Composite Nanofiber Membranes Research Articles

Electrospun polyacrylonitrile-based lace nanostructures and their Cu(Ⅱ) adsorption

High performance nanostructures for efficient heavy metal treatment are highly desired in our daily life. A functionalized porous nanofibrous membrane loaded with MgO nanoparticles prepared by coaxial electrospinning and post-processing method was studied to remove copper ions from aqueous solutions. The solid core layer is used to support the functional layer of the sheath with lace-like porous structure, and to obtain the composite nanofiber membrane with super adsorption performance. The functional fiber membrane has a larger specific surface area, a more uniform diameter distribution and surface pores than other nanofibers, moreover, showing the dual advantages of good mechanical properties and hydrophilicity. Adsorption of copper ions reached equilibrium within 3 h with an optimal adsorption pH of 5 and a maximum adsorption capacity of 354 mg/g. The pseudo-second-order kinetic model and the Langmuir model can well describe the single-layer chemisorption process between copper ion and functional membrane. After the functional fiber membrane was repeatedly used for 5 times, the adsorption removal efficiency remained at 70%, which indicates that the recycling performance was good. The functionalized nanofiber membrane has a simple preparation and high removal efficiency, and is an effective material that can address heavy metal-polluted water.

Study on the PI/SPEEK nanofiber composite proton exchange membrane for fuel cells

Sulfonated poly ether ether ketone (SPEEK) can be selected as the candidate for proton exchange membrane (PEM) used in the fuel cell for its cheap price, great proton conductivity and stability. To further improve its performance, more SO3H were induced into SPEEK but would result in excessive swelling and losing its stability. Polyimide (PI) nanofibers have excellent mechanical properties and can be a supporter to improve stability. In this work, the PI nanofiber was put in the middle of the SPEEK to create the PI/SPEEK nanofiber composite membranes (NCMs). Its morphology of PI/SPEEK NCMs observed by SEM showed that PI nanofiber was almost in the middle of these NCMs. The proton conductivity and swelling ratio of 3%PI/SPEEK were 271.7 mScm-1 and 20.0% at 60°C and 100% RH, which is 29.6% higher and 90.4% lower than that of pristine SPEEK. It was intact after the single-cell test in the fuel cell and its power density was 199.1 mWcm-2, but for pure SPEEK there was some broken area on it. The reason was that PI/SPEEK can maintain the durability of the channels for the proton to transport and it can be attributed to an interaction at their interface of PI nanofiber and SPEEK. The 3%PI/SPEEK NCM will have a broad application prospect in PEM fuel cells.

Sandwich-structure PI/SPEEK/PI proton exchange membrane developed for achieving the high durability on excellent proton conductivity and stability

The proton exchange membrane (PEM) is the core unit in fuel cells, in which the balance among proton conductivity, dimensional stability and durability is a long-term pursuit. Nanofiber composite membrane as the most facile and practical strategy, however, commonly suffers from the obviously reduced proton conductivity although the dimensional stability and durability can be improved distinctly. Herein this work, we proposed a sandwich-structure nanofiber composite PEM, in which the inexpensive proton-transport matrix of sulfonated poly (ether ether ketone) (SPEEK) is sandwiched between polyimide (PI) nanofibers mats via simple steps. Thanks to the support for the matrix and resistance to the tough working condition provided by the PI nanofiber mats, significantly improved stability and durability in contrast to the referenced PEM of SPEEK. More importantly, with respect to the proton conductivity, a numerically equivalent initial proton conductivity and significantly improved proton conductivity stability, in comparing to the SPEEK membrane, has been achieved; where the conductivity only decreased by 21% in our sandwich-structure PEM after 6 weeks, much less than that of commercial Nafion 117 of 30% and pure SPEEK of 55%. Such results can be attributed to the hydrogen bond interaction between PI nanofibers and SPEEK matrix and thus the formation of the sulfonic acid-rich layer in our developed PI/SPEEK/PI membrane, confirmed by in situ Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). This combination of high proton conductivity, long-term stability, low cost, simple preparation suggests the sandwich-like PEM will provide a promising commercial application for future PEMs. • The sandwich structure PI/SPEEK/PI nanofiber composite membrane was proposed. • The proton conductivity of PI/SPEEK/PI membrane with high durability was achieved. • The interaction between PI nanofiber and SPEEK matrix was confirmed by in-suit FTIR, XPS and TEM.

