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• MnO 2 /CNF/Ag nanofabric electrodes are developed for flexible supercapacitors. • The brittle issue in the CNF electrode is greatly improved by an Ag incorporation. • The optimized MnO 2 /CNF/Ag electrode has a specific capacitance of 184 F/g at 1 A/g. • An energy density of 16.3 Wh/kg and a power density of 400 W/kg was achieved. • A capacitance retention rate of 87 % was demonstrated when subjected to bending. Flexible supercapacitors are gaining increasing popularity due to their potential in powering portable, wearable, and lightweight electronic devices. In this study, we have successfully developed a high-performance flexible electrode for quasi-solid-state supercapacitors by incorporating Ag into carbon nanofibers (CNF) through electrospinning, and growing MnO 2 as an active material on the electrode using an in-situ redox method. The Ag and MnO 2 co-decorated CNF electrode offers several advantages over conventional CNF electrodes, including an enlarged reaction area, higher charge storage capacity, and improved resistance to brittleness issues. Among all the quasi-solid-state supercapacitors tested, the MnO 2 -decorated electrode with an optimized Ag incorporation exhibited the highest specific capacitance of 184 F/g at a current density of 1 A/g, representing a remarkable 17-fold increase compared to the reference CNF electrode. Furthermore, the Ag and MnO 2 co-decorated electrode demonstrated an energy density of 16.3 Wh/kg and a power density of 400 W/kg at the same current density. Notably, the electrode exhibited excellent flexibility, with a capacitance retention rate of 87 % when subjected to bending with a curvature ranging from 5 to 1.25 cm. Our results suggest that the Ag and MnO 2 co-decorated CNF electrode holds great promise for flexible energy storage applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Lithium-ion battery (LIBs) applications using antimony (Sb) based anodes with high specific capacity and suitable operating voltage have showed tremendous potential. However, the large volume variation during electrochemical cycling limits their application. In this paper, M-Sb (M=Co, Ni) nanoparticles embedded in nitrogen doped carbon nanofibers have been prepared by an electrospinning method, 3D interconnected M-Sb@CN (NiSb@CN and Sb/CoSb 2 @CN) fiber composites are obtained finally. M-Sb nanoparticles are uniformly distributed in N-doped carbon nanofibers, which can prevent their direct exposure to the electrolyte. Compared with bare Sb-M and Sb-C binary electrodes, the M-Sb-C three-component composite electrodes show smaller volume change and stronger charge transport ability. The introduction of the transition metal (Co, Ni) not only serves as buffer substrate for volume change, but also regulates the properties of carbon fibers as a catalyst. High reversible capacities of 647.4 and 620.2 mA h g−1 of NiSb@CN and Sb/CoSb 2 @CN fiber composites can be maintained after 600 cycles at a current rate of 500 mA g−1. First principles calculation demonstrates that N-doping and the incorporation of transition metal M have favorable effect on the improved Li binding energy, offering a possibility for the material design of the high-performance LIBs. [ABSTRACT FROM AUTHOR]

• The crednerite CuMnO 2 and CuMnO 2 /CNFs nanocomposite were prepared by one-pot synthesis with high quality. • To the best of our knowledge, there is the first time to report the in situ simple oxidation of CNFs and preparation of CuMnO 2 /CNFs nanocomposites. • The CuMnO 2 /CNFs/GCE sensor exhibited a nanomolar LOD of 0.21 nM. • The CuMnO 2 /CNFs/GCE sensor showed high sensitivity of 0.511 μA μ M −1 cm−2. • The ORD practical feasibility tests were carryout in food, biological, and environmental water samples to achieve an above 90% of retained response. A large number of antibiotics used as additives with feedstocks to promote the production capacity in cattle rearing and poultry farming are finally abandoned in the environment. Hence, the tracing of such antibiotics from the route is vital to environmental safety. Herein, the crednerite CuMnO 2 and CuMnO 2 /CNFs nanocomposite were prepared by one-pot synthesis. The CNFs in precursor solution have been sonicated and the crednerite CuMnO 2 was grown on CNFs hydrothermally with in-situ oxidation of CNFs. The as-prepared CuMnO 2 /CNFs covered glassy carbon electrode (GCE) reached a sensing range of 0.01 to 350 μM to ornidazole (ORD) antibiotics in the laboratory solution. The articulated detection limit of CuMnO 2 /CNFs/GCE to ORD and sensitivity are 0.21 nM and 0.511 μA μ M −1 cm−2 respectively. Furthermore, the CuMnO 2 /CNFs nanocomposite has been tested for ORD in real samples and retrieved responses at a minimum of 90% in food, environmental and biological samples. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Polyaniline hollow nanofibers (PANI-HNFs) are successfully synthesized by using poly (methyl methacrylate) nanofibers as a sacrifice-template via an in-situ polymerization with a subsequent dissolution process. The polyaniline hollow nanofibers as cathode material for sodium-ion batteries exhibit a high reversible capacity of 153 mA h g−1 at 0.3 C (1C = 150 mA g−1), high cycling stability (73.3% capacity retention after 1000 cycles) and rate capability (70 mA h g−1 at 8 C). The high electrochemical performance of the polyaniline hollow nanofibers originates from the one dimension hollow nanostructures with unique morphologies and highly reversible doping/dedoping property of the conducting polymer, so as to ensure well structural stability and good electrical/ionic conducting connectivity. Furthermore, this strategy can controllably prepare various hollow one dimension structures with different tube diameters and wall sizes, which has potential application for energy storage materials, catalysts, drug-delivered materials and chemical microreactors. Graphical abstract Image 1 Highlights • PANI-HNFs are synthesized via a sacrifice-template method. • PANI-HNFs exhibits a high reversible capacity, cycling stability and rate capability. • The unique hollow fiber structure can be widely applied in other fields. [ABSTRACT FROM AUTHOR]

