Reduced Graphene Oxide Fiber Research Articles

Nonwoven rGO Fiber‐Aramid Separator for High‐Speed Charging and Discharging of Li Metal Anode

AbstractLi metal, which has a high theoretical specific capacity and low redox potential, is considered to the most promising anode material for next‐generation Li ion‐based batteries. However, it also exhibits a disadvantageous solid electrolyte interphase (SEI) layer problem that needs to be resolved. Herein, an advanced separator composed of reduced graphene oxide fiber attached to aramid paper (rGOF‐A) is introduced. When rGOF‐A is applied, F− anions, generated from the decomposition of the LiPF6 electrolyte during the SEI layer formation process form semi‐ionic CF bonds along the surface of rGOF. As Li+ ions are plated, the “F‐doped” rGO surface induces the formation of LiF, which is known as a component of a chemically stable SEI, therefore it helps the Li metal anode to operate stably at a high current of 20 mA cm−2 with a high capacity of 20 mAh cm−2. The proposed rGOF‐A separator successfully achieves a stable SEI layer that could resolve the interfacial issues of the Li metal anode.

Copper-Coated Reduced Graphene Oxide Fiber Mesh-Polymer Composite Films for Electromagnetic Interference Shielding

Expected to become mainstream in the electronic industry, flexible electronics still face major challenging issues. For polymeric based flexible electronic substrates in particular, these challenge...

Tuning Properties of Partially Reduced Graphene Oxide Fibers upon Calcium Doping.

The arrangement of two-dimensional graphene oxide sheets has been shown to influence physico-chemical properties of the final bulk structures. In particular, various graphene oxide microfibers remain of high interest in electronic applications due to their wire-like thin shapes and the ease of hydrothermal fabrication. In this research, we induced the internal ordering of graphene oxide flakes during typical hydrothermal fabrication via doping with Calcium ions (~6 wt.%) from the capillaries. The Ca2+ ions allowed for better graphene oxide flake connections formation during the hydrogelation and further modified the magnetic and electric properties of structures compared to previously studied aerogels. Moreover, we observed the unique pseudo-porous fiber structure and flakes connections perpendicular to the long fiber axis. Pulsed electron paramagnetic resonance (EPR) and conductivity measurements confirmed the denser flake ordering compared to previously studied aerogels. These studies ultimately suggest that doping graphene oxide with Ca2+ (or other) ions during hydrothermal methods could be used to better control the internal architecture and thus tune the properties of the formed structures.

Non-woven fabric electrodes based on graphene-based fibers for areal-energy-dense flexible solid-state supercapacitors

Abstract Nowadays, lightweight, flexible, and wearable sustainable electric-power sources have attracted increasing attention due to the rapid development of portable electronics. Graphene fiber fabrics, as newly discovered carbon textiles, have exhibited attractive properties for wearable power devices. How to realize scalable construction of non-woven graphene-based fabric electrodes with high areal capacitance is challenging for portable electronics. Here, a novel coagulation bath fabrication technique was firstly reported to prepare reduced graphene oxide fiber fabrics (rGOFFs) for areal-energy-dense supercapacitors. The as-prepared rGOFFs showed high flexibility and conductivity. The symmetric supercapacitors (SCs) assembled with rGOFFs (95 μm) based fabric electrodes performed a high specific gravimetric capacitance (Cm) of 285 F/g at 0.1 A/g and 220 F/g at 1 A/g. The areal capacitance (Ca) of rGOFFs (220 μm) based electrode reached up to 2812 mF/cm2 at 1 mA/cm2. After electrochemical deposition of polyaniline (PANI) on rGOFFs (220 μm) substrate, the Ca of rGOFF@PANI – 220 μm based electrode was intensified to 3828 mF/cm2 at 1 mA/cm2 (172 F/cm3). The symmetric all-solid-state SCs showed an energy density from 28 μWh/cm2 (254 μW/cm2) to 11 μWh/cm2 (4950 μW/cm2). Overall, the as-designed rGOFFs based fabric electrodes and their fabrication techniques are of great potential for the next-generation multi-functional textile electronics.