Route to a Porous Carbon Nanofiber Membrane Containing FexCy/Fe by Facile In Situ Ion-Exchange Functionalization of the PAA Carboxyl Group: Exemplified by a Supercapacitor

In this paper, the concept of facile carboxyl in situ ion-exchange (CISIE) functionalization is utilized in preparing polyimide (PI)-derived carbon materials for the first time. Taking Fe species as an example, a high-performance FexCy/Fe composite porous carbon nanofiber (PCF) membrane is obtained by electrospinning of the PI precursor. The morphology and structure are characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and other means. Then, the electrochemical performance is taken as an example to highlight the prospect of this preparation method of functional porous carbon materials. The cyclic voltammetry curves are analyzed by means of b-values, Trasatti’s method, and Dunn’s method, and it was found that porous carbon materials can show pseudocapacitance due to the introduction of Fe3+. Herein, the activated PCF-Fe electrode exhibits a high specific capacitance, which reaches 340 F g–1 at a current density of 1 A g–1 and shows a rate capability of 35.29% (120 F g–1 at 50 A g–1). In addition, PCF-Fe also shows great potential for application in self-standing electrodes. Furthermore, an assembled asymmetric supercapacitor made of PCF-Fe exhibits an energy density of 16.3 W h kg–1 at a power density of 0.6 kW kg–1 and a long cycle life. The FexCy/Fe composite PCF membranes obtained based on facile CISIE functionalization exhibit an excellent electrochemical storage performance and are expected to be utilized as electrode materials for supercapacitors.

Flexible hybrid perovskite nanofiber for all-inorganic perovskite solar cells

Metal halides perovskite materials with their excellent light absorption coefficient, rendering perovskite solar cells (PSCs) as potential candidates for the next generation of solar cells, have been attracting worldwide attention. One-dimensional flexible perovskite nanowires/nanoroads, with appropriate aspect ratios, can reduce crystal surface defect level and allow a smooth carrier transport channel. Herein, the all-inorganic perovskite/polymer composite nanofiber membranes were fabricated via electrospinning technique. The hybrid all-inorganic perovskite nanofiber membranes possessed the characteristics of bending under force, which emerged pleasurable flexibility. The viscosity of the spinning solution and the morphology of the perovskite nanofibers were prominent affected by the concentration of PbBr2 into the perovskite precursor solution. With the concentration of PbBr2 increased, both the grain sizes of perovskite nanocrystals on the nanofiber membranes and the corresponding PCE of the as-assembled PSCs were gradually increased, with a champion efficiency of 2.28% for 3 mol/L PbBr2. This research could assist in establishing systematic research on perovskite fiber structure and expanding its application in wearable electronic devices.

Preparation and characterization of biodegradable electrospinning PHBV/PBAT/TiO2 antibacterial nanofiber membranes

To reduce the environmental pollution caused by medical protective materials, such as masks and protective clothing, biodegradable antibacterial materials have received more and more attention in recent years. In this study, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(butylene-adipate-co-terephthalate) (PBAT) were electrospun together and then treated with nano-TiO2 to develop and evaluate a biodegradable, antibacterial nanofiber membrane for medical protective fabric. The SEM images displayed that the nanofiber membrane with a mass fraction of 13 and a mass ratio of 50:50 PHBV/PBAT had the smallest diameter and the best morphology of all samples. In addition, the mechanical properties test and water contact angle test results demonstrated that the PBAT/PHBV composite nanofiber membrane had better mechanical properties and hydrophobicity without compromising its fundamental structure than pure PHBV. The addition of TiO2 nanoparticles decreased the fiber diameter of this nanofiber membrane. When the TiO2 concentration was 1.0 wt%, the average fiber diameter was 367 nm, which might approach the sub-micron level. Meanwhile, the presence of TiO2 reduced adhesion between fibers of the PBAT/PHBV membrane, resulting in a more uniform fiber distribution. Additionally, the elongation at the break of the PHBV/PBAT/TiO2 nanofiber membrane with 1.0 wt% TiO2 was raised from (135 ± 5)% to (203 ± 2)%. The PHBV/PBAT/TiO2 nanofiber membrane containing 1.0 wt% TiO2 inhibited Escherichia coli and Staphylococcus aureus, and its antibacterial rate was over 98%. In this research, we successfully prepared composite materials that were both biodegradable and antibacterial, which can be applied in the field of medical protection. It can promote the development of protective textile materials in the direction of functionalization and degradation.

