Carbon Nanofiber Network Research Articles

2D Film of Carbon Nanofibers Elastically Astricted MnO Microparticles: A Flexible Binder-Free Anode for Highly Reversible Lithium Ion Storage.

MnO as anode materials has received particular interest owing to its high specific capacity, abundant resources, and low cost. However, serious problems related to the large volume change (>170%) during the lithiation/delithiation processes still results in poor rate capability and fast capacity decay. With homogenous crystals of MnO grown in the network of carbon nanofibers (CNF), binding effect of CNF can effectively weaken the volume change of MnO during cycles. In this work, a CNF/MnO flexible electrode for lithium-ion batteries is designed and synthesized. The CNF play the roles of conductive channel and elastically astricting MnO particles during lithiation/delithiation. CNF/MnO as binder-free anode delivers specific capacity of 983.8 mAh g-1 after 100th cycle at a current density of 0.2 A g-1 , and 600 mAh g-1 at 1 A g-1 which are much better than those of pure MnO and pure CNF. The ex-situ morphologies clearly show the relative volume change of MnO/CNF as anode under various discharging and charging times. CNF can elastically buffer the volume change of MnO during charging/discharging cycles. A facile and scalable approach for synthesizing a novel flexible binder-free anode of CNF/MnO for potential application in highly reversible lithium storage devices is presented.

Bacterial-cellulose-derived interconnected meso-microporous carbon nanofiber networks as binder-free electrodes for high-performance supercapacitors

Abstract Bacterial cellulose (BC), a typical biomass prepared from the microbial fermentation process, has been proved that it can be an ideal platform for design of three-dimensional (3D) multifunctional nanomaterials in energy storage and conversion field. Here we developed a simple and general silica-assisted strategy for fabrication of interconnected 3D meso-microporous carbon nanofiber networks by confine nanospace pyrolysis of sustainable BC, which can be used as binder-free electrodes for high-performance supercapacitors. The synthesized carbon nanofibers exhibited the features of interconnected 3D networks architecture, large surface area (624 m2 g−1), mesopores-dominated hierarchical porosity, and high graphitization degree. The as-prepared electrode (CN-BC) displayed a maximum specific capacitance of 302 F g−1 at a current density of 0.5 A g−1, high-rate capability and good cyclicity in 6 M KOH electrolyte. This work, together with cost-effective preparation strategy to make high-value utilization of cheap biomass, should have significant implications in the green and mass-producible energy storage.

Cobweb-Inspired Superhydrophobic Multiscaled Gating Membrane with Embedded Network Structure for Robust Water-in-Oil Emulsion Separation

The separation of oil–water mixtures using superwetting membranes is increasingly desired, particularly for the practical processes of environmental protection and industrial production. However, achieving durability and multifunction in current separation systems, among other issues, remains challenging. Herein, a cobweb-inspired gating multiscale pore-based membrane has been created as the framework system for removing emulsified water from an oil phase. This membrane was assembled using macroscale chemically etched stainless steel mesh (ESSM), a microscale network of carbon nanofibers (CNFs), and a nanoscale network of single-walled carbon nanotubes (SWCNTs). Superhydrophobic and superoleophilic interfaces were then fabricated on the ESSM/CNFs–SWCNTs gating membrane using a polydimethylsiloxane (PDMS) coating. The ability of this membrane with a discrete water-repellent property to resist mechanical damage was demonstrated in gravity-driven water-in-oil emulsion separation with high performance; this b...

A Non-Woven Network of Porous Nitrogen-doping Carbon Nanofibers as a Binder-free Electrode for Supercapacitors

A non-woven network of porous nitrogen-doping carbon nanofibers (PNCNFs) is prepared by electrospinning of polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP), followed by stabilization and carbonization. The specific surface areas, porosity and nitrogen content of PNCNFs can be easily controlled by adjusting the content ratio of PVP to PAN. The non-woven PNCNFs based network provides abundant interface sites and hierarchical porosity for solvated ions. In a three-electrode configuration, PNCNFs-2-3 provides a high specific capacitance of 198Fg−1 at 1Ag−1 in 6M KOH. A two-electrode configuration supercapacitor using PNCNFs-2-3 delivers 148Fg−1 capacitance at 1Ag−1 as well as excellent cycling stability.