The Effect of pH, Coagulation Bath, and Reduction on Characteristic Properties of Continuous Graphene Oxide Fiber

Abstract This study focuses on the effect of different process parameters including pH of GO dispersion, hydrazine reduction, number of coagulation bath on the properties of graphene oxide (GO) fibers produced through wet spinning method. Produced GO fibers have been characterized by scanning electron microscopy, Raman, X-ray diffraction methods, and an electrical conductivity meter. Results show that pH3 hydrazine reduction causes an expansion of the fiber volume and formation of porous fiber structure with higher defects. The crystal structure of GO fibers was also observed to be affected by hydrazine reduction, leading to decreased interlayer spacing and increased crystalline size and number of layer as compared to the reference (unreduced) one. Single coagulation bath was found to result in crystal on the fiber surface because of the calcium chloride (CaCI2) salt, which provides higher electrical conductivity than triple coagulation bath. The pH value of GO dispersion was found to influence the crystal structures of the GO fiber, resulting in lower interlayer spacing, lower crystallinity degree, and higher crystallite size in the pH5 sample as compared to that of pH3 for triple coagulation baths. The results obtained in this study are expected to contribute to and shed light for further studies on carbon-based fiber materials such as GO fiber and reduced GO fiber that can have different application fields including electronic smart textiles, graphene-based membranes, gas adsorption, energy application such as lithium ion battery, and ultrafiltration applications.

One-pot sulfur-containing ion assisted microwave synthesis of reduced graphene oxide@nano-sulfur fibrous hybrids for high-performance lithium-sulfur batteries

Carbon nanomaterials have been frequently used to physically inhibit the lithium polysulfide's shuttle in lithium–sulfur batteries, especially those crumpled structure of graphene. Here, a type of reduced graphene oxide fiber enwrapped nano-sulfur (rGOF@nano-S) hybrids were synthesized by a simple sulfur-containing-ion assisted microwave (MW) synthesis method and then utilized as a sulfur host for lithium–sulfur batteries. The synergistic reactions of MW treatments and sulfur-containing-ion force on the precursor GO nanosheets (NSs) have induced a well-crumpled fibrous structure, and simultaneously uniformly wrapped the nano-S particles in them, which would make the resultant cathodes achieve improved electrochemical performances. The rGOF@nano-S hybrid cathodes showed a high reversible capacity (886 mA h g−1 at 0.1 C rate), a high rate capability (remaining 61% at 2 C rate), and an excellent cycling stability (with a minimal decay rate of 0.04% per cycle over 800 cycles at 1 C), which are highly improved compared to those of the hybrids without MW treatments. In addition, the optimal MW treatment time on rGOF@nano-S hybrid cathodes were also explored to be 2.4 min under 700-W power. This work suggests that MW treatments would be a useful strategy for the preparation of high-performance cathodes for Li–S batteries.

Highly Compressible and Sensitive Pressure Sensor under Large Strain Based on 3D Porous Reduced Graphene Oxide Fiber Fabrics in Wide Compression Strains.

The development of highly sensitive wearable and foldable pressure sensors is one of the central topics in artificial intelligence, human motion monitoring, and health care monitors. However, current pressure sensors with high sensitivity and good durability in low, medium, and high applied strains are rather limited. Herein, a flexible pressure sensor based on hierarchical three-dimensional and porous reduced graphene oxide (rGO) fiber fabrics as the key sensing element is presented. The internal conductive structural network is formed by the rGO fibers which are mutually contacted by interfused or noninterfused fiber-to-fiber interfaces. Thanks to the unique structures, the sensor can show an excellent sensitivity from low to high applied strains (0.24-70.0%), a high gauge factor (1668.48) at an applied compression of 66.0%, a good durability in a wide range of frequencies, a low detection limit (1.17 Pa), and anultrafast response time (30 ms). The dominated mechanism is that under compression, the slide of the graphene fibers through the polydimethylsiloxane matrix reduces the connection points between the fibers, causing a surge in electrical resistance. In addition, because graphene fibers are porous and defective, the change in geometry of the fibers also causes a change in the electrical resistance of the composite under compression. Furthermore, the interfused fiber-to-fiber interfaces can strengthen the mechanical stability under 0.01-1.0 Hz loadings and high applied strains, and the wrinkles on the surface of the rGO fibers increased the sensitivity under tiny loadings. In addition, the noninterfused fiber-to-fiber interfaces can produce a highly sensitive contact resistance, leading to a higher sensitivity at low applied strains.