A high-performance wearable pressure sensor based on an MXene/PVP composite nanofiber membrane for health monitoring.

Flexible and wearable pressure sensors have attracted extensive attention in domains, such as electronic skin, medical monitoring and human–machine interaction. However, developing a pressure sensor with high sensitivity, mechanical stability and a wide detection range remains a huge challenge. In this work, a flexible capacitive pressure sensor, based on a Ti3C2Tx (MXene)/polyvinyl pyrrolidone (PVP) composite nanofiber membrane (CNM), prepared via an efficient electrospinning process, is presented. The experimental results show that even a small mass fraction of MXene can effectively decrease the compression modulus of the PVP nanofiber membrane, thus enhancing the sensing performance. Specifically, the sensor based on (0.1 wt% MXene)/PVP CNM has a high sensitivity (0.5 kPa−1 at 0–1.5 kPa), a fast response/recovery time (45/45 ms), a wide pressure detection range (0–200 kPa), a low detection limit (∼9 Pa) and an excellent mechanical stability (8000 cycles). Due to its superior performance, the sensor can monitor subtle changes in human physiology and other signals, such as pulse, respiration, human joint motions and airflow. In addition, a 4 × 4 sensor array is fabricated that can accurately map the shape and position of objects with good resolution. The high-performance flexible pressure sensor, as developed in this work, shows good application prospects in advanced human–computer interface systems.

Preparation and Performance Characterization of Flexible and Washable Zr-MOFs Composite Nanofiber Membrane

Preparation and Performance Characterization of Flexible and Washable Zr-MOFs Composite Nanofiber Membrane

Pvdf/Fe3o4 Composite Nanofiber Membrane Prepared by Electrospinning for Improving Lithium-Sulfur Batteries

Pvdf/Fe3o4 Composite Nanofiber Membrane Prepared by Electrospinning for Improving Lithium-Sulfur Batteries

Pvdf/Fe3o4 Composite Nanofiber Membrane Prepared by Electrospinning for Improving Lithium-Sulfur Batteries

Pvdf/Fe3o4 Composite Nanofiber Membrane Prepared by Electrospinning for Improving Lithium-Sulfur Batteries

Design and preparation of hollow SiO2 nanospheres/SiC-based nanocomposite fiber membrane for high temperature thermal insulators

Silicon carbide (SiC) fibers are attractive for their thermal stability and chemical erosion resistance. However, the practical application of SiC fiber in the fields of thermal insulation is limited owing to its high intrinsic thermal conductivity. Herein, a novel closed cell structured SiC-based nanocomposite fiber (NCF) using hollow SiO 2 nanospheres (HSNSs) as pore forming agent were designed by precursor conversion method combined with electrospinning technology. According to the content and size of HSNSs, NCFs with different pore size and porosity could be obtained. When the content of HSNSs reached 15%, a large number of closed cells were constructed inside the fiber, which broke the continuity of solid heat transfer and endowed it with excellent thermal insulation performance (∼0.105 W m −1 K −1 at 1000 °C). Meanwhile, the NCFs showed excellent high-temperature resistance and mechanical properties, which makes it have a wide application prospect as a high temperature thermal insulator. This research also offers a new insight for the development of SiC-based fiber with multiple functions to meet various applications, such as catalyst supporters and microwave absorbers. • A new type of porous insulation material with closed cell structure is designed. • Multiple phases enhance interface thermal resistance and infrared shielding performance. • Hollow SiO 2 spheres significantly reduces the thermal conductivity of the fibers. • The nanocomposite fibers show great application prospects as high temperature thermal insulators.

Directional Water Transport Janus Composite Nanofiber Membranes for Comfortable Bioprotection.

