Carbon Nanofiber Membranes Research Articles

Synergetic interface between NiO/Ni3S2 nanosheets and carbon nanofiber as binder-free anode for highly reversible lithium storage

A novel heterostructure of NiO/Ni3S2 nanoflake is synthesized and composited with carbon nanofibers (CNF) membrane. NiO/Ni3S2 nanoflakes are homogeneously dispersed in CNF network, herein, NiO/Ni3S2 like leaf and CNF like branch. Carbon nanofibers network efficiently prevents the pulverization and buffers the volume changes of NiO/Ni3S2, meanwhile, NiO/Ni3S2 nanoflakes through the conductive channels of carbon nanofibers own improved Li+ diffusion ability and structural stability. The capacity of NiO/Ni3S2/CNF reaches to 519.2 mA g−1 after 200 cycles at the current density of 0.5 A g−1 while NiO/Ni3S2 fades to 71 mAh g−1 after 40 cycles. Owing to the synergetic structure, the resultant binder-free electrode NiO/Ni3S2/carbon nanofibers shows an excellent reversible lithium storage capability.

Lotus root-like porous carbon nanofiber anchored with CoP nanoparticles as all-pH hydrogen evolution electrocatalysts

The development of highly active and cost-effective hydrogen evolution reaction (HER) catalysts is of vital importance to addressing global energy issues. Here, a three-dimensional interconnected porous carbon nanofiber (PCNF) membrane has been developed and utilized as a support for active cobalt phosphide (CoP) nanoparticles. This rationally designed self-supported HER catalyst has a lotus root-like multichannel structure, which provides several intrinsic advantages over conventional CNFs. The longitudinal channels can store the electrolyte and ensure fast ion and mass transport within the catalysts. Additionally, mesopores on the outer and inner carbon walls enhance ion and mass migration of the electrolyte to HER active CoP nanoparticles, thus shortening the ion transport distance and increasing the contact area between the electrolyte and the CoP nanoparticles. Moreover, the conductive carbon substrate provides fast electron transfer pathways by forming an integrated conductive network, which further ensures fast HER kinetics. As a result, the CoP/PCNF composites exhibit low onset-potentials (−20, −91, and −84 mV in 0.5 M H2SO4, 1 M PBS, and 1 M KOH, respectively). These findings show that CoP/PCNF composites are promising self-supporting and high-performance all-pH range HER catalysts.

Highly efficient capacitive deionization electrodes from electro spun carbon nanofiber membrane containing reduced graphene oxide and carbon nanotubes

Highly efficient capacitive deionization electrodes from electro spun carbon nanofiber membrane containing reduced graphene oxide and carbon nanotubes

Flexible polypyrrolone-based microporous carbon nanofibers for high-performance supercapacitors.

Flexible materials have drawn considerable attention due to the demand for wearable and flexible electronic products. Seeking new kinds of precursors for preparing carbon nanofibers with good flexibility for high-performance supercapacitors is a hot issue. In this work, a flexible polypyrrolone (BBB)/polyimide (PI) composite-based carbon nanofiber membrane (PBPICF) is prepared by a facile electrospinning and carbonization process. The PBPICF membranes exhibit a three-dimensional (3D) porous, fluffy and self-standing structure with good mechanical performance and flexibility, and can be arbitrarily bent and folded. PBPICF-65-35 (consisting of BBB (65 wt%) and PI (35 wt%)) exhibits a high specific capacitance of 172.44 F g−1 in 6 M KOH aqueous solution, which is two-fold more than that of commercial polyacrylonitrile-based carbon nanofibers. In addition, PBPICF-65-35 also displays good power density (90 W kg−1) and energy density (19.4 W h kg−1), and the capacitance remains at 96% even after 10 000 cycles at 1.0 A g−1. Therefore, the simple preparation and good capacitance performance of PBPICFs make them a promising binder-free electrode for wearable supercapacitors.