Flexible and smart fibers decorated with Ag nanoflowers for highly active surface‐enhanced Raman scattering detection

AbstractSurface‐enhanced Raman scattering (SERS) is a useful detection technique for molecule recognition. However, the relative difficulty in producing low‐cost highly active SERS substrates in large quantities hinders their practical implementation. Here, a fast and facile approach using a one‐step solution‐phase synthesis is proposed to directly achieve highly active fibrous SERS substrates by uniformly and densely growing silver nanoflowers on reduced graphene oxide fibers within several minutes. Attributed to the abundance of nanogaps throughout the silver nanoflower network, the fibrous substrate exhibits superior stability and high sensitivity in the SERS detection of Rhodamine 6G, with a detection limit of 10−12 M. Importantly, the proposed method is energy efficient and can work well at room temperature and manually stirring conditions based on naturally shed hair and plant fibers. Due to the advantages of high‐volume production, the processing cost is greatly reduced to approximately $0.008 for each substrate. This newly designed approach may greatly improve the practical application of SERS detection in environmental monitoring, medicine and food safety, especially in resource‐limited environments.

Magnetic induced wet-spinning of graphene oxide sheets grafted with ferroferric oxide and the ultra-strain and elasticity of sensing fiber

One dimensional neat reduced graphene oxide (RGO) fiber has low elongation and elasticity under external force, hindering its promising applications in electronics, sensors, etc. In our work, the RGO fibers with wrinkled packing structure of sheets were fabricated by magnetic induced wet-spinning of graphene oxide (GO) sheets grafted with ferroferric oxide (GFO) dope and followed by chemical reduction. The value of ultimate strain for RMGFO12.5 fiber was up to 51.97%, which was 9 times of RGO fiber (5.6%). The value of creep recovery of neat RGO fiber was 28.2%, and this value could reach up to 75.0% for RMGFO12.5 fiber with magnetic field induction, maintaining the ultra-strain and elastic property. Such RGO fibers with wrinkled packing structure will yield great advances in ductibility, elasticity and electromechanical properties and have potential high-tech applications, including wearable electronics, strain sensors, e-skins, etc.

All-carbon fiber-based chemical sensor: Improved reversible NO2 reaction kinetics

All-carbon fiber-based chemiresistor is fabricated by assembling reduced graphene oxide (RGO) fiber and carbon nanotube (CNT) fiber as reversible NO2 sensing layer and flexible heater, respectively. Both graphene oxide (GO) and CNT fibers were synthesized by wet-spinning technique facilitating lyotropic nematic liquid crystal (LC) property. Randomly entangled CNT fiber-based heater, which is embedded in one surface of colorless polyimide (cPI) film with thickness of ˜200 μm, exhibits high bending stability and heating property up to 100 °C. Single reduced graphene oxide (RGO) fiber obtained after heat treatment at 900 °C in H2/N2 ambient was integrated on the CNT fiber-embedded cPI heater, thereby establishing a new type of all-carbon fiber sensing platform. As a result, accelerated NO2 adsorption and desorption kinetics were achieved with RGO fiber at an elevated temperature. In particular, a 9.22-fold enhancement in desorption kinetic (kdes = 8.85 × 10–3 s–1) was observed at 100 °C compared with the desorption kinetic (kdes = 0.96 × 10–3 s–1) at 50 °C, which was attributed to the effective heating by CNT fiber networks. This work pioneered a research on the use of emerging carbonaceous fibers for potential application in wearable chemical detectors.

Heterogeneous Metal Oxide-Graphene Thorn-Bush Single Fiber as a Freestanding Chemiresistor.

