Single-nozzle Electrospinning Research Articles

Synthesis of porous CaTiO3 nanotubes with tunable hollow structures via single-nozzle electrospinning

The synthesis of porous CaTiO3 (CTO) nanotubes with controlled microstructure was demonstrated via a single-nozzle electrospinning approach. Homogenous sols comprising polyvinylpyrolidine (PVP), Pluronic F127 and CTO (metal salt) were electrospun, which resulted in fine CTO nanotubes due to phase separation phenomenon. PVP/CTO molar ratio was confirmed to induce the effective manipulation of its structural characteristics. Altering the ratio from 0.24m to 0.12m was found to result in the increased fiber diameter, from ~105nm to ~230nm, and the enhanced hollow structure (diameter of ~70nm). Further development of biocompatible inorganic CaTiO3 nanotubes with such tunable hollow structures provides a platform for sustained drug loading and delivery.

Fe3O4 nanoparticles encapsulated in electrospun porous carbon fibers with a compact shell as high-performance anode for lithium ion batteries

Fe3O4 nanoparticles encapsulated in porous carbon fibers (Fe3O4@PCFs) as anode materials in lithium ion batteries are fabricated by a facile single-nozzle electrospinning technique followed by heat treatment. A mixed solution of polyacrylonitrile (PAN) and polystyrene (PS) containing Fe3O4 nanoparticles is utilized to prepare hybrid precursor fibers of Fe3O4@PS/PAN. The resulted porous Fe3O4/carbon hybrid fibers composed of compact carbon shell and Fe3O4-embeded honeycomb-like carbon core are formed due to the thermal decomposition of PS and PAN. The Fe3O4@PCF composite demonstrates an initial reversible capacity of 1015mAhg−1 with 84.4% capacity retention after 80 cycles at a current density of 0.2Ag−1. This electrode also exhibits superior rate capability with current density increasing from 0.1 to 2.0Ag−1, and capacity retention of 91% after 200 cycles at 2.0Ag−1. The exceptionally high performances are attributed to the high electric conductivity and structural stability of the porous carbon fibers with unique structure, which not only buffers the volume change of Fe3O4 with the internal space, but also acts as high-efficient transport pathways for ions and electrons. Furthermore, the compact carbon shell can promote the formation of stable solid electrolyte interphase on the fiber surface.

Preparation of hollow bioactive glass nanofibers by a facile electrospinning method

AbstractIn this communication, hollow bioactive glass (BG) nanofibers were fabricated via a single-nozzle electrospinning method. The morphology of the prepared hollow BG nanofibers was observed by SEM and TEM, and the results showed that BG nanofibers had a continuous hollow interior. The hollow BG nanofibers were incubated in simulated body fluid (SBF) to investigate their apatitemineralization ability, and the result showed that after incubation for 6 h a flower-like apatite was observed on the surface of hollowBGnanofibers, and the Fourier transform infrared (FTIR) result further confirmed the formation of apatite. The results suggested that hollow BG nanofibers could be used for drug delivery and bone regeneration applications due to their unique hollow structure and bioactivity.

Porous Ni nanofibers with enhanced catalytic effect on the hydrogen storage performance of MgH2

Porous Ni nanofibers (NFs) were synthesized via a single-nozzle electrospinning technique with subsequent calcination and reduction.

Thin-walled SnO₂ nanotubes functionalized with Pt and Au catalysts via the protein templating route and their selective detection of acetone and hydrogen sulfide molecules.

