Conductive Nanofibers Research Articles

Encapsulating Sb/MoS2 Into Carbon Nanofibers Via Electrospinning Towards Enhanced Sodium Storage

AbstractMetallic antimony (Sb) and molybdenum disulfide (MoS2) are identified as promising anode materials for sodium ion batteries (SIBs) owing to their high theoretical capacities. Herein, both Sb and MoS2 are integrated and fully embedded into carbon nanofibers (CNFs) to form Sb/MoS2@CNFs nanocomposite via an electrospinning technique followed by heat treatment. When employed as anode material for SIBs, the Sb/MoS2@CNFs electrode presents a reversible capacity of 282.7 mAh g−1 after 300 cycles at 1 A g−1, and even 197.5 mAh g−1 after 1350 cycles at a high current density of 5 A g−1. The superior sodium storage performance of the Sb/MoS2@CNFs can be ascribed to the synergistic effect of the integrated Sb/MoS2 components and their full encapsulation into the one‐dimensional (1D) conductive carbon nanofibers. The well‐dispersed Sb/MoS2 nanoparticles ensure good Na+ ions accessibility and high storage capacity, while 1D nanostructure facilitates ion/electron transport, tolerates the volume expansion, and prevents the Sb/MoS2 nanoparticles from aggregating during cycling. This work provides a simple and efficient synthetic route of multicomponent anode materials in advanced SIBs.

MXene bridging graphite nanoplatelets for electrically and thermally conductive nanofiber composites with high breathability

Electrically and thermally conductive polymer composites (CPCs) have promising applications in flexible and wearable electronics, and it remains difficult for the trade-off between the electrical and thermal properties and the breathability. We propose a “MXene bridging graphite nanoplatelets (GNPs)” strategy to prepare conductive membranes with high conductivity and excellent breathability. Rigid GNPs are randomly distributed inside polyurethane nanofibers and expand the network. MXene nanosheets are decorated onto the nanofibers and bridge GNPs to reduce the thermal and electrical contact resistance. The synergy of MXene and GNPs improves electrical and thermal conductivity without sacrificing their breathability. The electrical and thermal conductivity of the composites can reach 64.4 S/m and 4.9 W (m K)−1, respectively. In addition, the nanofiber composites with strong interfacial interactions and thus superior durability show outstanding photothermal conversion and heat dissipation capability. This study can provide inspiration for designing multi-functional, breathable CPCs with potential applications in wearable electronics.

SnS2 nanosheets/Ag2S quantum dots heterojunction supported by YSZ nanofibers enable real-time room-temperature NO2 gas sensor

Air pollution has emerged as a critical global issue, necessitating the development of effective real-time gas monitoring technologies. However, conventional gas sensors face limitations such as high energy consumption and sluggish response/recovery kinetics. In this study, we report a novel SnS2/Ag2S heterojunction supported by yttria-stabilized zirconia nanofibers (YSZ@SnS2/Ag2S) through a facile electrospinning, hydrothermal and subsequent cation-exchange method. This hierarchical composite nanofiber consists of well-distributed Ag2S quantum dots (QDs) attached to vertical anchored SnS2 nanosheets, forming an interconnected network supported by YSZ nanofibers. The integrated sensor exhibited high response of 3.27 and swift response/recovery times of 12/27 s to 1 ppm NO2 at room temperature, respectively. Benefited from highly permeable three-dimensional continuous conductive nanofibers, along with the hierarchical nanosheets/QDs structure, the gas transmission/diffusion and number of reactive sites were ensured. Additionally, the interfacial built-in electric field of SnS2/Ag2S heterojunction further enhanced the electron transfer, carrier migration and gas-sensitive reaction kinetics. This study provides insights into the development of functional composite nanofibers and paves the way for the exploitation of real-time room-temperature gas sensing applications.

