N-doped Carbon Nanofibers Research Articles

Incorporation of Fe/FeOx Nanoparticles into Interlinked N-Doped Porous Carbon Nanofiber Networks to Realizing Sequential Catalytic Conversion of Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries (LSBs) with energy density (2600 Wh/kg) much higher than typical Li-ion batteries (150-300 Wh/kg) have received considerable attention. However, the insulation nature of solid sulfur species and the high activation barrier of lithium polysulfides (LiPSs) lead to slow sulfur redox kinetics. By the introduction of catalytic materials, the effective adsorption of LiPSs, and significantly reduced conversion, energy barriers are expected to be achieved, thereby sharpening electrochemical reaction kinetics and fundamentally addressing these challenges. In this work, a multifunctional catalyst consisting of highly dispersed heterostructure Fe-Fe2O3 nanoparticles was synthesized and introduced to the LSB. Experimental and theoretical analyses revealed that the spontaneous interfacial charge redistribution, resulting in moderate polysulfide adsorption, facilitates the transfer of polysulfides and diffusion of electrons at heterogeneous interfaces. This catalyst achieves sequential catalytic processes on polysulfides with different components. Furthermore, the reduced conversion energy barriers enhanced the catalytic activity of Fe/Fe2O3-NG for expediting LiPS conversion. Consequently, the battery exhibited long-term stability for 300 cycles with 0.03% capacity decay per cycle at 5C. This work provides in-depth insight into the fundamental design principles of effective catalysts for LSBs.

Fast kinetics for lithium storage rendered by Li3VO4 nanoparticles/porous N-doped carbon nanofibers

Li3VO4 (LVO) has been recognized as an alternative anode material for lithium-ion batteries (LIBs) because of its appropriate lithium storage potential and capacity merits. However, its practical application is seriously hindered by slow reaction kinetics stemming from poor electronic conductivity. Herein, Li3VO4/porous N-doped carbon nanofibers (LVO/PNC NFs) are firstly designed and fabricated via an electrospinning method, utilizing the thermal decomposition characteristics of polylactic acid (PLA). The porous N-doped carbon nanofibers provide efficient electrolyte diffusion paths and facilitate ion transport. In addition, LVO nanoparticles are uniformly dispersed along the nanofibers to effectively inhibit particle aggregation. The obtained LVO/PNC NFs are evaluated as anodes for LIBs and deliver high reversible capacity of 768 mAh g−1 after 300 cycles at 0.2 A g−1, along with excellent rate capability (average capacity of 355 mAh g−1 at 8 A g−1 after 6 periodic rate testing) and long cycling life (286 mAh g−1 after 2000 cycles at 4 A g−1). The special porous nanofiber represents an effective strategy for improving the electronic conductivity, inhibiting particle aggregation, and ensuring rapid ion/charge transport towards advanced energy storage technologies.

N-doped porous carbon nanofibers with high specific capacitance and energy density for Zn-ion hybrid supercapacitors

N-doped porous carbon nanofibers have shown a wide application prospect for Zn-ion hybrid supercapacitors (ZHSs), but so far, the affordable synthesis remains a daunting challenge. Using the exfoliated silk nanofibrils (SNFs) as carbon and nitrogen sources, NaCl/KCl as carbonization medium and KOH as active agent, herein, a new variety of N-doped porous carbon nanofibers, SPCN-x, is prepared, involved a sequential ‘SNFs exfoliation’ and ‘mixture pyrolysis’. Results confirm that, with the activation of KOH, porosity structure and specific surface area of the nano-fibriform products are clearly enriched, thus forming a hierarchically porous structure. Typically, SPCN-10 shows a N doping content of 5.6 wt%, pore volume of 0.33 cm3 g−1 and specific surface area of 645 m2 g−1, and presents a great energy storage property as cathode for ZHSs, such as energy density of 70.4 Wh kg−1 and specific capacitance of 197.9 F g−1. Besides, it has excellent durability with a capacitance retention rate of 90.2 % after 10,000 cycles. The electrochemical behavior of SPCN-10 is better than numerous reported ZHS cathodes, which not only highlights our ingenious synthesis, but also ensures a huge potential in large-scale practical application.

