Nanostructured Carbon Fiber Research Articles

Properties of Nanostructured Carbon Fiber Material and Process Features of Its Use in Producing Tableted Enterosorbent for Medical Applications

Properties of Nanostructured Carbon Fiber Material and Process Features of Its Use in Producing Tableted Enterosorbent for Medical Applications

Improvement of interfacial adhesion of CuO nanostructured carbon fiber reinforced polymer composites

AbstractHydrothermal technique was used to deposit copper‐oxide (CuO) nanostructures on woven carbon fibers (WCF) to produce a nanostructured interphase that increased the interfacial strength with an epoxy resin matrix. In order to create laminated hybrid composites, CuO‐modified WCF was reinforced with mixture of bisphenol‐A epoxy resin and dimethyl aniline hardener as matrix using the vacuum bagging approach. Enhanced mechanical qualities are the result of increased volume fraction of CuO nanostructures, where the void content is minimal. The mechanical characteristics such as impact strength and tensile strength of CuO‐coated WCF reinforced epoxy resin composite samples were assessed using drop‐down impact test and universal material testing system. The outcomes demonstrate a considerable improvement in impact energy absorption (74.8%), elastic modulus (52%) tensile strength (42%) and in‐plane shear strength (32%) for the CuO‐coated WCF reinforced epoxy resin composites. This work demonstrates that the development of CuO nanostructures can lessen composite delamination and enhance composite performance because of the increase in interfacial surface area between the matrix and the fiber by CuO nanostructures potentially expanding the spectrum of structural applications for these materials.

리튬-황 전지 양극재용 유기 금속 골격체 기반의 다공성 나노섬유 구조체

Metal organic framework-derived porous nanofibers were synthesized by electrospinning and subsequent heat treatment process. In this study, ZIF-8 and PS nanobeads were used as templates to form micro and meso pores in the structure. For this, ZIF-8 polyhedra were prepared by liquid-phase methode using 2-methylimidazole and zincnitrate-hexahydrate in ethylalcohol. After facile heat-treatment, ZIF-8, PS, and PVP were thermally decomposed to form pores and carbon matrix composing fiber structure. The porous carbon matrix improves the redox reaction kinetics and provides numerous chemisorption sites for the effective trapping and reuse of lithium polysulfide during cycles. As a result, the assembled Li-S cells employing unique nanostructure display superior rate capability and stable cycling performance. The Li-S cell delivered a stable discharge capacity of 655 mA h g^-1 after 100 charge-discharge cycles at 1.0 C. Thus, the uniquely nanostructured porous carbon fibers shows high potential for the development of advanced Li-S batteries utilizing pure sulfur electrodes with realistic battery parameters.

Triboelectric nanogenerator-integrated structural supercapacitor with in situ MXene-dispersed N-doped Zn–Cu selenide nanostructured woven carbon fiber for energy harvesting and storage

A woven carbon fiber (WCF)-based triboelectric nanogenerator (TENG)-cum-structural supercapacitor is an excellent multifunctional device for clean energy harvesting and storage. This type of device has high load-bearing capacity and functions smoothly under severe outdoor conditions. Herein, WCF-based multifunctional TENG is reported that generated 8.9 W m−2 power with 84% energy conversion efficiency. The energy generated by the TENG was simultaneously stored in a connected supercapacitor that provide 1.93 Wh kg−1 of energy density and delivers 39.23 W kg−1 of power density. The specific surface area of the WCF was enhanced several hundred-fold by coating with an N-doped Zn–Cu selenide nanoporous material, thereby enabling higher energy generation and elevated storage capacity of the device. The TENG use a polyester-based solid polymer electrolyte as the negative electrode and polydimethylsiloxane-coated WCF as the positive electrode. The device has a very high coulombic efficiency with high mechanical strength and ability to resist massive impact. An application of the multifunctional device was demonstrated. These types of multifunctional devices have great potential in the self-charging automobile, aerospace, sensor, and electronics sectors.

