Nitrogen-doped Carbon Nanofibers Research Articles

Hollow nitrogen-doped carbon nanofibers filled with MnO2 nanoparticles/nanosheets as high-performance microwave absorbing materials

The nitrogen-doped carbon nanofiber absorber (MnO2@HNCFs) filled with MnO2 nanoparticles/nanosheets is constructed through layer-by-layer coating assisted by vacuum carbonization and etching. The MnO2 nanoparticles/nanosheets filled in the hollow carbon fibers make the material exhibit a hierarchical porous structure, and reduce the density of the material as well. MnO2@HNCFs show excellent microwave absorbing properties, with a minimum reflection loss (RLmin) of −48.87 dB@14.9 GHz at a low loading of 10%, and the thickness is 2.5 mm. The corresponding effective absorption bandwidth (EAB) is 6.2 GHz, covering the entire Ku-band. When the thickness is adjusted to 2.8 mm, the EAB is up to 7.8 GHz and the RLmin is −32.17 dB. The EAB is 5.7 GHz at 3.4 mm, covering the X-band, and the RLmin is −30.62 dB. Through the comparison of the absorbing properties of materials, it is proved that the construction of porous structures can effectively enhance the absorbing properties, which provides a solid argument for the claim that multiple reflection can enhance the electromagnetic wave loss. This work is of great significance to the construction of porous structure microwave absorbing materials, and provides a new idea for the design of lightweight microwave absorbing materials.

Synergistic Effect of WN/Mo2C Embedded in Bioderived Carbon Nanofibers: A Rational Design of a Shuttle Inhibitor and an Electrocatalyst for Lithium-Sulfur Batteries.

To improve the innate shuttle effect and the sluggish redox kinetics of lithium-sulfur batteries, a composite made of a bimetallic compound embedded in nitrogen-doped carbon nanofibers (CNFs) is synthesized by employing biomass collagen fibers (CFs) as a structure template. Metal anions WO42- and MoO42- are grafted on plant polyphenol-modified CFs and then in situ converted into WN/Mo2C implanted in a matrix of CNFs (WMCNFs). The obtained WN/Mo2C is of quantum size and uniform distribution, exposing the active sites maximally. Further, the heterostructure of the bimetallic composite enables unique electronic interaction, thereby synergistically enhancing its adsorption capability toward soluble intermediates and activating its catalytic function for liquid-liquid and liquid-solid conversions. Combining these merits, when used as a separator modification material and a sulfur host simultaneously, the WMCNFs composite exhibits remarkable cycling stability with 91.45% capacity retention after 500 cycles at 2 C and also prominent rate performance of delivering 552.75 mAh g-1 at a current rate of 10 C. Meanwhile, the stable luminescence operation of LED lights powered by the assembled pouch cell demonstrates the application potential of this biomaterial-derived composite.

Self-supporting nitrogen-doped reduced graphene oxide@carbon nanofiber hybrid membranes as high-performance integrated air cathodes in microbial fuel cells

The traditional air cathode in microbial fuel cell (MFC) usually consists of catalyst layer (CL), supporting layer (SL) and conductive gas diffusion layer (GDL), the overall MFC performance is inevitably affected by the additional and expensive adhesives and conductive agents. Here, we developed an integrated air cathode in MFC without any additional SL, GDL or adhesives. The integrated air cathode was self-supporting nitrogen-doped reduced graphene oxide@carbon nanofiber (N-rGO@CNF) hybrid membranes fabricated by electrospinning with subsequent heat-treatment under ammonia atmosphere. The as-fabricated N-rGO@CNFs possessed far superior MFC performance and oxygen reduction reaction (ORR) activity to the pristine nitrogen-doped carbon nanofibers (NCNF) and commercial activated carbon (CAC). The amount of rGO embedded into CNF had prominent influence on their ORR activities and MFC performances. N-5-rGO@CNF had the lowest resistance and the maximal exchange current density, exhibiting desirable oxygen reduction performance via a four-electron pathway. The maximum power density of N-5-rGO@CNF can reach 826 mW m−2 in MFC, which is approximately 9, 2.53 and 1.82 times of pristine NCNF, CAC and Pt/C with values of 91, 327 and 454 mW m−2. The outstanding performance of the integrated air-cathodes originates from the integrality, brevity and hybrid composition of the electrospun nanofiber membrane. The appropriate embedded rGO not only improves the bulk conductivity of the rGO@CNF to promote ion adsorption, but also provides vacancies to accommodate ions, the doped nitrogen atoms facilitate O2 adsorption and/or subsequent O–O bond breaking, thus improving the electrochemical performance of N-rGO@CNF in MFC.