Enhanced electrochemical performance of an electrospun carbon/MoO2 composite nanofiber membrane as self-standing anodes for lithium-ion batteries

A flexible carbon nanofiber membrane (NFM) containing uniformly dispersed MoO2 nanoparticles is facilely fabricated via electrospinning and subsequent controlled reduction-carbonization. This NFM is used directly as a binder-free anode in lithium-ion batteries (LIBs). The self-standing carbon/MoO2 (C/MoO2) NFM electrode has a good capacity retention, a satisfactory rate capability and a high reversible capacity of 811 mAh g–1 after 100 cycles at a current density of 100 mA g–1, which is superior to most other MoO2-based anodes. The superior electrochemical properties of the resultant C/MoO2 NFM are attributed to the cooperative effects from the excellent conductivity of the carbon nanofiber matrix, the high electrochemical performance of MoO2, the unique one-dimensional nanofiber structure and the three-dimensional porous network structure. The present C/MoO2 NFM may be an attractive candidate as an anode material for LIBs.

Polyimide-derived carbon nanofiber membranes as anodes for high-performance flexible lithium ion batteries

The strategy of N-doping in carbon materials could provide additional Li-ion storage sites to improve their electrochemical properties. Heteroatom-containing polymers could serve as good precursors to fabricate doped carbons due to the capability to in situ dope heteroatoms into the structures. In this work, electrospun heterocyclic polyimide (PI) nanofiber membranes containing biphenyl and pyrimidine rings were carbonized to fabricate freestanding and flexible heteroatoms-containing carbon membranes. When the polymer membranes were subjected to various calcination temperatures (from 550°C to 950°C) and durations (0.5-10h), the structural evolutions strongly affect their electrochemical properties as anodes for lithium ion batteries. It demonstrated that the reversible specific capacity of obtained sample treated at 650°C for 3h could achieve 695mAh/g at 0.1A/g and retain 245mAh/g at 1.5A/g after 300 cycles. Furthermore, the electrospun membrane maintains a good electrochemical performance at bending state as a flexible electrode.

Brush-Like Cobalt Nitride Anchored Carbon Nanofiber Membrane: Current Collector-Catalyst Integrated Cathode for Long Cycle Li-O2 Batteries.

To achieve a high reversibility and long cycle life for lithium-oxygen (Li-O2) batteries, the irreversible formation of Li2O2, inevitable side reactions, and poor charge transport at the cathode interfaces should be overcome. Here, we report a rational design of air cathode using a cobalt nitride (Co4N) functionalized carbon nanofiber (CNF) membrane as current collector-catalyst integrated air cathode. Brush-like Co4N nanorods are uniformly anchored on conductive electrospun CNF papers via hydrothermal growth of Co(OH)F nanorods followed by nitridation step. Co4N-decorated CNF (Co4N/CNF) cathode exhibited excellent electrochemical performance with outstanding stability for over 177 cycles in Li-O2 cells. During cycling, metallic Co4N nanorods provide sufficient accessible reaction sites as well as facile electron transport pathway throughout the continuously networked CNF. Furthermore, thin oxide layer (<10 nm) formed on the surface of Co4N nanorods promote reversible formation/decomposition of film-type Li2O2, leading to significant reduction in overpotential gap (∼1.23 V at 700 mAh g-1). Moreover, pouch-type Li-air cells using Co4N/CNF cathode stably operated in real air atmosphere even under 180° bending. The results demonstrate that the favorable formation/decomposition of reaction products and mediation of side reactions are hugely governed by the suitable surface chemistry and tailored structure of cathode materials, which are essential for real Li-air battery applications.

Route to sustainable lithium-sulfur batteries with high practical capacity through a fluorine free polysulfide catholyte and self-standing Carbon Nanofiber membranes

We report on a new strategy to improve the capacity, reduce the manufacturing costs and increase the sustainability of Lithium-Sulfur (LiS) batteries. It is based on a semi-liquid cathode composed of a Li2S8 polysulphide catholyte and a binder-free carbon nanofiber membrane with tailored morphology. The polysulphides in the catholyte have the dual role of active material and providing Li+-conduction, i.e. no traditional Li-salt is used in this cell. The cell is able to deliver an areal capacity as high as 7 mAh cm−2, twice than that of commercial Lithium-ion batteries (LiBs) and 2–4 times higher than that of state-of-the-art LiS cells. In addition, the battery concept has an improved sustainability from a material point of view by being mainly based on sulfur and carbon and being completely fluorine-free, no fluorinated salt or binders are used, and has potential for upscaling and competitive price. The combination of these properties makes the semi-liquid LiS cell here reported a very promising new concept for practical large-scale energy storage applications.