Nanostructured Carbon Fiber Modified by Silver Nanoparticles for the Medical Application

In this work, the feasibility of synthesizing new composite system for the medical application using an activated carbon fiber nanostructured materials with silver nanoparticles through immobilization by adsorption from solutions (ACFNM/AgNP) has been studied. The stability of the obtained composite system in physiological solutions as a modern sorption application form has been examined. Optimal modes of carbonized fabric activation are proposed for synthesis of nanostructured carbon fiber with high sorption capacity. The size distribution of silver nanoparticles after the ultrasonic treatment of the original silver solution in glycerol was proved to significantly decrease in the size of the agglomerates formed in the solution. It has been shown that after ultrasonic treatment, the silver nanoparticles were actively adsorbed by the porous structure of the carbon matrix. Treatment of carbon fiber with silver nanoparticles showed their uniform adsorption on the surface of the carbon matrix to form silver agglomerates with sizes of ~90–120 nm and 250– 300 nm. When studying the physicochemical stability of the obtained composite systems in biological solutions it was revealed that the intensity of silver release from the surface of the ACFNM/AgNP composite depends on the volumetric capacity of the carbon matrix, the initial concentration of silver in the solution, and the chemical composition of biological media. At that, the amount of silver in the water filtrate was established to be greater than in physiological solutions after the interaction. It was shown that the initial silver concentration of 25 mg/L in a suspension of glycerol is most optimal for creating of stable ACFNM/AgNP composite systems. Besides, the slower release of silver from the surface of carbon matrices into physiological solutions of different salt composition ensures a prolonged effect of silver in modern sorption application forms for medical purposes. The ACFNM/AgNP composite system with a capacity of carbon matrix of 1.0 cm3/g and an initial concentration of silver in a solution of 25 mg/L was recommended for the future development of modern application materials.

Preparation of porous Co-Pt alloys for catalytic synthesis of carbon nanofibers

A simple and convenient procedure for the production of highly dispersed porous Co-Pt alloys to be used as catalysts for the synthesis of nanostructured carbon fibers (CNF) has been developed. The technique is based on the thermal decomposition of specially synthesized multicomponent precursors in a reducing atmosphere. A series of porous single-phase alloys Co-Pt (10–75 at% Pt) have been synthesized. The alloys containing 75 and 50 at% Pt were identified by the x-ray diffraction analysis as the intermetallics CoPt3 and CoPt, respectively. Within the region of 10–35 at% Pt, the synthesized alloys are represented by Co1−x Pt x random solid solutions with face-centered cubic lattice. The alloys obtained are characterized by a porous structure consisting of assembled fragments with a size of 50–150 nm. The obtained alloys were tested in the catalytic chemical vapor deposition of the ethylene to CNF. A significant synergistic effect between Co and Pt in the synthesis of carbon nanomaterials (CNMs) was revealed. The yield of CNF (for 30 min reaction) for catalysts containing 25–35 at% Pt was 30–38 g(CNF)/g(cat), whereas those for Co (100%) and Pt (100%) samples were as low as 5.6 and >0.1 g(CNF)/g(cat), respectively. The produced CNM composed of fibers with a segmented structure was shown to be characterized by a rather high specific surface area (200–250 m2 g−1) and structural homogeneity.

An Anthraquinone/Carbon Fiber Composite as Cathode Material for Rechargeable Sodium‐Ion Batteries