Linear sensing actuators of polypyrrole nanofiber scaffolds

AbstractIn the search for renewable materials for linear actuators, polypyrrole (PPy) glucose‐glycerin nanofiber scaffolds were used here to provide the actuator with a basic fibrillary structure, mimicking natural muscles. Each nanofiber was coated with a chemically synthesized PPy film, getting conductive nanofiber scaffolds (CNS), used then as electrodes to attain a second polypyrrole doped with dodecylbenzensulfonate (PPyDBS) coat forming PPyDBS‐CNS material structure. PPyDBS bulk films obtained by electropolymerization on stainless steel under the same condition were used to compare the linear actuation properties of both materials. Cyclic voltammetry, square potential waves, and square potential currents, in combination with linear actuation measurements, studied the samples. Three different potential ranges (PRs) were selected for those methodologies: 1.0 to −0.55 V (PR1), 0.8 to −0.4 V (PR2), and 0.65 to −0.55 V (PR3), revealing that PPyDBS‐CNS has anion‐driven actuation independent of the applied PR1–3, while in comparison PPyDBS films had in PR3 mixed ion actuation. The best strain from PPyDBS, 24.6%, was attained at PR1, and from PPyDBS‐CSN, 17.5% strain in the same PR. Further characterizations are conducted, such as scanning electron microscopy, Fourier transform infrared spectroscopy, and element determination using energy dispersive x‐ray spectroscopy.

Thermal conductive aramid nanofiber/surface-decorated alumina microsphere composite separator

The development of lithium-sulfur (Li–S) batteries is hindered by inhomogeneous Li plating and irreversible loss of active materials. In this work, a thermal conductive and electrocatalytic aramid nanofiber (ANF) composite separator containing surface-decorated alumina (Al2O3) microspheres is prepared through a simple filtration approach using ZnO nanosheets decorated Al2O3 microspheres (Al2O3@ZnO) as the thermal conductive filler and electrocatalyst. Compared with the separators fabricated by surface modification of commercial polyolefin separators, the as-prepared ANF/Al2O3@ZnO composite separator features homogeneous compositions and ensures uniform thermal distribution in both the through-plane and in-plane directions of the membrane. By rationally designing the structure of Al2O3@ZnO and adjusting the mass ratio of Al2O3@ZnO to ANF, excellent thermal conduction networks are formed by overlapping the ZnO nanosheets. Hence, the prepared ANF/Al2O3@ZnO composite separator possesses higher thermal conductivity than ANF/Al2O3 composite separator, which benefits uniform thermal distribution and homogeneous Li plating within the battery. Moreover, the electrocatalytic ZnO nanosheets catalyze the conversion of lithium polysulfides, efficiently inhibiting the shuttle effect and improving sulfur utilization. When subjected to a temperature gradient, the ANF/Al2O3@ZnO composite separator assembled cells display high initial capacity, low decay rate, and superb cycle stability. This novel composite separator integrates both thermal conductive and electrocatalytic functional components with the heat-resistant ANF matrix, offering a new design strategy of separator towards high-performance Li–S batteries.

Review—Electrostatic Spinning for Manufacturing Sensitive Layers of Flexible Sensors and Their Structural Design

Electrostatic spinning technology is widely used in the manufacturing of flexible sensors. It is a mature and reliable method to fabricate nanofibers with tailorable fiber diameter surface microstructure like porosities and specific surface areas. Based on these properties, the electrically conductive composite nanofiber mats achieved by functionalizing nanofibers with active conductive nanomaterials are used as a sensitive layer for flexible sensors with tunable sensing performance. However, it is crucial to select suitable materials and optimal electrospinning technology, as well as design of the sensitive layer structure, for tuning the mechano-electrical performance of flexible sensors. This paper first reviews the current methods for the fabrication of flexible sensors with a focus on preparation method based electrospinning technology. Then, we introduce in detail the types and properties of common substrate materials and conductive fillers used to make sensor sensitive layers, with emphasis on the design of sensitive layer structures for the properties of the materials themselves. Finally, there is a summary of improvements and derivations based on the traditional electrospinning technologies that have been reported in recent years. It is hoped that this review will provide both references and inspiration for researchers in the field of flexible sensors.