Large Areal Mass, Mechanically Tough and Freestanding Electrode Based on Heteroatom-doped Carbon Nanofibers for Flexible Supercapacitors.

A flexible and freestanding supercapacitor electrode with a N,P-co-doped carbon nanofiber network (N,P-CNFs)/graphene (GN) composite loaded on bacterial cellulose (BC) is first designed and fabricated in a simple, low-cost, and effective approach. The porous structure and excellent mechanical properties make the BC paper an ideal substrate that shows a large areal mass of 8 mg cm-2 . As a result, the flexible N,P-CNFs/GN/BC paper electrode shows appreciable areal capacitance (1990 mF cm-2 in KOH and 2588 mF cm-2 in H2 SO4 electrolytes) without sacrificing gravimetric capacitance (248.8 F g-1 and 323.5 F g-1 ), exhibits excellent cycling ability (without capacity loss after 20 000 cycles), and remarkable tensile strength (42.8 MPa). By direct coupling of two membrane electrodes, the symmetric supercapacitor delivers a prominent areal capacitance of 690 mF cm-2 in KOH and 898 mF cm-2 in H2 SO4 , and remarkable power/energy density (19.98 mW cm-2 /0.096 mW h cm-2 in KOH and 35.01 mW cm-2 /0.244 mW h cm-2 in H2 SO4 ). Additionally, it shows stable behavior in both bent and flat states. These results promote new opportunities for N,P-CNFs/GN/BC paper electrodes as high areal performance, freestanding electrodes for flexible supercapacitors.

Uniform growth of MoS2 nanosheets on carbon nanofibers with enhanced electrochemical utilization for Li-ion batteries

A facile route for the uniform growth of MoS2 nanosheets on carbon nanofibers (CNFs) via a simple hydrothermal method is reported. The CNF network provides a porous and three-dimensional scaffold for the deposition of ultrathin MoS2 nanosheets. Benefiting from the highly conductive and porous CNFs as well as the nanostructured MoS2, the coaxial MoS2@CNFnanocomposites(*), when served as a binder-free and flexible anode for Li-ion batteries, could generate a synergistic effect to gain a high electrochemical utilization of MoS2. As a result, the nanocomposites exhibit a high reversible capacity of 846mAhg−1 at 100mAg−1, excellent high-rate capability (455mAhg−1 even at 2Ag−1), and good cycling retention with only 7.4% capacity degradation after 100 cycles. The superior Li-ion storage properties enable the nanocomposites to hold great potential application in high-performance Li-ion batteries.

Carbonized Silk Nanofiber Membrane for Transparent and Sensitive Electronic Skin

Recent years have witnessed the explosive development of electronic skin. Highly sensitive pressure sensing is one of the primary abilities of electronic skin. To date, most of the reported skin‐like pressure sensors are based on nanomaterials and microstructured polydimethylsiloxane (PDMS) films, limiting their wide practical applications due to the unknown biotoxicity and the redundant fabrication procedure. A cost‐effective, large‐area‐capable, and biocompatible approach for fabrication of high‐performance skin‐like pressure sensors is highly desired. Silk fibroin (SF) is a natural protein that has recently drawn great attention due to its application as the substrate for flexible electronics. Here, the fabrication of skin‐like pressure sensors is demonstrated using SF‐derived active materials. Flexible and conformal pressure sensors can be fabricated using transparent carbonized silk nanofiber membranes (CSilkNM) and unstructured PDMS films through a cost‐effective and large‐scale capable approach. Due to the unique N‐doped carbon nanofiber network structure of CSilkNM, the obtained pressure sensor shows superior performance, including ultrahigh sensitivity (34.47 kPa−1) for a broad pressure range, an ultralow detection limit (0.8 Pa), rapid response time (<16.7 ms), and high durability (>10 000 cycles). Based on its superior performance, its applications in monitoring human physiological signals, sensing subtle touch, and detecting spatial distribution of pressure are demonstrated.