Layered double hydroxides-derived CoNi alloy nanoparticles encapsulated by porous N-doped carbon nanofibers as efficient methanol electrocatalysts for alkaline direct methanol fuel cells

The exploration of inexpensive electrocatalysts possessing high activity and increased stability to replace precious metal catalysts in the methanol oxidation reaction (MOR) is highly desirable for alkaline direct methanol fuel cells (ADMFCs). This study presents a novel approach to synthesize layered double hydroxides (LDHs)-derived CoNi alloy nanoparticles confined within porous N-doped carbon nanofibers (CoNi@NCNFs) via facile electrospinning and pyrolysis for methanol electrooxidation.The one-dimensional N-doped carbon nanofibers could effectively prevent nanoparticle agglomeration during the pyrolysis of LDH precursors. The optimized CoNi@NCNF3-900 composite exhibits exceptional catalytic activity (80.3mAcm−2) for MOR in alkaline solution, attributed to its hierarchical porous structure, high surface area, and abundant accessible active sites. Furthermore, the catalyst demonstrates competitive electrocatalytic stability, retaining over 90% of its initial current density after 1000 consecutive cyclic voltammetry (CV) cycles. Notably, a single-cell ADMFC assembled with CoNi@NCNF3-900 as the anode catalyst achieves a promising maximum power density of 29.5mWcm−2, highlighting the potential of CoNi@NCNF3-900 for application in DMFC technology and clean energy sources.

Redox Activity of Co Species in the Active Sites of CoNx/CoOx Facilitates Oxygen Electrocatalysis for Zn-Air Batteries.

Developing efficient bifunctional oxygen electrocatalysts is crucial for enhancing the performance of rechargeable Zn-air batteries (ZABs). In this study, cobalt/cobalt oxides embedded in N-doped carbon nanofibers (Co/CoOx/NCNFs) were synthesized through a combination of electrospinning and annealing processes. The resulting Co/CoOx/NCNFs catalysts feature abundant CoNx and CoOx active species, leveraging the large specific surface area of nanofibers to facilitate oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The optimized Co/CoOx/NCNFs-0.1 achieved a half-wave potential (vs. RHE) of 0.82 V and required only 429 mV to reach 10 mA cm-2 in a typical three-electrode system with 0.1 M KOH using an electrochemical workstation equipped with a pine instruments rotator, outperforming the Pt/C+RuO2. The assembled ZABs exhibited high specific capacity (771 mAh gZn -1), substantial power density (981.6 mWh gZn -1), and long-term stability (>325 h). In situ Raman spectroscopy confirmed that the electrocatalytic processes involve the redox activity of Co (II and III) species derived from abundant CoNx and CoOx, elaborating the origin of the catalysts' exceptional oxygen electrocatalysis performance. This work not only presents a straightforward and effective approach for producing bifunctional oxygen electrocatalysts in ZABs but also sheds light on the catalytic mechanisms underlying ORR and OER for CoNx/CoOx-based oxygen electrocatalysts.

Efficient solid-phase RNA extraction using carbon nanomaterials

Recent research highlights RNA’s therapeutic potential in nucleic acid-based therapies. However, effective RNA recovery and purification remain challenging due to similar impurities affecting therapeutic outcomes. Traditional RNA isolation methods are often slow, inefficient, and involve toxic reagents. Carbon-based materials offer a promising alternative as adsorbents for nucleic acids due to their excellent mechanical and chemical properties. This study describes an efficient, simple, and cost-effective method for RNA recovery from complex Escherichia coli extracts using carbon materials with different structures and surface modifications. RNA adsorption and desorption screening experiments were performed using different carbon materials. N-doped CNTs (CNT-N-ox) and carbon nanofibers (CNF-ox), both oxidized with HNO3, showed RNA adsorption capacities of 42 % and 55 %, respectively, also allowing effective RNA desorption (81 % and 72 %, respectively). Additionally, the materials demonstrated reusability, maintaining RNA adsorption capacity over four cycles. The selectivity of the materials enabled a simple method to recover RNA free from DNA contamination by performing three consecutive cycles. Moreover, no contaminating protein was found in the recovered sample. The analysis by circular dichroism also revealed that RNA maintained its integrity and stability when recovered from these materials. Overall, the study demonstrates the potential of carbon materials for efficient RNA capture and pre-purification.