The development of freestanding fiber-type chemiresistors, having high integration ability with various portable electronics including smart clothing systems, is highly demanding for the next-generation wearable sensing platforms. However, critical challenges stemming from the irreversible chemical sensing kinetics and weak reliability of the freestanding fiber-type chemiresistor hinder their practical use. In this work, for the first time, we report on the potential suitability of the freestanding and ultraporous reduced graphene oxide fiber functionalized with WO3 nanorods (porous WO3 NRs-RGO composite fiber) as a sensitive nitrogen dioxide (NO2) detector. By employing a tunicate cellulose nanofiber (TCNF), which is a unique animal-type cellulose, the numerous mesopores are formed on a wet-spun TCNF-GO composite fiber, unlike a bare GO fiber with dense surface structure. More interestingly, due to the superior wettability of TCNF, the aqueous tungsten precursor is uniformly adsorbed on an ultraporous TCNF-GO fiber, and subsequent heat treatment results in the thermal reduction of a TCNF-GO fiber and hierarchical growth of WO3 NRs perpendicular to the porous RGO fiber (porous WO3 NRs-RGO fiber). The freestanding porous WO3 NRs-RGO fiber shows a notable response to 1 ppm NO2. Furthermore, we successfully demonstrate reversible NO2 sensing characteristics of the porous WO3 NRs-RGO fiber, which is integrated on a wrist-type wearable sensing device.

Highly Sensitive, Selective, and Flexible NO2 Chemiresistors Based on Multilevel Structured Three-Dimensional Reduced Graphene Oxide Fiber Scaffold Modified with Aminoanthroquinone Moieties and Ag Nanoparticles.

Highly sensitive, selective, and room-temperature-performing gas sensors have always been the pursuit in the sensing field for practical applications. However, the existing gas sensors can seldom satisfy the aforementioned requirements. Here, we integrate zero-dimensional Ag nanoparticles (AgNPs), one-dimensional polymer fibers, and two-dimensional aminoanthroquinone-functionalized reduced graphene oxide (AQRGO) sheets into a three-dimensional sensing scaffold (AgNP-3D-AQRGO) for high-performance NO2 sensing. The AQ moieties and AgNPs are decorated onto the RGO sheets through a wet chemical route. Electrospinning and self-assembly techniques are employed to assemble the polymer fibers and the functional RGO sheets into a three-dimensional scaffold. The resulting AgNP-3D-AQRGO-based gas sensor can perform at room temperature and exhibits excellent sensing performance for NO2, including an ultrahigh sensitivity (10.3 ppm-1), an ultralow limit of detection (0.6 ppb), and an extremely remarkable selectivity to solely NO2 molecules. Furthermore, the sensor is also highly flexible, demonstrating great potential for portable and real-time monitoring of toxic gas in personal mobile electronics.

Self-assembly of chemically modified graphene sheets in an external magnetic field.

The rapid developments of effective self-assembly technologies indicated that ordered structures could be produced using external field inducement. We designed the alignment of graphene oxide nanosheets grafted with the modified ferroferric oxide by the application of a magnetic field. The results indicated that the morphologies of graphene oxide went through some changes from disordered to semi-ordered in the final and, highly oriented wrinkled structures. The orientation mechanism of graphene oxide demonstrated that the geometric features of the wrinkles were related to the edge stresses and the elastic stiffness of the sheets, magnetic force of magnetic field to magnetic-particles. The prepared reduced graphene oxide fibers indicated that the sheets with magnetic precipitates underwent shrinkage in the radial direction when an external magnetic field was exerted and the interior sheets aligned along the direction of the magnetic field, which was supported by the proposed theories. It is expected that the research could contribute to the applications of flexible graphene-based materials in preparation and controlling the formation of wrinkles in single layer graphene.

Structure and electrocatalytic activity of flexible reduced graphene oxide/fullerene smart fiber