The role of electrical current mode in calcium carbonate deposition on conductive carbon nanofiber–epoxy coating

AbstractCalcium carbonate is one of the most common scaling minerals. In this paper we have used different electrical current modes (direct current [DC], pulsed DC, and alternating current [AC]) to control the amount, morphology, and distribution of calcium carbonate deposit on electroconductive epoxy/carbon nanofiber (CNF) coating. The effect of different current modes on surface scaling was visualized using scanning electron microscopy. It has been shown that both AC and DC anodic polarization limited scale deposition on epoxy/CNF coated surfaces, although the mechanisms of scale inhibition during AC and DC polarization were different. DC polarization of the coating at +2 V resulted in the smallest scale buildup without leading to coating degradation, while DC polarization at potentials as high as +5 V caused the coating to degrade. Interestingly, application of pulsed DC with high pulse frequency (50 Hz) inhibited the degradation. The type of current applied affected also the morphology of the precipitate at the cathode. The results presented in this work show, for the first time, how different modes of electrical current applied to electroconductive composite coatings can be used to control the morphology and distribution of calcium carbonate scale, and how the organic coating degradation at high polarization potentials can be avoided.

3D grape string-like heterostructures enable high-efficiency sodium ion capture in Ti3C2Tx MXene/fungi-derived carbon nanoribbon hybrids.

2D transition metal carbides and carbonitrides (MXenes) have emerged as promising electrode materials for electrochemistry ion capture but always suffer from severe layer-restacking and irreversible oxidation that restrains their electrochemical performance. Here we design a dual strategy of microstructure tailoring and heterostructure construction to synthesize a unique 3D grape string-like heterostructure consisting of Ti3C2Tx MXene hollow microspheres wrapped by fungi-derived N-doping carbon nanoribbons (denoted as GMNC). The 3D grape string-like heterostructure effectively avoids the aggregation of Ti3C2Tx MXene sheets and enhances the stability of MXenes, providing abundant active sites for ion capture, and an interconnected conductive bionic nanofiber network for high-rate electron transport. In consequence, GMNC achieves a superior adsorption capacity for sodium ions (Na+) in capacitive deionization (CDI) (162.37 mg gNaCl-1) with an ultra-high instantaneous adsorption rate (30.52 mg g-1 min-1) at an applied voltage of 1.6 V and satisfactory cycle stability over 100 cycles, which is a strong performer among the state-of-the-art values for MXene-based CDI electrodes. In addition, in situ electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) measurement combined with density functional theory (DFT) reveals the mechanisms of the Na+ capture process in the GMNC heterostructure. This work opens a new avenue for designing high-performance MXenes with a 3D hierarchical heterostructure for advanced electrochemical applications.

Enhanced PEMFC performance through high O2 permeation and proton conductive electrospun nanofiber electrodes with unique ionomer construction

Significant performance enhancement in nanofiber-based PEMFCs featuring highly O2 permeable ionomer films, highly proton-conductive ionomer fibers, and increased active sites.

Mechanically durable MXene based nanofiber composite membranes with asymmetric superhydrophilicity/hydrophobicity for unidirectional water transport and temperature sensing

Wearable fibric materials have shown wide applications in flexible electronics, and it is desired that smart fibric/fiber materials possess excellent breathability, durability and sweat-wicking capabilities. Here, we develop an electrically conductive Janus nanofiber composite (CJNCs) with outstanding unidirectional water transportation (UWT) ability by regulating MXene nanosheet distribution. MXene/chitason are assembled on the polyurethane (PU) surface to obtain a superhydrophilic layer with a large thickness, while MXene nanosheets embedded PU nanofibres with a smaller thickness is deposited onto the superhydrophilic layer to construct a Janus structure with asymmetric wettability. The Janus structure demonstrates outstanding interfacial stability, guaranteeing the excellent durability of the UWT behavior. The UWT time can be diminished to around 10 s, and the anti-gravity water transportation time is only 18 s. In addition, CJNCs displays superior photo-thermal effect and temperature sensing behavior. This work presents an effective and facile strategy toward fabricating multifunctional fibrous materials with potential applications in smart and wearable sensing electronics.