Two birds with one stone: Bimetallic ZnCo2S4 polyhedral nanoparticles decorated porous N-doped carbon nanofiber membranes for free-standing flexible anodes and microwave absorption

Cost-efficient material with an ingenious design is important in the engineering applications of flexible energy storage and electromagnetic (EM) protection. In this study, bimetallic ZnCo2S4 (ZCS) polyhedral nanoparticles homogenously embedded in the surface of porous N-doped carbon nanofiber membranes (ZCS@PCNFM) have been fabricated by electrospinning technique combined with carbonization and hydrothermal processes. As a self-assembled electrode for lithium-ion batteries (LIBs), the bimetallic ZCS nanoparticles possess rich redox reactions, good electrical conductivity, and pseudocapacitive properties, while the three-dimensional (3D) multiaperture architecture of the nanofiber film not only shortens the transfer spacing of lithium ions and electrons but also effectively tolerates the volume variation during lithiation and delithiation cycles. Benefiting from the above merits, the ZCS@PCNFM electrode exhibits good cycle performance (662.3 mA h/g at 100 mA/g after 100 cycles), superior rate capacity (401.3 mA h/g at 1 A/g) and an extremely high initial specific capacity of 1152.2 mAh/g at 100 mA/g. Meanwhile, depending on the hierarchical nanostructure and multi-component heterogeneous interface effects constructed by 3D inlaid architecture, the ZCS@PCNFM nanocomposite exhibits fascinating microwave absorption (MA) characteristics with a superhigh reflection loss (RL) of –49.7 dB at a filling content of only 20 wt% and corresponding effective absorption bandwidth (EAB, RL<–10 dB) of 5.2 GHz ranging from 12.8 to 18.0 GHz at 2.2 mm.

Homogeneous Deposition of Zinc on N-Doped Carbon Fibers Interconnected with Sn Nanoparticles for Advanced Aqueous Zinc Batteries.

Currently, inhomogeneous distribution of Zn2+ on the surface of the Zn anode is still the essential reason for dendrite formation and unsatisfactory stability of zinc ion batteries. Given the merits of strong interaction between Sn and Zn, as well as a low nucleation barrier during Zn deposition, the combination of metallic Sn with carbon material is expected to improve the deposition of zinc ions and inhibit the growth of zinc dendrites by guiding the homogeneous plating/stripping of zinc on the electrode surface. In this article, zincophilic Sn nanoparticles with low nucleation barriers and strong interaction with Zn2+ were embedded into 3D N-doped carbon nanofibers using a simple electrostatic spinning technique. Accordingly, when serving as an artificial coating layer for the zinc metal anode, an ultrastable Sn@NCNFs@Zn||Sn@NCNFs@Zn symmetric cell can be achieved for over 3500 h with a low nucleation overpotential of 29.1 mV. Significantly, the full cell device assembled with the as-prepared anode and MnO2 cathode exhibits desirable electrochemical behaviors. Moreover, this simple method could be extended to other metal-carbon composites, and to ensure ease in scaling up as required. Such significant approach can provide an effective strategy for the design of high-performance zinc anodes.

Unraveling a High-Performance Self-Supported Flexible Zinc-Ion Battery Cathode with Tailored Electrospun MnOx/N-Doped Carbon Nanofibers

Unraveling a High-Performance Self-Supported Flexible Zinc-Ion Battery Cathode with Tailored Electrospun MnO_<i>x</i>/N-Doped Carbon Nanofibers

Ni/Ni4N nanoparticles anchored on 3D necklace-like carbon framework as free-standing bifunctional host for practical Li-S full cells

