Carbon Nanofiber Hybrid Research Articles

Platinum Nanoparticles on Interconnected Ni3P/Carbon Nanotube–Carbon Nanofiber Hybrid Supports with Enhanced Catalytic Activity for Fuel Cells

AbstractA new class of hybrid support is prepared by chemical vapor deposition of acetylene yielding carbon nanofibers (CNFs) on electrolessly plated Ni3P on carbon nanotubes (Ni3P/CNT). The as‐prepared Ni3P/CNT–CNF hybrid is used to support platinum nanoparticles, produced by the microwave‐assisted ethylene glycol reduction method, as an electrocatalyst (Pt/Ni3P/CNT–CNF). The as‐prepared Ni3P/CNT–CNF hybrid and Pt/Ni3P/CNT–CNF catalyst are characterized by SEM, TEM, XRD, and thermogravimetric analysis. Electrochemical evaluations of the electrocatalyst are performed for methanol oxidation and oxygen reduction reactions. The electrochemical active surface area of Pt/Ni3P/CNT–CNF, evaluated both by hydrogen adsorption cyclic voltammetry (CV; 95 m2 g−1) and CO anodic stripping CV (106 m2 g−1), is higher than that of a Pt/CNT benchmark. Electrochemical evaluation of methanol oxidation and oxygen reduction reactions indicate that as‐prepared Pt/Ni3P/CNT–CNF shows enhanced activity relative to that of commercial Pt/C‐JM and Pt/CNT. The superior performance of as‐prepared Pt/Ni3P/CNT–CNF is mostly attributed to the improved electron transfer and facilitated mass transport originating from the tailor‐made Ni3P/CNT–CNF hybrid support.

Facile one-pot synthesis of graphene-porous carbon nanofibers hybrid support for Pt nanoparticles with high activity towards oxygen reduction

Graphene-porous carbon nanofiber (G-PCNF) and Graphene-carbon nanofiber (G-CNF) hybrid materials were prepared by the one-pot modified Hummers method followed by thermal annealing as the unique Pt nanoparticles supports for oxygen reduction reaction (ORR). Particularly, 1D PCNF and CNF can be spacers for 2D graphene (G) to make full utilization of the high intrinsic surface area of graphene and the Pt nanoparticles can be uniformly deposited on the hybrid supports, resulting in excellent activity for ORR. The newly developed Pt/G-PCNF and Pt/G-CNF catalysts exhibit higher activity compared to the Pt/G catalyst. The electrochemical activity and durability of Pt/G-PCNF as well as the commercial catalyst Pt/C (JM20) were also researched. The ORR results show that the onset potential of Pt/G-PCNF is 38mV higher than JM20 and the mass activity (at 0.8V) is twice higher than JM20. Pt/G-PCNF also demonstrates better stability, maintaining 50.4% of its electrochemical active surface area (ECSA) after accelerated durability testing (ADT) whereas JM20 only retain 17.0%. Furthermore, the half-wave potential of Pt/G-PCNF loses about only 9mV, significantly superior to the 154mV half-wave potential loss for JM20. These results indicate that G-PCNF can be a promising candidate as highly promising class of catalyst supports for the improvement of electrochemical activity of proton exchange membrane fuel cells (PEMFCs).

Tailoring of interface of polypropylene/polystyrene/carbon nanofibre composites by polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene

Mechanical and physical properties of polypropylene (PP)/polystyrene (PS) blend, PP/PS/polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) ternary blend and their composites with carbon nanofibers (CNF) were investigated. Composites of ternary blend exhibited superior properties compared to those of binary blends. Mechanical performance of nanocomposites was intimately related to their phase morphology. PP/PS/SEBS/0.1 wt% CNF hybrid composites exhibited excellent impact strength (Four-fold increase compared to PP/PS blend) and ductility (12-fold increase in elongation at break, with respect to PP/PS blend). Moreover, these composites displayed good tensile strength and modulus (15% increase in Young's modulus, compared to PP/PS/SEBS blend) and are suitable for various end-use applications including automobile applications. Although crystallinity of PP phase is decreased by the incorporation of CNF, thermal stability of the composites remained almost unaffected. Contact angle measurements revealed that ternary composites exhibited maximum hydrophobicity.