AbstractThe transition from rare to natural abundant materials in rechargeable batteries is becoming a grand challenge in developing a resource sustainable power supply. Since decades, scientists attempt to circumvent the lithium's resource problem by innovating alternative active metal ions. A cost‐effective alternative to lithium is to use sodium (Na) as the carrier ion in rechargeable batteries. We present an electrode composite material comprising anthraquinone (AQ) and nanostructured carbon fibers, as a cathode material for Na‐ion batteries. These electrodes are characterized by a large surface area, ordered porous network, large pore volume and good electrical conductivity. The material is further compared to the water soluble, mono‐substituted anthraquinone derivative, sulfonated 9,10‐anthraquinone (SAQ). While the SAQ/carbon fiber composite demonstrates a moderate initial discharge capacity of ∼95 mAh g−1 accompanied by substantial, initial capacity fading, the AQ/carbon fiber composite shows a remarkably high discharge capacity of ∼307 mAh g−1 and exhibit reasonable cycling stability over 115 charge/discharge cycles in a Na containing electrolyte. This may be best explained by the well‐structured intermolecular π‐π stacking of the thermally evaporated AQ layers and with the subjacent carbon fibers. Since AQ and SAQ are widely‐used industrial pigments, they may offer a cost‐effective, abundant and environmentally benign cathode material for secondary Na‐ion and Na‐flow batteries.

Electrocatalytic phenol degradation by a novel nanostructured carbon fiber brush cathode coated with graphene ink

A new promising electrochemically-exfoliated graphene-based cathode for the electrocatalytic Fenton process was elaborated by an ink-coating technique. For this purpose, a method to coat graphene ink over a carbon-fiber brush substrate (referred to as Gr-Brush) was optimized and a 1:3 (w/w) Nafion®:graphene ratio increased the H2O2 accumulation yield by 40% (4.23 mg-H2O2 L−1 cm−2), as compared to an uncoated brush. Such improvement was attributed to the higher electroactive surface area and conductivity of Gr-Brush, a fact confirmed by cyclic voltammetry and impedance measurements. Due to a remarkable raise of OH production during the electro-Fenton (EF) process, the phenol degradation rate more than doubled and the mineralization yield increased from 78% (final total organic carbon, TOC, concentration of 5.28 mg-C L−1) with an uncoated brush to 98.5% (final TOC concentration of 0.34 mg-C L−1) with Gr-Brush, following 6 h of EF treatment. Furthermore, the energy required to achieve 40% of phenol mineralization with Gr-Brush was as low as 0.10 kWh g-1 TOC, which outcompeted any other existing graphene-based carbon cathode material coated with either electrochemically-exfoliated graphene (e.g., 0.20 kWh g-1 TOC with carbon cloth) or reduced graphene oxide (rGO) (e.g., 0.53 kWh g-1 TOC with carbon felt), a crucial feature for prospective applications of the novel electrode.

Flexible electrodes for supercapacitors assembled with NiOx(OH)y nanoflakes on H-plasma nanosculptured carbon fiber patches

A surface nanosculpturing is performed on twill wave carbon fibers patches by means of hydrogen plasma treatments in a dual-mode MW-RF CVD reactor. A tufts-like texture is realized on the surface of the single fibers of the patches that show an enhanced electrochemical reactivity and capacitive behavior with respect to the pristine material. The nanostructured carbon fiber fabrics are successfully used as support for the electrochemical growth of nickel species nanoflakes. The hybrid NiOx(OH)y-carbon fibers electrodes exhibit remarkable increases of both capacitive and pseudo-capacitive currents up to specific capacitance values of 1050 F g−1. Charge storage capability given by the coupling of Ni-species and etched carbon fibers is preserved after long time cycling and is also maintained after mechanical deformation, making such composite systems promising as suitable electrode materials for flexible energy storage devices.

High Sensitivity and Fast Oxidation of Caffeine in Coffee and Theophylline at Nanostructured Electrodes

AbstractSignificantly higher than previously reported sensitivity was achieved in the electrochemical determinations of caffeine (CA) and theophylline (TP) at a nanostructured carbon fiber electrode (CFE) sensor by fast scan voltammetry (FSV), where apparent catalysis of the oxidation was observed. For CA the oxidation was reversible and the oxidation potential in aqueous solutions was similar to the potentials reported from cyclic voltammetry (CV) in aprotic solvents, indicating similar oxidation pathways, forming CA radicals. For TP, the reversible oxidation potential was higher, in agreement with TP structure. Formal potentials in aqueous solutions that have been previously unavailable from electrochemistry of CA and TP were thus obtained. In the determinations of CA and TP, sensitivity and linear dynamic range (LDR) in FSV were 1.84 mA cm−2 µM−1 and 0.20–22.0 µmol L−1 and 1.46 mA cm−2 µM−1 and 0.50–30.0 µmol L−1, respectively. FSV determination of CA in coffee sample is demonstrated and the results are in agreement with the results obtained by HPLC‐UV.

