A well-known approach to improve the electrochemical activity of CNFs for energy storage, and conversion applications is chemical doping. Numerous heteroatoms such as boron (B), nitrogen (N), phosphorous (P), and sulfur (S) have been examined to modify the electronic structure, and surface chemistry of CNFs. Among them, N is the commonly utilized heteroatom to tailor the electrochemical reactivity, electrical conductivity, and wettability of electrospun CNFs. The carbon atoms in the hexagonal lattice are substituted by N doping, which subsidizes more electrons to the π-system of graphitic layers, and enhances the electronic conductivity of CNFs. Liu et al. designed a porous nitrogen-doped CNFs incorporating ultra-small tin nanoparticles (SnNDs@PNC) by an electrospinning technique, and subsequent thermal carbonization for Na ion batteries . PAN, PMMA, and SnCl2 were used as precursors for the synthesis of SnNDs@PNC, by conducting electrospinning experiment at an applied voltage of 15 kV, and further thermally treated 700 ˚C under N2 to complete the carbonization, and reduction process. The morphology studies of CNFs with different shapes, typically straight, dendritic and spiral structure was displayed a fibrous structure with a diameter of about 120 nm, and Sn nanodots with 1-2 nm diameters. The SBET of the prepared materials was found to be 316 m g -2 , and the XPS analysis showed the presence of pyridinic-N, pyrrolic-N, and graphitic-N. The SnNDs@PNC was fabricated as a binder-and current collector-free anode, and demonstrated excellent electrochemical performance in Na ion batteries, which were attributed to the N heteroatom for contributing more electrons to the π-conjugated system of carbon for the enhancement in the electronic conductivity of CNFs. Moreover, the presence of pyridinic-N, and pyrrolic-N also created defect sites among the CNFs, and provided more open channels, and active sites for the insertion of Na ions. by the combination of electrospinning followed by KOH activation of PAN at elevated temperature for oxygen reduction reaction studies . The SBET of ANCNFs were found to be temperature dependent, and increased with the rise of the activation temperature. The ANCNFs heat treated at 800 ˚C resulted to a high SBET of upto 1362 m g -2 with a uniform micropores with a size of 0.9 mm. The porous ANCNFs displayed high electrocatalytic activity along with superior long-life stability, and tolerance to medium, which were mainly ascribed to the largest percentage of graphitic nitrogen groups, and increase exposure of catalytic sites resulting from the high specific surface area. In general, the post-treatment with ammonia, while NGQDs@NCNFs had a relatively rough surface than that of NCNFs, due to the anchoring of NGQDs on the surface of NCNFs. The doping of N content in NCNFs was found to be 4.28%, and in contrast the NGQDS@NCNFs showed 10.87% of N content, due to the fact that N-containing compound dicyandiamide was used as nitrogen source to dope N atoms into the framework of NGQDs. The prepared NGQDS@NCNFs composites were fabricated as electrochemical biosensors, and exhibited potential application for high-performance determination of nitrite content in food. (P@N-PHCNFs) as potassium-ion battery (PIB) . In this study, polycaprolactone (PCL) electrospun nanofibers were fabricated, and used as a sacrificial template to develop hollow polypyrrole (PPy) nanofibers, which was further activated using KOH to give rise to the P@N-PHCNFs. The average outer diameter of P@N-PHCNFs was found to be about 350 nm with the tube-wall thickness ranging from 65 to 75 nm. The SBET of N-PHCNFs was obtained as 2345 m g -2 , which was decreased after combined with red P indicating the encapsulation of red P into the pores. The P@N-PHCNFs showed excellent cycling stability, and high specific capacity of 465 mA h g -1 at 2 Ag -1 after 800 cycles. The authors stated that the embedment of ultrafine red P nanoparticles within a porous carbon matrix has played a favourable role towards reducing the absolute strain, and preventing the pulverization, and agglomeration, which has preserved the integrity of whole electrode. Further, the N doping in the CNFs has favoured the adsorption of P atoms with higher adsorption energy, and CNFs without the presence of any binder, and conductive additives have significantly enriched the entire were carried out at the applied voltage of 20 kV by keeping the distance between the needle and collector as 20 cm, and the obtained nanofibers were stabilized at 300 ˚C for 3h under air atmosphere, which was then carbonized at 1000 ˚C under N2 flow. As determined from SEM analysis, the average diameter of CNFs was about 700 nm, and the interlayer thickness was approximately 40 µm. The SBET of the nanofibers was as high as 844 m g -2 , and the XPS analysis showed the presence of N, and O heteroatoms with the maximum at% of 6.0, and 4.06, respectively. The freestanding 3D interwoven structure with conductive pathways for electrons, and ions has found to effectively enhance the interaction between polysulfides, and N/O atoms through high polar interaction. The heteroatom doped CNFs prepared via electrospinning from various precursors are exhibited in Table . Maldonoda et al. reported the preparation of N doped CNF through a CVD method, using xylene, ferrocene, and pyridine as precursors in order to control the content of nitrogen in the resultant product . The SBET of the materials was estimated as 130 m g -2 , and the content of nitrogen determined from XPS analysis was found to be 4 at%. The N-CNF as ORR catalysts showed significant activity towards the reduction of H2O2 in alkaline media, which is an essential stage in the whole ORR process. However, as reported in some papers, the notable issue related to the employment of oxide catalytic supports is that of low electronic conductivity due to the purification steps, including refluxing in concentrated alkaline, and acidic solutions that are essential before applying the N-CNFs in electrocatalytic studies. Lim et al. reported the synthesis of N-doped CNFs from acetonitrile or acrylonitrile/hydrogen mixture over a NiFeMgO catalyst at low temperatures of 400-600 °C using CVD method .