Oxygen Vacancy-Induced Structural, Optical, and Enhanced Supercapacitive Performance of Zinc Oxide Anchored Graphitic Carbon Nanofiber Hybrid Electrodes.

Zinc oxide (ZnO) nanoparticles (NPs) anchored to carbon nanofiber (CNF) hybrids were synthesized using a facile coprecipitation method. This report demonstrates an effective strategy to intrinsically improve the conductivity and supercapacitive performance of the hybrids by inducing oxygen vacancies. Oxygen deficiency-related defect analyses were performed qualitatively as well as quantitatively using Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. All of the analyses clearly indicate an increase in oxygen deficiencies in the hybrids with an increase in the vacuum-annealing temperature. The nonstoichiometric oxygen vacancy is mainly induced via the migration of the lattice oxygen into interstitial sites at elevated temperature (300 °C), followed by diffusion into the gaseous phase with further increase in the annealing temperature (600 °C) in an oxygen-deficient atmosphere. This induction of oxygen vacancy is corroborated by diffuse reflectance spectroscopy, which depicts the oxygen-vacancy-induced bandgap narrowing of the ZnO NPs within the hybrids. At a current density of 3 A g(-1), the hybrid electrode exhibited higher energy density (119.85 Wh kg(-1)) and power density (19.225 kW kg(-1)) compared to a control ZnO electrode (48.01 Wh kg(-1) and 17.687 kW kg(-1)). The enhanced supercapacitive performance is mainly ascribed to the good interfacial contact between CNF and ZnO, high oxygen deficiency, and fewer defects in the hybrid. Our results are expected to provide new insights into improving the electrochemical properties of various composites/hybrids.

Synthesis of MoSe2/Carbon Nanofibers Hybrid and Its Hydrogen Evolution Reaction Performance

We present a facile method of growing MoSe2 on carbon nanofibers (CNFs) via chemical vapor deposition (CVD). Polyacrylonitrile (PAN) was electrospun into nanofibrous mats and graphitized to form CN...

Excellent mechanical properties of carbon fiber semi-aligned electrospun carbon nanofiber hybrid polymer composites

The excellent mechanical properties of carbon fiber fabric hybrid polymer composites is achieved by integrating continuous semi-aligned carbon nanofiber layers in the interlaminar region between carbon fiber fabric plies.

Facile and gram-scale synthesis of metal-free catalysts: toward realistic applications for fuel cells.

Although numerous reports on nonprecious metal catalysts for replacing expensive Pt-based catalysts have been published, few of these studies have demonstrated their practical application in fuel cells. In this work, we report graphitic carbon nitride and carbon nanofiber hybrid materials synthesized by a facile and gram-scale method via liquid-based reactions, without the use of toxic materials or a high pressure-high temperature reactor, for use as fuel cell cathodes. The resulting materials exhibited remarkable methanol tolerance, selectivity, and stability even without a metal dopant. Furthermore, these completely metal-free catalysts exhibited outstanding performance as cathode materials in an actual fuel cell device: a membrane electrode assembly with both acidic and alkaline polymer electrolytes. The fabrication method and remarkable performance of the single cell produced in this study represent progressive steps toward the realistic application of metal-free cathode electrocatalysts in fuel cells.