Abstract Mesoporous ribbon-shaped graphitic carbon nanofibers (MRCNFs) have been prepared by combination of electrospinning technique, template method and catalytic graphitization of transition metal. Transition metal Co, originated from Co(NO 3) 2 ·6H 2 O doped in spinning solution, serves as both template of mesopores and catalyst for graphitic structure. The microstructure of MRCNFs has been optimized by adjusting doping amount of Co(NO 3) 2 ·6H 2 O. The resultant MRCNFs present a relatively centralized distribution of 2–10 nm mesopores, modest specific surface area of 463 m2 g−1 and pore volume of 0.575 cm3 g−1. In addition, considerable nitrogen- and oxygen-containing functionalities (2.88 at.% of N and 4.88 at.% of O) are detected on MRCNFs. In view of electrode materials for supercapacitors, as-obtained ribbon-shaped morphology, mesoporous structure, considerable surface heteroatom-containing functionalities and high graphitization degree synergistically enhance the electrolyte ion diffusion and electron conduction. In a three-electrode test system, the resultant MRCNFs electrodes exhibit high specific capacitance (228 F g−1 at 0.2 A g−1), rate capability (of 58% capacitance retention at 20A g−1) and excellent cycle stability(of 95% capacitance retention after 5000 cycles at 2 A g−1). Graphical abstract Image 1 Highlights • Mesoporous ribbon-shaped graphitic carbon nanofibers (MRCNFs) have been prepared. • Co particles serves as template of mesopores and catalyst for graphitic carbon. • With SSA of 463 m2 g−1, MRCNFs present a capacitance of 228 F g−1 at 0.2 A g−1. [ABSTRACT FROM AUTHOR]

• The flexible FeCo@NFM was prepared by simple electrospinning method. • Small FeCo nanoparticles (∼10 nm) are uniformly encapsulated in the CNFs. • The as-prepared FeCo@NFM is directly used as a binder-free electrode. • The hierarchical structure can greatly promote Li+ insertion/extraction kinetics. • The electrode exhibits high capacity, good rate capability and cycling stability. The design of electrodes with excellent mechanical elasticity is the significant to developing flexible electronic devices with mechanical endurance and outstanding lithium storage properties. Herein, the flexible FeCo/carbon hybrid nanofiber membranes (named as FeCo@CNFM) were successfully prepared via electrospinning and subsequent carbonization process. From the macroscopic perspective, the FeCo@CNFM can bend at a large angle without any destruction, and be directly used as working electrode of lithium ions batteries (LIBs) without any expensive additives, demonstrating its extraordinary mechanical flexibility. From the microscopic perspective, the homogeneously dispersed fine FeCo nanoparticles and the three-dimensional (3D) interconnected transport network constructed of carbon nanofibers significantly shorten the lithium-ion transfer distance, eliminate the volume fluctuation during lithiation/delithiation process, enhance the utilization rate of active materials, and promote the electrical conductivity of the composite electrode, thus leading to remarkably improved electrochemical properties. As a consequence, the optimized FeCo@CNFM manifests a superior discharge capacity of 584.9 mA h g−1 at 100 mA g−1 after 100 cycles with long cycling stability and good rate capability of 227.1 mA h g−1 even at a large current rate of 2 A g−1, making it a promising flexible self-supporting anode for LIBs. [Display omitted] [ABSTRACT FROM AUTHOR]

