Graphene-based Fiber Research Articles

Broadband and tunable fiber polarizer based on a graphene photonic crystal fiber.

The recent flourishing development of two-dimensional (2D) graphene has sparked considerable interest and extensive research on graphene-based optical fiber polarizers. However, studies on graphene-optical fiber polarizers focused on the structure with graphene films attached to side-polished fibers, which face challenges such as low birefringence of 10-6, low polarization extinction ratio (PER), and narrow polarizing window of tens of nanometers. Here, a fiber polarizer based on a graphene-photonic crystal fiber (Gr-PCF) is proposed firstly, which exhibits high birefringence of ∼2.5 × 10-3, high PER of ∼111 dB/mm, broad polarizing window of >400 nm, and tunable polarization states. Graphene or graphene/hBN/graphene (Gr/hBN/Gr) heterojunctions are attached to the surface of two square holes in the PCF to make one of the polarizing modes attenuate significantly. The tunability of the Fermi level (EF) in Gr/hBN/Gr enables the proposed device to function as a polarizer or a polarization-maintaining fiber. The combination of PCF's endless single-mode feature and graphene's broadband optical response feature enables the fiber polarizer to exhibit a wide spectrum range with single-mode transmission characteristics.

Covalently bridging graphene edges for improving mechanical and electrical properties of fibers

Assembling graphene sheets into macroscopic fibers with graphitic layers uniaxially aligned along the fiber axis is of both fundamental and technological importance. However, the optimal performance of graphene-based fibers has been far lower than what is expected based on the properties of individual graphene. Here we show that both mechanical properties and electrical conductivity of graphene-based fibers can be significantly improved if bridges are created between graphene edges through covalent conjugating aromatic amide bonds. The improved electrical conductivity is likely due to extended electron conjugation over the aromatic amide bridged graphene sheets. The larger sheets also result in improved π-π stacking, which, along with the robust aromatic amide linkage, provides high mechanical strength. In our experiments, graphene edges were bridged using the established wet-spinning technique in the presence of an aromatic amine linker, which selectively reacts to carboxyl groups at the graphene edge sites. This technique is already industrial and can be easily upscaled. Our methodology thus paves the way to the fabrication of high-performance macroscopic graphene fibers under optimal techno-economic and ecological conditions.

Wet-spinning of reduced graphene oxide composite fiber by mechanical synergistic effect with graphene scrolling method

Carbon-based fibers have attracted attention in various field owing to their exceptional properties, including high tensile strength, thermal stability, and electrical conductivity. In particular, graphene-based high-strength fibers are promising materials in aerospace, automotive, and marine sectors. Recently, the hybrid fiber, consisting of carbon nanotubes (CNTs) and graphene with enhanced toughness was reported by deflecting cracks and enabling high deformation. However, complex synthesis and structural optimization of composite fiber with two different materials make challenge for mass production. Here, we introduce a novel graphene composite fiber, consisting of reduced graphene oxide (rGO) and scrolled rGO (SrGO), showing remarkable toughness. A multidimensional-state solution with 2D rGO and 1D SrGO was obtained by using a simple sonication technique. Mass production of high-toughness composite fibers was achieved via wet-spinning, with enhanced toughness attributed to microstructure optimization by controlling the SrGO ratio. Additionally, the use of poly(vinyl alcohol) (PVA) as the matrix facilitated high deformation, resulting in a remarkable 90.7 % increase in mechanical toughness without complex composite material synthesis.

3D Architecting triple gradient graphene-based fiber electrode for high-performance asymmetric supercapacitors

High-performance fibrous architectures and controllable fabrication methods for active nanomaterials are fundamental in the development of fiber-based supercapacitors (FSCs). Herein, we rationally designed a triple gradient structured fibrous electrode based on three-dimensional (3D) architectural approach with Ni3S2 nanoflakes (Ni3S2 NFs) in situ growth on Ni-coated graphene fiber (Ni3S2-NiGFs) for highly energy-dense asymmetric supercapacitors. Remarkably, the Ni-metal coating imparted the Ni3S2-NiGFs exceptional electrical conductivity (619.8 S cm−1), mechanical strength (335.0 MPa), and flexibility without significantly compromising its density. Moreover, the unique 3D interconnected ultrathin Ni3S2 NFs significantly increase the contact area between the electrode and the electrolyte solution, providing abundant redox activity to facilitate ion transport and accumulation. Therefore, the fibrous electrode showcased a remarkable areal specific capacitance of 1387.6 mF cm−2 at 3 mA cm−2 in 3 M KOHaq electrolyte, while its asymmetric FSCs delivered an impressive areal energy density of 15.6 μW h cm−2 at power density of 1.0 mW cm−2 along with durable cycle life (86.7 % of the initial specific capacitance retention over 10,000 cycles). In summary, the featured work provides a facile but robust electrode design to realize highly energy-dense flexible energy storage devices for next-generation wearable industries.

