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[en] Highlights: • ZnMn_2O_4 nanofibers were successfully synthesized by a facile electrospinning and calcination method for lithium-ion batteries. • The as-prepared ZnMn_2O_4 nanofibers, containing PVP and PAN with ratio of 1:9, exhibited a high initial discharge capacity of 1274 mAh g"−"1, and the stabilized capacity was as high as 603 mAh g"−"1 after 60 cycles at a current density of 50 mA g"−"1. • The as-prepared ZnMn_2O_4 anode material showed good lithium storage performances and excellent rate capability and can be a promising electrode material for lithium-ion batteries in the future. - Abstract: In this paper, ZnMn_2O_4 nanofibers were synthesized by a facile electrospinning and calcination method. Electrochemical properties of the nanofiber anode material for lithium-ion batteries were investigated. The as-prepared ZnMn_2O_4 nanofibers, containing PVP and PAN with ratio of 1:9, exhibited a high initial discharge capacity of 1274 mAh g"−"1, and the stabilized capacity was as high as 603 mAh g"−"1 after 60 cycles at a current density of 50 mA g"−"1. Besides the high specific capacity and good cyclability, the electrode also showed good rate capability. Even at 2000 mA g"−"1, the electrode could deliver a capacity of as high as 352 mAh g"−"1. The results suggest a promising application of the electrospun ZnMn_2O_4 nanofibers as anode material for lithium-ion batteries
[en] Graphical abstract: We successfully synthesized magnesium ferrite (MgFe_2O_4) nanofibers by a facile electrospinning technique followed by calcining at 800 °C. Electrochemical property demonstrated that MgFe_2O_4 nanofibers possessed high reversible capacity and cycling stability. Moreover, the MgFe_2O_4 nanofibers electrode also exhibits high capacity at higher charge/discharge rate. - Highlights: • We successfully synthesized electrospun magnesium ferrite (MgFe_2O_4) anode material for lithium-ion batteries for the first time. • The as-prepared MgFe_2O_4 nanofibers calcined at 800 °C exhibited a high initial discharge capacity of 1304 mAh g"−"1, and maintained a stable capacity of 714 mAh g"−"1 after 100 cycles. • The as-prepared MgFe_2O_4 nanofibers calcined at 800 °C also showed high capacity at higher discharge and charge rate. - Abstract: In this study, we successfully synthesized magnesium ferrite (MgFe_2O_4) nanofibers by a facile electrospinning technique followed by calcining at 800 °C. The lithium storage properties of MgFe_2O_4 nanofibers as anode materials for lithium-ion batteries have been discussed for the first time. It is demonstrated that MgFe_2O_4 nanofibers electrode not only deliver a high initial discharge capacity of around 1304 mAh g"−"1, but also maintain a reversible capacity of 714 mAh g"−"1 after 100 cycles. Moreover, the MgFe_2O_4 nanofibers electrode also exhibits high capacity at higher charge/discharge rate. Even at a current density of 2000 mA g"−"1, the reversible capacity can attain 409 mAh g"−"1 after 100 cycles, suggesting its excellent rate capability. The superior lithium storage properties of the MgFe_2O_4 nanofibers electrode may be related to the unique continuous fibrous morphologies, nanostructured architectures, porous structures, and large specific surface area, which provide an easily Li"+ diffusion path and promote electron transfer. In addition, the formation of MgO appears to act as a buffer layer that prevents agglomeration of nanocrystalline, accommodate the large volume change and reduces polarization during cycling
[en] Graphical abstract: We successfully synthesize ordered Sn/CMK-3 nanocomposites by sonochemical method and carbonization process. The lithium storage properties demonstrated that Sn/CMK-3 nanocomposites possessed high reversible capacity and cycling stability. Moreover, the Sn/CMK-3 nanocomposites electrode also exhibits high capacity at higher charge/discharge rate. Display Omitted - Highlights: • We successfully synthesize ordered Sn/CMK-3 nanocomposites by sonochemical method and carbonization process. • The lithium storage properties shows that the Sn/CMK-3 nanocomposites obtained at 800 °C delivers an initial discharge capacity of 1450 mAh g"−"1, and a reversible capacity as high as 674 mAh g"−"1 after 50 cycles. • The ordered Sn/CMK-3 nanocomposites also showed high capacity at higher discharge and charge rate. - Abstract: In this work, we successfully synthesize ordered Sn/CMK-3 nanocomposites by sonochemical method and carbonization process. XRD results verify that SnO_2 has been completely reduced to metal Sn for the samples obtained at 800 °C. Sn nanoparticles are good dispersed into the pore channels of ordered CMK-3 for Sn/CMK-3 nanocomposites according to the nitrogen adsorption–desorption isotherms. The lithium storage properties shows that the Sn/CMK-3 nanocomposites obtained at 800 °C delivers an initial discharge capacity of 1450 mAh g"−"1, and a reversible capacity as high as 674 mAh g"−"1 after 50 cycles at a current density of 100 mA g"−"1, much higher than those of the samples obtained at 600 °C (1352 and 411 mAh g"−"1, respectively). The Sn/CMK-3 nanocomposites obtained at 800 °C also demonstrates an excellent rate capability with capacity of 546 mAh g"−"1 even at a current density of 1000 mA g"−"1 after 50 cycles. The improved lithium storage properties of Sn/CMK-3 nanocomposites obtained at 800 °C can be attributed to a synergistic reaction between Sn nanoparticles and CMK-3 matrix, as well as the high crystallinity