Synthesis of hybrid carbon nanofiber–graphene nanosheet materials with different morphologies and comparison of their performance as anodes for lithium-ion batteries

Hybrid carbon nanofiber–graphene nanosheet (CNF–GN) materials with different morphologies were synthesized by chemical vapor deposition using ethyne (C2H2) as the carbon source and Ni as a catalyst. By adjusting the C2H2 flow rate, hybrid materials with different CNF diameters and CNF/GN weight ratios were prepared. The cycling performance and rate capability of the products as electrodes for lithium-ion batteries were investigated and compared. We found that not all of the CNF–GN anodes we synthesized exhibited better lithium storage properties than a GN electrode. Only materials with a relatively smaller CNF diameter and a lower CNF/GN weight ratio in GN-supported CNF architectures achieved high performance for reversible lithium storage. The reasons for the differences in electrochemical performance of our CNF–GN electrodes are explained.

Fabrication and characterization of vapor grown carbon nanofiber/epoxy magnetic nanocomposites

Co3O4 nanoparticle‐decorated vapor‐grown carbon nanofiber (VGCNF) hybrid materials were successfully synthesized and served as nanofillers for preparing magnetic epoxy (EP) nanocomposites. The Co3O4‐decorated VGCNF (Co3O4‐VGCNF) and Co3O4‐VGCNF/EP nanocomposites were systematically and explicitly investigated by combined analytical techniques. The composition and phase structure of Co3O4‐VGCNF hybrid materials were characterized by Fourier transform infrared spectroscopy and X‐ray diffraction analyses. The morphology of Co3O4 was investigated using field‐emission scanning electronic microscopy (FE‐SEM). Results revealed the presence of Co3O4 nanoparticles firmly immobilized on VGCNF sidewalls. The tensile mechanical, thermomechanical, and magnetic properties of Co3O4‐VGCNF/EP nanocomposites were also investigated in detail. Results indicated that the tensile strength of Co3O4‐VGCNF/EP nanocomposites (filler = 0.5 wt%) improved by 44.6% compared with that of raw VGCNF/EP nanocomposites (filler = 0.5 wt%). Magnetization measurements revealed that Co3O4‐VGCNF/EP nanocomposites exhibited ferromagnetic behavior, and the saturation magnetization and coercivity of the nanocomposites with 2 wt% of Co3O4‐VGCNF were 0.055 emu g−1 and 0.75 kOe, respectively. POLYM. COMPOS., 37:1728–1734, 2016. © 2014 Society of Plastics Engineers

Facile Fabrication of Binder-free Metallic Tin Nanoparticle/Carbon Nanofiber Hybrid Electrodes for Lithium-ion Batteries

In this work, a Sn nanoparticle (NP)/carbon nanofiber (CNF) hybrid with unique structure has been designed and fabricated via electrospinning and subsequent heat treatment. The cell assembled by the binder-free Sn NP/CNF hybrid demonstrates an effective capacity (46mAhg−1 at 200mAg−1 after 200 cycles) with high coulombic efficiency (up to 99.8%), suggesting a facile strategy for the scalable fabrication of electrochemically stable electrodes for LIBs. For understanding the electrochemical behaviors of the metallic Sn and carbon nanofibers in the lithiation/delithiation process, in situ transmission electron microscopy was applied to study the single hybrid structure. In the first charge/discharge process, real-time size variation of the Sn NP and CNFs was mainly focused, suggesting a two-step lithiation process in the metallic Sn NP. Structural characterization also indicates an irreversible delithiation in a single Sn NP/CNF hybrid structure. The electrochemical performance based on influence of carbonization temperature has also been discussed. The results and fundamental understanding of the lithiation/delithiation in the Sn-based hybrid anodes enables the communities to design flexible high-performance electrodes based on metallic active materials in a rational way.

Sulfur encapsulated in a TiO2-anchored hollow carbon nanofiber hybrid nanostructure for lithium-sulfur batteries.