Enhanced osteogenic and selective antibacterial activities on micro-/nano-structured carbon fiber reinforced polyetheretherketone.

Carbon fiber reinforced polyetheretherketone (CFRPEEK) possesses a similar elastic modulus to that of human cortical bone and is considered as a promising candidate to replace metallic surgical implants. However, the bioinertness and deficiency of antibacterial activities impedes the application of CFRPEEK as orthopedic and especially oral implants. In this work, dual zinc and oxygen plasma immersion ion implantation (Zn/O-PIII) is applied to modify CFRPEEK, achieving both zinc incorporation and introduction of unique micro-/nano-structures on the surface. Scanning electron microscopy (SEM) observation reveals the formation of micro-pits with the size of around 800 nm on the CFRPEEK surface. X-ray photoelectron spectroscopy (XPS) test results confirm the existence of ZnO on the near surface. In vitro cell adhesion, viability assay, and real-time PCR analyses disclose enhanced adhesion, proliferation, and osteo-differentiation of mouse osteoblasts (MC3T3-E1) and rat bone mesenchymal stem cells (bMSCs) on the structured surface. Furthermore, the multilevel structures on CFRPEEK exhibit great antibacterial activity to biofilm-positive Staphylococcus aureus (ATCC 25923), MRSA (ATCC 43300) and Staphylococcus epidermidis (ATCC 35984) while show no obvious inhibition to Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and biofilm-negative Staphylococcus epidermidis (ATCC 12228). The obtained results indicate that the CFRPEEK surface with specific biological properties can be enhanced by zinc incorporation and multilevel structure introduction, through which the application of CFRPEEK to orthopedic and dental implants can be further broadened.

Nanostructured Carbon Fibers for the Oxygen Reduction Reaction

Despite efforts to obtain the optimal carbon electrocatalyst while taking advantage of carbon’s desirable properties, i.e. high conductivity, large surface area, and low cost, the challenge remains to create an ideal material that possesses all required properties such as durability, efficient mass-transport, anchoring sites for nucleation of nanoparticles, and catalytically active sites. In this work, we present the electrocatalytic activity of nanostructured carbon fibers (NCF) for the oxygen reduction reaction. Synthesis of NCF was achieved via a polymer templating technique of nitrogen-rich polymer (PAN) along with a rigid sacrificial polymer (Nafion®). The pyrolysis process of these precursors results in the decomposition of the sacrificial polymer resulting in the formation of intra-fiber micro/mesopores with controllable surface areas ranging from 100-1500 m2/g [1]. Our results show that depending on the porosity and surface area of the NCF, the electrocatalyst exhibits selectivity towards either the two-electron process generating hydrogen peroxide or the four-electron reduction of oxygen to water. In addition to the tunability of these materials, the controlled 3D morphology facilitating reactant and product transport, high electronic conductivity, high double layer capacitance, enhanced durability, and large concentration of heteroatom doped sites which can function as active sites or as anchors for the nucleation of metal catalyst nanoparticles make CNF an attractive alternative to replace precious metal catalysts for hydrogen peroxide production and four-electron oxygen reduction in fuel cells. 1. Tran, C. and V. Kalra, Fabrication of porous carbon nanofibers with adjustable pore sizes as electrodes for supercapacitors. Journal of Power Sources, 2013. 235: p. 289-296.

Facile synthesis of three-dimensional structured carbon fiber-NiCo2O4-Ni(OH)2 high-performance electrode for pseudocapacitors.