Multifunctional quasi-solid-state zinc-ion hybrid supercapacitors beyond state-of-the-art structural energy storage

Structural energy storage devices offer both electrochemical and mechanical performance in a single multifunctional platform, making them promising for weight- and/or volume-restricted applications such as electric vehicles, aircraft, and satellites. However, the development of state-of-the-art multifunctional energy storage is predominately hindered by poor energy density. Other parameters that influence the mechanical and electrochemical properties are also neglected, such as temperature, safety, etc. Herein, we assembled the first freeze-resistant, multifunctional quasi-solid-state zinc-ion hybrid supercapacitor (ZIHSC) using mechanically-strong hot-drawn, highly-porous nitrogen-doped carbon nanofibers as the load-bearing cathode and zinc foil as a paintable, malleable, low cost, highly safe, and robust anode. Considering the novel “two-birds-one-stone” strategy, the as-prepared multifunctional ZIHSCs outperform state-of-the-art structural energy storage devices in terms of a combination of energy storage and load-bearing capability. The structural ZIHSCs offer a battery-level gravimetric energy density of 113.1 Wh/kg, areal energy density of 300.0 μWh/cm2, strength of 308 MPa, Young's modulus of 14.40 GPa, toughness of 1.82 MJ/m3, and cycling stability over 7500 cycles. In addition, multifunctional ZIHSCs offer outstanding electrochemical and mechanical performance under a wide range of temperatures from cryogenic (−25 °C) to ambient (+25 °C) conditions.

Rationally designed hierarchical tree-like Fe-Co-P@Ni(OH)2 hybrid nanoarrays for high energy density asymmetric supercapacitors

Transition metal phosphides (TMPs) are regarded as promising materials for supercapacitors (SCs) owing to their excellent redox activity and electrical conductivity. However, their inferior rate performance and poor long-term cycling stability hinder their real-world applications. Engineering nanostructured multicomponent TM-based hybrid materials with rational core@shell architectures is a promising approach to prepare advanced electrodes for SCs. Herein, hierarchical Fe-Co-P@Ni(OH)2 core@shell nanoarrays assembled from needle-type Fe-Co-P nanoarrays and ultrathin Ni(OH)2 nanosheets have been grown vertically on Ni-foam via a successive hydrothermal reaction, phosphorization, and chemical bath deposition method. The as-fabricated Fe-Co-P@Ni(OH)2 electrode exhibits an ultra-high specific capacity of 380.61 mA h g−1 at 5 mA cm−2, high rate capability (61% at 50 mA cm−2) and retains 90% of its capacity after 5000 galvanostatic charge/discharge cycles. Moreover, an asymmetric supercapacitor device was assembled by integrating Fe-Co-P@Ni(OH)2 (positive) and polyacrylonitrile-derived nitrogen doped carbon nanofiber (negative) electrodes, which delivers a high energy density of 65.09 W h kg−1 at a power density of 530.06 W kg−1, outstanding rate capability (54% at 80 mA cm−2), and excellent cycling performance.