Enhanced Nonradiative Charge Recombination in Microfiber-Based Bismuthene.

After the first report of a graphene-based passive mode-locking ultrafast fiber laser, two-dimensional materials as efficient saturable absorbers offer a new horizon in ultrafast fiber laser. However, the interactions on atomic scale between these two-dimensional materials and fiber and the fiber effect on the carrier dynamics have not been realized. To figure out the exact role of fiber and the carrier dynamics affected by the fiber substrate related to ultrafast photonics, bismuthene, a newly reported 2D quantum material used in a passive mode-locking fiber laser, deposited on α-quartz has been investigated. We surprisingly found that the α-quartz substrate can strongly accelerate the nonradiative electron-hole recombination of bismuthene in theory, and the transient absorption spectra of bismuthene on normal glass and α-quartz further verify the substrate effect on carrier dynamics of bismuthene. The discovery provides new thinking about substrate effect to regulate the performance of ultrafast mode-locking fiber lasers as well as ultrafast photonics.

High Performance Nacre Fibers by Engineering Interfacial Entanglement.

Biological materials exhibit fascinating mechanical properties for intricate interactions at multiple interfaces to combine superb toughness with wondrous strength and stiffness. Recently, strong interlayer entanglement has emerged to replicate the powerful dissipation of natural proteins and alleviate the conflict between strength and toughness. However, designing intricate interactions in a strong entanglement network needs to be further explored. Here, we modulate interlayer entanglement by introducing multiple interactions, including hydrogen and ionic bonding, and achieve ultrahigh mechanical performance of graphene-based nacre fibers. Two essential modulating trends are directed. One is modulating dynamic hydrogen bonding to improve the strength and toughness up to 1.58 GPa and 52 MJ/m3, simultaneously. The other is tailoring ionic coordinating bonding to raise the strength and stiffness, reaching 2.3 and 253 GPa. Modulating various interactions within robust entanglement provides an effective approach to extend performance limits of bioinspired nacre and optimize multiscale interfaces in diverse composites.

Flexible microwave absorbing fabrics woven by high-strength graphene-based hybrid fibers with broadband electromagnetic response

Fabrics, a class of carriers, have been pioneered in electromagnetic protection, but their microwave absorbing potential has not been fully explored for a considerable period. Herein, aramid nanofibers (ANFs) enhanced reduced graphene oxide fabrics (ANF/rGO fabrics) were synthesized by wet spinning-chemical reduction. The ANF/rGO fabrics can achieve the minimum reflection loss (RLmin) of −15.8 dB with a thickness of 2.7 mm. On this basis, ANF/rGO fabrics grown with polyaniline (ANF/rGO-PANi fabrics) through in-situ doping polymerization were obtained. Polyaniline compensates for the lack of conductivity of the dielectric fabrics, bringing higher impedance matching and attenuation capability. The corresponding RLmin can reach −52.3 dB under 2.9 mm and the effective absorption bandwidth (EAB) increases to 6 GHz covering the whole Ku band under 2.5 mm. The fabrics woven by high-strength graphene-based hybrid fibers proposed in this study provide a new angle to achieve high-efficiency microwave absorption.

Anchoring polypyrrole on nitrogen and sulfur codoped graphene fibers to construct flexible supercapacitors

Graphene fiber-based flexible supercapacitors could function as flexible energy storage and supply equipment for wearable electronic devices. However, the future applications are restricted because of the low energy density for flexible supercapacitors. In this paper, the polypyrrole is anchored on nitrogen/sulfur co-doped graphene fibers (PPy/NSGF) by a hydrothermal self-assembly method and in situ polymerization process. The as-fabricated PPy/NSGF possess a high specific areal capacitance of 424.8 mF cm−2 and an excellent energy density of 43.3 μW h cm−2. The fiber-shaped supercapacitor assembled by PPy/NSGF can be utilized to power light. The improved properties of PPy/NSGF are mostly attributed to the increased electroactive sites from heteroatom nitrogen and sulfur codoping and in situ polymerization of polypyrrole. The produced graphene-based composite fibers are expected to become potential flexible electrode materials for fiber-shaped supercapacitors in future smart clothes and miniaturized flexible wearable electronics.

