# Electrospinning-Based Carbon Nanofibers for Energy and Sensor Applications
## 3 Different Carbon Nanofibers Obtained by Electrospinning
### Carbon Nanofibers from Common Electrospinning  
Common electrospinningning generates fibers from a simple solution containing only one kind of polymer or containing an inorganic composition. The inorganic material should not react or change shape in a high-temperature environment. Since it is affected by only one factor from the host material, it is easier to control the common electrospinningning process. In addition, there is almost no effect from the inorganic material during the calcination, so the carbon fiber can retain its shape. The common electrospinningning method cannot create a complicated structure, but studies are being conducted on the characteristics of CNFs depending on the changes in manufacturing conditions. [PERSON] et al. used electrospinningning to study the unidirectional PAN yarn fibers with different alignments (Figure 7a) [65]. Then, the properties of the CNFs from the prepared polymer nanofibers were then studied. The electrospun PAN yarn nanofibers were stabilized and carbonized under many conditions, such as draw ratio, heating rate, temperature, as well as exposure time. It was concluded that 16 kV can give the best strength for CNFs with optimized condition stabilization at 200 \({}^{\circ}\)C and carbonization at 1350 \({}^{\circ}\)C. Later, [PERSON] et al. investigated the effect of PAN isotacticity on CNF manufacturing (Figure 7b) [66]. They compared the differences in the prepared solutions, the electrospinningning parameters, and the stabilization and carbonization processes. The authors used magnesium chloride \begin{table}
\begin{tabular}{c c c c c} \hline
**Precursor** & **Temperature (\({}^{\circ}\)C)** & **Environment** & **Purpose** & **Ref.** \\ \hline PAN & 200–300 & Air & Oxidation stabilization & \\ PAN & 900–1300 & Argon/Nitrogen & Carbonization & [38] \\  & Up to 2500 & Argon/Nitrogen & Orientation & \\  & 180–300 & Air & Oxidation stabilization & \\ PVA & 600–1000 & Argon/Nitrogen & Carbonization & [46] \\  & Before softening point & Air & Oxidation stabilization & \\ Pitch & of material & & & [64] \\  & Up to 1200 & Argon/Nitrogen & Carbonization & \\ PI & Up to 1000 & Argon/Nitrogen & Carbonization & [50] \\ Carbohydrate/PEO & 105 & Air & Oxidation stabilization & \\  & Up to 800 & Argon/Nitrogen & Carbonization & [55; 56] \\ PXTC/PPV & Up to 1800 & Argon/Nitrogen & Carbonization & [63] \\ \hline \end{tabular}
\end{table} 
Table 1: Changes in carbonization temperature and gas-exposure conditions by polymer type. Figure 6: Chemical structure of sp\({}^{2}\) carbon (PPV) produced after heat treatment of PXTC. to increase the percentage of isotactic in the structure of the polymer chain. The presence of a higher isotactic structure causes cyclization to occur at a lower temperature, yet it also makes electrospinningming more difficult to control and reduces the carbon yield. The CNFs that were made by electrospinning from the PAN and MXene mixing solution were investigated by [PERSON] et al. in order to find the optimized conditions for the electrospinningming solution (Figure 7c) [67]. It has been concluded that electrospinningming is possible with a concentration of MXene up to 16 wt% of the solution containing 8 wt% PAN. However, it is noted that when the MXene concentration is lower than 16 wt%, the fiber is less uniform with the MXene flakes produced from the surface. The carbonization of the electrospun nanofiber with only a small quantity of MXene decomposed at 800 \({}^{\circ}\)C was also investigated. Not only were the CNFs stable, but the shape of them also became more uniform at an 800 \({}^{\circ}\)C carbonization. In addition, the MXene-containing CNFs also exhibit a much lower resistance between the working electrode material and the electrolyte. Though common electrospinning can manufacture CNFs easily with high uniformity, the material has a low surface area and porous volume, thus they have low working performance in the applications of carbon materials. Figure 7: (**a**) The study of PAN as a precursor of electrospinningming [65].