Effect of high temperature treatment on electrochemical properties of carbon nanofiber membrane

In this study, polyacrylonitrile was used as the nanofiber membrane material. Through A two-stage continuous process, namely, oxidation process and carbonization and activation process, an activated nanofiber membrane material was fabricated. Subsequently, the membrane underwent high-temperature heat treatment (1100-1500 °C) to explore the effect of temperature on its properties. Charge/discharge rate was employed to determine the capacitance retention ratio to evaluate the applicability of the fabricated membrane in high-power super capacitor electrodes. The results revealed that in the treated membrane, the lattice size increased from 1.24 nm to between 3.20 and 4.72 nm. In addition, the volume resistivity was reduced from 6 Ω-cm to between 9.70E-2 and 3.85E-2 Ω-cm, substantially improving the electric conductivity. The activated carbon nanofiber membrane treated with high temperature at 1100 °C exhibited the highest capacitance of 704 F/g at a scan rate of 5 mV/s.

Electrospun lignin carbon nanofiber membranes with large pores for highly efficient adsorptive water treatment applications

The adsorption performance of activated carbon largely depends on its physical and chemical properties. Carbon formed into nanofiber mats/membranes has the potential to improve the performance of traditional activated carbon. For this study, electrospun carbon nanofiber membranes were prepared from lignin or polyacrylonitrile (PAN). These carbon nanofibers, along with PAN microfibers (MF), and a commercial granulated activated carbon (GAC), were evaluated by determining methylene blue adsorption capacity, iodine number, kinetics of adsorption, efficacy in removing organic acids from a contaminated water and flow permeability. Results suggest that the electrospun lignin nanofiber membranes offer approximately 10-times higher adsorption capacity, provide two-times faster adsorption kinetics, and six-times higher permeability than traditional activated carbon sources. A high specific surface area (583m2/g), larger average pore diameter (3.5nm), and high pore volume (0.29cm3/g) for the lignin nanofibers relative to other carbon adsorbents provided the opportunity to capture more contaminants in shorter residence times, making them highly efficient for adsorptive water treatments. A preliminary energy and economic evaluation for implementation of the lignin carbon nanofiber membranes into a water treatment process showed that lignin nanofibers could reduce energy consumption by 87%.

Rough-surfaced molybdenum carbide nanobeads grown on graphene-coated carbon nanofibers membrane as free-standing hydrogen evolution reaction electrocatalyst

A novel free-standing pie-like paper electrode composed of Mo2C nanobeads on graphene-coated carbon nanofibers (G-CNF) membrane was rationally designed as advanced electrocatalyst for hydrogen evolution reaction (HER). A thin layer of graphene is coated on the surface of CNF membrane, forming a “crust” on fibrous web architecture. The unique design of the all-carbon membrane, which is a 3D interconnected conductive framework of nanofibers, reduces the resistance of electron and ion transport during the electrocatalyzing process. With G-CNF performing as support, well-shaped Mo2C nanobeads were immobilized on the fibers through hydrothermal and calcination procedures, offering rich catalytic sites on the exposed rough surface. Owing to all these merits, the composite membrane of Mo2C-G-CNF exhibits high HER catalytic activity with onset potential of 115 mV in acidic solution and 108 mV in basic solution. Furthermore, the good durability in both acidic and basic environment guarantees its practical application as free-standing electrode material.

Highly flexible NiCo2O4/CNTs doped carbon nanofibers for CO2 adsorption and supercapacitor electrodes

Controllable synthesis of carbon nanofibers (CNFs) with hierarchical porosity and high flexibility are extremely desirable for CO2 adsorption and energy storage applications. Herein, we report a nickel cobaltite/carbon nanotubes doped CNFs (NiCo2O4/CNTs CNFs) mesoporous membrane that shows well-developed flexibility, tailored pore structure, hydrophobic character, and high stability. Ascribed to these unique features, NiCo2O4/CNTs CNFs membrane shows high CO2 capture of 1.54mmol/g at 25°C and 1.0bar, and electrochemical measurements for supercapacitors exhibit good performance with specific capacitances of 220F/g (in 1M KOH) at a current density of 1A/g. The successful synthesis of such hybrid membrane provides new insight into development of various multifunctional applications.