The commercial applications of lithium metal anodes are still hindered by safety concerns resulting from uncontrollable lithium dendrite growth and serious volume changes during the discharge and charge processes. In this study, N-rich hollow porous carbon nanofibers decorated with various zinc oxide morphologies as the lithiophilic phase are fabricated through simple coaxial-electrospinning. The ZnO nanostructure gradually changes from small nanoparticles to needle-like structures with increasing Zn(Ac) 2 fraction, resulting in lithiophilic to lithiophobic scaffold transfer, owing to current density concentration, long Li ion diffusion distances, and inhomogeneous Li deposition behavior with ZnO needle-like shapes. The small ZnO nanoparticles on the NHCNF as the Li metal deposition scaffold also efficiently reduce the local current density and guide the Li ions to homogenously nucleate and deposit. The hollow porous structure provides ultra-high Li metal space accommodation, which can prevent uncontrollable Li dendrite growth. These excellent scaffold characteristics display a high Columbic efficiency of 97% after 150 cycles at 1 mA cm−2 and a stable cyclic lifespan of 1000 cycles in the symmetrical cells, even at a super high current density of 5 mA cm−2 on the 5-ZnO@NHCNF/Li composite anode, full cells coupled with an LiFePO 4 commercialized cathode deliver excellent cyclic and rate performance. [ABSTRACT FROM AUTHOR]

• Double heteroatom (B and N) doped carbon nanofibers (BNC NFs) were constructed. • GITT method was used to investigate the storage mechanism of Na. • The 5BNC NFs (5 wt% boric acid) exhibited the highest electrochemical performance. A double heteroatom doping strategy is proposed to synthesize boron- and nitrogen-doped heteroatom carbon nanofibers (BNC NFs) as anode materials for sodium-ion batteries (SIBs). The specific capacity and rate performance of the BNC NF anode are higher than those of the NC NF anode. Particularly, the composite containing 5 wt% boric acid provides the highest reversible capacity of 249 mAh g−1 at a current density of 0.02 A g−1 and excellent cyclic stability of 144 mAh g−1 at 2 A g−1 after 3000 cycles. The excellent cyclic performance of the BNC NFs can be attributed to the defect-rich nanostructure derived by optimally doping boron under annealing, which is conducive to accelerating ion transport and introducing additional Na-ion storage active sites. The excellent capacity and long cycle stability of the full cell SIBs comprising the optimized BNC NFs anode and Na 3 V 2 (PO 4) 3 cathode suggest the promising potential of B-doped C NFs as anodes for rechargeable Na-ion batteries. The BNC NFs with double heteroatom (B and N) doped structure is realized as superior anode for sodium ion batteries providing excellent Na+ storage capacity and long-term cycling performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Porous graphene-doped copper indium disulfide/carbon (p-GN@CuInS 2 /C) composite nanofibers were fabricated via electrospinning, in situ synthesis, and carbonization. A polyacrylonitrile (PAN) solution containing graphene oxide nanosheets, copper dichloride (CuCl 2 ), indium trichloride (InCl 3 ), and thiourea (Tu.) in a mixed solvent of N,N-dimethylformamide/trichloromethane (DMF/CF) was used as the precursor solution for electrospinning. The resulting porous GN@CuInS 2 /C nanofibers were 107 ± 24 nm in diameter, and graphene nanosheets anchored with chalcopyrite CuInS 2 nanocrystals 7–12 nm in diameter were overlapped and embedded in the carbon matrix, aligning along the fiber axial direction. The Brunauer–Emmett–Teller (BET) surface area of the p-GN@CuInS 2 /C composite nanofibers was 795 m 2 /g, with a total pore volume of 0.71 cm 3 /g. These values were significantly larger than those of the sample without graphene and CuInS 2 /C nanofibers. A dye-sensitized solar cell (DSSC) assembled using the p-GN@CuInS 2 /C nanofibers as the counter electrode (CE) delivered a photoelectric conversion efficiency of 7.23%, which was higher than the efficiencies of DSSCs assembled using the samples without graphene (6.48%) and with the CuInS 2 /C nanofibers (5.45%). It was also much higher than that of the DSSC with a Pt CE (6.34%). The excellent photoelectric performance of the p-GN@CuInS 2 /C CE was attributed to its special hierarchical porous structure, which facilitated permeation of the liquid electrolytes and provided additional active catalytic sites for the oxidation reaction of the electrolytic (I − /I 3 − ). The doping of reduced graphene oxide (RGO) resulted in the well-dispersed growth of CuInS 2 nanocrystals in the carbon nanofibers, which further increased the number of active catalytic sites and promoted electron and ion transfer. [ABSTRACT FROM AUTHOR]

Chiral carbon-based nanomaterials possess many superior properties originated both from their nano-sized structure and their chirality. We presented a facile way to synthesize chiral mesoporous carbonaceous nanofibers (chiral MCNFs) through a supramolecular templating method, using a pair of chiral low-molecular-weight gelators as the templates, resorcinol, formaldehyde and tetraethyl orthosilicate as the precursors, respectively. Besides, the chiral MCNFs exhibited optical activity; the electrochemical measurements implied that they also showed good capacitance and lithium-ion storage performances. [ABSTRACT FROM AUTHOR]