A strategy to prepare flexible reduced graphene oxide/fullerene (RGO/C60) smart fiber by utilizing a wet-spinning assembly of graphene oxide (GO) and hydroxylated fullerene and followed underwent chemical reduction is presented. Zero-dimensional fullerene acts a capture introduced into reduced graphene oxide fiber and causes a significant improvement of trapping free radicals and accessible surface area to chemicals, finally entrusting the electrocatalytic activity to reduced graphene oxide fiber. We found that C60-intervention might induce the disordered structure of RGO layers turning into an ordered one. Moreover, the 95/5-RGO/C60 fiber displayed the highest surface area of 42.03 m2/g and the maximum micropore volume of 46.43 × 10−3 mL/g compared with those of pure RGO (27.22 m2/g and 24.75 × 10−3 mL/g respectively) and other fibers with different mass ratio. Additionally, the rhodamine B catalyzed by the 95/5-RGO/C60 fiber produced better degradation efficiency (70% within 48 h) than pure RGO fiber (35% within 48 h). The results of electrical resistivity analysis revealed that the RGO/C60 fibers have high electrosensitivity under different thermal and mechanical conditions. This work provides fundamental insight into the effect of the RGO layers turning in hybrid fibers and sheds light on the design of next-generation sensitive and high flexible smart sensor.

Wire-Shaped Li-Ion Battery Based on Iron Sulfide Nanostructures on Carbon Based Electrode

In recent years, the development of new materials, electrode architectures and manufacturing strategies has opened Li-ion batteries to new application areas. In particular, the implementation of high-performances and reliable energy storage devices is a challenging task in the sector of smart-fabrics and wearable electronics. Wire-shaped batteries (WSBs) are one of the most active and rapidly growing research fields, because of their flexibility and easy integration in fabrics. The development of a suitable technique for the production of graphene fibers as electrodes boosted the interest in WSBs [1]. Typically, Li-ion WSBs rely on self-supported all-carbon electrodes made of reduced graphene oxide (RGO) and/or carbon nanotubes (CNTs) fibers [2], synthesized through the wet-spinning process. The incorporation of higher capacity active materials in carbon fibers like TiO2 nanosheets [3], SiO2 [4] and S nanoparticles [5,6] has already been demonstrated as a successful strategy to further increase battery performances. However, the incorporation of active material during the wet-spinning of the carbon-based fibers limits this technique to 2D materials only. Here, we propose Li-ion WSB based on RGO fibers electrode and iron sulfide. Iron nanostructures have been deposited on RGO fibers by an easy electrochemical route and converted in iron sulfide as active material through sulfurization process by thermal treatment in presence of sulfur. Half-cell configuration with Li wire as cathode has been evaluated as well as a full-cell configuration. Electrochemical stability of the active materials were investigated through cyclic voltammetries while capacity, efficiency and cycle stability were evaluated for both half-cell and full-cell configurations. Morphological and structural investigations were performed on the electrodes by means of SEM, XRD and Raman analysis.

Mechanical property enhancement of high conductive reduced graphene oxide fiber by a small loading of polydopamine

Improving the interaction of individual reduced graphene oxide sheet is an effective way to enhance the mechanical property of reduced graphene oxide fiber. In this study, to enhance the interaction forces of graphene sheets, large-sized graphene oxide sheets were used to assemble graphene fiber, and dopamine was mixed with the graphene oxide spinning drop. During the wet-spinning procedure, polydopamine was formed by polymerizing. It is found that such obtained composite fiber shows enhanced tensile strength (increased from 314 MPa to 527 MPa) and increased toughness (increased from 3.5 MJ m−3 to 12.9 MJ m−3) compared with pure reduced graphene oxide fiber. Fourier-transform infrared spectra, Raman spectra and x-ray photoelectron spectroscopy were performed to characterize the interaction between reduced graphene oxide sheets and polydopamine, and a possible enhancement mechanism of C-N bonds formation was proposed. It is suggested that this newly formed C−N bonds can not only enhance the tensile strength, but also increase the elongation simultaneously. Additionally, the graphene fiber remains great electrical conductivity (33 100 s m−1) since the conductive network can be maintained.

