Carbon Nanofiber Composites Research Articles (Page 1)

In this study, the structural and morphological changes of carbon composite nanofibers based on tin phosphide/phosphate were investigated depending on the synthesis conditions. The composites were obtained through electrospinning and two-step thermal treatment, comprised of pre-oxidation and carbonization, from a mixture of polyvinylpyrrolidone (PVP), tin chloride dihydrate (SnCl 2 ⋅2H 2 O), and phosphoric acid in ethanol: H 2 O solution. The physical-chemical properties of the resultant nanofibers were studied by X-Ray diffraction, scanning electron microscopy (SEM), and CHNS elemental analyzer. The mass ratio of SnCl 2 ⋅2H 2 O:PVP, the pre-oxidation temperature, and the annealing time determined the phase composition and morphology of the nanofibers. Samples annealed at 900°C for 10 min exhibited high crystallinity, the formation of the SnP phase, and phosphorus evaporation, which contributed to the development of a gradient structure. SEM results showed that the fiber diameter depended on the mass fraction of SnCl 2 ⋅2H 2 O. An increase in the pre-oxidation temperature led to carbon oxidation and the formation of an amorphous structure. Thus, by adjusting the annealing conditions, the structural properties of carbon composite nanofibers can be controlled. These materials have the potential to serve as promising anode materials for high-performance energy storage systems.

Herein, an advanced conductivity model for polymer-carbon nanofiber (CNF) samples is introduced, stated as PCNFs. This model considers the length (l), radius (R) and amount of CNFs, interphase depth, percolation onset (PT), waviness, network portion, and tunneling length (d), by reasonable and meaningful equations. The proposed model is verified through the measured conductivity of samples and by studying the features’ influences on the PCNF conductivity. The model calculations display respectable fitting with the experimented facts from numerous CNF samples. Additionally, all factors sensibly affect the conductivity of PCNFs. Longer and thinner CNFs, higher CNF amount, thicker interphase, shorter tunnels, and lower percolation onset lead to higher conductivity in PCNF. R > 50 nm and l < 15 μm produce an insulative composite, but the top conductivity of 0.21 S/m is displayed at R = 10 nm and l = 25 μm. Accordingly, narrower and bigger nanofibers can improve the conductivity. Furthermore, an insulative material is produced by PT = 0.04 nm and d > 5 nm, nevertheless the conductivity maximizes to 0.25 S/m at the least values of PT = 0.01 nm and d = 2 nm. These results disclose that the lowest percolation onset and narrowest tunnels yield the highest conductivity in the composite.

Variation of the general mixing rule to explore the interphase in the AC electrical conductivity of polypropylene melt-mixed with as-grown carbon nanofiber composites

Construction of RGO and Fe3O4-decorated carbon nanofibers composites for efficient electromagnetic wave absorption performance

Developing efficient Zn-air battery (ZAB) cathode catalysts is key to driving their commercialization process and tackling the pressing issues of environmental pollution and energy scarcity. Modulating the electronic structure and micronano configuration to expose more active sites is expected to boost the catalysts' electrochemical activity. Among different materials, one-dimensional (1D) carbon composite materials offer distinct advantages in electrocatalysis. Nevertheless, a common challenge is that conventional electrospinning synthesis often results in inaccessible metal active sites due to the rapid prototyping and solidification of the polymer slurry under an electric field. Herein, the polystyrene (PS)-induced electrospinning strategy is employed to fabricate porous composite carbon nanofibers (CoFePx/FeCo@PNCF) assisted by phosphating pyrolysis. This approach integrates polystyrene (PS) nanospheres as stents within the carbon nanofibers, thereby creating open channels and preventing the aggregation of nanoparticles, ensuring optimal functionality. The resulting CoFePx/FeCo@PNCF catalysts, which feature abundant pores near the metal nanoparticles, exhibit superior oxygen reduction reaction-oxygen evolution reaction (ORR-OER) activity, achieving a small potential gap of 0.648 V. Density functional theory (DFT) calculations demonstrate electron redistribution following heterojunction formation, with the electron localization function (ELF) confirming the localized electron density. The aqueous ZABs assembled with CoFePx/FeCo@PNCF cathodes deliver a high peak power density (183.40 mW cm-2), high specific capacity (791.20 mAh g-1), robust initial discharge capability (>300 h), and stability upon cycling (∼563 h, ∼1690 cycles). The solid-state ZABs demonstrate strong performance, and two devices sustain a 2.5 V light-emitting diode (LED) lamp for over 7 days.

