces. XPS measurements were performed using laboratory spectrometers with sample charge compensation, and Near Edge X-ray Absorption Fine Structure (NEXAFS) studies using the Russian–German dipole beamline (RGBL) synchrotron radiation at BESSY-II. The studied samples were tested by scanning and transmission electron microscopy, X-ray diffractometry, Raman scattering and NEXAFS spectroscopy. It was shown that the interface between MWCNT and the pyrolytic coating of tungsten carbide has a three-layer structure: (i) an interface layer consisting of the outer graphene layer carbon atoms, forming bonds with oxygen atoms from the oxides adsorbed on the MWCNT surface, and tungsten atoms from the coating layer; (ii) a non-stoichiometric tungsten carbide WC_1-x nanoscale particles layer; (iii) a 3.3 nm thick non-stoichiometric tungsten oxide WO_3-x layer on the WC_1-x/MWCNT nanocomposite outer surface, formed in air. The tungsten carbide nanosized particle’s adhesion to the nanotube outer surface is ensured by the formation of a chemical bond between the carbon atoms from the MWCNT upper layer and the tungsten atoms from the coating layer.

更新日期：2020-07-09

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