A flexible nanofiber-based membrane with superhydrophobic pinning properties

A nanofiber-based TiO2(B)/carbon nanofiber membrane has been synthesized by a facile and effective route that incorporates electrospinning approach with hydrothermal method. The prepared membrane shows high flexibility and hydrophilicity. After treatment with a low surface energy fluorosilane, the obtained superhydrophobic surface endows the membrane a high adhesive force due to the hybrid microstructure of TiO2(B) nanotubes and nanoplates on fibers. A water droplet on the surface of the membrane appears spherical in shape, which cannot roll off even when the membrane is bent and turned upside down. When a water droplet dropped from a certain height above the tilt membrane, the rolled water droplet can be stopped after a small displacement. In addition, a 12μl water droplet can be quickly captured from a hydrophobic surface by curvature change of the superhydrophobic TiO2(B)/carbon nanofiber membrane. The membrane with excellent static and dynamic pinning performance to water may be expected to apply to biomedical and microfluidic devices.

A highly flexible and conductive graphene-wrapped carbon nanofiber membrane for high-performance electrocatalytic applications

Graphene-wrapped electrospun carbon nanofiber membranes with greatly improved electrical conductivity have been synthesized through an effective surface-induced assembly strategy.

Highly porous cellulosic nanocomposite membranes with enhanced performance for forward osmosis desalination

Novel highly porous carbon nanofiber (CNF)/cellulosic membranes were fabricated for water desalination using the forward osmosis (FO) process. Neat, carboxylic and amine functionalized CNFs were used for modification of cellulosic membranes. The prepared FO membranes were characterized by field emission scanning electron microscope (FESEM), atomic force microscope (AFM), hydrophilicity analysis and tensile strength. The hydrophilicity and porosity of modified cellulosic membranes were significantly enhanced. The membrane modified by amine functionalized CNFs exhibited the most promising results by showing high FO flux and low reverse solute flux. The osmotic water flux of the amine functionalized CNF membrane reached to 18L/m2h when the feed and draw solutions were 10mM and 1M NaCl solutions, respectively. This result is above 2 times higher than FO water flux of the neat cellulosic membrane. The reverse salt flux of the amine functionalized CNF membrane was less than 0.5g/m2h which is very low compared to the commercial cellulose triacetate (CTA) membrane. Surprisingly, the aforementioned membranes show a water flux of about 15L/m2h under the FO mode when tested for seawater desalination. The structural parameter of membranes decreased significantly with the addition of functionalized CNFs in the casting solution. Furthermore, the tensile strength measurement of the fabricated membranes with CNFs is also greater than that of the unmodified membrane.

Controllable synthesis of carbon-coated Sn⿿SnO2⿿carbon-nanofiber membrane as advanced binder-free anode for lithium-ion batteries

A carbon-coated composite consisting of Sn, SnO2, and porous carbon-nanofiber membrane (Sn⿿SnO2⿿CNF@C) was successfully prepared via electrospinning followed by carbonization and low-temperature hydrothermal treatment. The thickness of the carbon overlayer formed by using sucrose as the carbon source could be well controlled by adjusting the sucrose concentration. The three-dimensional (3D) nanofiber network structure allowed the Sn⿿SnO2⿿CNF@C membrane to be used directly as an anode in lithium-ion batteries without adding any polymer binders or electrical conductors. The composite electrodes of this material exhibited a high discharge capacity of 712.2mAhg⿿1 at a high current density of 0.8Ag⿿1 after 200 cycles, as well as good cycling stability and excellent rate capability, which can be ascribed to the improved electrochemical properties of the Sn⿿SnO2 particles provided by the protective carbon coating and the 3D carbon nanofiber membrane. The composite can thus be widely used as an advanced binder-free anode material in high-current rechargeable lithium-ion batteries and extended to the fabrication of flexible electrodes.

Electrical conductive and structural characterization of electrospun aligned carbon nanofibers membrane

In the paper, the membrane with aligned carbon nanofibers (CNFs) was prepared by electrospinning, stabilization and carbonization. The electrical conductivity of the membrane was examined. The effect of stabilization temperature and drum rotating speed on the conductivity of aligned CNFs membrane was discussed. The study on stabilization temperature showed that 250 °C was optimum parameter for preparing fibrous aligned CNFs membrane with uniform diameter, but 270 °C was benefit to fiber conglutination which could improve the electrical conductivity of the final CNFs membrane. The study on drum rotating speed showed that when drum rotating speed reached 2500 rpm, graphitic structures with parallel graphene sheets could be observed and 1000, 1500 and 2000 rpm CNFs membranes presented desirable conductivity with only 1.3 Ω·cm in the parallel directions and 2.0 Ω·cm in the perpendicular direction.