Nitrogen-doped carbon nanofibers derived from phenolic-resin-based analogues for high-performance lithium-ion batteries

The preparation of one-dimensional (1-D) carbon nanofibers (CNFs) for lithium-ion battery (LIB) anode materials plays a crucial role in electrochemical energy storage, but it still remains a great challenge due to the limited synthesis methods. Herein, we use a facile strategy to prepare the nitrogen-doped porous CNFs with high aspect ratio by direct pyrolysis of their phenolic-resin-based precursors in ammonium atmosphere. The polymer precursors are synthesized via a hydrothermal approach and have very high carbon yield over 50% in mass. Benefited from the unique 1-D porous structure, high nitrogen content and good conductivity, the ammonium-treated N-doped porous CNFs demonstrate an outstanding electrochemical lithium storage performance. The as-prepared N-doped porous CNFs demonstrates a high irreversible capacity of 325.2 mA h g−1 at 1000 mA g−1 together with an excellent long cycling performance (485.1 mA h g−1 at 500 mA g−1) after 500 cycles. This work offers a facile preparation strategy of the N-doped porous CNFs for high-efficiency energy storage electrode materials.

Valence Engineering of Polyvalent Cobalt Encapsulated in a Carbon Nanofiber as an Efficient Trifunctional Electrocatalyst for the Zn-Air Battery and Overall Water Splitting.

The rapid development of electrochemical power systems has prompted high demand for nonprecious trifunctional electrocatalysts with superior performance, prolonged stability, and low cost for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Here, a valence engineering strategy is devised to construct a morphology with polyvalent cobalt encapsulated in nitrogen-doped carbon nanofibers (Co/N-CNFs). The diverse cobalt valence states of the Co/N-CNF catalysts contribute to their excellent catalytic effect and high durability in multiple electrochemical processes. The optimal Co/N-CNF catalyst fabricated exhibits a high half-wave potential of ORR (0.86 V) and low overpotentials of OER (380 mV) and HER (241 mV) at 10 mA cm-2. The Co/N-CNF-based Zn-air battery possesses a high charge-discharge efficiency as well as a good cycle stability (50 h at 10 mA cm-2 and 120 h at 20 mA cm-2), much superior to the Pt/C-based batteries. Furthermore, the Co/N-CNF catalyst could perform efficient overall water splitting.

Heterostructural Snse/Snte Ultrasmall Nanoparticles Embedded in Nitrogen-Doped Carbon Nanofibers (Snse/Snte@N-Cnfs) for High Performance Sodium-Ion Batteries

Heterostructural Snse/Snte Ultrasmall Nanoparticles Embedded in Nitrogen-Doped Carbon Nanofibers (Snse/Snte@N-Cnfs) for High Performance Sodium-Ion Batteries

Nitrogen-Doped Porous Carbon Nanofiber Decorated with Feni Alloy for Dendrite-Free High-Performance Lithium Metal Anode

Nitrogen-Doped Porous Carbon Nanofiber Decorated with Feni Alloy for Dendrite-Free High-Performance Lithium Metal Anode

Efficient ambient ammonia synthesis by Lewis acid pair over cobalt single atom catalyst with suppressed proton reduction

A Lewis acid pair over a single Co atom anchored on sponge-like nitrogen-doped mesoporous hollow carbon nanofibers was designed. The catalyst exhibits an NH3 production rate of 67.6 μg h−1 mg−1 and a maximum Faraday efficiency of 56.9% at a peak potential of −0.1 V vs. RHE.

FeCoS2 polyhedral spherical nanoparticle decorated nitrogen doped hollow carbon nanofibers as high-performance self-supporting anodes for K-ion storage.

Herein, we present a freestanding and flexible 3D nanocomposite made of polyhedral spherical FeCoS2 and nitrogen-doped hollow carbon nanofibers (FeCoS2@N-HCNFs) that is synthesized through coaxial electrospinning, high-temperature calcination, and a facile solvothermal process. As a binder-free anode composite for potassium-ion batteries (PIBs), FeCoS2@N-HCNF presents a high specific discharge capacity on the first lap (701.2 mA h g-1 at 100 mA g-1) and superior cycling stability (132.6 mA h g-1 at 3200 mA g-1 after 600 cycles). The impressive electrochemical performance can be ascribed to the unique 3D structure, such as the enormous specific surface area of the mesoporous structure beneficial for K+ transfer, the three-dimensional hollow carbon nanofiber scaffold enhances the structural stability, and polyhedral spherical FeCoS2 improves the overall specific capacity. According to the above description, the FeCoS2@N-HCNF anode is a promising candidate for advanced potassium-ion batteries.