Hydrothermal growth of FeMoO4 nanosheets on electrospun carbon nanofibers as freestanding supercapacitor electrodes

In this study, an electrospinning method was used to produce highly conductive freestanding carbon nanofibers (CNFs). The freestanding CNFs are compatible with hierarchical growth techniques, such as hydrothermal processes, for the nanostructure engineering of supercapacitor electrodes with enhanced electrochemically active sites. Therefore, the flower-like FeMoO4@CNF nanosheets were investigated to improve the electrochemical performance using aqueous and neutral electrolytes (Na2SO4 and K2SO4). The optimized FeMoO4@CNF electrode exhibits areal capacitances of 252 and 220 mF·cm−2 at a high current density of 2.5 mA·cm−2 with Na2SO4 and K2SO4 electrolytes, respectively. The wide potential window (1.6 V) of the symmetric supercapacitor delivered maximum energy densities of 22.4 and 19.6 μWh·cm−2 at a power density of 2 mW·cm−2 for Na2SO4 and K2SO4 electrolytes, respectively.

Carbon-Based Nanomaterials Decorated Electrospun Nanofibers in Biosensors: A Review.

Nanomaterials have revolutionized scientific research due to their exceptional physical and chemical capabilities. Carbon-based nanomaterials such as graphene and its derivates have excellent electrical, optical, thermal, physical, and chemical properties that have made them indispensable in several industries worldwide, including medicine, electronics, and energy. By incorporating carbon-based nanomaterials as nanofillers in electrospun nanofibers (ESNFs), smoother and highly conductive nanofibers can be achieved that possess a large surface area and porosity. This approach provides a superior alternative to traditional materials in the development of improved biosensors. Carbon-based ESNFs, among the most exciting new-generation materials, have many applications, including filtration, pharmaceuticals, biosensors, and membranes. The electrospinning technique is a highly efficient and cost-effective method for producing desired nanofibers compared to other methods. Various types of natural and synthetic organic polymers have been successfully utilized in solution electrospinning to produce nanofibers directly. To create diagnostics devices, various biomolecules like antibodies, enzymes, aptamers, ligands, and even cells can be bound to the surface of nanofibers. Electrospun nanofibers can serve as an immobilization matrix to create a biofunctional surface. Thus, biosensors with desired features can be produced in this way. This study comprehensively reviews biosensors that integrate nanodiamonds, fullerenes, carbon nanotubes, graphene oxide, and carbon dots into electrospun nanofibers.

Self-Adhesive, Conductive, and Antibacterial Hydrogel Nanofiber Composite as a Flexible Strain Sensor

Self-Adhesive, Conductive, and Antibacterial Hydrogel Nanofiber Composite as a Flexible Strain Sensor

Nucleation and property enhancement mechanism of robust and high-barrier PLA/CNFene composites with multi-level reinforcement structure

The demand for biopolymer-based green packaging has attracted growing attention because of its outstanding properties and consistency with clean environmental principle, unfortunately, its slow crystallization rate and narrow processing window are challenging. Inspired by combined functions in nanocellulose-based conductive hybrids, this work developed high-performance polylactic acid (PLA) composites using conductive cellulose nanofiber (CNFene). Interestingly, CNFene has multiple functions as highly graphitized carbon and abundant hydroxyl groups, delivering stimulating properties to PLA composites. As nucleating agents, 3 wt% CNFene has a carbon layer on the surface combined with a hydrogen bonding network synergistically enhancing the tensile and crystallization properties of PLA-C3, with a tensile strength of ∼ 53.7 MPa, crystallinity of ∼ 33.9 %, and 6.6 °C decrease in the cold crystallization temperature. Additionally, the compatibility between CNFene and PLA can form a multi-level “reinforcement” network structure, further improving thermal stability and barrier properties. The resultant PLA-C3 showed higher thermal decomposition onset temperature (T0), wider melt-processing window (197.6 °C) and extremely lower overall migration levels in ethanol (68.6 μg/kg) and isooctane (16.3 μg/kg), due to that improved interaction between CNFene and PLA positively affects crystallization ability and kinetic/mechanism of PLA to meet the requirements of industrial and green biopackaging applications.