Electromagnetic shielding effectiveness of carbon fabric/epoxy composite with continuous graphene oxide fiber and multiwalled carbon nanotube

Carbon fabric composite is used in technical applications such as aircrafts in which electromagnetic shielding (electromagnetic interference–shielding effectiveness) is required. Traditionally, metallic coatings or metal plates are used for electromagnetic shielding, however, conductive filler-filled composite is also alternative to metal sheets due to its light weight. In the literatures, there are studies about effect carbon nanotube and graphene oxide flakes on electromagnetic interference; however, there are no studies encountered that search the effect of carbon nanotube/graphene oxide fiber and alignment of graphene oxide fiber on electromagnetic interference. Thus, in this study, fabrication of light-weight carbon fabric/epoxy composite filled with graphene oxide fiber, reduced graphene oxide fiber and multiwalled carbon nanotube and alignment of graphene oxide fiber was studied for the first time for both electromagnetic shielding (electromagnetic interference–shielding effectiveness) and electrical conductivity. It was found that reduced graphene oxide with two layers at the same alignment (0–0) leads to increment in the electromagnetic interference–shielding effectiveness value, while reduced graphene oxide with opposite alignment (0–90) leads to decrease in the electromagnetic interference–shielding effectiveness value. Opposite to literatures for graphene oxide flakes, highly rough surface of graphene oxide fiber and reduced graphene oxide fiber causes a deterioration in electromagnetic interference–shielding effectiveness due to disruptive multiple reflections resulted from highly rough surface of graphene oxide fiber, which causes multiple reflection effect. Multiwalled carbon nanotube generally provides higher electromagnetic interference–shielding effectiveness than graphene-based fiber because it has higher conductivity and has no disruptive effect of crimpy surface as graphene oxide fiber. Multiwalled carbon nanotube loading of 15 wt% results to 32 dB electromagnetic interference–shielding effectiveness, which is considered an adequate and moderate level of shielding for many applications.

Quantitative characterisation of conductive fibers by capacitive coupling.

This work presents a study on a capacitively coupled contactless conductivity detector (C4D) for micron-sized fibers. Following a previous report on the qualitative application of C4D for fibers, the present study provides a thorough analysis of the signal response to fiber conductivity. Using reduced graphene oxide (RGO) fibers, the detector response as a function of fiber length, cross-sectional area and resistance has been investigated. To study the effect of insulating coatings, Parylene-coated RGO fibers were also investigated. In addition, measurements were performed in different coupling environments, such as in a capillary tube or air. The analysis of the measured data allowed the determination of the C4D conductivity of various RGO fibers, and the correlation with contact methods through empirical relationships to be determined. It was found that the detection limit and sensitivity of resistance measurements are mainly dependent on the sensor design, and also on the fiber properties. The detection threshold can be defined as the ratio of the coupling impedance to fiber resistance. In our case, the detection limit was found for impedance ratios equal to 14. This limit sets a functioning mode in C4D for fibers, which may be used as an area or resistance detector for the impedance ratio above or below the detection threshold. A semi-log linear response of the fiber resistance to the voltage output was found for impedance ratios between 2.66 and 0.63. These impedance ratios may serve as a reference for designing C4D, depending on the fibers to be tested and the analytical information needed. In summary, we suggest that C4D has the capacity to emerge as a new characterisation tool for micron-sized fibers, due to its applicability to any conductive material, ease of use, and the contactless nature of the measurement.

Amorphous Molybdenum Sulfide Deposited Graphene Liquid Crystalline Fiber for Hydrogen Evolution Reaction Catalysis

Amorphous Molybdenum Sulfide Deposited Graphene Liquid Crystalline Fiber for Hydrogen Evolution Reaction Catalysis

Highly Stretchable and Self-Healable Supercapacitor with Reduced Graphene Oxide Based Fiber Springs.

In large-scale applications of portable and wearable electronic devices, high-performance supercapacitors are important energy supply sources. However, since the reliability and stability of supercapacitors are generally destroyed by mechanical deformation and damage during practical applications, the stretchability and self-healability must be exploited for the supercapacitors. Preparing the highly stretchable and self-healable electrodes is still a challenge. Here, we report reduced graphene oxide fiber based springs as electrodes for stretchable and self-healable supercapacitors. The fiber springs (diameters of 295 μm) are thick enough to reconnect the broken electrodes accurately by visual inspection. By wrapping fiber springs with a self-healing polymer outer shell, a stretchable and self-healable supercapacitor is successfully realized. The supercapacitor has 82.4% capacitance retention after a large stretch (100%), and 54.2% capacitance retention after the third healing. This work gave an essential strategy for designing and fabricating stretchable and self-healable supercapacitors in next-generation multifunctional electronic devices.