Switching and vector characteristics of bound-state solitons in a graphene-based mode-locked fiber laser

A passive mode-locked erbium-doped fiber laser based on graphene operating in the anomalous dispersion state is designed in this paper. In this experiment, the complete convert process from traditional soliton pulses to soliton rains and bound-state (BS) soliton pulses, and ultimately to traditional soliton pulses, is achieved by adjusting the pump power and polarization controller (PC) to control factors such as nonlinearity, dispersion, and birefringence in the cavity. In the BS soliton state, switching between the 0 phase and π phase BS solitons is achieved. We also replaced the 20/80 coupler with the 30/70 coupler to achieve the soliton rains by varying the energy alteration of the intracavity pulse. When the pump power is increased to 350 mW, the laser generates multi-pulses and eventually forms a new BS. In addition, we also studied the soliton vector characteristics during this conversion process and found the polarization-locked vector soliton (PLVS). The research results enrich nonlinear vector soliton dynamics and provide valuable data for further theoretical studies.

Nanoengineered Carbon Surfaces for Ultrasensitive Neurochemical Detection

Hypothesis-driven methods to tailor the functionality, topology, carbon orientation, and three-dimensional (3D) structure of carbon microelectrodes, for specific classes of neurochemicals, would significantly improve analyte specificity and lower the limits of detection for fast-scan cyclic voltammetry (FSCV) detection in the brain and beyond. FSCV at carbon-fiber microelectrodes is an established technique to study the signaling dynamics of many different neurochemicals in the brain. Despite its widespread applicability to many analytes, most in vivo studies are conducted on bare, unmodified carbon-fiber microelectrodes and many of the fundamental studies of new electrode materials focus on dopamine detection. Manipulations of the carbon surface can have profound effects on electrochemical detection and carefully controlled experiments to manipulate the analyte-electrode interface could provide exquisite information for future design of electrode materials. Here, we will discuss our latest work on synthesizing and manipulating the surfaces of carbon-based materials including graphene-based fibers and porous PAN-derived carbon-fiber, to exploit specific neurochemical-electrode interactions for improved detection. This presentation will demonstrate the importance of understanding the analyte-structure-electrode-surface interface for designing optimal electrodes.

A novel graphene-based circular dual-core photonic crystal fiber pressure sensor with high sensitivity

A novel graphene-based circular dual-core photonic crystal fiber pressure sensor with high sensitivity

Microfluidic-oriented assembly of Mn3O4@C/GFF cathode with multiscale synergistic structure for high-performance aqueous zinc-ion batteries

The electrochemical activity and long-term stability of cathodic materials, as well as active ion transport, are key factors for efficient energy storage in aqueous zinc-ion batteries (ZIBs). Here, a freestanding Mn3O4@C nanowire-implanted graphene-based fiber fabric (Mn3O4@C/GFF) cathode with a multiscale synergistic structure was fabricated using a facile microfluidic assembly method. In this architecture, Mn3O4 nanowires are hosted by a conductive carbon layer and then anchored in the interlayer of a self-assembled graphene-based fiber framework. The hierarchical structure enhances electrical conductivity and relieves ion leaching, thereby boosting the electrochemical activity and long-term stability of cathodic materials. Furthermore, the layer-by-layer assembled structure of the Mn3O4@C/GFF cathode provides ample available channels for active ion transport, accelerating the electrochemical kinetics. Consequently, the Mn3O4@C/GFF cathode exhibits enhanced electrochemical performance with a high capacity of 374.8 mAh g−1 at 0.2 A g−1 and ultralong cycle life (158.7 mAh g−1 retained over 5000 cycles at 2 A g−1). Therefore, this study provides a multiscale synergistic strategy for fabricating advanced cathodes for high-performance ZIBs.

Effects of nano-particles on the MRR and TWR of graphene-based composite by EDM using copper tool

This experimental research graphene-based carbon fibre composite used as the workpiece and copper as tool electrode. Graphene-based carbon fibre composite used in aerospace, automotive, and other industries due to its lightweight and high strength-to-weight ratio. Four processing parameters—input current (Ip), voltage gap (Vg), pulse on time (Ton), and pulse off time (Toff) used to determined Material Removal Rate (MRR) and Tool Wear Rate (TWR) (TWR). In this work the influence of copper nanoparticles were investigated over the MRR and TWR. The design of experiments is based on standard L9 orthogonal array. 5.24% enhancement and 3.84% reduction were reported in the MRR and TWR, respectively, using the copper nanoparticle mixed dielectric compared to the simple dielectric oil.