[en] Graphical abstract: (A) Formation mechanism of A-CZNF and (B) reaction principle and formation mechanism of A-CZUF biosensor. - Highlights: • We utilized the hydrophobic protein nanofibers to fabricate a laccase-based biosensor for the first time. • The composite containing gold nanoparticles was prepared by combining electrospinning and one-step reduction method, which is a novel nanomaterial. • It is noticeable that the laccase biosensor showed a high electrochemical response and electrochemical activity toward catechol. • The novel biosensor will offer a simple, convenient and high efficient method for detecting polyphenolic compounds in environment. - Abstract: A novel laccase biosensor based on a new composite of laccase–gold nanoparticles (Au NPs)-crosslinked zein ultrafine fibers (CZUF) has been fabricated for catechol determination in real solution samples. Firstly, crosslinked zein ultrafine fibers containing gold nanoparticles (A-CZUF) were prepared by combining electrospinning and one-step reduction method using poly(ethyleneimine) (PEI) as reducing and crosslinking agent. A smooth morphology and relative average distribution of A-CZUF were depicted by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The Fourier transform infrared spectroscopy (FT-IR) analysis indicated that PEI molecules attached to the surface of the zein ultrafine fibers via the reaction of functional groups between PEI and glyoxal. The results obtained from ultraviolet visible spectroscopy (UV–vis spectroscopy), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA) for A-CZUF confirmed the existence of Au NPS coated on the surface of CZUF. Square wave voltammetry (SWV) and cyclic voltammetry (CV) were used to detect the electrochemical performance of the proposed biosensor. The results demonstrated that this biosensor possessed a high sensitive detection to catechol, which was attributed to the direct electron transfer (DET) facilitated by Au NPs and high catalytic ability obtained from laccase. In addition, the proposed biosensor exhibited good reproducibility, stability and selectivity
[en] A novel graphene oxide/polyester (GO/PET) composite fabric as a recyclable adsorbent was prepared via electrostatic self-assembly. The structure, morphology, and properties of the GO/PET composite fabrics were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and contact angle (CA), respectively. The absorption property was evaluated by the absorption amount and removal efficiency of methylene blue (MB) solution on the GO/PET composite fabric. The results indicated that the absorption amount was found to be 21.80 mg/g and the removal efficiency reached 99.93 % under the experimental conditions of GO concentration of 2 mg/ml, initial concentration of 50 mg/l, and area of 64 cm2. The experimental parameters were investigated including the concentration of GO, the initial concentration of MB solutions, and adsorbent area. Simultaneously, according to a series of dynamic analysis, the absorption process revealed that the kinetics was well-described by pseudo-second-order model. This study showed that the GO/PET composite fabric could be a recyclable, efficient adsorbent material for the environmental cleanup.
[en] Highlights: • Fe-doped Co9S8 nanosheets have been prepared on flexible carbon cloth (Fe-Co9S8 NSs/CC) via facile one-pot reaction. • Fe-Co9S8 NSs/CC delivers prominent electrocatalytic performance under all pH. • Enormous interconnected nanosheets and good hydrophilicity guarantee its efficiency toward the HER. - Abstract: Heteroatom doping is a feasible approach to adjust catalytic performance of the HER catalysts. In this work, we report a design of Fe-doped Co9S8 nanosheets grown on carbon cloth (Fe-Co9S8 NSs/CC) as a hydrophilic 3D monolithic electrocatalyst for efficient hydrogen evolution under all pH. The water contact angle and electrochemical measurements proved that the resultant material was hydrophilic for its nano hierarchitectures and dopant Fe enhanced the catalytic capability of singular Co9S8. In 1.0 M KOH, the Fe-Co9S8 NSs/CC possessed a relatively small Tafel slope (95.3 mV dec−1) and required the overpotential of 83 mV to achieve 10 mA cm−2. To drive the same current density, the overpotentials were 65 and 192 mV in 0.5 M H2SO4 and 1.0 M PBS, respectively. Meanwhile, it showed good cycle stability and durability over 20 h static test at alkaline and neutral condition. The flexible freestanding catalyst has great potential in practical applications.