Conductive Nanofiber Web Film with Polydimethylsiloxane Sidewalls Selectively Coated through a Plasma Process for High Performance Flexible Transparent Electrodes.

Transparent electrodes are commonly used in various applications, such as solar cells, touch screens, smart windows, wearable electronic devices, and rollable flexible displays. Currently, indium tin oxide (ITO) is widely used as a transparent electrode material. However, ITO is not suitable for next-generation transparent electrodes that require flexibility; therefore, alternative nanomaterials, such as carbon nanotubes, conductive polymers, and metal nanowires, are being studied. However, these nanomaterials have poor mechanical strength and limited substrate availability. In this study, we developed a high-performance transparent electrode web film fabrication process based on conductive nanofibers, in which metal nanofibers are semiembedded in polydimethylsiloxane (PDMS). The mechanical strength of the conductive nanofibers was improved through the PDMS coating on the entire surface of the film, and the semiembedded structure of the nanofibers was realized using the reactive ion etching (RIE) process. In this study, we confirmed through transparency/conductivity analysis and bending, cycle, and taping tests that the transparent electrode fabricated using our approach has excellent mechanical strength and conductivity. Finally, the transparent electrode fabricated using our method can be widely applied as a next-generation transparent electrode because the process is easy and simple and requires inexpensive equipment and materials.

High capacity, silica-based anion-exchange nanofiber membranes for the selective recovery of lactic acid

Fermentation processes offer a sustainable way for green organic acid production such as lactic acid (LA). However, the recovery and purification of LA from fermentation broths is typically very energy demanding. The in-situ recovery of LA via migration of its lactate anion through an anion-exchange membrane (AEM), combining electrochemical systems with fermentation, offers a viable solution for this. In this work, sustainable silica-based nanofiber AEMs were developed with excellent ionic properties and a strong selectivity for organic acids. Starting from a tetraethoxysilane/chloropropyltriethoxysilane (TEOS/CPTES) sol-gel system, anion conductive nanofiber membranes were obtained via the alkylation of the CCl moieties on the electrospun nanofibers with 1-methylimidazole, resulting in an ion-exchange capacity (IEC) of 1.9 ± 0.3 mmol g−1. Post-functionalization with octyltriethoxysilane (OTES) resulted in hydrophobic porous nanofiber AEMs with excellent separation properties. It was shown that the nanofiber AEM had an improved lactate selectivity compared to a commercially dense AEM in the presence of SO42− (selectivity of 8.8 vs. 1.1) with an energy consumption of 1.6 kWh kg−1 vs. 3.0 kWh kg−1 for lactate migration, proving its potential as a sustainable material for industrial applications.

N-Doped Graphene Nanofibers with Porous Channel Comprising Fe x S y Nanocrystals and Intertwined N-Doped CNTs as Efficient Interlayers for Li-S Batteries

Hierarchically porous and conductive nanofibers (NFs) comprising nitrogen-doped reduced graphene oxide (N-rGO) and iron sulfide (Fe x S y ) nanocrystals along with highly intertwined nitrogen-doped carbon nanotubes (N-CNTs) abbreviated as “P-rGO@Fe x S y /N-CNT NFs” were synthesized via electrospinning technique as multifunctional interlayers via coating on the commercial separator for stable lithium-sulfur (Li-S) batteries. The porous N-rGO framework acts as a backbone to enhance the structural integrity of the nanostructure. The N-CNTs and N-rGO guarantee various conductive channels for quick electron transfer thus allowing fast redox reactions. The thermal breakdown of polystyrene (PS) resulted in the formation of continuous longitudinal channels. Correspondingly, the Li-S cell incorporating the P-rGO@Fe x S y /N-CNT NF-modified separator and S electrode (2.41 mg cm-2) exhibited boosted electrochemical properties such as justifiable rate capability and steady cycling performance (after 800 charge-discharge, cell exhibits a capacity of 464 mA h g-1 with 44% retention at 0.1 C). The novel synthesis strategy discussed herein will provide significant intuitions to the advancement of innovative nanostructures for different rechargeable purposes.

