Carbon Fiber Film Research Articles

Design of 3-Dimensional Hierarchical Architectures of Carbon and Highly Active Transition Metals (Fe, Co, Ni) as Bifunctional Oxygen Catalysts for Hybrid Lithium–Air Batteries

Flexible power sources and efficient energy storage devices with high energy density are highly desired to power a future sustainable community. Theoretically, rechargeable metal–air batteries are promising candidates for the next-generation power sources. The rational design of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts with high catalytic activity is critical to the development of efficient and durable metal–air batteries. Herein, we propose a novel strategy to mass synthesize nonprecious transition-metal-based nitrogen/oxygen codoped carbon nanotubes (CNTs) grown on carbon-nanofiber films (MNO-CNT-CNFFs, M = Fe, Co, Ni) via a facile free-surface electrospinning technique followed by in situ growth carbonization. With a combination of the high catalytic activity of Fe-catalyzed CNTs and the efficient mass-transport characteristics of 3D carbon fiber films, the resultant flexible and robust FeNO-CNT-CNFFs exhibit the highest bifunctional oxygen catalytic activities in t...

Experimental demonstration of sequence recognition of serial memristors

The sequence recognition is very essential in mimicking brain’s neocortical function because most of input patterns to brain’s neocortex are dynamically changing over time, not static regardless of time. In this paper, we experimentally demonstrate the sequence recognition for various input sequences using serial memristors, for the first time. In this experiment, the serial memristors are used, which were fabricated with carbon fiber and aluminum film on glass substrate. To verify the sequence recognition, we store the following 3 sequences in the fabricated serial memristors, which are ‘A’→‘B’→‘C’, ‘B’→‘A’→‘C’, and ‘C’→‘B’→‘A’, respectively. By performing this experiment, it is verified the serial memristors are changed to Low Resistance State only when the input sequence matches the stored one. When the input sequence is different from the stored one, the serial memristors remain unchanged. The simple voltage comparator can be used to sense the output voltage to indicate whether the sequence matching happens or not. This experimental demonstration can be very useful to realize memristor crossbars which can process the temporal and sequential patterns in future.

Scalable Fabrication of Nanoporous Carbon Fiber Films as Bifunctional Catalytic Electrodes for Flexible Zn-Air Batteries.

A flexible nanoporous carbon-fiber film for wearable electronics is prepared by a facile and scalable method through pyrolysis of electrospun polyimide. It exhibits excellent bifunctional electrocatalytic activities for oxygen reduction and oxygen evolution. Flexible rechargeable zinc-air batteries based on the carbon-fiber film show high round-trip efficiency and mechanical stability.

Porous carbonized graphene-embedded fungus film as an interlayer for superior Li–S batteries

Graphene-embedded carbon fiber (GFC) film has been fabricated by using filamentous fungus (Aspergillus niger) as carbonizable fibers to drive the graphene nanosheets to embed in the hyphae network system and then carbonizing at 700°C. The molecular structure of the GFC film is primarily composed of aromatic components, and the film is doped by N (8.62%) and O (8.12%) elements. The conductivity of the final product reaches as high as 0.71Scm−1. The GFC film serves as the conductive interlayer to greatly improve the performance of Li–S batteries including capacity retention and rate capability. By inserting the GFC film, the battery can deliver a capacity of ~700mAh g−1 after 300 cycles at 1C. Even performed at 5C, it is able to deliver a reversible capacity of more than 650mAhg−1. This research presents a facile and effective method for the fabrication of superior macroscopic carbon monolith, which holds great potential in other forms of electrochemical energy storage.

Induction of Osteogenic Differentiation of Human Adipose-Derived Stem Cells by a Novel Self-Supporting Graphene Hydrogel Film and the Possible Underlying Mechanism.

Graphene and its derivatives have received increasing attention from scientists in the field of biomedical sciences because of their unique physical properties, which are responsible for their interesting biological functions. With a range of extraordinary properties such as high surface area, high mechanical strength, and ease of functionalization, graphene is considered highly promising for application in bone tissue engineering. Here, we examined the effect of using a self-supporting graphene hydrogel (SGH) film to induce the osteogenic differentiation of human adipose-derived stem cells (hADSCs). In comparison to conventional graphene and carbon fiber films, the SGH film had higher mechanical strength and flexibility. Moreover, we found that the SGH film was nontoxic and biocompatible. Of particular interest is the fact that the film alone could stimulate the osteogenic differentiation of hADSCs, independent of additional chemical inducers. Such effects are stronger for the SGH film than for graphene or carbon fiber films, although the induction capacity of the SGH film is not as high as that of the osteogenic-induced medium. The excellent osteoinductivity of the SGH film is closely related to its remarkable physical properties that include specific nanostructures, surface morphology, strong cell adherence, reasonable surface hydrophilicity, and high protein absorption.

Macroscopically Aligned Graphite Films Prepared from Iodine-Doped Stretchable Polyacetylene Films Using Morphology-Retaining Carbonization.

We prepared graphite films using typical Shirakawa-type and stretchable polyacetylene (PA) films as precursors through a morphology-retaining carbonization. A macroscopically aligned PA film was prepared from the drawable PA film using a mechanical-stretching procedure. The degree of orientation of the aligned PA film was evaluated by measuring polarized infrared absorption spectra and an azimuthal-angle profile of a Laue X-ray diffraction (XRD) pattern. The carbonization was performed from the iodine-doped PA films as precursors at 800 °C. The carbon films were subsequently graphitized at 1400-3000 °C, yielding graphite films with almost the same surface morphology as that of the original PA films and that of the carbon films as precursors. The typical PA film graphitized at 2600 °C exhibited tensile strengths of up to 224 MPa, moduli of up to 10 GPa, and an average electrical conductivity of 2.5 × 10(2) S/cm. In contrast, the graphite film prepared from the stretched PA film presented a Laue XRD pattern in which graphitic crystal structures are aligned parallel to the direction of stretching of the PA film. The anisotropic graphite film showed an enhanced conductivity of up to 1.5 × 10(3) S/cm along the stretching direction. We demonstrated that an iodine-doped PA film is a highly efficient carbon source for producing graphite films with good mechanical and electrical properties. The total yield of a graphite film is as high as 61-74% at up to 3000 °C, which is considerably higher than that of polyacrylonitrile-based carbon fiber and polyimide-based graphite film.

