## 1 Introduction
Using MWCNTs allows us to increase the specific surface area of the deposited nanoparticles due to the stabilization of highly dispersing tungsten carbide nanoparticles. Tungsten carbide nanocoatings are also of interest primarily in the context of the fabrication of high-efficiency electrocatalysts for fuel cells, where it should replace platinum, which is very costly [32]. A considerable number of studies that focus on the synthesis of hybrid materials with MWCNT and tungsten carbide nanocoatings and on their possible applications in various research fields have already been published. [PERSON] et al. [33] obtained one-dimensional tungsten carbide nanostructuredmaterial. Carbon nanotubes were used as a carbonaceous template and carbon source for carburizing pre-impregnated tungsten oxide into tungsten carbide under synthesis conditions such as 1300 \({}^{\circ}\)C for 7 h, resulting in one-dimensional metal-free tungsten carbide. [PERSON] et al. [34] prepared multi-walled carbon nanotube-tungsten carbide composites by the reduction and carbonization process using MWCNTs and WO\({}_{3}\) precursor by molecular-level mixing and calcinations at 800 \({}^{\circ}\)C for 20 h with additional carbon source CH\({}_{4}\). Recently, carbon nanotubes have attracted increasing attention as an effective catalyst support for tungsten carbide catalyst due to their unique properties such as high current carrying ability, thermal conductivity, mechanical strength and chemical stability [35; 36; 37; 38]. [PERSON] et al. [35] observed that WC/CNTs nanocomposite prepared by the approach of surface decoration and in situ reduction-carbonization show that the electrocatalytic activity of the sample is higher than that of purified carbon nanotubes, hollow globe tungsten carbide with mesoporousity and granular tungsten carbide. These results indicate that (tungsten carbide)/(carbon nanotubes) composite creation is the effective method of increasing the tungsten carbide electrocatalytic activity. The Pt supported on WC-modified MWCNT catalysts (PtWC/MWCNTs) were synthesized by a combination of organic colloidal and intermittent microwave heating methods [36]. The results proved the better performance of the PtWC/MWCNT catalyst than that of the Pt/C for methanol oxidation. [PERSON] et al. [37] grew MWCNTs directly on the graphite rod surface by using the CVD process. Tungsten carbide was used as a platinum co-catalyst to modify the resulting MWCNTs with subsequent deposition of Pt catalyst nanoparticles using the electrochemical pulse deposition method. According to the electrochemical measurements results, the prepared catalysts show better electrocatalytic performance towards methanol oxidation compared to a commercial Pt/C catalyst with about four-times higher Pt loading. [PERSON] et al. [38] reported that they prepared a Ni-WC/MWCNT catalyst for the electrooxidation of urea in alkaline conditions. The micro-morphology and composition of the hybrid materials are determined by transmission and scanning electron microscopy (TEM and SEM), and X-ray diffraction (XRD) analysis. The characterization results indicate that the Ni nanoparticles are uniformly distributed on the WC/MWCNT framework, and the Ni-WC/MWCNT catalyst shows an improved activity for the urea electrooxidation that is higher than those of Ni-WC/C and Ni/C catalysts. The authors believe that the higher activity on the Ni-WC/MWCNT catalyst is attributed to the support effect of MWCNT as well as the synergetic effect between Ni and WC. Herein, we report a simple method for synthesis of WC\({}_{1\text{-}\text{x}}\)/MWCNT composites by metal-organic chemical vapor deposition with tungsten hexacarbonyl as a precursor [39]. It was found that the initial mass ratio of MWCNTs and \(\text{W(CO)}_{6}\) was dependent on the desired thickness of the WC\({}_{1\text{-}\text{x}}\) coating. It was found that if the initial MWCNT/\(\text{W(CO)}_{6}\) ratios were less than three, the coating was discontinuous. The size of the WC\({}_{1\text{-}\text{x}}\) particles varied from 10 to 50 nm.