Nitrogen-enriched Carbon Nanofibers Research Articles

Electrospun polyethylenimine (PEI)-derived nitrogen enriched carbon nanofiber for supercapacitors with artificial neural network modeling

This paper presents the utilization of polyethylenimine (PEI) polymer to obtain freestanding, binder-free, and nitrogen- enriched carbon nanofibers (NCNFs) by electrospinning which is an easy and fast method. The PEI polymer played a significant role as a poring agent for the adjustment of surface area and as the heteroatom doping to increase conductivity. NCNFs-10 electrode exhibited a specific capacitance of 200 F/g at 1 A/g with a good retention of 84.25 % at 10 A/g in three electrode system. The assembled supercapacitor had a specific energy of 5.57 Wh/kg at 125 W/kg with a good cycling performance of 80.5 % after 10,000 cycles. Furthermore, an artificial neural network (ANN) method was utilized to understand the relationship between the CNF's structure and supercapacitor performance by modeling the specific capacitance. The input factors were specific surface area (SBET), nitrogen doping (N% at), graphitization degree (ID/IG), internal resistance (Rs), pore size (Vpor), micropore volume (Vmic), the average diameter (Dave), and mesopore volume (Vmeso). Results showed that the first three remarkable variables are SBET, N (%at), and ID/IG.

Hierarchical nickel cobaltite nanoneedle arrays armored flexible electrospinning carbon nanofibers membrane for electrochemical deionization

Crafting an ideal capacitive deionization (CDI) cathode presents a significant challenge, owing to the myriad requisites it must fulfill. These entail a high specific capacitance, commendable conductivity, stability, and the counteraction of the shortcomings inherent in additive/binder electrodes. Realizing all these attributes from a single-component material, however, is a daunting task. In this investigation, we present our findings on the in-situ cultivation of ultrathin NiCo2O4 nanoneedle arrays on freestanding electrospinning nitrogen-enriched carbon nanofibers devised to tackle these hurdles. The resultant material boasts remarkable features that not only alleviate tension triggered by phase transition but also accentuate electric conductivity. Electrochemical evaluations authenticate the effectiveness of structural modulation, reflected through a markedly augmented specific capacitance, superior stability, and diminished electrochemical resistance. Furthermore, the assembled pliable, asymmetric CDI cell incorporating electrospinning carbon nanofiber showcases superior desalination capabilities (38.86 mg g−1 at 1.2 V), a swift desalination rate (0.65 mg g−1 min−1), and improved cycle stability. This work finding contribute valuable interpretations towards proficiently designing and developing advanced CDI electrode materials capable of meeting the stringent requisites for high specific capacitance, good conductivity, and stability. It further propels progress towards industrialization, thereby expediting the realization of practical applications.

Nitrogen-enriched carbon nanofibers with tunable semi-ionic C[sbnd]F bonds as a stable long cycle anode for sodium-ion batteries

The quest for getting more efficient carbonous anodes for sodium ion batteries (NIBs) prepared by simple and economical methods continues to be an important endeavor. Herein, a plasma-controlled method is developed for preparing semi-ionic CF bonds decorating nitrogen-enriched electrospinning carbon nanofibers (NCNFs) as a free-standing anode for NIBs. The semi-ionic CF bonds are beneficial to the fast ion and electron transfer for a free-standing electrode, which remarkably improves the rate performances of NCNFs as the NIBs anodes. The optimized sample delivers a reversible capacity of 199 mA h g−1 at 0.1 A g−1 and displays excellent long-term stability with reversible specific capacity around 150 mA h g−1 over 2000 cycles at 500 mA g−1 after the rate capability test. Moreover, the presence of semi-ionic CF bonds on plasma nitrogen-enriched electrospinning carbon nanofibers surfaces can reduce the resistance of the anode, thereby showing a more stable solid electrolyte interphase SEI) after electrochemical cycles.

