## 3 Results and Discussion
### NEXAFS Spectroscopy Research of the Nanocomposites and Initial MWCNTs
The unchanged structure characteristic of the MWCNT C1 spectrum indicates that in the composite, the MWCNT outer layers remain almost intact. However, in the intermediate energies region (285.4-291.8 eV) between \(\pi^{\text{*}}\)- and \(\sigma^{\text{*}}\)-resonances, there is an extra structure in the form of explicit peak C together with low-intensity peaks A, B, E and shoulder D with energies of 288.5 eV, 287.2 eV, 287.5 eV, 289.2 and 290.4 eV, respectively. In addition, it can be seen from the partial C1 dependences of the normalized TEY signals (Figure 7b) that the integral values of the partial C1 absorption cross sections (the area under the spectral dependences) noticeably decrease upon transition from MWCNTs to nanocomposites. There is also a strong decrease in the intensity of \(\pi^{\text{*}}\)-resonance by more than a factor of two in the partial NEXAFS C1 absorption spectrum of the nanocomposite as compared with the spectrum of the initial MWCNTs. In this case, the absorption decrease in the continuum in the region of 320 eV is 1.2. The latter is in good agreement with the ratio of the carbon atom content in the MWCNTs and WC1-x/MWCNT composite (sample 2) obtained from the EDS analysis (95% and 75%) and from the atomic cross-section model sum (Figure 6) equal to 97% and 80%. Figure 6: The normalized total electron yield (TEY) signal of MWCNTs (black) and nanocomposite Sample 2 (red) in arbitrary units (**left scale**) and atomic cross sections sums [67] C(97%) + O(3%) (green), W(10%) + C(80%) + O(10%) (blue) in Megabarns (**right scale**). The absorption decrease in the NEXAFS region is due to the weakening of the photoelectrons, secondary and Auger electrons flow from the outer surface of the MWCNT in the layer of pyrolytic tungsten carbide and the MWCNT free-surface reduction. However, this decrease is partially compensated by the contribution to the absorption from the WC1-x coating layer carbon atoms. Therefore, the NEXAFS C1 spectrum of the WC1-x/ MWCNT composite is a superposition of the spectra of the MWCNT surface, noncoated and coated with a thin WC1-x layer, the interface between the coating and the nanotube outer surface and the WC1-x layer of different thicknesses. The participation of some carbon atoms of the nanotube in the oxides and tungsten carbides formation also leads to a decrease in the \(\pi^{*}\)-resonance intensity compared with the absorption intensity in the continuum. While the absorption outside the NEXAFS region in the continuum is determined by the carbon atoms concentration, which remains unchanged during the formation of the coating on the initial nanotube surface. Unfortunately, the correct separation of the contributions to the NEXAFS C1 spectrum mentioned above is not possible due to the complexity of the spectrum decomposition. The peaks A-E energies are equal to the energies of the elements in the C1 NEXAFS spectrum of the graphite oxides, and correspond to electron transitions from the C1 level to \(\pi^{*}\) unoccupied orbital of C-O-C (A), C-O (B), C=O (C) [68] and [CO3]\({}^{2-}\) (D) [69] atomic groups and to hybridization of C2p and metal W5d orbitals 286.8 eV (A) and 289.0 eV (E) of WC [70; 71; 72]. In Figure 7a, the positions of the peaks are indicated by arrows. The presence of A-D peaks in the composite NEXAFS C1 spectrum indicates the carbon oxides and carbides formation in the sample. This can occur both on the MWCNT and WC1-x surfaces, and inside the coating layer. The tungsten carbide deposition during the tungsten pentacarbonyl W(CO)6 pyrolysis at a temperature of 300 \({}^{\circ}\)C is a complex chemical process. The main chemical reaction can be accompanied by a number of secondary reactions with the formation of free carbon and tungsten oxides of various compositions in the form of impurities in the final WC1-x coating. In this case, in the initial stage, the carbide and oxide formation can occur with the participation of the nanotube outer surface carbon atoms.