Conductive electrospun nanofiber based on silk fibroin/cellulose nanocrystals/reduced graphene oxide as a wound healing material

Composite electrospun nanofibers based on silk fibroin (SF), aminated reduced graphene oxide (NH2rGO), and oxidized-cellulose nanocrystals (AD-CNCs) were designed to promote the healing process by electrical conductivity. In this respect, CNCs were produced from cotton cellulose and oxidized in the presence of sodium periodate, and reduced GO was synthesized and functionalized with amine with p-anthranilic acid via an esterification reaction. Then the crosslink was prepared by the Schiff-base reaction between oxidized CNCs and NH2rGO. Electrospun nanofibers were prepared from silk fibroin, previously prepared from Bombyx Mori cocoons, AD-CNCs, and different ratios of NH2rGO. The SF/AD-CNCs/NH2rGO nanofibrous scaffold presented multiple propitious characteristics for cell proliferation and wound dressing including low cytotoxicity, a hydrophilic surface, thermal stability, and degradability. The physicochemical evaluations showed that with increasing the NH2rGO content, hydrophilicity and electroconductivity of nanofibers increased. The SF/AD-CNCs/NH2rGO biodegradable conductive scaffold with 2.5% NH2rGO content showed favorable nanofibrous structure, supporting and stimulating fibroblast cell proliferation and attachment. The SF/AD-CNCs/NH2rGO nanofibrous scaffold demonstrates the application potential in wound healing management.

The effect of conductive aligned fibers in an injectable hydrogel on nerve tissue regeneration

Injectable hydrogels are a promising treatment option for nervous system injuries due to the difficulty to replace lost cells and nervous factors but research on injectable conductive hydrogels is limited and these scaffolds have poor electromechanical properties. This study developed a chitosan/beta-glycerophosphate/salt hydrogel and added conductive aligned nanofibers (polycaprolactone/gelatin/single-wall carbon nanotube (SWCNT)) for the first time and inspired by natural nerve tissue to improve their biochemical and biophysical properties. The results showed that the degradation rate of hydrogels is proportional to the regrowth of axons and these hydrogels’ mechanical (hydrogels without nanofibers or SWCNTs and hydrogels containing these additions have the same Young's modulus as the brain and spinal cord or peripheral nerves, respectively) and electrical properties, and the interconnective structure of the scaffolds have the ability to support cells.

Cardiac patches made of brown adipose-derived stem cell sheets and conductive electrospun nanofibers restore infarcted heart for ischemic myocardial infarction.

Cell sheet engineering has been proven to be a promising strategy for cardiac remodeling post-myocardial infarction. However, insufficient mechanical strength and low cell retention lead to limited therapeutic efficiency. The thickness and area of artificial cardiac patches also affect their therapeutic efficiency. Cardiac patches prepared by combining cell sheets with electrospun nanofibers, which can be transplanted and sutured to the surface of the infarcted heart, promise to solve this problem. Here, we fabricated a novel cardiac patch by stacking brown adipose-derived stem cells (BADSCs) sheet layer by layer, and then they were combined with multi-walled carbon nanotubes (CNTs)-containing electrospun polycaprolactone/silk fibroin nanofibers (CPSN). The results demonstrated that BADSCs tended to generate myocardium-like structures seeded on CPSN. Compared with BADSCs suspension-containing electrospun nanofibers, the transplantation of the CPSN-BADSCs sheets (CNBS) cardiac patches exhibited accelerated angiogenesis and decreased inflammation in a rat myocardial infarction model. In addition, the CNBS cardiac patches could regulate macrophage polarization and promote gap junction remodeling, thus restoring cardiac functions. Overall, the hybrid cardiac patches made of electrospun nanofibers and cell sheets provide a novel solution to cardiac remodeling after ischemic myocardial infarction.