Enhanced stability of nitrogen doped porous carbon fiber on cathode materials for high performance lithium-sulfur batteries.

Lithium–sulfur (Li–S) batteries are considered to be one of the candidates for high-energy density storage systems due to their ultra-high theoretical specific capacity of 1675 mA h g−1. However, problems of rapid capacity decay, sharp expansion in volume of the active material, and the shuttle effect have severely restricted their subsequent development and utilization. Herein, we design a nitrogen-doped porous carbon nanofiber (NPCNF) network as a sulfur host by the template method. The NPCNF shows a feather-like structure. After loading sulfur, the NPCNF/S composite can maintain a hierarchically porous structure. A high discharge capacity of 1301 mA h g−1 is delivered for the NPCNT/S composite at 0.1C. The reversible charge/discharge capacity at 2C is 576 mA h g−1, and 700 mA h g−1 is maintained after 500 cycles at 0.5C. The high electrochemical performance of this NPCNT/S composite is attributed to the synergy effects of abundant N active sites and high electrical conductivity of the material.

Metal-Free Nitrogen-Doped Porous Carbon Nanofiber Catalyst for Solar-Fenton-Like System: Efficient, Reusable and Active Catalyst Over a Wide Range of Ph

Metal-Free Nitrogen-Doped Porous Carbon Nanofiber Catalyst for Solar-Fenton-Like System: Efficient, Reusable and Active Catalyst Over a Wide Range of Ph

Nitrogen-Doped Porous Carbon Nanofiber Decorated with Feni Alloy for Dendrite-Free High-Performance Lithium Metal Anode

Nitrogen-Doped Porous Carbon Nanofiber Decorated with Feni Alloy for Dendrite-Free High-Performance Lithium Metal Anode

Construction of Cos-Encapsulated in Ultrahigh Nitrogen Doped Carbon Nanofibers from Energetic Metal-Organic Frameworks for Superior Sodium Storage

Construction of Cos-Encapsulated in Ultrahigh Nitrogen Doped Carbon Nanofibers from Energetic Metal-Organic Frameworks for Superior Sodium Storage

WITHDRAWN: Petal-like NiCoP sheets on 3D nitrogen-doped carbon nanofiber network as a robust bifunctional electrocatalyst for water splitting

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal

Synthesis of MnO–Sn cubes embedding in nitrogen-doped carbon nanofibers with high lithium-ion storage performance

In this paper, a carbon nanofiber (CNF) hybrid nanomaterial composed of MnO–Sn cubes embedding in nitrogen-doped CNF (MnO–Sn@CNF) is synthesized through electrospinning and post-thermal reduction processes. It exhibits good electrochemical lithium-ion storage performance as the anode, such as high reversible capacity, outstanding cycle performance (754 mAh g−1 at 1 A g−1 after 1000 cycles), and good rate capability (447 mAh g−1 at 5 A g−1). The excellent electrochemical properties are derived from a unique nanostructure design. MnO–Sn@CNF has a three-dimensional conductive network with a stable core–shell structure, which improves the electrical conductivity and mechanical stability of the materials. In addition, the mesopores on the surface of carbon fibers can shorten the diffusion distance of lithium ions and promote the combination of active sites of the material with lithium ions. The internal MnO and Sn form a heterostructure, which enhances the stability of the physical structure of the electrode material. This material design method provides a reference strategy for the development of high-performance lithium-ion batteries anode.