Advances in Porous Graphene and Scalable Wet-Spinning Fiber Assembly

ConspectusTwo-dimensional (2D) materials with astonishing properties and thickness dimensions are attractive for nanodevices and optoelectronics devices. Among them, 2D graphene─an atomically thin single layer with a strong covalently bonded sp2-hybridized hexagonal carbon network─has fascinating physicochemical properties. 2D graphene is at the tip of the iceberg of 2D materials. However, graphene is prone to self-restacking and agglomeration, deteriorating its properties. The introduction of porous structures to graphene sheets ameliorates their properties, e.g., increasing the surface area, providing ion transport channels, and enhancing the stability; thus, the performance of graphene-based materials is improved. Owing to their exciting properties, 2D holey graphene (HG) with nanoholes in its 2D basal plane and three-dimensional (3D) porous graphene with structural pores and interconnected architectures structural derivatives of graphene are promising for addressing the aforementioned challenges synergistically. Perforation in 2D graphene with tunable pore size, pore density, and uniformity is crucial for improving the performance of dense graphene. The unique pore structure and large exposed edges indicate the improved properties of porous graphene. Furthermore, macroscopically assembled one-dimensional (1D) fibrous electrodes of holey and porous graphene building blocks are promising, as they are lightweight, have high flexibility, and have strong wearability for future next-generation electronics.In this Account, we systematically highlight our efforts related to the conventional synthesis methodologies to recent emerging methods of “holey” or “porous” graphene/graphene oxide. First, we focus on the synthesis strategies and advances of 2D HG in-plane holes suitable for fast ion transport. Recent emerging synthesis methodologies are discussed for preparing 2D HG, which uses an environmentally benign approach with low toxicity compared to conventional etching methods, which frequently involve the use of hazardous or toxic oxidizing reagents, thereby causing severe environmental pollution. Second, compared with graphene, the 3D porous graphene comprises self-assembled graphene sheets (holey) containing structural macropores with a larger accessible surface area, high pore volume, and better flexibility, stability, and mechanical properties preferred for energy conversion and storage applications. Here, the recent progress and emerging synthesis approaches for 3D porous graphene-based nanomaterials are comprehensively discussed. Furthermore, the advantages of 2D HG and 3D porous graphene are discussed for water transport and electrochemical storage. Third, recent advances in the use of straightforward, large-scale wet-spinning processes to fabricate macroscopically assembled 1D fibrous electrodes with excellent mechanical flexibility and deformability using holey or porous graphene-based fibers (GFs) are described. Different approaches are discussed for preparing holey or porous GFs, such as wet-spinning assembly of holey graphene oxide (HGO), coagulant-assisted porous structures, and the post-activation process. Thus, the wet-spun holey or porous GFs are promising for miniaturized-based next-generation wearable electronic devices. Finally, we focus on the current status, fundamental understanding, future directions, and challenges of wet-spinning assemblies of holey/porous graphene-based nanomaterials for the next generation of wearable electronics.

Fabrication of high strength and functional GO/PVA/PAN ternary composite fibers by gel spinning

Abstract Polyacrylonitrile (PAN) fiber is soft and comfortable, but its poor strength compared to other synthetic fibers has limited it wide range of applications. This study effectively improved the strength of PAN fibers by adding graphene oxide (GO) and polyvinyl alcohol (PVA) during PAN spinning. The composite fibers were prepared via gel spinning and subsequent hot drawing process. The results show that the PVA molecular chains embedded into the PAN molecular chain significantly improved the mechanical properties of the hybrid fiber. At the same time, the defect reduced the UV resistance and thermal stability of the hybrid fibers only when the PVA molecular was introduced in the PAN. Surprisingly, after the recomposition of GO in the above mixed polymer system, the interaction between the GO and matrix not only improved the mechanical properties of the fiber, but also enhanced the UV resistance and thermal stability. In addition, when the amount of GO was 0.3 wt%, the crystallinity of the GO/PVA/PAN composite fiber reached the maximum and the tensile strength was the highest. This strategic approach suggests an effective method to prepare graphene-based ternary composites fibers with high strength and novel functional characteristics.