A hollow carbon nanofiber hybrid nanostructure anchored with titanium dioxide (HCNF@TiO2) was prepared as a matrix for effective trapping of sulfur and polysulfides as a cathode material for Li-S batteries. The synthesized composites were characterized and examined by X-ray diffraction, nitrogen adsorption-desorption measurements, field-emission scanning electron microscopy, scanning transmission electron microscopy, and electrochemical methods such as galvanostatic charge/discharge, rate performance, and electrochemical impedance spectroscopy tests. The obtained HCNF@TiO2-S composite showed a clear core-shell structure with TiO2 nanoparticles coating the surface of the HCNF and sulfur homogeneously distributed in the coating layer. The HCNF@TiO2-S composite exhibited much better electrochemical performance than the HCNF-S composite, which delivered an initial discharge capacity of 1040 mA h g(-1) and maintained 650 mAh g(-1) after 200 cycles at a 0.5 C rate. The improvements of electrochemical performances might be attributed to the unique hybrid nanostructure of HCNF@TiO2 and good dispersion of sulfur in the HCNF@TiO2-S composite.

Highly uniform silicon nanoparticle/porous carbon nanofiber hybrids towards free-standing high-performance anodes for lithium-ion batteries

Novel silicon nanoparticle/porous carbon nanofiber (Si/PCNF) hybrids with high Si loading (52wt.%) have been designed and fabricated through a simple electrospinning. The Si/PCNF of uniform fiber diameter has exhibited high specific surface area and unique porous structure. The continuous three-dimensional porous carbon networks have effectively provided strain relaxation for Si volume expansion/shrinkage during lithium insertion/extraction. In addition, the carbon matrix could largely minimize the direct exposure of Si to the electrolyte, thus substantially improving the structural stability of Si. Moreover, the porous structure could also create efficient channels for the fast transport of lithium ions. As a consequence, this novel Si-based hybrid material has exhibited stable cycling performance (ca. 870mAhg−1 at 0.1Ag−1 after 100 cycles) in the absence of binders and conducting additives, promising great potential as a free-standing anode for lithium ion batteries.

Novel hybrid carbon nanofiber/highly branched graphene nanosheet for anode materials in lithium-ion batteries.

The novel hybrid carbon nanofiber (CNF)/highly branched graphene nanosheet (HBGN) is synthesized via a simple two-step CVD method and its application as the anode material in a lithium-ion battery (LIB) is demonstrated. The CNFs offer a good electrical conductivity and a robust supporting structure, while the HBGNs provide increased Li storage sites including nanoporous cavities, large surface area, and edges of exposed graphene platelets. The hybrid material showed a reversible capacity of 300 mAh g(-1) with excellent cycling stability. Our study provides a new avenue for design and synthesis of carbon-carbon hybrid materials for versatile applications.

Aptamer-functionalized hybrid carbon nanofiber FET-type electrode for a highly sensitive and selective platelet-derived growth factor biosensor.

Precise selectivity and rapid responses to target biomolecules are important in the development of biosensors. In particular, highly sensitive and selective biosensors have been used in clinical treatment to detect factors such as cancer oncoproteins and endocrine disruptors. Herein, highly sensitive liquid electrolyte field-effect transistor (FET) system biosensors were fabricated to detect platelet-derived growth factor (PDGF) using a PDGF-B binding aptamer conjugated with carboxylic polypyrrole-coated metal oxide-decorated carbon nanofibers (CPMCNFs) as the signal transducer. First, CPMCNFs were fabricated using vapor deposition polymerization (VDP) of the carboxylic pryrrole monomer (CPy) on metal oxide-decorated carbon nanofiber (MCNF) surfaces with no treatment for carbon surface functionalization. Furthermore, a 3 nm thick uniformly coated carboxylic polypyrrole (CPPy) layer was formed without aggregation. The CPMCNFs were integrated with the PDGF-B binding aptamer and immobilized on the interdigitated array substrate by covalent anchoring to produce a FET-type biosensor transducer. The PDGF-B binding aptamer conjugated CPMCNF (CPB-Apt) FET sensor was highly sensitive (5 fM) and extremely selective for isoforms of PDGFs. Additionally, the CPB-Apt FET sensor could be reused over a few weeks.