Inhibiting the shuttle effect, accelerating sulfur redox kinetics and controlling lithium homogeneous deposition are significant to achieve the flexible lithium-sulfur (Li-S) cells with high energy density and safety. In this study, we successfully synthesized a three-dimensional (3D) free-standing necklace-like fabric consisting of heterostructured Ni/Ni4N nanoparticles confined into hollow carbon cages implanted with N-doped carbon nanofibers (Ni/Ni4N@NCC). This unique 3D necklace-like framework and interface electronic structure of Ni/Ni4N@NCC could effectively addresses the challenges associated with both sulfur cathode and lithium anode in Li-S cells. Combine with experimental tests and DFT simulations, Ni/Ni4N@NCC not only strengthened chemical anchoring and accelerated lithium polysulfides conversion, but also induced Li uniform deposition and growth due to its excellent lithiophilicity and low Li diffusion energy barrier. For the anode, the lithium foil coating with Ni/Ni4N@NCC interlayer (denoted as Li-Ni/Ni4N@NCC anode) showed exceptional long-term cycling stability over 1000 h at the high current density of 5 mA cm−2 for high areal capacity of 5 mAh cm−2. The S-Ni/Ni4N@NCC||Li-Ni/Ni4N@NCC cell with sulfur loading (6.8mg cm−2) exhibited high areal capacities of 6.11 mAh cm−2. The synergetic effect of fascinating necklace-like structure and heterogeneous interface offer instruction for the practically viable design of high-performance flexible Li-S full cells.

Electrospun MOF-derived N-doped mesoporous carbon fibers embedded with ultrafine vanadium oxide as an ultralong cycling stability for potassium ion storage

Potassium-ion batteries (KIBs) are promising options for large-scale energy storage because of their low cost and low redox potential. The use of anodes with porous structures is an attractive strategy to improve the electrochemical properties of KIBs. However, the development of KIB anodes has been hindered by their low capacity and difficulty in synthesizing porous structures. Herein, ultrafine vanadium oxide nanoparticles embedded in porous N-doped carbon nanofibers (VO@PNCNFs) using electrospinning and one-step heat treatment are reported. The uniform growth of vanadium oxide crystals is facilitated by the porous structure of the carbon nanofiber. The numerous pores play a crucial role in the transfer of electrons and ions and provide structural stability to the N-doped carbon matrix. As a result, the VO@PNCNF electrode demonstrates a high reversible capacity (∼205 mA h g−1 at 1.0 A g−1), good cycle stability over 3000 cycles, and excellent rate performance (95 mA h g−1 at 3.0 A g−1).

Multifunctional Film Assembled from N-Doped Carbon Nanofiber with Co–N4–O Single Atoms for Highly Efficient Electromagnetic Energy Attenuation

HighlightsAsymmetrically coordinated Co–N4–O sites on N-doped carbon nanofiber were prepared.Co–O coordination along the axial direction led to enhanced dielectric polarization loss.Multifunctional films were developed for practical application in harsh environments.

Constructing heterojunction on N-doped porous carbon nanofibers for Li-S batteries: Effect of built-in electric field on efficient catalytic transformation kinetics

In this study, the CoP-Co2P heterojunction nanoparticles embedded in N-doping porous carbon nanofibers (CoP-Co2P/NPCNFs) are designed and prepared. The highly conductive grid of NPCNFs can physically confining lithium polysulfide (LiPS) and provide facilitated channels for Li+ transport. Furthermore, due to the spontaneous built-in electric field (BIEF) based on at the formed heterogeneous interfaces of CoP-Co2P, the heterojunction can significantly catalyze bi-directional conversion of LiPS and chemically adsorb LiPS which confirmed by the DFT calculations, suppressing the “shuttle effect” of LiPS. Thus, the Li-S batteries with the CoP-Co2P/NPCNFs modified separators exhibit a high initial specific capacity of 1322.86 mAh g−1 at 1 mA cm−2 and stable 695 cycles with a low decay rate (0.069 %). More importantly, the assembled pouch cell also can run with ultra-low specific capacity decay rate. Additionally, the pouch battery can also be applied to the operation of fans, temperature and humidity meters, mobile phone charging, etc.