• Hierarchical porous carbon (HPC) is obtained with three-dimensional (3D) structure. • The HPC with highly fluffy 3D continuous network is found as an ideal support. • HPC-supported MnO 2 nanofibers composite is achieved as a supercapacitor material. • The as-prepared MnO 2 @HPC composite has 3D interpenetrating network structure. • The MnO 2 @HPC composite presents excellent electrochemical performance. For improving the conductivity of porous carbon and the utilizations of its pore structures, a hierarchical porous carbon (HPC) had been developed with highly fluffy three-dimensional (3D) continuous network structure. Using the HPC as a support, a novel MnO 2 @HPC composite with 3D interpenetrating network structure was prepared as electrode material of supercapacitor via simple hydrothermal method. When the hydrothermal reaction temperature was 100°C, the MnO 2 nanofibers (∼5 nm) were uniformly grown on and within the fluffy 3D porous network of the HPC, forming a composite with interpenetrating network structure. The as-prepared composite (MnO 2 @HPC-100) exhibited the characteristics of both electric double-layer capacitance and pseudo-capacitance, which had a high specific capacity of 368 F g−1 at a current density of 0.5 A g−1 and 186 F g−1 at 10 A g−1 (50.5% retention). In addition, the asymmetric supercapacitor device was assembled with a relatively high energy density of 88.2 Wh Kg−1 at a power density of 162 W Kg−1. The device had a high capacity retention rate of 95% after 10000 cycles, and the coulomb efficiency was stable at 99.7%, showing the excellent stability of the composite. Therefore, the MnO 2 @HPC-100 composite has great application prospects in energy storage. [Display omitted] [ABSTRACT FROM AUTHOR]

Nanostructural carbon nanofibers are prepared through electrospinning in a precursor solution composed of polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and N,N-dimethylformamide. We investigate the effect of PMMA molecular weight on the morphology and electrochemical performance of the nanofibers. During pyrolysis, PMMA decomposition causes the nanofibers to develop from a porous structure into a hollow structure with increased PMMA molecular weight. The removal of PMMA also substantially increases the specific surface area and the pore volume of the carbon nanofibers. Electrochemical measurements reveal that the specific capacitance of the PAN/PMMA-derived carbon nanofibers with a low-molecular-weight PMMA exhibits a specific capacitance of 210 F/g, which is approximately 38% higher than that of the neat PAN-derived carbon nanofibers. Additionally, the fibers exhibit favorable cycling stability with a retention ratio of almost 100% after 2000 cycles. [ABSTRACT FROM AUTHOR]

Constructing electrode materials embracing with high effectivity and durable stability is of vital importance for hydrogen evolution reaction (HER) in electrochemical water splitting. Herein, a monolith electrode is designed with FeS 2 nanoparticles embedded in porous carbon nanofibers (FeS 2 @CNFs) via an in-situ electrospinning strategy, which is directly used as an efficient electrode for HER without any extra-substrates. Such monolithic electrode eliminates interface problems between active catalysts and carriers and expends more intrinsic catalysis regions, which effectively shortens the pathway of electron/ mass transport. The FeS 2 @CNFs electrode displays good HER activity only with an overpotential of 168 mV at 10 mA cm−2. It is worth noting that this monolith electrode shows the excellent HER stability for nearly a week in 1 M KOH without any destruction of fibrous structure. Such considerable activities can be ascribed to the interwoven nanofiber-meshes that engineer the self-supportive architecture with stable strength and the carbon-encapsulation structure that prevents FeS 2 from collapsing. The woven meshes and porous structure allow the sufficient penetration of electrolyte and fast gas diffusion. This work provides a valuable reference for rationally designing a monolith electrode effectively for gas-involved electrochemical application. [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon-based materials have emerged as promising anode candidates for lithium-ion capacitors (LICs) owing to the advantages of high electronic conductivity and environmental benignity. However, further development of carbonaceous anodes has been greatly hindered by the sluggish kinetics and insufficient cycling stability. Herein, mesopore-rich N-doped carbon nanofibers (MNCNF) membranes are designed as a free-standing anode material to achieve ultra-high rate and ultra-long lifespan Li storage performance. The interconnected network with rich mesopore volume, high doping level of pyridinic/pyrrolic N, and expanded interlayer spacing affords the as-fabricated MNCNF anode abundant active sites, promoted electronic conductivity and superior diffusion kinetics. With prominent merits of pore and defect engineering, MNCNF anode manifests extraordinary Li storage performance in terms of ultra-high rate capability (139 mA h g−1 at 50 A g−1) and ultra-long cycling stability (370 mA h g−1 after 10000 cycles at 10 A g−1). More importantly, LICs by using MNCNF as anodes deliver a high energy density of 165 Wh kg−1 and an ultra-high power density of 132 kW kg−1, together with a high capacitance retention of 84% after 20000 cycles. This study demonstrates the combination of pore and defect engineering for boosting Li storage performance and holds great promise for practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The poor conductivity of anodic carbon materials at low temperature hampers their high-level applications in Li ion batteries (LIBs). Introducing some reliable metals with good electrical conductivity into anodes could alleviate these problems. In this work, the novel composites of Fe-added Fe 3 C carbon nanofibers (Fe/Fe 3 C CNFs) were synthesized via facile electrospinning method and used as anode materials for LIBs. The resulting anodes with Fe/Fe 3 C CNF materials exhibited a high reversible capacity of 500 mAh g −1 tested at 200 mA g −1 even after 70 cycles and excellent performance at room temperature. Importantly, it delivered a high capacity of 250 mAh g −1 at 400 mA g −1 even after 55 cycles at a low temperature of −15 °C. The superior low-temperature electrochemical performance of the Fe/Fe 3 C CNF anodes is associated with an improved effect of the highly conducting Fe at low temperature. [ABSTRACT FROM AUTHOR]