Bio-inspired Pt (∼2 nm) and Au (∼2.7 nm) catalysts encapsulated by a protein shell, i.e., Pt-apoferritin (Pt@AF) and Au-apoferriten (Au@AF), were synthesized via the hollow protein nanocage (apoferritin) templating route and directly functionalized on the interior and exterior walls of electrospun SnO2 nanotubes (NTs) during controlled single-nozzle electrospinning followed by high temperature calcination with heating rate control. Fast crystallization of the exterior shell and outward diffusion of the interior Sn precursors and crystallites result in the continued growth of a tubular wall, which is related to rapid heating driven Ostwald-ripening behavior. Very importantly, the Pt and Au nanoparticles (NPs) were immobilized onto thin-walled SnO2 NTs with a diameter of ∼350 nm and a shell thickness of ∼40 nm without any aggregation of catalysts due to high dispersibility, which originated from repulsive electrostatic (Coulombic) forces acting on the surface charged protein shells, leading to an enhanced catalytic effect and outstanding gas sensing properties. Pt-loaded SnO2 NTs exhibited superior acetone response (R(air)/R(gas) = 92 at 5 ppm) compared to pure SnO2 NFs (R(air)/R(gas) = 4.8 at 5 ppm) and SnO2 NTs (Rair/Rgas = 11 at 5 ppm) while Au-loaded SnO2 NTs showed a high response when exposed to hydrogen sulfide (R(air)/R(gas) = 34 at 5 ppm), offering selective gas detection with minimal cross-sensitivity against other interfering gases such as NH3, CO, NO, C6H5CH3, and C5H12. Our results provide a new insight into facile, cost-effective, and highly dispersible catalyst loading on the interior and exterior walls of hollow metal oxide NTs via simple electrospinning as a potential breath analyzer.

Ultrafine Mo2C nanoparticles encapsulated in N-doped carbon nanofibers with enhanced lithium storage performance.

Rechargeable lithium ion batteries (LIBs) have attracted extensive attention globally due to their good cycling stability, high energy density, and rapid-rate capability, while the rational design of electrode materials can significantly improve their electrochemical performance. In this work, ultrafine Mo2C nanoparticles (NPs) were successfully encapsulated in one dimensional (1D) N-doped porous carbon nanofibers to form a hybrid (Mo2C-NCNFs) through a single-nozzle electrospinning approach coupled with post-pyrolysis. The sizes of the Mo2C NPs were in the range of 2-4 nm and the ultrafine Mo2C NPs were uniformly encapsulated in the N-doped carbon nanofibers forming a highly conductive and interconnecting network, which can facilitate fast electronic transport. When evaluated as an anode material for LIBs, the resultant hybrid exhibits stable cycling performance and excellent rate behavior. More remarkably, the Mo2C-NCNFs hybrid is capable of delivering a specific capacity of 658.0 mA h g(-1) under 100 mA g(-1) after 50 cycles. Even under 2000 mA g(-1), a relatively high specific capacity of 411.9 mA h g(-1) can be achieved, which surpasses the theoretical capacity of graphite (372 mA h g(-1)). The excellent lithium storage performance can be attributed to its unique nanostructure with a strong interaction between the ultrafine Mo2C NPs and N-doped carbon that effectively tolerates the volume change, suppresses the agglomeration of Mo2C NPs, and provides conductive pathways for highly efficient charge transfer during lithium insertion and extraction.

A template-free method for preparation of cobalt nanoparticles embedded in N-doped carbon nanofibers with a hierarchical pore structure for oxygen reduction.

Designing and preparing porous materials without using any templates is a challenge. Herein, single-nozzle electrospinning technology coupled with post pyrolysis is applied to prepare cobalt nanoparticles embedded in N-doped carbon nanofibers with a hierarchical pore structure (HP-Co-NCNFs). The resultant HP-Co-NCNFs have lengths up to several millimeters with an average diameter of 200 nm and possess abundant micro/meso/macropores on both the surface and within the fibers. Such a microstructure endows the surface area as high as 115 m(2) g(-1) . When used as an electrocatalyst for the oxygen reduction reaction (ORR), the HP-Co-NCNFs exhibit outstanding electrochemical performance in terms of activity, methanol tolerance, and durability. The hierarchically porous structure and high surface area can effectively decrease the mass transport resistance and increase the exposed ORR active sites. The sufficient amount of exposed ORR active sites along with accessible transport channel and enhanced electrical conductivity may be responsible for the good electrocatalytic performance.

Hierarchical porous Li₂Mg(NH)₂@C nanowires with long cycle life towards stable hydrogen storage.