Co9S8 activated N/S co-doped carbon tubes in situ grown on carbon nanofibers for efficient oxygen reduction

Herein, we report a facile and environment-friendly route for the preparation of Co9S8 activated N/S co-doped carbon tubes (denoted as Co9S8@N/S–CT) in situ grown on a carbon nanofiber network derived from bacterial cellulose.

Facile approach for synthesis of doped carbon electrocatalyst from cellulose nanofibrils toward high-performance metal-free oxygen reduction and hydrogen evolution

Multi-element doped metal-free carbon nanomaterials with a 3D architecture were prepared from inexpensive and naturally abundant cellulose nanofibrils. Compared to the most graphene-based carbons reported in the literature that show only good oxygen reduction reaction (ORR) activity, our N,S-doped carbon nanofiber network coated with N,P-doped carbon nanoparticles showed good bifunctionality toward ORR and hydrogen evolution reaction (HER) activities. The HER performance with doped carbon material exhibited an onset potential of 233mV (vs. RHE), a current density of 10mAcm-2 at 331mV (vs. RHE), and Tafel slope of 99mVdecade−1. The same material was also used for ORR, which could deliver an onset potential 10mV more negative than commercial Pt/C and a cathodic peak of 0.84V (vs. RHE). These values are better than most reported metal-free electrocatalysts. The superior performance of carbon hybrid may be attributed to the combination of a more exposed highly active N,P-doped carbon, a good integration of N,P-doped carbon with N,S-doped carbon nanofibers, and an accelerated electron transport through N,S-doped carbon nanofibers as good conductivity channels.

Chemical vapor deposited MoS2/electrospun carbon nanofiber composite as anode material for high-performance sodium-ion batteries

Due to its high theoretical capacity and unique layered structure, MoS2 has attracted attention as a sodium-ion battery anode material. However, the electrochemical performance of MoS2 based anodes is hindered by their low intrinsic conductivity and large volume change during cycling. In this report, nano-sized MoS2 sheets are synthesized using a scalable chemical vapor deposition method on the surface of electrospun carbon nanofibers (CNFs). The morphology of the resultant MoS2@CNFs is investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction, while their electrochemical performance is studied using cyclic voltammetry and galvanostatic charge-discharge. The results demonstrate that a strong interconnection between MoS2 nanosheets and CNFs is formed and the conductive network of CNFs is beneficial for the sodium ion kinetics. When investigated as an anode for sodium-ion batteries, a high reversible capacity of 380mAhg−1 is obtained after 50 cycles with good cycling stability. In particular, MoS2@CNFs can deliver a capacity of 198mAhg−1 under a high current density of 1Ag−1 after 500 cycles, indicating their great potential as anode material for long-life sodium-ion batteries.

Free-standing, binder-free polyacrylonitrile/asphalt derived porous carbon fiber – A high capacity anode material for sodium-ion batteries

A new kind of porous carbon nanofiber networks has been synthesized via electrospinning technique by using polyacrylonitrile and asphalt as carbon sources and Pluronic F127 as soft template. After stabilization and carbonization treatment, the obtained fabrics were directly utilized as self-supported anode materials for sodium-ion batteries. This kind of porous carbon nanofiber exhibits excellent sodium-ion storage properties, with a reversible capacity of 210mAhg−1 at current density of 500mAg−1 after 1000 cycles.