[en] Graphical abstract: - Highlights: • PANI nanorods have been grown onto the surface of CMC/cellulose nanofibers for the fabrication of biosensor substrate material. • The proposed laccase biosensor exhibited a low detection limit and high sensitivity in the detection of catechol. • Hierarchical PANI/CMC/cellulose nanofibers are the promising material in the design of high-efficient biosensors. - Abstract: We report a facile approach to synthesizing and immobilizing polyaniline nanorods onto carboxymethyl cellulose (CMC)-modified cellulose nanofibers for their biosensing application. Firstly, the hierarchical PANI/CMC/cellulose nanofibers were fabricated by in situ polymerization of aniline on the CMC-modified cellulose nanofiber. Subsequently, the PANI/CMC/cellulose nanofibrous mat modified with laccase (Lac) was used as biosensor substrate material for the detection of catechol. PANI/CMC/cellulose nanofibers with highly conductive and three dimensional nanostructure were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectra (FT-IR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimum conditions, the Lac/PANI/CMC/cellulose/glassy carbon electrode (GCE) exhibited a fast response time (within 8 s), a linear response range from 0.497 μM to 2.27 mM with a high sensitivity and low detection limit of 0.374 μM (3σ). The developed biosensor also displayed good repeatability, reproducibility as well as selectivity. The results indicated that the composite mat has potential application in enzyme biosensors
[en] In the present work, poly(methyl methacrylate) (PMMA)/organically modified montmorillonite (O-MMT) composite microfibers were firstly prepared by emulsion polymerization combined with electrospinning, and then coated by nanosize titanium dioxide (TiO2) using RF magnetron sputter technique. The modified surfaces of PMMA/O-MMT composite microfibers were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), UV-vis spectroscopy and drop shape analyzer. Finally, the photocatalytic properties of TiO2 coated PMMA/O-MMT composite microfiber membranes were evaluated by degradation of methylene blue(MB) under UV illumination. The experimental results revealed that anatase-TiO2 and rutile-TiO2 nanoparticles were well spread and physically deposited on the surface of PMMA/O-MMT microfibers, and the wettability of the PMMA/O-MMT composite microfibers was improved after surface modification by sputter coating. Furthermore, the PMMA/O-MMT microfibers membrane coated with TiO2 performed well in photocatalytic degradation of MB.
[en] The halogen-free flame retardant form-stable phase change materials (PCM) based on paraffin/high density polyethylene (HDPE) composites were prepared by using twin-screw extruder technique. The structures and properties of the form-stable PCM composites based on intumescent flame retardant system with expandable graphite (EG) and different synergistic additives, such as ammonium polyphosphate (APP) and zinc borate (ZB) were characterized by scanning electronic microscope (SEM), thermogravimetric analyses (TGA), dynamic Fourier-transform infrared (FTIR) spectra, differential scanning calorimeter (DSC) and Cone calorimeter test. The TGA results showed that the halogen-free flame retardant form-stable PCM composites produced a larger amount of charred residue at 700 deg. C, although the onset of weight loss of the halogen-free flame retardant form-stable PCM composites occurred at a lower temperature due to the thermal decomposition of flame retardant. The DSC measurements indicated that the additives of flame retardant had little effect on the thermal energy storage property, and the temperatures of phase change peaks and the latent heat of the paraffin showed better occurrence during the freezing process. The dynamic FTIR monitoring results revealed that the breakdowns of main chains (HDPE and paraffin) and formations of various residues increased with increasing thermo-oxidation temperature. It was also found from the Cone calorimeter tests that the peak of heat release rate (PHRR) decreased significantly. Both the decrease of the PHRR and the structure of charred residue after combustion indicated that there was a synergistic effect between the EG and APP, contributing to the improved flammability of the halogen-free flame retardant form-stable PCM composites
[en] Melt-electrospinning is an efficient and environmental-friendly technique for producing nano/micro fibers. In this work, the self-layering behavior of poly(ethylene terephthalate)(PET) fiber deposition during melt-electrospinning was investigated based on the electric field simulation analysis by ANSYS and high voltage insulation theory of capacitor for melt-electrospinning configuration. The simulation results demonstrated that during melt-electrospinning process, the electric field strength on the center and lateral surface of the collector changed alternately when some electrically charged jet deposited, making jet depositing location moved around between center and lateral surface, resulted in the formation of the binding fibers separating the inner and outer layers in the deposited PET fiber web. The PET fiber web electrospun in 90 minutes could be laminated freely into thirteen layers. The geometric dimensions of these layers were measured and their morphologies were observed by scanning electron microscopy (SEM). These laminated layers were concentric with almost linearly increasing radius from the inner to the outer. Inner layers featured themselves with appearance of thick center and thin edge, while for outer layers, they presented the appearance of thin center and thick edge. The fibers in the web were quite uniformly and had diameters of about 2 μm.