The hierarchical porous Li2Mg(NH)2@C nanowires full of micropores, mesopores, and macropores are successfully fabricated via a single-nozzle electrospinning technique combined with in-situ reaction between the precursors, i.e., MgCl2 and LiN3, under physical restriction upon thermal annealing. The explosive decomposition of LiN3 well dispersed in the electrospun nanowires during carbothermal treatment induces a highly porous structure, which provides a favourable way for H2 delivering in and out of Li2Mg(NH)2 nanoparticles simultaneously realized by the space-confinement of the porous carbon coating. As a result, the thus-fabricated Li2Mg(NH)2@C nanowires present significantly enhanced thermodynamics and kinetics towards hydrogen storage performance, e.g., a complete cycle of H2 uptake and release with a capacity close to the theoretical value at a temperature as low as 105°C. This is, to the best of our knowledge, the lowest cycling temperature reported to date. More interestingly, induced by the nanosize effects and space-confinement function of porous carbon coating, a excellently stable regeneration without apparent degradation after 20 de-/re-hydrogenation cycles at a temperature as low as 130°C was achieved for the as-prepared Li2Mg(NH)2@C nanowires.

New insight into modulated up-conversion luminescent silica nanotubes as efficient adsorbents for colored effluents.

We report a simple and easy method to fabricate silica nanotubes (SNTs) with multicolor up-conversion luminescence by single-nozzle electrospinning based on phase separation effect without any templates. Multicolor up-conversion nanoparticles (UCNPs) were first synthesized by a similar hydrothermal route. Then, the water solution containing NPs were added slowly into the electrospinning precursor solution in a dropwise manner. After electrospinning process and calcination at 600 °C, pure SNTs with uniformly dispersed NPs were obtained. The as-produced up-conversion (UC) luminescent SNTs were used as an adsorbent for the removal of colorful dye from aqueous solutions. Adsorption experiments indicated that the SNTs have good adsorption capacity and that the adsorption amount can be traced by two indicators: the decrease in UV adsorption of the solutions and changes in the UC intensity of the SNTs. More importantly, the UC-SNT adsorbents are piece-like and could be effectively and quickly separated via filtration or centrifugation. Furthermore, the SNTs can regenerate by calcination and retain almost the same absorption capability for recycling use. Considering cost, function and cyclic utilization, UCNPs decorated SNTs may create a new platform for the preconcentration and separation of colored pollutants from waste water.

Comparison of ethanol sensitivity based on cobalt–indium combined oxide nanotubes and nanofibers

Nano sized semiconductor oxide type gas sensor has been widely studied due to its high sensitivity. Therein, one-dimensional nanostructures have attracted a lot of interests. In this work, nanofiber and nanotube of one-dimensional nano sized cobalt–indium combined oxide were fabricated by single nozzle electrospinning. The ethanol gas sensing properties of Co–In oxide nanofiber and nanotube were investigated. The morphologies were observed by scanning electron microscopy (SEM). The elementary composition was characterized by powder X-ray diffraction (XRD), and energy-dispersive X-ray spectrometry (EDS). The BET surface area of the nanotube can be calculated to be 22m2/g, which is larger than 18m2/g of nanofiber. The results reveal that one-dimensional nanotubes have larger sensitivity to ethanol than that of one-dimensional nanofibers. Besides, the comparison of their response and recovery curves was tested. The selectivity was also investigated. Both nanofibers and nanotubes show a fast response and excellent selectivity.

Hollow SnO2-ZnO hybrid nanofibers as anode materials for lithium-ion battery

Hollow SnO2–ZnO hybrid nanofibers are prepared by a single-nozzle electrospinning technique followed with subsequent heat treatment. The structure and morphology of the samples are characterized by x-ray diffraction, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy and transmission electron microscopy. The as-prepared nanofibers are solid, which maintain after annealing up to 400 °C; while they turn to tubular morphology after annealing at 500 °C. After annealing at 700–900 °C, some of the tubular nanofibers combine together. The FTIR results show that poly (vinylpyrrolidone) is completely removed after annealing at 500 °C. The electrode of hollow SnO2–ZnO nanofibers obtained by calcination at 500 °C delivers a high discharge capacity of 546.5 mAh g−1 after 100 cycles at a current density of 100 mA g−1.