Confine Sulfur in Polyaniline-Decorated Hollow Carbon Nanofiber Hybrid Nanostructure for Lithium–Sulfur Batteries

A polyaniline-decorated hollow carbon nanofiber (HCNF@PANI) hybrid nanostructure was prepared as a conductive matrix for effective trapping of sulfur and polysulfides as a cathode material for Li–S batteries. The synthesized composites were characterized and examined by X-ray diffraction, Fourier transformation infrared spectroscopy, nitrogen adsorption–desorption measurements, field emission scanning electron microscopy, scanning transmission electron microscopy, and electrochemical methods, such as cyclic voltammetry, galvanostatic charge–discharge tests, and rate performance tests. The obtained HCNF@PANI-S composite showed an obvious core–shell structure with a PANI layer coating on the surface of the HCNF, and sulfur homogeneously distributes in the coating layer. The HCNF@PANI-S composite exhibited much better electrochemical performance than the HCNF-S composite, which delivered initial discharge capacity of 960 mAh g–1 and maintained 535 mAh g–1 after 200 cycles at 0.5 C rate. The improvements of electrochemical performances may be attributed to the unique hybrid nanostructure of HCNF@PANI and good dispersion of sulfur in the HCNF@PANI-S composite.

The development, fabrication, and material characterization of polypropylene composites reinforced with carbon nanofiber and hydroxyapatite nanorod hybrid fillers

This study focuses on the design, fabrication, microstructural and property characterization, and biocompatibility evaluation of polypropylene (PP) reinforced with carbon nanofiber (CNF) and hydroxyapatite nanorod (HANR) fillers. The purpose is to develop advanced PP/CNF–HANR hybrids with good mechanical behavior, thermal stability, and excellent biocompatibility for use as craniofacial implants in orthopedics. Several material-examination techniques, including X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, tensile tests, and impact measurement are used to characterize the microstructural, mechanical, and thermal properties of the hybrids. Furthermore, osteoblastic cell cultivation and colorimetric assay are also employed for assessing their viability on the composites. The CNF and HANR filler hybridization yields an improvement in Young’s modulus, impact strength, thermal stability, and biocompatibility of PP. The PP/2% CNF–20% HANR hybrid composite is found to exhibit the highest elastic modulus, tensile strength, thermal stability, and biocompatibility.

Synthesis of Palladium/Helical Carbon Nanofiber Hybrid Nanostructures and Their Application for Hydrogen Peroxide and Glucose Detection

We report on a novel sensing platform for H2O2 and glucose based on immobilization of palladium-helical carbon nanofiber (Pd-HCNF) hybrid nanostructures and glucose oxidase (GOx) with Nafion on a glassy carbon electrode (GCE). HCNFs were synthesized by a chemical vapor deposition process on a C60-supported Pd catalyst. Pd-HCNF nanocomposites were prepared by a one-step reduction free method in dimethylformamide (DMF). The prepared materials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. The Nafion/Pd-HCNF/GCE sensor exhibits excellent electrocatalytic sensitivity toward H2O2 (315 mA M(-1) cm(-2)) as probed by cyclic voltammetry (CV) and chronoamperometry. We show that Pd-HCNF-modified electrodes significantly reduce the overpotential and enhance the electron transfer rate. A linear range from 5.0 μM to 2.1 mM with a detection limit of 3.0 μM (based on the S/N = 3) and good reproducibility were obtained. Furthermore, a sensing platform for glucose was prepared by immobilizing the Pd-HCNFs and glucose oxidase (GOx) with Nafion on a glassy carbon electrode. The resulting biosensor exhibits a good response to glucose with a wide linear range (0.06-6.0 mM) with a detection limit of 0.03 mM and a sensitivity of 13 mA M(-1) cm(-2). We show that small size and homogeneous distribution of the Pd nanoparticles in combination with good conductivity and large surface area of the HCNFs lead to a H2O2 and glucose sensing platform that performs in the top range of the herein reported sensor platforms.