The Design and Preparation of X Band Absorbing Insulation Coatings

According to the principle of electromagnetic wave absorption, functionally reforming thermal insulating materials for building, through designing and theoretically simulating of the λ/4 model, using carbon fiber film, the article has successfully prepared insulation coatings for X-band electromagnetic wave absorption. Result shows, with the thickness of 3.0 mm in 8 ~ 12 GHz band, 100% of bandwidth below-10 dB can be reached. New materials can be used such as the surface of the thermal insulation of buildings and X-band electromagnetic interference protection.

A molecule-imprinted polyaniline membrane modified on carbon fiber for detection of glycine

A layer of L-glycine-molecule-imprinted polyaniline (LMIP-PANI) polymer film has been modified on a carbon fiber electrode for the determination of L-glycine standard samples and L-glycine in cerebrospinal fluid of wistar mice. It has been found that a linear relationship exists between current and concentration for the glycine standard samples in the range of 0-12 μM by using the LMIP-PANI-modified carbon fiber electrode as a sensor. However, there is no any relationship between current and concentration for the carbon fiber electrode modified with no-glycine-molecule-imprinted polyaniline (NIP-PANI). The MIP-PANI- and NIP-PANI-modified carbon fiber films have been characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemistry methods. The investigation shows that the MIP-PANI-imprinted carbon fiber electrode will have a potential application in in-situ monitoring neurotransmitter due to its easy fabrication, low cost, bio-compatibility and flexibility.

Effect of the interfacial adhesion on the tensile and impact properties of carbon fiber reinforced polypropylene matrices

Thermoplastic composites have been applied in a wide variety of industrial products, showing recently a great potential to be used in aeronautical field. The objectives of this work were to evaluate the fiber/matrix interface of carbon fiber reinforced polypropylene-based matrices after tensile and impact tests and also to compare the mechanical test results of the manufactured laminates. The laminates were prepared by stacking carbon fiber fabric style Plain Weave (CF) and films of four different polypropylene matrices, described as (a) polypropylene-PP, (b) polypropylene-polyethylene copolymer-PP-PE, (c) PP-PE with an interfacial compatibilizer-AM1 and (d) PP-PE containing an elastomeric modifier-AM2. The composites were processed using hot compression molding. The mechanical testing results showed that the CF-AM1 laminate family presented the lowest impact strength and the highest tensile strength values when compared to the other laminates. SEM analysis observations of both tensile and impact fractured specimens of the CF-PP/PE-AM1 specimens revealed a stronger fiber/matrix interface. The CF-PP/PE-AM2 laminate showed a lower tensile strength and higher impact strength values when compared to the CF-PP/PE-AM1 one. PP-PE and PP laminates presented the lowest impact strength values.

Composite hydrophone devices coupling piezoelectricity and tensegrity

The concept of tensegrity as conceived by Buckminster Fuller has been incorporated into a passive hydrophone device. Tensegrity is described as the physical phenomenon that produces a stable geometric structure using solid compressional elements arranged in tandem with flexible tensional cables. In the devices built by the authors, six PZT 5HTM bars acting as compressional elements in the tensegrity structure have been coupled with tensional bands of either polyaramid or carbon fiber. This stable system is then wrapped with an outer layer of either polyaramid or carbon fiber and rubber film to form a sealed device, which is referred to as a piezotensegritive device in this paper. The six bars are arranged in parallel electrical connectivity for all devices described. The resonant frequency for these devices ranged from 19.5 to 20.3 kHz depending on the material used for wrapping the piezoelectric bars. These devices were also tested in a hydrostatic environment to determine the relevant piezoelectric coefficients. For devices wrapped with carbon fiber, dh peaked at ∼6000 pC/N and gh at ∼ 275 mVm/N. For devices wrapped with polyaramid, dh peaked at ∼2000pC/N and gh at ∼ 100mVm/N. Sensitivities from—182–195 db ref. 1V/μPa were calculated for these devices.

Surface morphology and in-situ observation on the oxidation behavior of carbon materials by laser microscopy

Surface morphology and in-situ observation on the oxidation behavior of same carbon materials were investigated by laser microscope. From the observation of surface morphology of carbon fiber, glass-like carbon, C/C composite, natural graphite and heat-treated polyimide films, samples with relatively flat surface and with homogeneous reflectivity, such as glass-like carbon, natural graphite and heat-treated polyimide films, were found to be observed clearly and accurately with the limit of detectable scale of 0.1μm. From in-situ observation on oxidation behavior in air, oxidation of glass-like carbon was observed to start from surface flaw streaks, from boundary region of filler in matrix and from small pits in the matrix. And oxidation proceeded almost same speed along three dimensional all directions in the sample. On the other hand, oxidation of natural graphite and heat-treated polyimide film started from edge of graphite layer and proceeded two dimensionally along graphite layer plane. Particularly it was found that structure and texture of heat-treated polyimide films affected it's oxidation behavior. It was suggested that structure and texture of carbon materials could be clarified from in-situ observation of oxidation behavior by laser microscope.