Flexible Composite Nanofibers Research Articles

Highly efficient removal of salicylic acid from pharmaceutical wastewater using a flexible composite nanofiber membrane modified with UiO-66(Hf) MOFs

The successful development of a cost-effective and efficient adsorbent is crucial for the optimal treatment of pharmaceutical sewage. In this study, a UiO-66(Hf)–NH2 nanocrystal modified composite nanofiber membrane (HfPNFM) was synthesized through electrospinning and solvothermal techniques, for the removal of salicylic acid (SA). The in-situ growth of UiO-66(Hf)–NH2 on the nanofibers led to a significant increase in the specific surface area of the composite nanofiber membrane. Furthermore, HfPNFM demonstrated exceptional flexibility and reusability, with the removal efficiency of SA still at 96.85 % even after ten cycles. The adsorption process of SA onto HfPNFM was well described by the pseudo-second-order kinetic model and Langmuir isotherm model, with a maximum adsorption capacity of 128.21 mg/g. In dynamic adsorption experiments, HfPNFM effectively removed 100 % of SA at a concentration of 50 mg/L. The chemical oxygen demand (COD) concentration of SA was reduced from 165.89 mg/L to 41.47 mg/L by two layers of HfPNFM filtration, below the standard for pharmaceutical wastewater discharge (GB: 21904-2008). X-ray photoelectron spectroscopy (XPS) revealed that electrostatic interactions, π-π interactions, hydrogen bond interactions, and metal complexation interactions between SA and HfPNFM were responsible for the adsorption. This highly effective composite nanofiber membrane has promising potential for pharmaceutical wastewater treatment.

The construction of rod-like polypyrrole network on hard magnetic porous textile anodes for microbial fuel cells with ultra-high output power density

This study attempts to prompt the formation of microorganism films on flexible textile-based anodes and enhances the performance of living microorganisms by introducing magnetic properties to the anodes. A magnetic and electrically conductive anode for a microbial fuel cell is designed and fabricated by encapsulating uniformly dispersed SrFe12O19 nanoparticles into the poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibers and forming a three-dimensional (3D) polypyrrole (PPy) network on the surface of flexible composite nanofiber based fabric. A dual-chamber MFC equipped with the magnetized anode shows a maximum power density of 3317 mW m−2, which is significantly larger than that of the non-magnetized anode (2471 mW m−2). This study demonstrates that the hard-magnetic anode providing an inherent magnetic field can greatly promote bio-electrochemical reaction rates of E. coli, and decrease the anode charge transfer resistance in a MFC system.

Forcespinning: An Alternative Method to Produce Metal Sulfides/Carbon Composite Nanofibers As Anode Materials for Lithium-Ion and Sodium-Ion Batteries

We present results on the Forcespinning (FS) of SnS2/SnO2/PAN and MoS2/PAN precursors for the mass production of SnS2/SnO2 /carbon and MoS2/C as anode materials for Lithium-ion and Sodium-ion batteries. The binary composite nanofiber electrodes of SnS2/SnO2/C and MoS2/C are produced using a scalable technique (FS) and subsequent thermal treatment (calcination). The composite nanofiber anodes were porous and flexible. The nanofiber preparation process involved the FS of SnS2/SnO2/PAN and MoS2/PAN precursors into nanofibers and subsequent stabilization in air at 280oC and calcination at 800oC under an inert atmosphere. The flexible composite nanofibers were directly used as working electrode in lithium-ion and sodium-ion batteries without a current collector, conducting additives, or binder. The SnS2/C and SnS2/SnO2/C electrodes delivered a specific capacity of 556 mAhg-1 and 965 mAhg-1 respectively during the first sodiation cycle. This initial high capacity is attributed to the irreversible formation of a stable SEI layer and to the porous structure of the Forcespun composite nanofibers. In the subsequent cycles, the SnS2/C electrode exhibited a much stable cycling performance compared to SnS2/SnO2/C i.e. 145 mAhg-1 was maintained after 50 cycles. The MoS2/C composite nanofiber electrodes delivered a good electrochemical performance and Coulombic efficiency when used for Lithium-ion batteries. This study provides a novel and feasible pathway for designing and developing promising anodes and cathodes for high-performance lithium ion and sodium-ion batteries.