Highlights: [•] The interconnected carbon nanofibers were prepared by an electrospinning technique. [•] The interconnected fibers developed conductive pathways. [•] The interconnected fibers showed 24% enhancement on the specific capacitance. [•] The interconnected fibers are promising to be used as electrodes for supercapacitors. [ABSTRACT FROM AUTHOR]

• A novel 2 × 2 tunnel-structured K 1.28 Ti 8 O 16 @N-doped carbon nanofibers are prepared. • The electrode exhibits excellent long cycle performance. Sodium-ion batteries (SIBs) are one of the most potential candidates for large-scale energy storage due to the low cost and eco-friendliness, however, a stable and reversible anode is urgently developed. In this work, a novel 2 × 2 tunnel-structured K 1.28 Ti 8 O 16 @N-doped carbon nanofibers (KTO@N CNFs) anode is successfully synthesized via simple electrospinning and subsequent thermal treatment with urea acted as the additional convenient nitrogen source. In-situ X-ray diffraction (XRD) measurement confirms the intercalation reaction mechanism and robust structure during Na+insertion/extraction. This composite material exhibits a reversible capacity of 116.4 mAh g −1 at a current density of 100 mA g −1 after 1000 cycles. More impressively, even at a high current density of 1 A g −1, the battery delivers capacity retention of 98.4 mAh g −1 after 5000 cycles. The excellent electrochemical performance is attributed to the adequate 2 × 2 tunnel structure and the nano-confinement of N-doped nanofibers on K 1.28 Ti 8 O 16 nanocrystals, which offers enough diffusion paths and enhance the ionic diffusion of sodium ions. This work provides a facile strategy to synthesis stable, reversible, and long-cycle anode for sodium-ion batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

The excellent electrochemical performance of indium sulfide (In 2 S 3) in lithium ion batteries (LIBs) and sodium ion batteries (SIBs) prompted us to explore its energy storage mechanism in potassium ion batteries (PIBs). In this work, In 2 S 3 /C nanofibers are successfully synthesized by simple electrospinning and subsequent vulcanization. In K half cells, compared to commercial In 2 S 3 electrodes, In 2 S 3 /C nanofibers as anode materials for PIBs show outstanding electrochemical performance, which can deliver reversible capacities of 397.6 (25), 366.2 (50), 335.2 (100), 307.8 (200), 260.4 (500) and 212.2 mAh g−1 (1000 mA g−1), respectively. In K full cells, In 2 S 3 /C nanofibers can also show good potassium storage performance and can light up 15 light emitting diodes (LEDs). The superb electrochemical performance of In 2 S 3 /C nanofibers is due to the in-situ composite with self-nitrogen-doped carbon matrix and the nanoization of In 2 S 3 particles, which buffers the volume effect and improves the conductivity of the material during the potassium storage process. In addition, the mechanism of potassium storage of In 2 S 3 /C nanofibers was systematically studied by cyclic voltammetry (CV), ex-situ XRD, TEM and XPS methods. The mechanism of In 2 S 3 for K-ion storage can be described as the conversion reaction: In 2 S 3 + 6K+ + 6e− ⇌ In + 3K 2 S. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The composite films of activated carbon fibers (ACFs) and carbon nanofibers (CNFs) are prepared via chemical vapor deposition of CNFs onto ACFs in different times from 0.5 to 2h and their electrosorption behaviors in NaCl solution are investigated. The morphology, structure, porous and electrochemical properties are characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, N2 adsorption at 77K, contact angle goniometer and electrochemical workstation, respectively. The results show that CNFs have been hierarchically grown on the surface of ACFs and the as grown ACF/CNF composite films have less defects, higher specific capacitances, more suitable mesoporous structure and more hydrophilic surface than the pristine ACFs, which is beneficial to their electrosorption performance. The ACFs/CNFs with CNFs deposited in 1h exhibit an optimized NaCl removal ratio of 80%, 55% higher than that of ACFs and the NaCl electrosorption follows a Langmuir isotherm with a maximum electrosorption capacity of 17.19mg/g. [Copyright &y& Elsevier]

