Nitrogen-doped Carbon Fibers Research Articles

Research on the Effect of the Graphite Defect Type and Doping Structure on Microwave Absorption Properties in Nitrogen-Doped Carbon Fiber

Research on the Effect of the Graphite Defect Type and Doping Structure on Microwave Absorption Properties in Nitrogen-Doped Carbon Fiber

Hierarchical Bi2O3 nanosheets and ZIF-8 derived porous nitrogen-doped carbon fibers as novel assembled nanocomposites for high-performance flexible supercapacitors

The unique design of the core–shell heterostructure is significant for obtaining electrode materials with excellent electrochemical properties. In this paper, porous carbon nanofibers (NPC@PPZ) embedded with N-doped porous carbon nanoparticles are used to construct flexible electrodes (NPC@PPZ@Bi2O3). Zeolite imidazole skeleton (ZIF)-8 and poly(methyl methacrylate) (PMMA) derived porous carbon fibers and Bi2O3 nanosheets, were utilized as the porous core and multilayer shell, respectively. The unique core and shell result in abundant pores and channels for fast ion transport and storage, high specific surface area, and additional electroactive sites. This perfect structural design enables the NPC@PPZ@Bi2O3 composite electrode to have excellent electrochemical performance. The results show that this electrode can obtain a high specific capacitance of 697 F g−1 at a current density of 1 A g−1 and a stable cycling performance at a high current density of 5 A g−1. The strategy developed in this study provides a new approach for the design and fabrication of flexible supercapacitors by electrostatic spinning combined with hierarchical porous structures.

Enhancing electrochemical performance of lithium-ion batteries with diverse nanomaterials

Abstract Although lithium-ion batteries (LIBs) can be widely used, there are some challenges such as safety risks, lower energy density compared to fossil fuels, high cost, long charging times and limited range in electric vehicles. Nanomaterials, with their unique properties and surface effects, can effectively address these challenges and improve the electrochemical performance of LIBs. This research introduces six types of nanomaterials used in LIBs, including TiS3 nanoflakes, ZnMn2O4 nanobundles, ZrO2 surface-modified cathode material, nitrogen-doped carbon fibers with tin (Sn) nanoparticles, carbon nanosheets, and nanostructured bismuth-carbon composites. These recent advancements in nanomaterials can improve electrochemical performance of LIBs, such as specific capacity, cycling ability and stability. The study offers some innovative insights and approaches in using nanomaterials and synthesizing them for emerging battery technologies. In addition, this research is wished to provide a fresh perspective and methodology that can advance the performance and design of LIBs, and provide a new design approach for nanomaterials.

In Situ Chemical Modulation of Graphitization Degree of Carbon Fibers and Its Potassium Storage Mechanism.

Graphite is considered to be the most auspicious anode candidate for potassium ion batteries. However, the inferior rate performances and cycling stability restrict its practical applications. Few studies have investigated the modulating the graphitization degree of graphitic materials. Herein, a nitrogen-doped carbon-coated carbon fiber composite with tunable graphitization (CNF@NC) through etching growth, in-situ oxidative polymerization, and subsequent carbonization process is reported. The prepared CNF@NC with abundant electrochemical active sites and a rapid K+/electron transfer pathway, can effectively shorten the K+ transfer distance and promote the rapid insertion/removal of K+. Amorphous domains and short-range curved graphite layers can provide ample mitigation spaces for K+ storage, alleviating the volume expansion of the highly graphitized CNF during repeated K+ insertion/de-intercalation. As expected, the CNF@NC-5 electrode presents a high initial coulombic efficiency (ICE) of 69.3%, an unprecedented reversible volumetric capacity of 510.2 mA h cm-3 at 0.1 A g-1 after 100 cycles with the mass-capacity of 294.9 mA h g-1. The K+ storage mechanism and reaction kinetic analysis are studied by combining in-situ analysis and first-principles calculation. It manifests that the K+ storage mechanism in CNF@NC-5 is an adsorption-insertion-insertion mechanism (i.e., the "1+2" model). The solid electrolyte interphase (SEI) film forming is also detected.

Nitrogen-Doped Cellulose-Derived Porous Carbon Fibers for High Mass-Loading Aqueous Supercapacitors.