Non-preoxidation synthesis of MXene integrated flexible carbon film for supercapacitors

Although the flexible carbon film integrated with MXene has been proven to be a new generation of supercapacitor material with good energy storage prospects, the MXene oxidation and the lack of active sites during the preparation of the carbon film can lead to irreversible capacity loss. Herein, a flexible carbon film constructed by MXene-integrated N-doped cavity-interconnected porous carbon nanofibers was prepared by a non-pre-oxidation synthesis strategy combining electrospinning and metal–organic framework derivatization. This flexible carbon film overcomes the oxidation problem of MXene during the stabilization of polyacrylonitrile, and the derived porous structure of cavity interconnection exposes more active sites. Due to its unique structural characteristics and ideal chemical composition, this independent flexible carbon film exhibits significantly enhanced electrochemical performance as an electrode material for supercapacitors. It exhibits an energy density of 26.2 Wh kg−1 at a power density of 500 W kg−1, and a capacitance retention rate of 96.3 % after 10,000 charge–discharge cycles. This study provides a unique strategy for the preparation of high-performance flexible carbon films, and this technology can also be extended to other integrated CNF composites for the design of high-performance supercapacitor electrodes.

Cu-based active sites supported on nitrogen-rich polymer derived porous carbon fibers as an oxygen reduction electrocatalyst for zinc-air batteries

The rational design of electrocatalysts with highly exposed active sites and maximized active sites utilization is challenging and urgent problem. Herein, a facile strategy is employed to fabricate Cu-based active sites anchored in nitrogen doped porous carbon nanofiber as an effective and enduring oxygen reduction reaction (ORR) electrocatalyst, which is achieved by the coordination-pyrolysis way of the pre-designed covalent organic polymer (COP) precursors with unique molecular structure. Meanwhile, COP-derived N-doped carbon nanofiber could provide porous structure and facilitate the rapid mass/electron transport, which can insure the strong fastness and high reaction activity of Cu-based active sites. The as-obtained catalyst (Cu0·4/NPC) displays excellent activity (E1/2 = 0.845 V) and stability for ORR performance. Remarkably, the Cu0·4/NPC as cathode catalyst assembled Zn-air battery achieves the peak power density of 142 mA cm−2 and a large specific capacity of 829 mA h g−1 at large current. Additionally, the Cu0·4/NPC catalyst assembled in the solid Zn-air battery achieves the peak power density of 157 mA cm−2. This work offers great opportunity to design advanced ORR catalysts with high density and maximum utilization of active sites.

Spontaneous built-in electric field in heterostructure electrocatalysts with high catalytic activity and conductivity: Inducing 3D nucleation of Li2S

Lithium-sulfur (Li-S) batteries have become a research focus due to their high theoretical specific capacity and energy density. The shuttle effect and slow sulfur conversion kinetics of lithium polysulfides (LiPSs) severely hindered their practical application. Here, a N-doped carbon nanofiber self-supporting electrode modified with cobalt selenide/nickel selenide as a sulfur carrier (CoSe2/NiSe2@NCNFs) is designed and constructed. The experimental results show that a built-in electric field is formed at the interface of CoSe2/NiSe2 Mott-Schottky heterostructure, which promotes the conversion of LiPSs and induces 3D nucleation of Li2S. Furthermore, the calculation results of density functional theory clearly reveal high conductivity, adsorption and interfacial charge transfer between CoSe2/NiSe2 Mott-Schottky heterostructure electrocatalyst and LiPSs. As a result, the CoSe2/NiSe2@NCNFs/S cathode shows a specific capacity of 1050.8 mAh g−1 at 1 C, and maintains excellent cycling performance with a discharge capacity of 735.1 mAh g−1 and a capacity decay of 0.003 % per cycle over 1000 cycles. This work designed a Mott-Schottky heterostructure electrocatalyst to strengthen the adsorption and conversion of LiPSs and induce 3D nucleation of Li2S, providing a new idea for high-performance Li-S batteries.

Well-dispersed Sb particles embedded on N-doped carbon nanofibers toward high-performance Li-ion battery

Well-dispersed Sb particles embedded on N-doped carbon nanofibers toward high-performance Li-ion battery

Revealing the Indispensable Role of In Situ Electrochemically Reconstructed Mn(II)/Mn(III) in Improving the Performance of Lithium-Carbon Dioxide Batteries.