Carbon–silica composite nanofiber membrane for high flux separation of water-in-oil emulsion – Performance study and fouling mechanism

Abstract A flexible, hydrophobic and oleophilic carbon nanofiber membrane was prepared from electrospinning for cross-flow filtration of water-in-oil emulsion under various operating conditions. Experimental results show that the membrane has a high throughput of clean oil at low pressure. Furthermore, the membrane performance in terms of permeate flux was governed by the operating pressure and cross-flow velocity. The membrane has a water breakthrough pressure of 0.206 bar under constant cross-flow velocity. The investigation of membrane fouling mechanisms using pore blocking models and resistance model reveals that the membrane experiences either of external or internal fouling or a combination of both under different operating conditions. Using the contour plot analysis, it was suggested that the optimum operating conditions for the membrane to perform efficiently shall be at high cross-flow velocity and at low pressure (between 0.07 and 0.206 bar).

Controllable preparation of multi-dimensional hybrid materials of nickel-cobalt layered double hydroxide nanorods/nanosheets on electrospun carbon nanofibers for high-performance supercapacitors

Hybrid nanomaterials with hierarchical structures have been considered as one kind of the most promising electrode materials for high-performance supercapacitors with high capacity and long cycle lifetime. In this work, multi-dimensional hybrid materials of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanorods/nanosheets on carbon nanofibers (CNFs) were prepared by electrospinning technique combined with one-step solution co-deposition method. Carbon nanofiber membranes were obtained by electrospinning of polyacrylonitrile (PAN) followed by pre-oxidation and carbonization. The successful growth of Ni-Co LDH with different morphologies on CNF membrane by using two kinds of auxiliary agents reveals the simplicity and universality of this method. The uniform and immense growth of Ni-Co LDH on CNFs significantly improves its dispersion and distribution. Meanwhile the hierarchical structure of carbon nanofiber@nickel-cobalt layered double hydroxide nanorods/nanosheets (CNF@Ni-Co LDH NR/NS) hybrid membranes provide not only more active sites for electrochemical reaction but also more efficient pathways for electron transport. Galvanostatic charge-discharge measurements reveal high specific capacitances of 1378.2Fg−1 and 1195.4Fg−1 (based on Ni-Co LDH mass) at 1Ag−1 for CNF@Ni-Co LDH NR and CNF@Ni-Co LDH NS hybrid membranes, respectively. Moreover, cycling stabilities for both hybrid membranes are significantly enhanced compared with those of Ni-Co LDH NR and NS powders. This facile method provides a new strategy for designs and applications of binary transition metal oxides/hydroxides deposited on various substrates for next-generation energy storage devices.

Electrospun nickel-decorated carbon nanofiber membranes as efficient electrocatalysts for hydrogen evolution reaction

In this work, hierarchical nanostructures of nickel (Ni)-decorated carbon nanofibers have been obtained via a facile electrospinning technique and subsequent carbonization process for using as efficient catalysts of hydrogen evolution reaction (HER). During the carbonization process, nickel ions are reduced into Ni nanoparticles while polyimide nanofibers are simultaneously converted into carbon nanofibers. Moreover, the amount of Ni nanoparticles decorated on the nanofibers can be easily tuned by adjusting the content of Ni(NO3)2·6H2O in the electrospinning solution. SEM and TEM characterizations of the nanocomposites show Ni nanoparticles are uniformly distributed on the surface or partly embedded in the nanofibers, endowing intimate interactions and efficient charge transport between the nanoparticles and conducting carbon nanofiber network. Therefore, a low overpotential of -0.17V and a high current density of 3.05mAcm−2 at η=200mV are measured for the 8% Ni-decorated carbon nanofiber membrane, suggesting a relatively high catalytic activity for HER. This versatile and low-cost method may pave a way for fabricating high-performance metal-carbon nanocomposites for various applications.