Biomass-based porous carbon with renewability and flexible structure tunability is a promising electrode material for supercapacitors. However, there is a huge gap between experimental research and practical applications. How to maintain good electrochemical performance of high mass-loading electrodes and suppress the self-discharge of supercapacitors is a key issue that urgently needs to be addressed. The structure regulation of electrode materials such as heteroatom doping is a promising optimization strategy for high mass-loading electrodes. In this work, nitrogen-doped cellulose-derived porous carbon fibers (N-CHPCs) were prepared by a facile bio-template method using cotton cellulose as raw material and urea as dopant. The prepared N-CHPCs have high specific surface area, excellent hierarchical porous structure, partial graphitization properties and suitable heteroatom content. The assembled high mass-loading (12.8 mg cm-2; 245 μm) aqueous supercapacitor has excellent electrochemical performance, i. e., low open-circuit voltage attenuation rate (21.39 mV h-1), high voltage retention rate (78.81 %), high specific capacitance (295.8 F g-1 at 0.1 A g-1), excellent area capacitance (3.79 F cm-2 at 0.1 A g-1), excellent cycling stability (97.28 % over 20,000 cycles at 1.0 A g-1). The excellent performance of high mass-loading N-CHPCs is of great significance for their practical applications in advanced aqueous supercapacitors.

A nitrogen-doped carbon fiber coating embedded in the separator for stable zinc batteries.

A separator modification strategy was proposed by placing nitrogen-doped carbon fibers (NCF700) in the middle of the separator to prevent direct contact between the coating and the rigid zinc metal anode, resulting in coating cracks. The NCF700 coating can homogenize the electric field distribution and increase the transference number of zinc ions. Therefore, the battery assembled with the NCF700 coated separator exhibits superior cycling stability compared to the bare separator.

Metal-chelating-membrane-derived TM/TMOx nitrogen-doped carbon fibers as efficient oxygen reduction electrocatalysts.

A metal-chelating membrane was exploited for the facile synthesis of N-doped graphitic carbon fibers (N-CFs) with abundant TM/TMOx nanoparticles completely exposed on the surfaces of the fibers. The ready accessiblity to multiple active sites and strong synergistic effects endowed the Fe/Fe3O4@N-CFs with optimal qualities, in particular delivering enhanced ORR performance in alkaline and neutral medium.

Multichannel nitrogen-doped carbon fiber confined Fe3C nanoparticles for efficient electroreduction of nitrate

A novel 1D hierarchical architecture with dispersed Fe3C nanoparticles confined in multichannel nitrogen-doped carbon fibers (Fe3C/MNCFs) is reported as efficient NO3RR electrocatalyst. The Fe3C/MNCFs-800 demonstrates the nitrate conversion of 90.9%, N2 selectivity of 99.53%, for up to 15 cycles.

Copper nanoparticles embedded into nitrogen-doped carbon fiber felt as recyclable catalyst for benzene oxidation under mild conditions

Herein, an active and stable nanocatalyst based on copper nanoparticles embedded into nitrogen-doped carbon fiber felts (NCFFs) was fabricated through a co-assembly protocol. The catalytic performance of Cu (20 wt.%)/NCFF was contributed to its structural and morphological features, which were studied by various characterization techniques. The data illustrated that the catalyst showed reasonable activity and excellent selectivity in oxidation of benzene-to-phenol (25.2 and 100% for yield and selectivity respectively) in the presence of an environmentally-friendly oxidant. Furthermore, the microscopic catalyst kept its long-term performance until nine successive runs, which turns it into a bulk alternative in large-scale schemes.

Supramolecular imprinted cellulose-based N-doped biomass carbon fiber for visual detection and specific degradation of perfluorooctanoic acid

In this study, we successfully synthesized SMIP@N-CF, a nitrogen-doped biomass carbon fiber, using supramolecular imprinting technology. This material has good perfluorooctanoic acid (PFOA) adsorption properties and excellent photocatalytic ability. Therefore, it is possible to apply SMIP@N-CF to the detection system of PFOA for visual detection and to the photocatalytic process based on peroxymonosulfate (PMS) for the degradation of PFOA. The Independent Gradient Model (IGM) explains that visual detection relies on the rapid adsorption of PFOA by functional monomers, covering the catalytic site and resulting in a color change. Experimental evidence verifies its good linear response within the 0.07–90 µM range. Density Functional Theory (DFT) elucidates that charge transfer between pyridine N and C atoms activated PMS to produce reactive oxygen species to degrade PFOA, and the final degradation rate reached 94.3 %. The successful application of SMIP@N-CF provides a new idea for further understanding nitrogen-doped biomass materials and provides a scientific basis for detecting and degrading PFOA in water.