The Enhanced Encapsulation Capacity of Polyhedral Oligomeric Silsesquioxane‐based Copolymers for the Fabrication of Electrospun Core/Shell Fibers

This paper reports the use of polyhedral oligomeric silsesquioxane (POSS)-based copolymers to stabilize the core/shell interface for the facile fabrication of electrospun core/shell fibers. For the poly[(propylmethacryl-heptaisobutyl-polyhedral oligomeric silsesquioxane)-co-(methyl methacrylate)] (POSS-MMA)/poly(ε-caprolactone) (PCL) system, the bicontinuity of hybrid core/shell fibers can be tuned by controlling the phase separation of POSS-MMA/PCL in electrospinning solutions and therefore the size of PCL-in-POSS-MMA emulsion droplets. Our results demonstrate the enhanced encapsulation capacity of POSS-MMA copolymers as shell materials. Taking advantage of the rapid advancement of POSS-based copolymer synthesis, this study can potentially be generalized to guide the fabrication of various other POSS-based core/shell nano-/microstructures by using single-nozzle electrospinning or coaxial electrospinning.

Tuning electrochemical performance of Si-based anodes for lithium-ion batteries by employing atomic layer deposition alumina coating

A free-standing, conductive and three-dimensional network of Al2O3-coated Si/C composite nanofibers is fabricated by a single-nozzle electrospinning and atomic layer deposition. The as-obtained Al2O3-coated Si/C composite nanofibers exhibit excellent electrochemical performance for applications as anode materials for lithium-ion batteries.

Sb–C nanofibers with long cycle life as an anode material for high-performance sodium-ion batteries

Sb–C nanofibers are synthesized successfully through a single-nozzle electrospinning technique and subsequent calcination. The structural and morphological characterizations reveal the uniform nanofiber structure with the Sb nanoparticles embedded homogeneously in the carbon nanofibers. Electrochemical experiments show that the Sb–C nanofiber electrode can deliver large reversible capacity (631 mA h g−1) at C/15, greatly improved rate capability (337 mA h g−1 at 5 C) and excellent cycling stability (90% capacity retention after 400 cycles). The superior electrochemical performances of the Sb–C nanofibers are due to the unique nanofiber structure and uniform distribution of Sb nanoparticles in carbon matrix, which provides a conductive and buffering matrix for effective release of mechanical stress caused by Na ion insertion/extraction and prevent the aggregation of the Sb nanoparticles.

Synthesis and acetone gas sensing properties of α-Fe2O3 nanotubes

α-Fe2O3 nanotubes was successfully prepared by single nozzle electrospinning method. Scanning electron microscope (SEM) was used to characterize the morphology of α-Fe2O3 nanotubes. The gas sensing properties of α-Fe2O3 nanotubes were investigated in detail. The results exhibit relatively good sensing properties to acetone at 240 °C. The response and recovery times are about 3 and 5 s, respectively. The structure of nanotubes is beneficial to the gas sensing properties, which will enlarge the surface-to-volume ratio of α-Fe2O3 and then be available for the transfer of gas, and thus improved the sensor performance consequentially.

Ag-silica composite nanotube with controlled wall structures for biomedical applications

A range of Ag-silica composite nanotubes with tailored wall structures were successfully synthesized in situ by single-nozzle electrospinning. By increasing AgNO3 concentration, the wall structure of Ag-silica tubes changes from dense to porous, and eventually turns into a ‘lace-like’ structure. This is attributed to Ag ions doping into the SiOSi network of precursors, as illustrated in FTIR study. More importantly, Ag-silica composite nanotubes show robust antibacterial activity against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms. Therefore, it is a breakthrough of the nanostructure biomaterial research for future medical applications that require strong antibacterial properties.