Nanospike-engineered carbon nanofiber composites with interface synergy for enhanced electromagnetic wave absorption and corrosion resistance

The Loos-Manas-Zloczower model has been simplified and developed for conductivity predicting in polymer carbon nanofiber (CNF) systems (PCNFs). Herein, CNFs surrounded by interphase and tunneling distance (λ) are considered as extended CNFs, and their resistance is calculated to determine the PCNF conductivity. The developed model is analyzed across various factors, and its predictions are compared to the actual conductivity of different samples. For instance, when λ > 8 nm, the PCNF conductivity is minimized to 0.01 S/m, whereas with a λ of 1 nm and a polymer tunnel resistivity of 50 Ω.m, the nanocomposite conductivity increases to 0.79 S/m. Thus, both tunneling space and polymer resistivity conversely manage the conductivity. Furthermore, the conductivity of the nanocomposite maximizes at 0.75 S/m with a minimum CNF radius of 30 nm and a supreme CNF length of 60 μm, which indicates that the thinnest and longest CNFs provide the uppermost PCNF conductivity. The predictions of the developed method show a good agreement with the real conductivity of various samples, confirming its validity.

Phase-engineered molybdenum carbide embedded in nitrogen-doped carbon nanofiber composites for enhanced hydrogen evolution

Constructing magnetic carbon nanofiber composites with magnetic-electric synergistic loss effects for efficient microwave absorption

Lithium-sulfur batteries (LSBs) have been recognized as a promising candidate for next generation electrochemical energy-storage technologies owing to their unparalleled theoretical capacity and energy density compared to conventional lithium-ion batteries. However, the sluggish redox kinetics of the electrochemistry and the formidable dissolution of polysulfides during cycling lead to poor sulfur utilization, serious polarization, cyclic instability, and hazardous Li corrosion/dendrites issues. Herein, metal tellurides and carbon nanofibers composites (MTe2@CNFs) were designed, synthesized by facial electrospinning, and applied to modify the separator of Li–S batteries, providing a viable solution for these challenges. The composites feature polar MTe2 nanoparticles embedded in each carbon nanofiber, and the carbon nanofibers intertwine with each other to form an interconnected 3D nanofiber network. The sulfiphilic MTe2 nanoparticles exhibit dual functionality, as they both strongly interact with soluble polysulfides and dynamically facilitate polysulfide redox reactions. Moreover, the 3D nanofiber network not only provides an additional physical barrier to lithium polysulfides (LiPSs) but also enables uniform sulfur distribution, thereby significantly inhibiting LiPSs shuttling and accelerating sulfur conversion reactions. In summary, the functionally modified separator synergistically works as both redox mediators, catalyzing the sulfur conversion, and a buffer layer, regulating Li ions stripping/deposition behaviors. This work has provided a new avenue for designing nanomaterials with synergistic effect of catalytic conversion and chemisorption of polysulfides to promote high-performance Li-S batteries. Furthermore, it is expected to inspire the engineering of novel material architectures with enhanced properties for various energy-storage devices.