Flexible Ti3 C2 Tx MXene Bonded Bio-Derived Carbon Fibers Support Tin Disulfide for Fast and Stable Sodium Storage.

High energy density and flexible electrodes, which have high mechanical properties and electrochemical stability, are critical to the development of wearable electronics. In this work, a free-standing MXene bonded SnS2 composited nitrogen-doped carbon fibers (MXene/SnS2 @NCFs)film is reported as a flexible anode for sodium-ion batteries. SnS2 nanoparticles with high-capacity properties are covalently decorated in bio-derived nitrogen-doped 1D carbon fibers (SnS2 @NCFs) and further assembled with highly conductive MXene sheets. The addition of bacterial cellulose (BC) can further improve the flexibility of the film. The unique 3D structure of points, lines, and planes can not only offset the disadvantage of low conductivity of SnS2 nanoparticles but also expand the distance between MXene sheets, which is conducive to the penetration of electrolytes. More importantly, the MXene sheets and N-doped 1D carbon fibers (NCFs) can accommodate the large volume expansion of SnS2 nanoparticles and trap polysulfide during the cycle. The MXene/SnS2 @NCFs film exhibits better sodium storage and excellent rate performance compared to the SnS2 @NCFs. The in situ XRD and ex situ (XRD, XPS, and HRTEM) techniques are used to analyze the sodiation process and to deeply study the reaction mechanism of the films. Finally, the quasi-solid-state full cells with MXene/SnS2 @NCFs and Na3 V2 (PO4 )3 @carbon cloth (NVP@CC) fully demonstrate the application potential of the flexible electrodes.

Fuel cell type SO2 sensor based on Cu/CF-N sensing electrode and Nafion proton conductor at room temperature

In this work, nitrogen doped carbon fiber loaded copper (Cu/CF-N) sensing electrode and Nafion proton conductor are used to fabricate fuel cell type gas sensors that realize fast response/recovery for SO2 detection at room temperature. This is the first time that this type of sensor has been used to detect SO2. We investigated the effect of Cu content on sensors’ performance, and found that the Cu (20 wt%)/CF based sensor exhibited the highest response. This can be attributed to the optimal Cu content, which exposes the most active sites. Moreover, nitrogen was doped into electrode material to further improve the performance. Nitrogen atoms enhance the conductivity of the material and its ability to adsorb SO2. These are confirmed by the complex impedance measurement and TPD analysis. The upgraded Cu/CF-N fuel cell type gas sensor showed a response of − 435.6 nA to 50 ppm SO2 and a low detection limit of 500 ppb. Significantly, the Cu/CF-N sensor demonstrated short response time (44 s) and recovery time (87 s) at room temperature. Furthermore, with the advantages of no power consumption, excellent selectivity and good repeatability, the fuel cell type gas sensors have broad prospects in the field of room temperature gas detection.

Biomass-derived nitrogen-doped carbon fiber driven δ-MnO2 for aqueous zinc-ion batteries with high energy and power density

Aqueous zinc-ion batteries (AZIBs) are considered potential devices for energy storage because of their low cost and high level of safety. However, the efficiency of AZIBs is influenced by the cathode reaction kinetics. Herein, we propose the δ-MnO2 nanorods grow in situ on natural loofah sponge-derived nitrogen-doped hollow carbon fibers (HCF), which can significantly improve both ion/electron transfer rate and provide structural stabilization. The self-assembled δ-MnO2-HCF (HCM) electrodes exhibit excellent electrochemical performances, including an impressively specific capacity (341 mAh g−1 at 0.2 A g−1), exceptional long cycling stability (87% capacity retention after 3500 cycles at 2 A g−1), and superb energy density and power density (540 Wh kg−1 at 288 W kg−1 and 164 Wh kg−1 at 5485 W kg−1), all based on the mass of cathode. In addition, the inclusion of HCF leads to a notable enhancement in the electrical conductivity of HCM, and a reduction in the energy barriers for Zn ions to diffuse between the δ-MnO2 layers, according to density functional theory (DFT) calculations. It is promising that the HCM will serve as a design guide for developing cost-effective and high-performance cathode materials for AZIBs.