A comparative study on the performance of binary SnO2/NiO/C and Sn/C composite nanofibers as alternative anode materials for lithium ion batteries

The development of alternative anode materials out of flexible composite nanofibers has seen a growing interest. In this paper, binary carbon nanofiber electrodes of SnO2/NiO and Sn nanoparticles are produced using a scalable technique, Forcespinning (FS), and subsequent thermal treatment (carbonization). The Sn/C composite nanofibers were porous and flexible, while the SnO2/NiO composite nanofibers had “hairy-like” particles and pores on the fiber strands. The nanofiber preparation process involved the FS of Sn/PAN and SnO2/NiO/PAN solution precursors into nanofibers and subsequent stabilization in air at 280°C and calcination at 800°C under an inert atmosphere. The flexible composite nanofibers were directly used as working electrodes in lithium-ion batteries without a current collector, conducting additives, or binder. The electrochemical performance of the SnO2/NiO/C and Sn/C composite fiber anodes showed a comparable cycle performance of about 675 mAhg−1 after 100 cycles. However, the SnO2/NiO/C electrode exhibited a better rate performance than the Sn/C composite anode and was able to recover its capacity after charging with a higher current density. A postmortem analysis of the composite nanofiber electrode after the aging process revealed a heavily passivated electrode from the electrolyte decomposition by-products. The synthesis and processing methods used to produce these composite nanofibers clearly were a factor for the high rate capability and excellent cycle performance of these binary composite electrodes, largely on the account of the unique structure and properties of the composite nanofibers.

SnO2/NiO/Carbon Composite Nanofibers Produced By Forcespinning of Poly Acrylonitrile /SnO2 Precursor As Anodes for Lithium Ion Batteries

The development of alternative anode materials out of flexible nanofibers has seen a growing interest. In this paper, binary carbon nanofiber electrodes of SnO2/NiO and Tin nanoparticles are produced using a scalable technique, Forcespinning (FS) and subsequent thermal treatment (calcination). The Sn/C nanofibers were porous and flexible, while the SnO2-NiO nanofibers had “hairy-like” particles and pores on the fiber strands. The nanofiber preparation process involved FS the Sn/PAN and SnO2/NiO/PAN precursors into nanofibers and subsequently stabilizing in air at 280oC and calcination at 800oC under an inert atmosphere. The flexible composite nanofibers were directly used as working electrode in lithium-ion batteries without a current collector, conducting additives, or binder. The electrochemical performance of the SnO2/NiO/C and Sn/C electrodes showed a comparable cycle performance of about 675 mAhg-1 after 100 cycles. However, the SnO2/NiO/C electrode exhibited a better rate performance than Sn/C anode and was able to recover its capacity after charging with a higher current density. The synthesis and processing methods used to produce these nanofibers clearly was a factor for the high rate capability and excellent cyclic performance of these binary composite electrodes, largely on the account of the unique structure and properties of the composite nanofibers.

3D nanoarchitectures of α-LiFeO2 and α-LiFeO2/C nanofibers for high power lithium-ion batteries