Ultra-small MnCo2O4 nanocrystals decorated on nitrogen-enriched carbon nanofibers as oxygen cathode for Li-O2 batteries

Ultra-small MnCo2O4 nanocrystals/nitrogen enriched carbon nanofiber composites, with particle size as small as 2–4[Formula: see text]nm and nitrogen content as high as [Formula: see text][Formula: see text]at.%, were designed and used as oxygen cathode materials for Li-O2 batteries, with an aprotic electrolyte. Via an in-situ nucleation and growth, the morphology, size and distribution of MnCo2O4 nanocrystals were well controlled on surface of nanofibers, with strong interfacial interactions between the two components. Benefitting from the unique microstructure and high-level nitrogen doping, the MnCo2O4/NCF composite can deliver discharge and charge capacities of 4147.8 and 3842.8[Formula: see text]mAh/g as oxygen cathode materials, and columbic efficiencies are about 92.6%. More importantly, the discharge products can completely decompose in charging process as evidenced by an ex-situ FESEM investigation, while for pure NCF cathode, particle and plate-like Li2O2 were still observed on its surface, which confirmed that the MnCo2O4/NCF composite has a superior electrocatalytic activity that that of NCF.

A novel synthesis of controllable nitrogen-doped SnOx-ZnO supercapacitors to enhance electrochemical performance

Nitrogen-enriched carbon nanofibers carried Sn and Zn bimetallic composites with outstanding storage capacity and superior mechanical strength were facilely fabricated by electrospinning technology, amidoximation reaction modified polymer fiber, ion coordination technique introduced Zn2+ and carbonization of composite nanofibers. The introduction of amidoxime groups not only enhanced the coordination ability with Zn2+, but also increased the content of nitrogen element. In addition, due to the different thermal stability of amidoxime groups, the regulation of different types of nitrogen content can be achieved by changing the carbonization temperature, and the influence of nitrogen on the electrochemical performance was explained. At the same time, due to the role of carbothermal reduction, tin in different valence ratios was obtained and its contribution to the energy storage performance of supercapacitors was explored. Benefiting from high nitrogen-enriched level, mutation between Sn2+ and Sn4+ oxidation state and synergistic mechanism of ZnO-SnOx bimetal, the prepared composite had a high specific capacitance of 810.89 F g−1 at a current density of 0.5 A g−1, outstanding cycling stability of 119% over 5000 cycles in 4 M KOH electrolyte. What’s more, we conducted a two-electrode test with the energy density of 50 Wh kg−1 at a power density of 374 W kg−1. In consequence, this novel design is believed to have great potential in high energy and power density of energy storage devices in the future.

N-Enriched carbon nanofibers for high energy density supercapacitors and Li-ion batteries.

Nitrogen enriched carbon nanofibers have been obtained by one-step carbonization/activation of PAN-based nanofibers with various concentrations of melamine at 800 °C under a N2 atmosphere. As synthesised carbon nanofibers were directly used as electrodes for symmetric supercapacitors. The obtained PAN-MEL fibers with 5% melamine stabilised at 280 °C and carbonized at 800 °C under a nitrogen atmosphere showed excellent electrochemical performance with a specific capacitance of up to 166 F g−1 at a current density of 1A g−1 using 6 M KOH electrolyte and a capacity retention of 109.7% after 3000 cycles. It shows a 48% increase as compared to pristine carbon nanofibers. Two electrode systems of the CNFM5 sample showed high energy densities of 23.72 to 12.50 W h kg−1 at power densities from 400 to 30 000 W kg−1. When used as an anode for Li-ion battery application the CNFM5 sample showed a high specific capacity up to 435.47 mA h g−1 at 20 mA g−1, good rate capacity and excellent cycling performance (365 mA h g−1 specific capacity even after 200 cycles at 100 mA g−1). The specific capacity obtained for these nitrogen enriched carbon nanofibers is higher than that for pristine carbon nano-fibers.

