TY - JOUR

T1 - Studies of buried layers and interfaces of tungsten carbide coatings on the MWCNT surface by XPS and NEXAFS spectroscopy

AU - Sivkov, Danil

AU - Nekipelov, Sergey

AU - Petrova, Olga

AU - Vinogradov, Alexander

AU - Mingaleva, Alena

AU - Isaenko, Sergey

AU - Makarov, Pavel

AU - Ob'edkov, Anatoly

AU - Kaverin, Boris

AU - Gusev, Sergey

AU - Vilkov, Ilya

AU - Aborkin, Artemiy

AU - Sivkov, Viktor

PY - 2020/7/1

Y1 - 2020/7/1

N2 - 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 WC1-x nanoscale particles layer; (iii) a 3.3 nm thick non-stoichiometric tungsten oxide WO3-x layer on the WC1-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.

AB - 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 WC1-x nanoscale particles layer; (iii) a 3.3 nm thick non-stoichiometric tungsten oxide WO3-x layer on the WC1-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.

KW - MOCVD

KW - MWCNT

KW - NEXAFS

KW - TEY

KW - WC/MWCNTs

KW - XPS

KW - MULTIWALLED CARBON NANOTUBE

KW - THERMAL-STABILITY

KW - METAL CARBIDES

KW - HIGH-RESOLUTION XPS

KW - OPTICAL-PROPERTIES

KW - MECHANICAL-PROPERTIES

KW - HYBRID MATERIALS

KW - X-RAY

KW - WC1-x

KW - FUNCTIONAL-GROUPS

KW - MWCNTs

KW - PHOTOELECTRON-SPECTROSCOPY

KW - WC1-x/MWCNTs

UR - http://www.scopus.com/inward/record.url?scp=85088633087&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/6a58b0d4-fa51-308b-89ea-b723a4a9e81e/

U2 - 10.3390/app10144736

DO - 10.3390/app10144736

M3 - Article

AN - SCOPUS:85088633087

VL - 10

JO - Applied Sciences (Switzerland)

JF - Applied Sciences (Switzerland)

SN - 2076-3417

IS - 14

M1 - 4736

ER -