MoS2 nanoflowers implanted in nitrogen-doped carbon fibers with Fe2O3 nanoparticles decorated for enhanced lithium storage performance

MoS2 has attracted extensive attention due to its unique two-dimensional layered structure and high theoretical capacity. Unfortunately, the large volume variation and sluggish lithiation kinetics during charging/discharging result in low-rate capability and poor cyclic stability. To solve those issues, MoS2/Fe2O3 @ carbon fiber (CNF) composite was designed delicately by implanting MoS2 nanoflowers in nitrogen-doped carbon fibers with Fe2O3 nanoparticles decorated. The carbon nano-fibers served as a holder to accommodate the volume expansion of MoS2 and provide a high-speed channel for electron transport, while Fe2O3 nanoparticles are apt to form heterojunction with MoS2, producing an internal electric field to enhance the ionic dynamic. As a result, the optimized sample, denoted as MoS2/Fe2O3 @CNF-3, exhibits high first discharge capacity of ∼1370 mAh g−1 at 50 mA g−1 and excellent cycle performance (559.74 mAh g−1 after 500 cycles at 1 A g−1, with capacity retention rate of 71.6%). In summary, the design techniques of heterojunction building and carbon encapsulation can be applied to different energy storage materials and have significant potential for enhancing lithium-ion battery performance electrochemically.

Space-Confined Guest Synthesis to Fabricate Sn-Monodispersed N-Doped Mesoporous Host toward Anode-Free Na Batteries.

Severe issues including volume change and dendrite growth on sodium metal anodes hinder the pursuit of applicable high-energy-density sodium metal batteries. Herein, an in situ reaction approach is developed that takes metal-organic frameworks as nano-reactor and pore-former to produce a mesoporous host comprised of nitrogen-doped carbon fibers embedded with monodispersed Sn clusters (SnNCNFs). The hybrid host shows outstanding sodiophilicity that enables rapid Na infusion and ultralow Na nucleation overpotential of 2mV. Its porous structure holds a high Na content and guides uniform Na deposition. Such host provides favorable Na plating/stripping with an average Coulombic efficiency of 99.96% over 2000 cycles (at 3mA cm-2 and 3mA h cm-2 ). The Na-infused SnNCNF anode delivers extreme Na utilization of 86% in symmetric cells (at 10mA cm-2 and 10mA h cm-2 ), outstanding rate capability and cycle life in Na-SnNCNF||Na3 V2 (PO4 )3 full cells (at 1 A g-1 for over 1000 cycles with capacity retention of 92.1%). Furthermore, high-energy/power-density anode-less and anode-free Na cells are achieved. This work presents an effective heteroatom-doping approach for fabricating multifunctional porous carbon materials and developing high-performance metal batteries.

Waste Cigarette Butts-Derived Nitrogen-Doped Carbon Fibers Loaded with Ru Nanoparticles as an Efficient Cathode Catalyst for Lithium-Oxygen Batteries

Low catalytic activity and high cost of cathode catalysts hinder the large-scale commercial application of lithium-oxygen (Li-O2) batteries. In this work, waste cigarette butts, which inherently have a porous fiber structure, were selected as the precursor of the carbon material for the cathode catalyst of Li-O2 batteries. The porous nitrogen-doped carbon material was prepared by simple heat treatment of waste cigarette butts. The rich porous structure of the obtained carbon fiber material effectively enhances the diffusion of oxygen molecules and provides ample space for the discharge products. N doping in carbon fibers enhances the bifunctional catalytic activity toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which was corroborated by density functional theory (DFT) calculation. The assembled Li-O2 battery with C–N fibers-loaded Ru nanoparticles catalyst delivers an initial discharge capacity of up to 12 036.3 mA h g–1 and can be cycled stably for more than 800 cycles (4000 h) at a current density of 200 mA g–1 and a cutoff capacity of 500 mA h g–1. Even at a high current density of 500 mA g–1, the cells still show a high average discharge voltage of 2.28 V with excellent cycle stability and rate capability. XPS analysis proves that the cathode material can effectively inhibit the formation of Li2CO3 and Li2O byproducts. This work provides a cost-effective solution to solve the cathode catalyst problem of Li-O2 batteries and improve their cycling stability as well as environment protection.