Due to its high theoretical specific capacity, abundant resources, accessibility and environmental friendliness, Sn has been considered as a promising alternative to lithium-ion batteries (LIBs) anodes. However, Sn anodes still face great challenges such as huge volume change and low conductivity. Herein, a self-supporting Sn-based carbon nanofiber anode for high-performance LIBs was prepared. Sn-based nanoparticles with high theoretical specific capacity were uniformly embedded in carbon nanofibers, which not only mitigated the volume expansion of Sn-based nanoparticles, but also obtained composite carbon nanofibers with excellent mechanical properties by adjusting the ratio of polyacrylonitrile to polyvinylpyrrolidone, exhibiting excellent electrochemical performance. The obtained optimal self-supporting Sn-based carbon nanofiber anode (Sn-SnO2/CNF-2) showed a discharge specific capacity of 607.28 mAh/g after 100 cycles at a current density of 500 mA/g. Even after 200 cycles, Sn-SnO2/CNF-2 still maintained a capacity of 543.78 mAh/g and maintained its original fiber structure well, demonstrating its good long-term cycling stability. This indicated that the self-supporting Sn-SnO2/CNF-2 anode had great potential for advanced energy storage.

Dynamic performance of TEPA-impregnated carbon nanofibers composites for direct air carbon capture in fixed bed columns

Direct synthesis of composite conductive carbon nanofiber aerogels with continuous internal networks for collaborative physiological signal monitoring under complex environments

Abstract Metal‐organic framework (MOF)–carbon composite materials are promising candidates for use as electrocatalysts in zinc‐air batteries (ZAB). Electrospun carbon nanofibers (CNFs) are particularly advantageous as conductive substrates due to their porous and binder‐free architecture. However, achieving stable and efficient dispersion of MOFs on CNFs remains a significant challenge. In this study, we present the synthesis of a composite electrode comprising of nickel‐based metal‐organic framework decorated over cobalt oxide‐embedded carbon nanofibers (NM@CCNF), designed as a self‐standing bifunctional electrocatalyst for rechargeable ZABs. The NM@CCNF features a unique open flower petal‐like morphology providing abundant active sites for oxygen reduction (ORR) and oxygen evolution reactions (OER). Electrochemical testing demonstrated that NM@CCNF exhibited a low potential gap (Δ E ) between the ORR and OER of 0.794 V, surpassing individual noble metal catalysts and rivaling benchmark Pt/C and IrO₂ combinations. The assembled ZAB demonstrated a high specific capacity of 830 mA h g Zn −1 , and a peak power density of 77.36 mW cm −2 . Long‐term cycling stability tests over 200 cycles showed minimal voltage degradation, indicating excellent durability and rechargeability. Post‐mortem analysis confirmed the reversible formation of ZnO during operation, validating the battery's rechargeability. These findings highlight the potential of NM@CCNF as a promising candidate for next‐generation energy storage systems.

Electrochemical detection of essential amino acid tryptophan in food samples using CuZnS-modified carbon nanofiber composite

Carbon nanofibers (CNFs) exhibit inherent dielectric properties that enhance electromagnetic (EM) wave absorption, yet challenges exist in expanding their effective absorption bandwidth (EAB) and improving flexibility. Many studies fail to adequately consider how structural factors influence performance when combining CNFs with magnetic materials. To address these issues, a 1D carbon nanocomposite is developed by embedding magnetic oxide nanoparticles within CNFs using a simple electrospinning technique. This approach improves membrane flexibility by disrupting rigid alignment and introducing dynamic magnetic interactions, while also creating defect‐rich interfaces that increase the amorphous content (61%) of the CNFsF composite, leading to improved EM wave absorption. The unique macro/mesoporous morphology provides internal interfaces and heterogeneous boundaries that effectively trap and dissipate EM waves. As a result, the flexible CNF composites demonstrate significant EM wave absorption performance, achieving a minimum reflection loss (RLmin) of −39.8 dB at 4.64 GHz and an abroad EAB of up to 7 GHz at only 2.5 mm thickness. Computer simulation technology (CST) simulations indicate a maximum radar cross‐section reduction of 21.1 dB m2, highlighting the material's radar stealth capability. This research advances the development of high‐performance materials and offers new strategies for enhancing absorption properties through composite engineering.