Two-dimensional textured carbon fiber is an excellent electrode material and/or supporting substrate for active materials in fuel cells, batteries, and pseudocapacitors owing to its large surface area, high porosity, ultra-lightness, good electric conductivity, and excellent chemical stability in various liquid electrolytes. And Nickel hydroxide is one of the most promising active materials that have been studied in practical pseudocapacitor applications. Here we report a high-capacitance, flexible and ultra-light composite electrode that combines the advantages of these two materials for pseudocapacitor applications. Electrochemical measurements demonstrate that the 3D hybrid nanostructured carbon fiber–NiCo2O4–Ni(OH)2 composite electrode shows high capacitance, excellent rate capability. To the best of our knowledge, the electrode developed in this work possesses the highest areal capacitance of 6.04 F cm−2 at the current density of 5 mA cm−2 among those employing carbon fiber as the conductor. It still remains 64.23% at 40 mA cm−2. As for the cycling stability, the initial specific capacitance decreases only from 4.56 F cm−2 to 3.35 F cm−2 after 1000 cycles under a current density of 30 mA cm−2.

Synthesis of nanostructured carbon fibers from chlorohydrocarbons over Bulk Ni-Cr Alloys

The regularities of the formation and morphology of a nanostructured carbon product obtained by the decomposition of 1,2-dichloroethane on alloyed bulk catalysts Ni1 − x Cr x (x = 1–10 at %) at 600°C are considered. The carbon fibers were found to possess a strongly marked segmented structure consisting of regularly alternating friable and dense graphite-like blocks. The proposed mechanism of growth is based on a self-oscillatory process, which is supposed to take place at the surface of the active particles formed as a result of the carbon erosion of a bulk Ni1 − x Cr x alloy.

Electrochemically activated carbon fiber sensors as fast and sensitive adenine metabolite amperometric detectors

A direct and fast voltammetric method of determination of 2,8-dihydroxyadenine (2,8-DHA), with a novel nanostructured carbon fiber sensor (CFS), is revealed in this work. To achieve high sensitivity required in biological determinations, before the determination of 2,8-DHA, carbon fiber sensors were activated by electrochemical pretreatment method. The electrochemical activation process generates a nanostructured carbon fiber surface, which is stable. The high stability of the active surface, and the high reproducibility of the activation process, leads to reproducible and sensitive fast scan voltammetric (FSV) determinations of 2,8-DHA. The 2,8-DHA sensitivity was determined in 31 mM phosphate buffer and Hank’s Balanced Salt solution (HBSS) : phosphate buffer (1:5) pH = 7.4, with different scan rates of 250, 500 and 1000 V/s. The potential window in the determinations was from -1.0 to 1.5 V ( vs . SCE). A high sensitivity of the new method of 2,8-DHA determinations by FSV at 500 V/s was found to be 0.40±0.01 nA µM -1 ( r 2 = 0.998) from the calibration plot of 2,8-DHA, with a linear dynamic range from 1-20 µM, and a limit of detection of 1 µM under physiological conditions.

Nanomolar detection of p-nitrophenol via in situ generation of p-aminophenol at nanostructured microelectrodes

A new method and a new buffer medium, expected to be practical for miniaturized electrochemical immunoassays, were developed for rapid detection of nanomolar levels of p-nitrophenol (p-NP). The method exploits rapid reduction of p-NP to p-aminophenol (p-AP) by fast scan cyclic voltammetry at 500 V s(-1) at nanostructured carbon fiber microdisk electrodes (~7 μm dia.) fabricated from polyacrylonitrile (PAN) fibers. Large surfaces of the nanostructured microdisks facilitate the rapid reduction of p-NP to p-aminophenol (p-AP), as confirmed by the overlap with the analytical signals of the standards, which is then rapidly detected by fast scan cyclic voltammetry. A new 2-amino-2-(hydroxymethyl)propane-1,3-diol (Tris)-HAc buffer medium was developed in order to allow adaptation of this detection strategy to alkaline phosphatase (ALP)-based immunoassays. Tris-HAc is a stable medium, while the traditional Tris-HCl buffer medium produces large residual faradaic currents attributed to chloride oxidation. Addition of sodium acetate to a Tris-HAc buffer medium allows sensitivity enhancement by a factor of 2 to 0.85 nA μM(-1), similar to the best sensitivity reported at the nanostructured PAN carbon fiber microdisk sensors.