Abstract: Electrodes made of carbonized polyacrylonitryle (cPAN) nanofibers, with and without embedded multiwall carbon nanotubes (MWCNTs) were fabricated by the electrospinning (ES) process and evaluated as anodes in glucose fuel cell (FC) application. The effect of several processing and structural characteristics, such as the presence of MWCNTs, polymer concentration in the ES solution and silver electroless plating on FC performance were measured. The carbon electrodes were successful as anodes showing significant activity even without additional silver catalyst, with noticeable improvement by the incorporation of MWCNTs. The orientation of graphitic layers along the fiber axis and the coherence of layer packing were shown to be important for enhanced electrode activity. The maximal values of open circuit voltage (OCV) and peak of power density (PPD) of unmetalized electrodes, 0.4V and 30μW/cm2 respectively, were found to be for composite cPAN/CNT electrode. Electroless silver metallization of the carbon nanofiber electrodes leads to much better FC performance. Maximal values of OCV and PPD of silvered carbon electrodes were measured to be about 0.9V and 400μW/cm2, respectively. Thus, carbonized nanofibers with embedded MWCNTs may form a good basis for glucose FC anodes, but better metallization and cell-configuration allowing proper mixing are required. [Copyright &y& Elsevier]

Abstract: Copper-loaded carbon nanofibers are fabricated by thermally treating electrospun Cu(CH3COO)2/polyacrylonitrile nanofibers and utilized as an energy-storage material for rechargeable lithium–ion batteries. These composite nanofibers deliver more than 400mAg−1 reversible capacities at 50 and 100mAg−1 current densities and also maintain clear fibrous morphology and good structural integrity after 50 charge/discharge cycles. The relatively high capacity and good cycling performance of these composite nanofibers, stemmed from the integrated combination of metallic copper and disordered carbon as well as their unique textures and surface properties, make them a promising electrode candidate for next-generation lithium–ion batteries. [Copyright &y& Elsevier]

Abstract: Pt/carbon composite nanofibers were prepared by electrodepositing Pt nanoparticles directly onto electrospun carbon nanofibers. The morphology and size of Pt nanoparticles were controlled by the electrodeposition time. The resulting Pt/carbon composite nanofibers were characterized by running cyclic voltammograms in 0.20M H2SO4 and 5.0mMK4[Fe(CN)6]+0.10M KCl solutions. The electrocatalytic activities of Pt/carbon composite nanofibers were measured by the oxidation of methanol. Results show that Pt/carbon composite nanofibers possess the properties of high active surface area and fast electron transfer rate, which lead to a good performance towards the electrocatalytic oxidation of methanol. It is also found that the Pt/carbon nanofiber electrode with a Pt loading of 0.170mgcm−2 has the highest activity. [Copyright &y& Elsevier]

Abstract: Carbon nanofibers (CNFs) are grown on metal catalysts and electrochemical treatment is used to remove the metal catalyst residuals from the as-grown CNFs. For comparison, the CNFs are also purified by a chemical method and a thermal method. The oxygen reduction reaction (ORR) properties of CNFs purified by these three methods are examined by cyclic voltammetry. CNFs treated by the electrochemical method have a more positive ORR onset reduction potential and peak potential compared with those treated by chemical and thermal methods, and this is because the microstructures of CNFs are less changed by electrochemical method. However, they have a lower electrochemical capacity and ORR peak current than those treated by the chemical method. Cyclic voltammetric measurements at different scan rates confirm that the oxygen reductions on CNFs treated by electrochemical and chemical methods are controlled by diffusion, while on CNFs treated by thermal method is partially influenced by diffusion. [Copyright &y& Elsevier]