Nitrogen and oxygen co-doped carbon nanofibers with rich sub-nanoscale pores as self-supported electrode material of high-performance supercapacitors

Self-supported porous carbon nanofibers (CNFs) network has been prepared by electrospinning technology assisted with template method. The as-prepared material is rich in sub-nanoscale pores and nitrogen and oxygen functional groups, which can serve as a fast conductive network with abundant electrochemical active sites and greatly facilitates the transport of electrons and ions. When the porous CNFs network is used as an electrode for supercapacitor in a three electrode system, it displays a high capacitance of 233.1F/g at 0.2A/g, and a capacitance of 130.2F/g even at 14A/g. It maintains a capacitance of 154.0F/g with 90.17% retention after 4000 cycles at 2A/g. Moreover, the assembled symmetric supercapacitor not only exhibits excellent rate capability and cycle performance, but also delivers an energy density of 4.17Wh/kg and a power density of 2500W/kg. The experimental results demonstrate that the prepared N, O co-doped carbon nanofibers with rich sub-nanoscale pores are a promising electrode material for high-performance supercapacitors.

Improved lithium-ion battery anode capacity with a network of easily fabricated spindle-like carbon nanofibers.

A novel network of spindle-like carbon nanofibers was fabricated via a simplified synthesis involving electrospinning followed by preoxidation in air and postcarbonization in Ar. Not only was the as-obtained carbon network comprised of beads of spindle-like nanofibers but the cubic MnO phase and N elements were successfully anchored into the amorphous carbon matrix. When directly used as a binder-free anode for lithium-ion batteries, the network showed excellent electrochemical performance with high capacity, good rate capacity and reliable cycling stability. Under a current density of 0.2 A g−1, it delivered a high reversible capacity of 875.5 mAh g−1 after 200 cycles and 1005.5 mAh g−1 after 250 cycles with a significant coulombic efficiency of 99.5%.

Multifunctional Cr2O3 quantum nanodots to improve the lithium-ion storage performance of free-standing carbon nanofiber networks

Enhanced lithium-ion storage performance of carbon nanofiber networks decorating with uniformly dispersed Cr2O3 quantum nanodots (∼4nm) totally embedded within them were fabricated via a facile electrospinning method. The composite networks were directly employed as free-standing anode materials for Li ion batteries, which exhibited high specific capacity and stable cyclic performance (527mAhg−1 in the 100th cycle). The outstanding electrochemical properties of carbon nanofiber networks could be ascribed to the existence of multifunctional Cr2O3 quantum nanodots and the synergistic effect between the Cr2O3 quantum nanodots and carbon. On one hand, Cr2O3 with high theoretical capacity can improve the specific capacity of composites. On the other hand, the embedded Cr2O3 quantum nanodots can effectively promote the defects concentration of carbon nanofibers, resulting in extra lithium-ion storage sites in carbon fiber. In addition, the carbon nanofibers can provide sufficient room to accommodate the huge volume changes of Cr2O3 quantum nanodots during cycling, and also enhance the electronic conductivity and ion diffusion rate as well as granting a good free-standing matrix.

Nanofibrous Electrodes with Tunable Electrodeposited Pt Morphologies with High ORR Activity and Durability

A new approach for the preparation of PEMFC cathode electrocatalysts based on thin layers of platinum deposited on a support instead of conventional Pt nanoparticles supported on carbon black could be achieved adopting various Pt deposition techniques including atomic layer deposition, electrochemical atomic layer epitaxy, self-terminated Pt electrodeposition, thermal dealloying, and galvanostatic displacement of Ni and Cu ions with Pt1,2. This morphology allows for a more effective utilisation of the highly priced noble metal, while increases the durability of the electrodes over time. The morphology and nature of the support material also plays a crucial role. Nanostructured 1D materials have attracted significant research attention due to the influence of their nanostructure and porosity on performance and durability of the PEMFC3. In this regard, electrospinning is a reliable and scalable technique for the preparation of nanofibers with controlled and uniform diameters and structures. Its versatility allows the production of organic, hybrid and inorganic nanofibres, as well as the possibility of creating different geometries, assemblies and architectures4. We developed novel nanofibrous electrodes (NFE) based on 3D nanostructured networks of carbon nanofibers covered by Pt nanoislands, merging the advantage of Pt thin layers catalyst and a highly porous robust support. This was achieved by combining electrospinning and high overpotential pulsed Pt electrodeposition. These catalysts are based on self-standing electrospun carbon nanofibers covered by platinum thin platinum nanoislands. NFEs are highly durable when compared to commercial standards and have a higher degree of platinum exploitation. Electrochemical active specific surface areas as high as 140 m2g-1 Pt with retention in the order of 70 % after accelerated stress testing are measured, making them a suitable alternative to currently available commercial catalyst. 1. S. M. Alia, Y. Yan, and B. Pivovar, Catal. Sci. Technol., 4, 3589–3600 (2014) 2. G. Ercolano, S. Cavaliere, D. Jones, and J. Rozière, ECS Trans., 69, 1237–1242 (2015). 3. S. Cavaliere et al., ChemElectroChem, 2, 1966–1973 (2015). 4. S. Subianto et al., in Electrospinning for Advanced Energy and Environmental Applications, vol. 1, p. 29–60 (2015).