Three-Dimensionally Conducting Network in Graphene-Based Composite Fibers toward Enhanced Electrochemical and Toughness Performance in Fibrous Supercapacitors

As one of the most promising energy storage devices, graphene-based fibrous supercapacitors (FSSCs) are attracting intensive attention. However, the conflict between specific capacitance and intrinsic brittleness of pure graphene fibers hinders their practical applications. Herein, we develop a strategy to fabricate graphene-based ternary composite CNT/MXene/graphene (CMG) fiber electrodes with high toughness and high electrical and electrochemical performance. These resulting properties are attributed to the three-dimensional cross-linked conducting network within graphene sheets through covalent bonding and π–π interaction among acidified carbon nanotubes, graphene sheets, and MXene, which greatly contributes to the enhanced tensile strength, toughness, and electrical transport in the CMG fiber. The CMG fiber with the optimized mass ratio of different components shows a high toughness of ∼1.7 MJ m–3 and an electrical conductivity of 420 S cm–1, which is 4- and 2-fold that of reduced graphene oxide fiber, respectively. The assembled FSSC based on the optimized CMG fiber exhibits an areal capacitance of 237 mF cm–2 and a good rate performance of 85%.

Nitrogen-Doped Porous Core-Sheath Graphene Fiber-Shaped Supercapacitors.

In this study, a strategy to fabricate nitrogen-doped porous core-sheath graphene fibers with the incorporation of polypyrrole-induced nitrogen doping and graphene oxide for porous architecture in sheath is reported. Polypyrrole/graphene oxide were introduced onto wet-spun graphene oxide fibers by dip-coating. Nitrogen-doped core-sheath graphene-based fibers (NSG@GFs) were obtained with subsequently thermally carbonized polypyrrole/small-sized graphene oxide and graphene oxide fiber slurry (PPY/SGO@GOF). Both nitrogen doping and small-sized graphene sheets can improve the utilization of graphene layers in graphene-based fiber electrode by preventing stacking of the graphene sheets. Enhanced electrochemical performance is achieved due to the introduced pseudo-capacitance and enhanced electrical double-layered capacitance. The specific capacitance (38.3 mF cm−2) of NSG@GF is 2.6 times of that of pure graphene fiber. The energy density of NSG@GF reaches 3.40 μWh cm−2 after nitrogen doping, which is 2.59 times of that of as-prepared one. Moreover, Nitrogen-doped graphene fiber-based supercapacitor (NSG@GF FSSC) exhibits good conductivity (155 S cm−1) and cycle stability (98.2% capacitance retention after 5000 cycles at 0.1 mA cm−2).

Low threshold Q-switched pulses based on a WTe2-graphene saturable absorber

Low-threshold and narrow-pulse-width Q-switched optical pulses are obtained using a tapered fiber-based WTe2-graphene saturable absorber (SA) in an erbium-doped fiber laser (EDFL) for the first time. Benefiting from the low unsaturated loss of graphene, the Q-switching threshold (25.8 mW) is an order of magnitude lower than that using SA with WTe2 only. Meanwhile, owing to the high carrier mobility of WTe2, the minimum pulse width (1.2 µs) is the narrowest among the graphene-based fiber lasers. The results indicate the potential of the WTe2-graphene SA in future application and development of laser pulses.

Graphene-Based Fiber Supercapacitors

Graphene-Based Fiber Supercapacitors

Mechanical Reinforcement in Nylon 6 Nanocomposite Fiber Incorporated with Dopamine Reduced Graphene Oxide.

The emergence of graphene-based polymer composite fibers provides a new opportunity to study the high-performance and functional chemical fibers. In this work, we have developed an efficient and convenient method with polydopamine (PDA) to functionalize and reduce graphene oxide (GO) simultaneously, and the modified graphene nanosheets can obtain uniform dispersion and strong interfacial bonding in nylon 6 (PA6). Furthermore, the reinforced PA6 composite fibers were prepared through mixing PDA-rGO into the PA6 polymer matrix and then melt spinning. The functional modification was characterized by surface analysis and structural testing including SEM, TEM, FTIR, and Raman. When the addition amount of the modified GO was 0.15 wt%, the tensile strength and Young’s modulus of the composite fiber reached 310.4 MPa and 462.3 MPa, respectively. The results showed a meaningful reinforcement with an effect compared to the pure nylon 6 fiber. Moreover, the composite fiber also exhibited an improved crystallinity and thermal stability, as measured by DSC and TGA.