A highly performance binder-free and freestanding cathode for Li-O 2 battery (LOB) receives much attention to solve the major obstacles including sluggish oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) kinetics, unstable cathode, and irrational architecture design. Herein, we develop an effectively electrospinning to embed the oxygen vacancy-containing Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) particles into carbon nanofibers (BSCF@C nanofibers) towards the self-assembly cathode with high ORR and OER performance. Predictably, the BSCF@C nanofibers successfully prevent the BSCF particles from aggregation, facilitate O 2 adsorption and diffusion, enhance the electron transfer, accelerate the Li 2 O 2 nucleation/decomposition, and enhance the stability of cathode. Different from the conventional cathode, the LOBs with the BSCF@C nanofibers cathode perform an outstanding electrochemical performance, which providing a high discharge specific capacity of 11976 mAh g−1 and ultralong cycling stability of 98 times at the current density of 400 mA g−1. Notably, this work opens up an opportunity for the perovskite oxides with high crystallization temperature for high-performance energy storage systems at ambient temperature. [Display omitted] [ABSTRACT FROM AUTHOR]

It is crucial to design effective cathode catalysts for high performance of Li–O 2 batteries (LOBs). Herein, porous LaCo 0.6 Ni 0.4 O 3 nanofibers decorated with ultrafine Co 3 O 4 nanoparticles (Co 3 O 4 @LCN NFs) are designed and employed as cathode catalyst for LOBs. The X-ray photoelectron spectroscopy measurement results suggested that uniform dispreading of Co 3 O 4 nanoparticles on LCN NFs surface could largely increase the surface chemisorbed oxygen, resulting in enhanced catalytic activity. Furthermore, with the assistance of Co 3 O 4 nanoparticles, Co 3 O 4 @LCN NFs can significantly facilitate O 2 adsorption and diffusion, Li 2 O 2 nucleation/decomposition and the formation of tiny sheet-like Li 2 O 2 , thereby achieving a low charge overpotential. A high specific capacity of 11,288 mA h g−1, a low charge voltage plateau of 3.72 V at first cycle and excellent cycle stability of 116 cycles at 1000 mA g−1 are obtained for LOBs with Co 3 O 4 @LCN NFs. [ABSTRACT FROM AUTHOR]

Acrylic and discarded acrylic fabrics are appealing for use as raw materials to prepare low-cost carbon nanofibers (CNFs), which can solve the problem of high spinning raw material cost in the industrialization of CNFs. However, the extremely poor thermal properties caused by the high content of comonomers make it difficult to prepare CNFs with good mechanical properties. Here, we successfully used clothing acrylic yarn to prepare deformable CNFs (Zn-CAY-CNF), which is accomplished by using trace amounts of zinc acetate (Zn(Ac) 2) in the spinning solution and stepwise carbonization. As-obtained materials exhibit excellent cycle stability (101.6 mAh g −1, 2 A g −1, 2000th) and rate-capacity retention (51 mAh g −1, 10 A g −1), with good flexibility. A soft pack battery can light a LED under bending state. The excellent flexibility can be attributed to the role of Zn(Ac) 2 in initiating chemical pre-cyclization, promoting thermal cyclization and aromatization, which are contributed to cyclization and carbonization of PAN chain segments in acrylic molecular chains and improves the carbon yield of CNFs. More importantly, discarded acrylic fabric is also used to successfully prepare flexible CNFs via the same preparation process, indicating that the preparation strategy is universal and feasible. Acrylic and discarded acrylic fabrics are appealing for use as raw materials to prepare low-cost carbon nanofibers (CNFs) as high spinning raw material costs are a key factor limiting the industrialization of CNFs. However, their extremely poor thermal properties caused by high-content co-monomers make it difficult to prepare CNFs with good mechanical properties. Here, clothing acrylic yarn is successfully used to prepare deformable CNFs (Zn-CAY-CNF), which is accomplished by modifying a standard CNF preparation process using trace amounts of zinc acetate (Zn(Ac) 2) in the spinning solution. The roles that Zn(Ac) 2 plays in initiating a pre-chemical cyclization, promoting thermal cyclization and aromatization are revealed, which are contributed to cyclization and carbonization of PAN chain segments in acrylic molecular chains. As-obtained Zn-CAY-CNF was successfully used in free-standing sodium ion battery anodes with excellent cycle stability and rate-capacity retention. A soft pack battery consisting of a Zn-CAY-CNF anode and Na 3 V 2 (PO 4) 3 cathode was assembled, which can light a LED under bending state. More importantly, discarded acrylic fabric is also used to successfully prepare flexible CNFs via the same preparation process, indicating that this preparation strategy is practicable and that low-cost CNFs with good mechanical properties derived from discarded acrylics are feasible for practical use. [ABSTRACT FROM AUTHOR]