Desirable electrical and mechanical properties of continuous hybrid nano-scale carbon fibers containing highly aligned multi-walled carbon nanotubes

The continuous highly aligned hybrid carbon nanofibers (CNFs) with different content of acid-oxidized multi-walled carbon nanotubes (MWCNTs) were fabricated through electrospinning of polyacrylonitrile (PAN) followed by a series of heat treatments under tensile force. The effects of MWCNTs on the micro-morphology, the degree of orientation and ordered crystalline structure of the resulting nanofibers were analyzed quantitatively by diversified structural characterization techniques. The orientation of PAN molecule chains and the graphitization degree in carbonized nanofibers were distinctly improved through the addition of MWCNTs. The electrical conductivity of the hybrid CNFs with 3wt% MWCNTs reached 26S/cm along the fiber direction due to the ordered alignment of MWCNTs and nanofibers. The reinforcing effect of hybrid CNFs in epoxy composites was also revealed. An enhancement of 46.3% in Young’s modulus of epoxy composites was manifested by adding 5wt% hybrid CNFs mentioned above. At the same time, the storage modulus of hybrid CNF/epoxy composites was significantly higher than that of pristine epoxy and CNF/epoxy composites not containing MWCNTs, and the performance gap became greater under the high temperature regions. It is believed that such a continuous hybrid CNF can be used as effective multifunctional reinforcement in polymer matrix composites.

WO3 nanonodule-decorated hybrid carbon nanofibers for NO2 gas sensor application

WO3 nanonodule-decorated carbon nanofibers (CNFs) of various diameters were fabricated by single-nozzle co-electrospinning using two phase-separated polymer solutions. Using more polyvinylpyrrolidone (PVP) solution decreased the CNF diameter from 130 to 40 nm and increased the Brunauer–Emmett–Teller (BET) surface area from 147 to 276 m2 g−1. A spin-coating method was used to deposit the hybrid CNFs on the sensor substrate to minimize the contact resistance between them. In addition, ultraviolet (UV) irradiation lowered the desorption energy level of the NO2 gas between the transducer materials during the recovery time. As a result, the recovery time decreased to ca. 7 min using UV light with an intensity of 75 mW cm−2. The sensitivity of the hybrid CNF gas sensors increased with decreasing diameter of the CNFs; the minimum detectable level (MDL) was 1 ppm at room temperature for 40 nm hybrid CNFs dispersed uniformly on the electrode. Furthermore, increasing the amount of decorated WO3 nanonodules on the CNF surface enhanced the sensitivity to NO2 gas. The NO2 sensor made with the hybrid CNFs had sensing performance comparable to those made with conventional metal oxide-based nanomaterials and pristine carbon nanotubes (CNTs).

PH-controlled electrocatalysis of amino acid based on electrospun cobalt nanoparticles-loaded carbon nanofibers

Carbon nanofibers (CNFs) decorated with cobalt nanoparticles (CoNPs) were synthesized by a two-step procedure consisting of electrospinning and thermal treatment. The CoNPs–CNFs hybrid materials were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction spectrum, which showed that the CoNPs were of the cubic phase and well dispersed on the surface of CNFs. The electrochemical behaviors and electrocatalytic performances towards the oxidation of the amino acids at the CoNPs–CNFs modified glassy carbon electrode (GCE) were evaluated. The results indicated that the CoNPs–CNFs showed good electrocatalytic activity towards the oxidation of cysteine and N-acetyl cysteine, and the current response of the CoNPs–CNFs/GCE was sensitive to pH of the electrolyte solution. The peak current was quite large at pH 13.0 but greatly suppressed at pH 7.5, suggesting that the electrode can realize pH-controlled oxidation of amino acids. The good catalytic activity, well conductivity and high stability made the CoNPs–CNFs promising materials for constructing an enzymeless sensor.