## 1 Introduction  
Recently, nitrogen-doped carbon materials have been widely applied to the fuel cell [1], solar cell [2], lithium-ion battery [3], lithium air battery [4], electrocatalysis [5], and adsorption [6, 7]. Various nitrogen-doped carbon materials [8, 9, 10, 11, 12, 13, 14, 15, 16, 17], such as carbon nanotube [9, 10, 11, 12], porous carbons [13], nanofiber [14], and graphene [15], have been investigated for supercapacitor electrode materials. As we know, electrode material is the key component of electrochemical capacitors and the role of efficient charging of the electrode/electrolyte interface by ions is essential. Based on previous reports [18, 19, 20, 21, 22], the nitrogen-containing functional groups can provide a pair of electrons to change the electron donor/acceptor characteristic of carbon materials [8, 9, 13]. The nitrogen containing functional groups can improve the wettability of carbon material to increase the effective specific surface area for double layer formation and offer extra redox reactions, producing more pseudocapacitance [8, 9, 10, 11, 12, 14]. The charge storage capability of carbon materials also depends primarily on their textural behavior except the surface chemistry [16, 22]. An appropriate microstructure of carbon-based electrode materials can provide a high electrochemically accessible surface area to improve ionic transportation [16]. One-dimensional (1D) nanostructured carbon materials have been recognized as one kind of an effective approach in this regard [23].  
Nitrogen-enriched carbon materials obtained by carbonization of N-containing polymers have aroused increasing interest due to their simple preparation, sustainability, and excellent physicochemical performances [24, 25, 26, 27]. polyaniline (PANI), an N-containing conducting polymer, has the advantages of low cost, environmental stability, and is easy to synthesize [28]. The carbonizedproducts of PANII (15 wt % N, 79 wt % C) have been successfully employed in other articles as electrode materials [29; 30; 31; 32; 33; 34; 35; 36]. However, most of the present reported PANI-derived carbon materials are irregular and agglomerate. Furthermore, the PANI-derived carbon materials by one-step carbonization usually have a low specific surface area while the chemical activation process is complex and increases costs. Recently, one-dimensional (1D) nanostructured PANI, such as nanofibers, nanotubes, nanowires, and nanorods, have attracted intensive attention for their unique structure, properties, and new potential applications [37; 38; 39; 40; 41; 42]. Various methods, such as hard or soft template [32; 39], interfacial polymerization [40], and rapid mixing polymerization, have been used to tailor the morphology of the products in the chemical oxidative polymerization. Compared with other methods, the rapid mixing polymerization method is the most common non-template route to produce PANI nanofibers owing to its simplicity, cost effectiveness, being environmental friendly, and pure production [43; 44; 45; 46; 47].  
Furthermore, the molecular structure and functional groups of doped acids also influence the morphology and structure of resulting PANI particles [41; 47; 48; 49; 50; 51; 52; 53; 54; 55; 56; 57; 58; 59; 60; 61; 62; 63; 64;  
The specific surface area and the analysis of porosity for the materials were characterized by N\({}_{2}\) adsorption/desorption isotherms at 77 K with an ASAP 2010 instrument (Micromerities, Norcross, GA, USA). The composition was characterized using fourier transform infrared spectroscopy (FTIR, Nicolet 6700, USA), X-ray diffraction (XRD, PANalytical X' Pert Pro, The Netherlands), and X-ray photoelectron spectroscopy (XPS, Kratos AXIS Ultra DLD, Shimadzu, Japan).