Li-CO2 batteries are regarded as promising high-energy-density energy conversion and storage devices, but their practicability is severely hindered by the sluggish CO2 reduction/evolution reaction (CORR/COER) kinetics. Due to the various crystal structures and unique electronic configuration, Mn-based cathode catalysts have shown considerable competition to facilitate CORR/COER. However, the specific active sites and regulation principle of Mn-based catalysts remain ambiguous and limited. Herein, this work designs novel Mn dual-active sites (MOC) supported on N-doped carbon nanofibers and conduct a comprehensive investigation into the underlying relationship between different Mn active sites and their electrochemical performance in Li-CO2 batteries. Impressively, this work finds that owing to the in situ generation and stable existence of Mn(III), MOC undergoes obvious electrochemical reconstruction during battery cycling. Moreover, a series of characterizations and theoretical calculations demonstrate that the different electronic configurations and coordination environments of Mn(II) and Mn(III) are conducive to promoting CORR and COER, respectively. Benefiting from such a modulating behavior, the Li-CO2 batteries deliver a high full discharge capacity of 10.31 mAh cm-2, and ultra-long cycle life (327 cycles/1308h). This fundamental understanding of MOC reconstruction and the electrocatalytic mechanisms provides a new perspective for designing high-performance multivalent Mn-integrated hybrid catalysts for Li-CO2 batteries.

Achieving High-Rate and Stable Sodium-Ion Storage by Constructing Okra-Like NiS2/FeS2@Multichannel Carbon Nanofibers.

Transition metal sulfides (TMSs) are considered as promising anode materials for sodium-ion batteries (SIBs) due to their high theoretical capacities. However, the relatively low electrical conductivity, large volume variation, and easy aggregation/pulverization of active materials seriously hinder their practical application. Herein, okra-like NiS2/FeS2 particles encapsulated in multichannel N-doped carbon nanofibers (NiS2/FeS2@MCNFs) are fabricated by a coprecipitation, electrospinning, and carbonization/sulfurization strategy. The combined advantages arising from the hollow multichannel structure in carbon skeleton and heterogeneous NiS2/FeS2 particles with rich interfaces can provide facile ion/electron transfer paths, ensure boosted reaction kinetics, and help maintain the structural integrity, thereby resulting in a high reversible capacity (457 mA h g-1 at 1 A g-1), excellent rate performance (350 mA h g-1 at 5 A g-1), and outstanding long-term cycling stability (93.5% retention after 1100 cycles). This work provides a facile and efficient synthetic strategy to develop TMS-based heterostructured anode materials with high-rate and stable sodium storage properties.

Hierarchical porous N-doped carbon fibers enable ultrafast electron and ion transport for Zn-ion storage at high mass loadings

Zinc-ion capacitors (ZICs) are a promising and safe energy storage system for portable electronics but usually limited by relatively low areal capacity and energy density. Although increasing the mass loading has been suggested, thick electrode layers and clogged pores unavoidably lead to sluggish electron transport and ion diffusion as well as “dead volume” of active materials. Herein, a millimeter-scale 3D thick-network electrode, composed of closely intertwined hierarchical porous N-doped and free-standing carbon nanofibers (HPNCFs), was fabricated via carbonization of nanoscale zeolitic imidazolate framework (ZIF-8) particles embedded in electrospun polyacrylonitrile (PAN) nanofibers. With fast electron/ion transport, large ion-accessible surface area and high utilization rate of active materials, the mass loading of the HPNCFs electrode can reach 48.67 mg cm−2 with a thickness of 4.46 mm. Moreover, the HPNCFs-based ZICs can yield a superior areal/gravimetric capacity of 4.13 F cm−2 /280 F g−1, superior rate capability up to 193.7 F g−1 even at 100 A g−1, high energy density of 99.6 Wh kg−1, and long-term stability for 40,000 cycles. The straightforward approach can provide an opportunity to prepare efficient thick electrodes that could be applied in electrocatalysis, energy storage/conversion, and other electrochemical energy-related techniques.