High Performance Supercapacitors Electrode Based on N-Doped Carbon Nanofibers

Supercapacitors (also known as electrochemical capacitors) are considered to be the most promising devices to meet the urgent and pressing requirements of energy storage. Supercapacitive electrode materials, which are strongly related to the high-efficiency storage of energy, have provoked more attentions and interests. Heteroatom doping (nitrogen, oxygen, phosphorus, boron et.al) has been conceived as a promising approach to increase the special surface area, tune pore size distribution, and incorporate pseudo-capacitance. Recently, nitrogen-doped three-dimensional (3D) nanostructured carbon electrode materials have attracted immense interest due to their great potential merits, including enhance the electrical conductivity, surface polarity, wettability and electro-active surface area, provide an additional pseudo-capacitance and achieve high rate performance and good cycling stability. Herein, a simple, eco-friendly, novel, and effective way to fabricate N-doped carbon nanofiber networks (N-CNFs) is studied. The N-CNFs are successfully fabricated through in situ polymerization using pyrrole and ammonium persulfate as the monomer and oxidant, respectively, then followed by pyrolyzed in a nitrogen atmosphere. The fabricated electrode exhibits an excellent reversible specific capacitance of 233.5 F g-1 at the current density of 0.5 A g-1, and a high rate performance of 80.2 % retention at 5 A g−1 in 6.0 mol L-1 KOH electrolyte. The exceptional properties mostly stem from robust redox reactions of N-doping in the CNFs, which providing enhanced pseudo-capacitance. Furthermore, this kind of hybrid doped material could be easily scaled up and represents an alternative promising candidate for an efficient electrode material for supercapacitors.

A carbon nanofiber network for stable lithium metal anodes with high Coulombic efficiency and long cycle life

Li metal is considered one of the most promising candidates for the anode material in high-energy-density Li-ion batteries. However, the dendritic growth of Li metal during the plating/stripping process can severely reduce Coulombic efficiency and cause safety problems, which is a key issue limiting the application of Li metal anodes. Herein, we present a novel strategy for dendrite-free deposition of Li by modifying the Cu current collector with a three-dimensional carbon nanofiber (CNF) network. Owing to the large surface area and high conductivity of the CNF network, Li metal is inserted into and deposited onto the CNF directly, and no dendritic Li metal is observed, leaving a flat Li metal surface. With Li metal as the counter electrode for Li deposition, an average Coulombic efficiency of 99.9% was achieved for more than 300 cycles, at large current densities of 1.0 and 2.0 mA·cm−2, and with a high Li loading of 1 mAh·cm−2. The scalability of the preparation method and the impressive results achieved here demonstrate the potential for the application of our design to the future development of dendrite-free Li metal anodes.

Ultrafine TiO2 Decorated Carbon Nanofibers as Multifunctional Interlayer for High-Performance Lithium-Sulfur Battery.

