**3. Experimental Section**

### *3.1. Carbon Nanofiber Hybrids/IF-WS2*

The amounts of IF-WS2 included into CNF were determined by the knowledge gained in previous studies of composites by different groups [14,15,19], and consistent with the intent of generate lightweight materials, making the less dense carbon nanostructure component the most abundant phase. The multistep process employed to generate *in situ* structures is depicted in Figure 10.

**Figure 10.** CNF/IF-WS2 preparation steps. Ni nanoparticles and WO3 precursors were combined in solution using sonication in ethanol, dried and placed in a crucible inside a quartz tube of a tubular furnace. The mixture was then exposed to diverse environments and thermal treatments to generate Carbon Nanofiber/tungsten disulfide hybrids (CNF/IF-WS2).

The gas flow rates employed for each step were: 300 sccm N2 for air removal, 37 sccm of Ar/H2 (93%/7%) for reduction, a mixture of 44 sccm N2/15 sccm Ethylene/2 sccm O2 for fiber growth (both low temperature and high), a mixture of 150 sccm N2/15 sccm H2S for sulfurization and 300 sccm N2 during the cool down process.
