## 3 Results and Discussion
### NEXAFS Spectroscopy Research of the Nanocomposites and Initial MWCNTs  
The MWCNTs and WC\({}_{\text{1-x}}\)/MWCNT nanocomposites were studied using NEXAFS spectroscopy method in TEY mode. The background radiation contributions in the incident beam and in the TEY signal was determined using the method detailed in [65; 42; 66]. To normalize the TEY signal from MWCNTs and MWCNT-based nanocomposites, the use of gold TEY signals divided by the absorption cross section of the Au atom is necessary  
In the work [42], it was shown that to normalize the TEY signal from MWCNTs and MWCNT-based nanocomposites, the use of the TEY signal of gold divided by the Au atom absorption cross section is necessary. The normalized TEY signal can be obtained as [42]:  
\[\sigma_{s}(E_{0})\text{-}Y_{s}\left(E_{0}\right)\text{-}Y_{Au}\left(E_{0} \right)\text{,} \tag{2}\]  
where \(Y_{s}\left(E_{0}\right)\) and \(Y_{Au}\left(E_{0}\right)\) is the TEY signal of sample and Au-plate. Figure 6 shows the spectral dependences in the same relative units (left scale) of the TEY signal for the MWCNTs and nanocomposite WC\({}_{\text{1-x}}\)/MWCNTs (Sample 2) together with the atomic absorption cross sections spectral dependences in the absolute scale in Mb (right scale) obtained by modeling the samples atomic composition. It is known that the absorption cross section of any compounds far from their constituent atoms absorption edges can be represented with good accuracy as the sum of the atomic absorption cross sections with weight coefficients equal to the fraction of their atomic composition [67]. This allows us to estimate the corresponding atom's percentage by comparing the calculated and experimental absorption cross sections dependences outside the absorption edges. From EDS data, it is known that the MWCNT contains mainly carbon and several percentage-points of oxygen atoms, and the nanocomposite contains tungsten, carbon and oxygen. In the case of the initial MWCNTs, good agreement with the experimental curve is observed at weights of 97% and 3% for carbon and oxygen atoms, respectively, which correlates with the EDS data. In the case of the WC\({}_{\text{1-x}}\)/MWCNT nanocomposite (Sample 2), the optimal atomic ratios are 10%, 80% and 10% for tungsten, carbon and oxygen, respectively. It should be noted that in the case of sample 2, the coating of the nanotube surface with tungsten carbide nanoparticles is incomplete and nonuniform in thickness. For this reason, the contribution to the TEY signal is made in addition to the WC\({}_{\text{1-x}}\) covering layer  
and tungsten oxides thin layers, the MWCNT free surface and the surface of MWCNTs coated with WC1-x layers of different thicknesses. Therefore, the proportions of carbon and oxygen atoms are qualitative characteristics, in contrast to tungsten atoms, which are contained only in the pyrolytic tungsten carbide coating layer. This is also due to the fact that the absorption cross sections of tungsten atoms in the energy range 250-800 eV outside the NEXAFS C1 and O1 absorption edges exceed the cross sections of carbon and oxygen atoms by an order of magnitude or more [67], and therefore make the main contribution to the nanocomposite normalized TEY signal. As noted earlier in the analysis of SEM data, the WC1-x coating has good adhesion to the outer surface of the MWCNTs. This indicates that the pyrolytic tungsten carbide layer and the MWCNT router graphene layers chemically interact with each other. To analyze this interaction, the C1 NEXAFS spectra of the initial MWCNTs and composites were compared. The \(\pi^{\text{*}}\)- and \(\sigma^{\text{*}}\)-resonances, characteristic of the initial MWCNT spectrum, are retained in the composite spectrum (Figure 7a). It should be noted that the MWCNT C1 spectrum has a very low-intensity broad band in the 286-289 eV region, which is probably associated with the interaction of carbon with a small amount of oxides adsorbed on the nanotube outer surface. The presence of the oxide is confirmed by XPS studies.