Although lithium-sulfur (Li-S) batteries deliver high specific energy densities, lots of intrinsic and fatal obstacles still restrict their practical application. Electrospun carbon nanofibers (CNFs) decorated with ultrafine TiO2 nanoparticles (CNF-T) were prepared and used as a multifunctional interlayer to suppress the volume expansion and shuttle effect of Li-S battery. With this strategy, the CNF network with abundant space and superior conductivity can accommodate and recycle the dissolved polysulfides for the bare sulfur cathode. Meanwhile, the ultrafine TiO2 nanoparticles on CNFs work as anchoring points to capture the polysulfides with the strong interaction, making the battery perform with remarkable and stable electrochemical properties. As a result, the Li-S battery with the CNF-T interlayer delivers an initial reversible capacity of 935 mA h g(-1) at 1 C with a capacity retention of 74.2% after 500 cycles. It is believed that this simple, low-cost and scalable method will definitely bring a novel perspective on the practical utilization of Li-S batteries.

Nanocubic-Co3O4 coupled with nitrogen-doped carbon nanofiber network: A synergistic binder-free catalyst toward oxygen reduction reactions

Abstract High-performance electrocatalysts with excellent catalytic activity and long durability competitive to Pt are urgently necessary for fuel cell development. Here, a novel self-standing membrane of nitrogen-doped carbon nanofibers (NCNF) has been developed, acting as a three-dimensionally networked and conductive template for immobilization of electrochemically active Co 3 O 4 particles. Thus, nanocubic-Co 3 O 4 coated NCNF (NCNF@Co 3 O 4 ) composite fiber membrane with hierarchical structures is obtained, which subtly combines the synergistic effects between the electroactive nanocubic-Co 3 O 4 , efficient surface nitrogen doping and highly conductive NCNF network. Therefore, the NCNF@Co 3 O 4 composite exhibits excellent catalytic activity toward oxygen reduction reactions with positive E peak potential, high current density and superior durability over the commercial Pt/C catalyst, being a promising noble metal-free catalyst for practical fuel cell applications.

Mo2C nanoparticles embedded within bacterial cellulose-derived 3D N-doped carbon nanofiber networks for efficient hydrogen evolution

Molybdenum carbide (Mo2C) has been considered as a promising non-noble-metal hydrogen evolution reaction (HER) electrocatalyst for future clean energy devices. In this work, we report a facile, green, low-cost and scalable method for the synthesis of a Mo2C-based HER electrocatalyst consisting of ultrafine Mo2C nanoparticles embedded within bacterial cellulose-derived 3D N-doped carbon nanofiber networks (Mo2C@N-CNFs) using 3D nanostructured biomass as a precursor. The electrocatalyst exhibits remarkable HER activity (an overpotential of 167 mV achieves 10 mA cm−2 and a high exchange current density of 4.73 × 10−2 mA cm−2) and excellent stability in acidic media as well as high HER activity in neutral and basic media. Further theoretical calculations indicate a strong synergistic effect between Mo2C nanoparticles and N-CNFs in the Mo2C@N-CNF catalyst, which leads to an impressive HER performance. Embedding metal-based nanoparticles in bacteria-generated aerogels is a promising way to produce hydrogen fuel using water and electricity. Most water electrolysis methods use platinum catalysts to make hydrogen–oxygen bond splitting easier. But platinum's scarcity has prompted investigations into alternatives such as molybdenum carbide (Mo2C), a catalyst that shows increased activity when coupled with carbon nanofibers. Shu-Hong Yu and colleagues from Hefei, University of Science and Technology of China, now report that bacterial cellulose — a low-cost biomass synthesized by microbes — can act as a favorable support for Mo2C nanocatalysts. Straightforward immersion of bacterial cellulose in an ammonium molybdate precursor solution, followed by freeze drying and pyrolysis, yielded a three-dimensional porous network dotted with spatially separated Mo2C nanoparticles and nitrogen dopants. Tests showed the catalyst had excellent water splitting capabilities over the pH range 0 to 14. A new type of non-noble-metal hydrogen evolution reaction (HER) electrocatalyst based on ultrafine Mo2C nanoparticles embedded within 3D N-doped carbon nanofiber networks was fabricated by using a cheap, green, 3D nanostructured biomass (bacterial cellulose) as precursor. It exhibits remarkable electrocatalytic HER performance from pH 0 to pH 14.