Superhydrophobic carbon fiber surfaces prepared by growth of carbon nanostructures and polydimethylsiloxane coating

We prepared nanostructured carbon fiber surfaces using chemical vapor deposition in which Ni nanoparticles were used as carbon nanostructure growth catalysts. The surface of the nanostructured carbon fiber was covered by a thin polydimethylsiloxane film. This surface showed superhydrophobic behavior with a water contact angle close to 170 °C, and its superhydrophobicity was sustained in a wide pH range (1–13). Open image in new window

Permeable porous 1–3 nm thick overoxidized polypyrrole films on nanostructured carbon fiber microdisk electrodes

Ionically conducting 1–3 nm thick porous films of overoxidized polypyrrole (OPPY) were electrodeposited on nanostructured 7 μm diameter carbon fiber microdisk electrodes. The microdisk electrodes were fabricated from two types of polyacrylonitrile (PAN) carbon fibers, PAN T650 and PAN HCB. The electrodes were nanostructured by electrochemical etching of the microdisk electrode surface. Ultrathin porous polypyrrole (PPY) films were electrodeposited by the electropolymerization of pyrrole (PY) to PPY by a short (10 ms) single potential pulse. During the electropolymerization, the polymer “precipitated” on the nanostructured surface producing ultrathin porous film. OPPY films were fabricated by constant potential overoxidation of PPY. In steady-state voltammetry of ferricyanide, the nanostructured electrodes behave as a random array of microscopic nodules and pores. At potential scan rates of 0.050 V s −1 diffusion fields at the 300–600 nm nodules on the 7 μm diameter microdisk electrode overlap. The surface area of the electroactive nanofeatures decreases after deposition of insulating OPPY. Kinetics of ferricyanide at bare and OPPY-coated nanostructured electrodes reflect the electrode surface area, as predicted by the model for charge transfer at a partially blocked surface. A model reflecting the 58–94% coverage of the nanostructured electrodes by OPPY was developed to address the high permeability of the porous OPPY-coated microdisk electrodes.

Rapid measurements of 2,8-dihydroxyadenine (2,8-DHA) with a nanostructured electrochemical sensor in 5-fold diluted supernatants of endothelial cells exposed to oxidative stress

Fast scan cyclic voltammetry (FSV) with a nanostructured carbon fiber sensor (N-CFS) was developed for direct measurements of the purine metabolite 2,8-dihydroxyadenine (2,8-DHA; i.e. 6-amino-1H-purine-2,8-dione) in endothelial cell supernatants as a marker of cell stress. The 2,8-DHA was measured in the supernatant of aortic (AECs) and pulmonary artery endothelial cells (PAECs), which were maintained in Hank's Balanced Salt solution (HBSS) and exposed to physiological oxygen pressures as well as to oxidative stress, hypoxia (specifically 3% O(2) for AECs) and hyperoxia (20% O(2) for PAECs). Dilution of the supernatants with phosphate buffer in the ratio of 1 : 5 allowed the optimization of FSV measurements with the N-CFS in cell supernatants.The LOD for 2,8-DHA was 1 microM and the LDR was 2-15 microM with the sensitivity of (0.34 +/- 0.01) nA microM(-1) (R(2) = 0.99). The changes in 2,8-DHA concentration when the cells were exposed to stress confirm that PAECs can adapt to stress. However, the results also show that the tolerance of AECs to hypoxia is low. Cellular pathways involved in the response of PAECs and AECs to oxidative stress are outlined.

Advantages of Nano Structured Carbon Fibers as Catalyst Support for Membrane-Electrode-Assemblies (MEA) in PEMFC

not Available.