Much of the research on biodegradable polymers is currently aimed at developing alternative materials to fossil fuel plastics. Among the biodegradable polymers, the bio-based aliphatic polyesters (e.g. poly-ε-caprolactone, PCL) have had important success in replacing single-use plastics as well as durable consumer goods, mainly in the packaging and biomedical sectors. In other sectors, like electronics, the use of bio-based plastics has received little attention, despite e-waste (pollutant and difficult to handle) being the fastest growing solid waste stream in the world. In this work, P(CL-DL)/carbon black and P(CL-DL)/carbon nanofiber composites with enhanced thermal and electrical properties were prepared and studied. P(CL-DL) copolymers were synthesized via ring opening polymerization (ROP) at CL/DL molar compositions of 95/5, 90/10, 80/20, and 70/30. Their number-average molecular weight (M̄ n) and dispersity index (Đ) lie between 17.5 and 21.8 kDa, and 1.72 and 1.99, respectively. They are thermally stable to up to 300 °C, and show a melting temperature (T m) and a crystalline degree (X c) that decrease with increasing contents of DL in the polymer chains. The thermal (k) and electrical (σ) conductivities of copolymers were enhanced by adding, through melt blending, carbon black (CB) or carbon nanofibers (CNF) at 1.25, 2.5, and 5.0 wt%, reaching a maximum value of 0.55 W m-1 K-1 and 10-7 S cm-1, respectively. The frequency-dependence of the dielectric constant (ε') and dielectric losses (tan δ) was also measured. Two of the composites showed a marked increase of ε' near percolation whereas their tan δ remained low. The thermal and electrical conductivity performances, as well as the increment found in ε' near percolation, are discussed in terms morphology changes produced by variations in both the DL mol% and the nanoparticles wt%. Finally, biodegradable composites with heat and electron dissipative capacities are materials that can contribute to alleviating the problem of e-waste.

As the energy requirement constantly increases and paying attention to environmental protection day by day, the lithium-ion battery is a sort of efficient energy storage technique and is applied in many areas widely. However, it is of great importance to satisfy the demand for high- performance applications such as electric vehicles and increase the performance of lithium-ion batteries further, especially the performance of anode materials. The article first introduces the working mechanism of lithium-ion batteries. Later advantages and disadvantages of graphite, tin, and silicon are emphatically discussed as anode materials. Finally, regarding the above issues. Various modification strategies are proposed. For graphite, its electrochemical properties can be effectively improved by surface modification such as gas phase oxidation and physical coating. Using the structure design strategy of hollow carbon nanofiber and silicon composite, the silicon carbon anode material can obtain higher conductivity, and its cycle stability is also significantly improved. The modification of tin-carbon composite improves the electrochemical stability of tin-based material by optimizing the preparation process. These modification strategies greatly improve the properties of lithium-ion batteries. The paper reviews the properties, optimization methods, and obstacles of anode materials for lithium-ion batteries, with the intention of providing insights into further exploration and advancement in this field.

Reduced zinc phosphate-based carbon composite (Zn3PxOy@C) nanofibers are synthesized via electrospinning, followed by a two-step heat treatment. The effect of precursor concentration on structural evolution, phosphate distribution, and electrochemical performance is investigated. Solution viscosity influences fiber formation and component interactions, leading to distinct differences in phosphate confinement and porosity. Before annealing, phosphate species are predominant on the surface at low concentrations, balanced at optimal concentrations, and suppressed by polymer accumulation at high concentrations. After annealing, fiber diameters increase at low and optimal concentrations but shrink at high concentrations due to phase redistribution. The optimized nanofibers exhibit a specific surface area of 454 m2 g-1 and 45 wt% carbon, achieving high initial discharge and charge capacities of 1180.6 and 772.6 mAh g-1 at 100 mA g-1, respectively, as free-standing lithium-ion battery anodes. These results provide insights into composition-driven nanofiber design for energy storage applications.

A predictive model for electrical conductivity of polymer carbon nanofiber composites considering nanofiber/interphase network and tunneling dimensions