Excellent Toluene Sensing Properties of SnO2–Fe2O3 Interconnected Nanotubes

SnO2-Fe2O3 interconnected nanotubes were obtained by combining the single nozzle electrospinning and thermal treatment methods. The results of scanning electron microscopy revealed the special structure of ruptures and interconnected nanotubes in the as-prepared materials. The toluene sensing test results of SnO2-Fe2O3 interconnected nanotubes show that SnO2-Fe2O3 interconnected nanotubes possess excellent toluene gas-sensing properties. The sensitivity of detecting limit (50 ppb) is 2.0 at the optimum operating temperature of 260 °C. The response and recovery times to 1 ppm toluene are about 5 and 11 s, respectively. Moreover, the SnO2-Fe2O3 interconnected nanotube gas sensors exhibit the remarkable selectivity to toluene, and good long-term stability.

Electrospinning La0.8Sr0.2Co0.2Fe0.8O3−δ tubes impregnated with Ce0.8Gd0.2O1.9 nanoparticles for an intermediate temperature solid oxide fuel cell cathode

In order to reduce the polarization resistance of the cathode, we have developed one-dimensional (1D) nanostructured La0.8Sr0.2Co0.2Fe0.8O3−δ (LSCF) tubes/Ce0.8Gd0.2O1.9 (GDC) nanoparticles composite cathodes for solid oxide fuel cell. Uniform LSCF/PVP composite nanofibers have been firstly synthesized by a single-nozzle electrospinning technique, followed by firing at 800 °C for 2 h to form one-dimensional LSCF tubes. Subsequently, the GDC phases were introduced into tube structured LSCF scaffold pre-sintered on a GDC pellet by a multi-impregnation process. Electrochemical Impedance spectra reveal that nanostructured LSCF tubes/GDC nanoparticles composite cathodes have a better electrochemical performance, achieving area-specific resistances of 4.70, 1.12, 0.27 and 0.07 Ω cm2 at 500, 550, 600 and 650 °C for the composite of GDC and LSCF in a weight ratio of 0.52:1. The low ASR values are mainly related to its optimal microstructure with larger triple-phase boundaries and higher porosity. These results suggest that LSCF tube/GDC nanoparticle composite can be an alternative cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC).

Two-nozzle electrospinning of (MWNT/PU)/PU nanofibrous composite mat with improved mechanical and thermal properties

Composite nanofibrous mat composed of neat polyurethane (PU) and multiwalled carbon nanotubes/polyurethane (MWNT/PU) nanofibers have been fabricated by one-step angled two-nozzle electrospinning. The morphological, thermal, and mechanical properties of the electrospun nanofibers were evaluated. The diameters of electrospun neat PU and composite nanofibers ranged from 239 to 1058 nm. The two-nozzle electrospun (MWNT/PU)/PU composite nanofibers showed curly, and randomly-oriented fibers with interfiber bonding, and were generally bigger in size than single-nozzle electrospun nanofibers. The tensile strength of the neat PU composite nanofiber mat obtained from two-nozzle electrospinning was 25% higher than that obtained from neat PU single-nozzle electrospinning. The incorporation of MWNTs in the composite nanofiber increased the tensile strength by as much as 64% without reducing elongation, made the composite nanofiber more thermally stable, and improved the melting zone. The present results showed that side-by-side angled two-nozzle electrospinning can improve the quality of the electrospun nanofibers that could have potential application in different fields such as filtration, protective clothing and tissue engineering.

Synthesis, characterization, and lithium-storage of ZnO–SnO2 hierarchical architectures

Hierarchical ZnO–SnO2 composite nanofibers have been prepared through the single-nozzle electrospinning technique and subsequent calcinations using polyvinyl pyrrolidone as the fiber template and N,N-dimethylformamide as the solvent. The structures and morphologies of the samples were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The mesoporous nanofibers are composed of homogeneous grain-like nanoparticles, and heterostructures are formed between ZnO and SnO2. When used as the anode of lithium ion batteries, the ZnO–SnO2 composite nanofibers show first discharge and charge capacities of 1795 and 1364 mA h g−1 at a current density of 50 mA g−1. A reversible capacity of 588 mA h g−1 is obtained after 100 cycles. The ZnO–SnO2 composite nanofibers prepared by such a simple and cheap method are expected to have a potential application in energy storage.