SnCo Nanoparticles Loaded in Hollow Carbon Spheres Interlinked by N-Doped Carbon Fibers for High-Performance Sodium-Ion Batteries.

The development of Sn-based materials with electrochemically inactive matrices is a novel strategy to alleviate the volume expansion and giant structure strain/stress during the sodiation/desodiation process. In this work, a freestanding membrane based on the unique bean pod-like host composed by nitrogen-doped carbon fibers and hollow carbon spheres (HCSs) encapsulated with SnCo nanoparticles is synthesized by electrospinning (B-SnCo/NCFs). In this unique bean pod-like structure, Sn acts as a host for Na+ storage, while the Co plays the important role of an electrochemically inactive matrix that can not only buffer the volume variations but also inhibit aggregation and particle growth of the Sn phase during the electrochemical Na-Sn alloying process. Meanwhile, the introduction of hollow carbon spheres can not only provide enough sufficient void space to withstand the volume expansion during the (de)sodiation processes but also improve the conductivity of the anode along the carbon fibers. Furthermore, the B-SnCo/NCF freestanding membrane can increase the contact area between the active material and the electrolyte, which can provide more active sites during the cycling process. When used as an anode material for Na-ion batteries, the freestanding B-SnCo/NCF anode exhibits an outstanding rate capacity of 243.5 mA h g-1 at 1.6 A g-1and an excellent specific capacity of 351 mA h g-1 at 0.1 A g-1 for 300 cycles.

A feather-like interlayer design with highly exposed active sites for high-performance lithium-sulfur batteries

Improving the conversion efficiency of lithium polysulfides (LiPSs) within the interlayer plays a significant role in inhibiting the shuttle effect of polysulfides for lithium-sulfur (Li-S) batteries, and this can be addressed by constructing highly exposed catalytic active sites. Herein, a feather-like interlayer material featured with highly exposed active sites is prepared by combining electrospinning technology and chemical vapor deposition. In the interlayer design, the growth of carbon nanotubes (CNTs) on the nitrogen-doped carbon fiber (NCF) surface greatly exposes the active Co and N-dopant adsorption-catalytic sites and forms a feather-like Co/CNT@NCF composite. The feather-like structure design endows the interlayer with good blockage effect for LiPSs shuttling. Meanwhile, the abundant active catalytic sites can effectively promote the conversion of polysulfides, and thus further suppress the shuttle of LiPSs. The cell with Co/CNT@NCF interlayer achieves excellent discharge performance (901.5 mAh g−1) with low capacity decay (0.025% per cycle) after 500 cycles at 1 C. Moreover, the cell exhibits a discharge capacity of 809 mAh g−1 at 5 C and an areal capacity of 5.05 mAh cm−2 under a sulfur loading of 6.9 mg cm−2. This work offers a facile interlayer design from the perspective of high active sites exposure in Li-S cells.

Nitrogen doped carbon fiber supported nickel phosphide for efficient electrocatalytic overall urea splitting

Urea oxidation reaction (UOR) is expected to be one of the effective means to replace oxygen evolution reaction (OER) in specific urea-containing wastewater treatment field. The synchronization of urea electrooxidation and hydrogen production has become an increasingly attractive energy development way. However, UOR faces the challenges of relatively sluggish kinetics and catalyst activity degradation. Here, nitrogen-doped carbon fiber supported nickel phosphide (Ni5P4/NCF-400) is developed as a bifunctional self-supporting electrocatalyst, which is synthesized by electrodeposition and high temperature nitriding. The HER overpotential of Ni5P4/NCF-400 in alkaline medium is 77 mV at 10 mA cm−2, the Tafel value is 98.04 mV dec-1, and the activity does not decrease significantly after continuous hydrogen evolution for 24 h. The UOR potential is 1.376 V at 100 mA cm−2, the Tafel value is 16.45 mV dec-1, and can steadily work at 1.38 V for 48 h. Moreover, Ni5P4/NCF-400 is assembled into a water-urea electrolytic cell device, which could achieve a current density of 40 mA cm−2 at a voltage of 1.67 V and achieve the stability of the catalytic system for 24 h. The excellent electrocatalytic performance of Ni5P4/NCF-400 is attributed to N doping and abundant active sites.

Nitrogen-doped hollow porous carbon fibers derived from polyacrylonitrile for Li-S batteries

Nitrogen-doped hollow porous carbon fibers derived from polyacrylonitrile for Li-S batteries