The development of high-energy lithium-ion and sodium-ion capacitors (LICs and SICs) is still a challenge due to the kinetics mismatch between the insertion/deinsertion anode and adsorption/desorption cathode. Here, high-level N/P-doped Sn-carbon nanofibers (Sn-NP-CNFs) were fabricated via an electrospinning technique followed by pre-oxidization and carbonization. The N/P-doping increased the defects and carbon interlayer distance to inhibit the precipitation and volume expansion of the Sn and improve the Li/Na-adsorption, resulting in an ultrahigh pseudocapacitance and rate capability of the Sn-NP-CNF. An advanced LIC and SIC were composed of an activated carbon cathode and a Sn-NP-CNF anode. The LIC and SIC displayed ultrahigh energy densities (186.0 Wh kg−1 and 134.6 Wh kg−1) and power densities (20.0 kW kg−1 achieved at 22.2 Wh kg−1) with superior energy retentions (83.7% and 79.8% after 10,000 cycles at 5.0 A g−1). [ABSTRACT FROM AUTHOR]

• MoP@nitrogen-doped carbon nanofibers are synthesized via electrospinning and an in-situ carbothermic self-reduction. • The as-prepared nanofibers with uniformly distributed MoP nanoparticles are interconnected into a conductive network. • The unique structure alleviates pulverization of active material and enhances ion/charge-transfer for a high Li/Na storage. • Quantitative kinetics analysis confirms that the charge storage behavior is governed by pseudocapacitance. Transition metal phosphide anodes have received increasing attention for lithium/sodium-ion batteries due to their high theoretical capacities and apposite intercalation potential range. However, the mechanical stress induced dramatic volumetric expansion upon a conversion reaction mechanism has hindered the practical applications. Herein, we demonstrate a high performance anode of MoP@nitrogen-doped carbon nanofibers (MoP@NCNFs), which are prepared from an electrospinning method followed by an in-situ carbothermic self-reduction process. The well-crystallized MoP nanoparticles are uniformly distributed in the interweaving nanofibers, affording a conductive network for fast charge/ion transport and adequate buffer space for volumetric expansion. Benefit from the unique structure, the MoP@NCNFs synthesized at 800 °C delivers a reversible capacity of 840 mAh g−1 at 100 mA g−1 after 200 cycles. At 2 A g−1, longer cycling upto 1300 cycles is achieved with a capacity of 377 mAh g−1 along with a Coulombic efficiency of 99% for Li storage. And a decent performance is also available for sodium storage. Quantitative kinetics analysis confirms that the charge storage behavior is governed by pseudocapacitance, especially at high rates (75.9% at 1 mV s–1), boosting the high-rate lithium/sodium storage performance. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The exploration of sodium ion batteries (SIBs) cathodes with high voltage and high performance has stimulated the research on the honeycomb-layered oxides. However, their performance are severely restricted by the slow ion intercalation kinetics and inferior high rate capability. Herein, 1D nanofibers with controlled morphology and crystallinity have been constructed for the honeycomb-layered Na 3 Ni 2 BiO 6 and Na 3 Ni 2 SbO 6. The formation mechanisms of the nanofibers are probed. The significant effects of the porosity and particle crystallinity on ion transport kinetics and electrochemical properties of the oxide nanofibers are studied. Notably, the highly porous structure and low particle crystallinity are highly effective on promoting fast ion transport and improving high rate properties. Surprisingly, both modified nanofibers with uniform porous structure and low-crystallized nanoparticles achieve the better rate capability and faster ion transport capability than the reference samples. Moreover, the excellent sodium storage performance and stable high-rate cycling properties further demonstrate the high efficiency of 1D porous architecture on reversible sodium intercalation. Image 1 [ABSTRACT FROM AUTHOR]

One dimensional SiO 2 /C composite nanofibers were successfully synthesized from precursor solutions with polyvinylpyrrolidone (PVP) as a carbon source by electrospinning with two-step heat treatment, comprising preoxidation at 280 °C in the air followed by annealing at 700 °C for 1 h in a reduced atmosphere. The effects of the preoxidation treatment on the morphology, chemical structure, and electrochemical properties of the synthesized materials were studied by scanning electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, and solid-state nuclear magnetic resonance spectroscopy. The two-step heat treatment had strong positive impacts not only on the morphology but also on the structure and electrochemical performance of the materials. Furthermore, free-standing SiO 2 /C composite nanofiber mats (FS–SiO 2 /C-CNFMs) were prepared from precursor solutions with different PVP concentrations by electrospinning with the two-step heat treatment. The FS-SiO 2 /C-CNFM obtained from the precursor solution with 5 wt.% PVP had a geometric mean diameter of 79 nm and a specific surface area of 642 m2 g−1. It exhibited high initial discharge and charge capacities of 1800 and 984 mA h (SiO 2 -g)−1, respectively, and finally retained a charge capacity of 754 mA h (SiO 2 -g)−1 after 200 cycles with 100% Coulombic efficiency. [ABSTRACT FROM AUTHOR]