Microbial synthesis of efficient palladium electrocatalyst with high loadings for oxygen reduction reaction in acidic medium

Whereas limited amount of precious metal adsorbed by bacteria conflicting the needs of high loadings for better catalytic performances, cell disruption technology was adopted to smash Shewanella cells in this work, releasing abundant oxygen functional groups inside the cells for better adsorption of palladium ion. Then palladium catalysts were synthesized in two ways: 1) Pd catalyst supported on carbonized-broken-bacterial (Pd/FHNC) was obtained after direct carbonization and reduction; 2) Electrospinning technology was used to spin the broken Shewanella into fibers, and Pd nanoparticles supported on nitrogen-doped carbon nanofiber (Pd/NCNF) was prepared following carbonization and hydrogen reduction. The as-prepared catalysts exhibit excellent oxygen reduction reaction (ORR) electrocatalytic performance in the acid medium. The mass specific activities at 0.7 V of Pd/FHNC and Pd/NCNF were 0.213 A mg−1 and 0.121 A mg−1 which were 5.92 and 3.36 times than those of commercial Pd/C(0.036 A mg−1) respectively, and they also displayed higher stability than Pd/C. Furthermore, the Pd loadings of Pd/FHNC and Pd/NCNF were 21.52% and 17.13% respectively. An explanation for the improved performance is the co-doping of nitrogen and phosphorus, also the tight integration of Pd and broken-bacterial. Herein, we propose a novel and effective method for synthesis of ORR electrocatalysts.

Rationalization on high-loading iron and cobalt dual metal single atoms and mechanistic insight into the oxygen reduction reaction

Rational design of single-atom catalysts (SACs) with high metal loadings is essential to enhance the sluggish kinetics of oxygen reduction reactions in metal-air batteries and proton-exchange membrane fuel cells (PEMFCs). Herein, an effective plasma engineering strategy to construct Fe/Co dual single atoms densely dispersed on porous nitrogen-doped carbon nanofibers (Fe, Co SAs-PNCF) with a high mass loading of 9.8 wt% is proposed without any acid leaching. The electrocatalyst exhibits superior ORR performances in both alkaline and acidic media (e.g., Eonset = 1.04 V and E1/2 = 0.93 V). The N3-Fe-Co-N3 moieties are identified to be the main active sites by X-ray absorption spectroscopy (XAS) and density functional theory calculations. The in situ XAS and Raman spectroscopy quantitively reveal the decrease in oxidation states of Fe/Co and the increase in bond lengths of the Fe-N/Co-N in the N3-Fe-Co-N3 during the ORR. Benefitting from the high loading of single atoms and enhanced activity, the Fe, Co SAs-PNCF endows the Al-air batteries and PEMFCs with excellent discharge performances, demonstrating promising practical applications.

Nanoscale CuFe2O4 Uniformly Decorated on Nitrogen‐Doped Carbon Nanofibers as Highly Efficient Catalysts for Polysulfide Conversion in Lithium‐Sulfur Batteries

AbstractLithium‐sulfur (Li−S) batteries have been considered one of the most promising energy storage systems, owing to the theoretical specific capacity (1675 mAh g−1) and energy density (2600 Wh g−1). However, it is challenging to solve the shuttling and low reduction kinetics of lithium polysulfides. Hence, the combination of electrospun and hydrothermal treatments acts as an effective strategy to synthesize copper ferrite nanoparticles decorated on nitrogen doped carbon nanofibers (CF/NC). The resultant material is employed as a positive current collector containing Li2S6 catholyte for Li−S batteries. The addition of CF nanoparticles plays a vital role in capturing polysulfides in both physical and chemical adsorption. Besides, promoted sulfur conversion kinetics are obtained due to the excellent catalytic effect, which enabled significantly improved sulfur utilization, high‐rate capability, and cycling stability. Under a 5.75 mg sulfur loading, the cell with CF/NC delivers an excellent cycling stability with 609 mAh g−1 after 300 cycles at 0.2 C. Even at 12.15 mg high sulfur loading, the high initial capacity of the cell is 9.4 mAh at 0.1 C.