Nitrogen-Enriched Carbon Nanofibers Derived from Polyaniline and Their Capacitive Properties

Nitrogen-doped carbon materials derived from N-containing conducting polymer have attracted significant attention due to their special electrochemical properties in the past two decades. Novel nitrogen-enriched carbon nanofibers (NCFs) have been prepared by one-step carbonization of p-toluene sulfonic acid (P-TSA) doped polyaniline (PANI) nanofibers, which are successfully synthesized via the rapid mixing oxidative polymerization at room temperature. NCFs with diameters ranging from 100 nm to 150 nm possess a highly specific surface area of 915 m2 g−1 and a relatively rich nitrogen content of 7.59 at %. Electrochemical measurements demonstrate that NCFs have high specific capacitance (172 F g−1, 2 mV s−1) and satisfactory cycling stability (89% capacitance retention after 5000 cycles). The outstanding properties affirm that NCFs can be promising candidates for supercapacitor electrode materials. Interestingly, the carbonization of PANI opens the possibility to tailor the morphology of resulting nitrogen-enriched carbon materials by controlling the reaction conditions of PANI synthesis.

Self-assembled heteropolyacid on nitrogen-enriched carbon nanofiber for vanadium flow batteries.

A novel polyoxometalate-based electrode was developed by incorporating phosphotungstic acid (PWA) in nylon-6,6 nanofiber, followed by carbonization. The developed PWA-carbon nanofiber (PWA-CNF) showed the characteristics of the dual-scale porosity of micro- and mesoporous substrate with surface area of around 684 m2 g-1. The compound exhibited excellent stability in vanadium electrolyte and battery cycling. Evaluation of electrocatalytic properties toward V2+/V3+ and VO2+/VO2+ redox couples indicated promising advantages in electron transfer kinetics and increasing energy efficiency, particularly for the VO2+/VO2+ couple. Moreover, the developed electrode exhibited substantially improved energy efficiency (14% higher than that of pristine carbon felt) in the single cell vanadium redox flow battery. This outstanding performance was attributed to high surface area and abundant oxygen-containing linkages in the developed electrode.

Nitrogen-Enriched Carbon Nanofiber Aerogels Derived from Marine Chitin for Energy Storage and Environmental Remediation

Nitrogen-enriched (N-enriched) carbon nanofiber aerogels (NCNAs) with an ultrafine nanofiber network structure were designed and prepared by using chitin nanofiber aerogels as the precursor. Because of the uniform nanofibrous architecture and nitrogen-rich composition of chitin nanofiber aerogels, the NCNAs exhibited large specific surface area (490–1597 m2 g–1) and a high nitrogen content (2.07–7.65%). As a consequence, supercapacitor electrodes prepared from NCNA-900 showed specific capacitances as high as 221 F g–1 at the current density of 1.0 A g–1 and good capacitance retention of 92% over 8000 cycles in a 6.0 mol L–1 KOH electrolyte without further activation. Moreover, the NCNA-900 could also be applied as an effective adsorbent for dye adsorption, such as Congo red (496 mg g–1) and Rhodanine B (489 mg g–1). In view of an excellent electrochemical performance and high adsorption capacities for dyes as well as cost-effective and eco-friendly approaches, NCNAs derived from marine chitin show great p...

Freestanding highly defect nitrogen-enriched carbon nanofibers for lithium ion battery thin-film anodes

To transform lithium ion batteries into large-scale energy storage technologies, high energy/power densities and long cycling life of carbon-based anodes must be achieved.

A bifunctional oxygen electrocatalyst from monodisperse MnCo2O4 nanoparticles on nitrogen enriched carbon nanofibers

Monodisperse MnCo2O4 nanoparticles supported on nitrogen enriched carbon nanofibers (NCF) exhibited a synergy of component interactions that resulted in higher ORR and OER activities than commercial Pt/C catalysts.

High-performance lithium storage in nitrogen-enriched carbon nanofiber webs derived from polypyrrole

Nitrogen-doped carbon nanofiber webs (N-CNFWs) are prepared by direct pyrolyzation of polypyrrole (PPy) nanofiber webs at 600°C. The structure and morphology of N-CNFWs are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Raman spectra and elemental analysis. Both the doped N content and the N existing type in carbon, change with the pyrolysis time. As anode material for lithium-ion battery, the N-CNFWs show high capacity and good rate capability. The reversible capacity is up to 668mAhg−1 at a current density of 0.1Ag−1 and 238mAhg−1 at 5Ag−1, which can be ascribed to the nanofiber structure and high nitrogen content.