Hydrodynamic structuring of alkoxide-based sols in an electrical field is a promising technique to fabricate one-dimensional materials as free-standing fiber mats with high surface area and precisely controlled microstructure. Hollow α-LiFeO2 and composite α-LiFeO2/C nanofibers were prepared as self-supported 3D architectures of ceramic fibers by single-step electrospinning of metal alkoxide sols. The spinel fibers exhibited a crystalline spinel phase with uniform fiber diameter and morphology that was modified by a thin sheath of amorphous carbon in the composite fibers that enhances the electrical conductivity and also has a structure-holding influence. The atomic scale mixing and pre-existing LiOFe units in the spinning solution were the delivers of observed phase purity and control over the surface properties verified by high resolution TEM data. Galvanostatic and potentiostatic studies confirmed the superior electrochemical behaviors of α-LiFeO2 and α-LiFeO2/C nanofibers as high-energy density anode materials in half-cell configuration. α-LiFeO2/C composite nanofibers showed after 50 cycles a discharge capacity of 821mAh/g at 0.1C with a capacity retention of 75% from the 2nd to 50th cycle, whereas the discharge capacity of α-LiFeO2-hollow nanofibers was found to be 756mAh/g with a capacity retention of 68%. Flexible composite nanofiber networks are promising solution enabling improved electronic and ionic conductivity and mechanical stability for the development of lithium-ion batteries with high power and energy densities. Investigations on the stability and rate capability of α-LiFeO2/C-composite electrode studied at different rates of 0.1C, 0.25C and 0.5C for 75 cycles also showed high capacity values that indicated their potential as anode materials.

Dy3+ and Eu3+ complexes co-doped flexible composite nanofibers to achieve tunable fluorescent color

Color-tunable flexible composite nanofibers containing Dy(BA)3phen and Eu(BA)3phen complexes have been successfully fabricated via a facile electrospinning process. Scanning electron microscopy, energy dispersive spectrometry and fluorescence spectroscopy were used to characterize the samples. The diameter of the composite nanofibers is 420.83 ± 6.55 nm. Tunable color from greenish blue to white to orange can be realized in a single flexible composite nanofiber by varying the mass ratio of Dy(BA)3phen–Eu(BA)3phen, and it is the first time to obtain white-light-emitting flexible nanofibers using rare earth complexes as luminescent centers. In particular, the composite nanofibers can respectively emit cool and warm white light with certain doping contents of Dy(BA)3phen and Eu(BA)3phen. The novel color-tunable composite nanofibers have potential applications in the fields of fluorescent lamps, field emission displays and color displays.

A new strategy to assemble enhanced magnetic–photoluminescent bifunction into a flexible nanofiber

A new type of magnetic–photoluminescent bifunctional [Fe3O4@Y2O3:Eu3+]/polyvinyl pyrrolidone (PVP) flexible composite nanofibers were successfully prepared via electrospinning through dispersing Fe3O4@Y2O3:Eu3+ core–shell structured nanoparticles (NPs) into the PVP matrix. The structure, morphology, and properties of the flexible composite nanofibers were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), and fluorescence spectroscopy. The diameter of [Fe3O4@Y2O3:Eu3+]/PVP nanofibers is ca. 128.57 ± 36.72 nm. Fluorescence emission peaks of Eu3+ in both Fe3O4@Y2O3:Eu3+ NPs and [Fe3O4@Y2O3:Eu3+]/PVP nanofibers are observed and assigned to the energy levels transitions of 5D0 → 7F0 (580 nm), 5D0 → 7F1 (533, 586, 592, 599 nm), 5D0 → 7F2 (612 nm), and 5D0 → 7F3 (629 nm) of Eu3+ ions. Compared with Fe3O4/Y2O3:Eu3+/PVP nanofibers, [Fe3O4@Y2O3:Eu3+]/PVP nanofibers possess much stronger luminescence. The as-prepared [Fe3O4@Y2O3:Eu3+]/PVP flexible composite nanofibers simultaneously exhibit excellent magnetism and photoluminescent performance. The intensities of magnetism and luminescence of the composite nanofibers can be simultaneously tuned by adjusting the amount of Fe3O4@Y2O3:Eu3+ NPs introduced into the nanofibers. The high performance [Fe3O4@Y2O3:Eu3+]/PVP flexible composite nanofibers have potential applications in bioimaging, cell separation, and future nanomechanics.