The Janus membrane has a huge prospect for personal comfortable protection. However, there still is a huge imbalance between the comfort and protection of the existing Janus membrane. There is an urgent need to further improve the comprehensive performance of the protective membrane to realize both protection and comfort. Herein, we report the Janus membrane with directional water transport capacity and dust rejection performance by compounding the polyvinyl chloride hydrophobic nanofiber membrane and polyamide-6 blended polyvinyl pyrrolidone hydrophilic nanofiber membrane. This Janus composite nanofiber membrane exhibited an excellent dust rejection efficiency of 99.99%, air permeability of 42.15 mm/s, which was 76 times that of the commercial waterproof and breathable PTFE membrane, water vapor transmission rate of 4.89 kg/(m2 × 24 h), and accumulative one-way transport capacity of 888.7%. In addition, the breakthrough pressure of the Janus membrane in the reverse direction (i.e., hydrophilic layer to hydrophobic layer) was four times that in the positive direction (i.e., hydrophobic layer to hydrophilic layer), suggesting it to be a potential substrate for comfortable bioprotection with a comprehensive protection capability.

Increased ion transport and high-efficient osmotic energy conversion through aqueous stable graphitic carbon nitride/cellulose nanofiber composite membrane

Increased attention has evoked on the utilization of renewable energy, particularly osmotic power as a potential solution to the energy crisis and environmental pollution. Herein, we fabricate graphitic carbon nitride (g-C3N4)/cellulose nanofiber (CNF) composite membranes with tailored lamellar nanochannels for capturing osmotic energy from salinity gradients. Composite membranes exhibiting charge-governed ion conductivity were prepared via co-homogenization of g-C3N4 with CNF and vacuum filtration. Ion conductivity was efficiently modulated by fine-tuning the charge density through controlling the weight content of CNF in the composite membranes. Higher ion conductivity of 0.014 S cm−1 at low concentrations (<10−2 M KCl) was achieved due to the increased charge density of the lamellar nanochannels and the excellent aqueous stability of the membranes. We demonstrate the potential of the composite membranes in nanofluidic osmotic energy conversion, displaying thermo-enhanced power output performance. This work could inspire new designs of cellulose-based nanofluidic devices for improved osmotic energy conversion.

Biobased polymer SF/PHBV composite nanofiber membranes as filtration and protection materials

With the emergence of the COVID-19, masks and protective clothing have been used in huge quantities. A large number of non-degradable materials have severely damaged the ecological environment. Now, people are increasingly pursuing the use of environmentally friendly materials to replace traditional chemical materials. Silk fibroin (SF) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) have received increasing attention because of their unique biodegradability and biocompatibility. In this paper, a series of biodegradable SF/PHBV nanofiber membranes with different PHBV content were fabricated by using electrospinning technology. The morphology of the electrospun SF/PHBV composite nanofiber was observed by scanning electron microscopy (SEM). The average diameters of the pure SF, SF/PHBV (4/1), SF/PHBV (3/1), and SF/PHBV (2/1) nanofibers were 55.16 ± 12.38 nm, 75.93 ± 21.83 nm, 69.35 ± 21.55 nm, and 61.40 ± 12.31 nm, respectively. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were used to explore the microstructure of the electrospun SF/PHBV composite nanofiber. The crystallization ability of the composite nanofiber was greatly improved with the addition of PHBV. The results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicated that the thermal stability of SF was better than PHBV obviously, so SF could improve the thermal stability of the composite materials within a certain range. The mechanical properties of the electrospun nanofiber membranes were evaluated by using a universal testing machine. In general, the elongation of the composite nanofiber membranes decreased, and the breaking strength increased with the addition of PHBV. The small pore size of the nanofiber membranes ensured that they had good application prospects in the field of filtration and protection. When the spinning time was 1 h, the filtration efficiency of SF/PHBV/PLA composite materials remained above 95%.

Electrospun nanofiber composite membranes based on cellulose acetate/nano-zeolite for the removal of oil from oily wastewater

Electrospun nanofiber composite membranes based on cellulose acetate/nano-zeolite for the removal of oil from oily wastewater

Catalytic nanofiber composite membrane by combining electrospinning precursor seeding and flowing synthesis for immobilizing ZIF-8 derived Ag nanoparticles

An Ag@PAN catalytic nanofiber composite membrane has been fabricated by combining electrospinning PAN nanofiber seeding with 2-MI and flowing synthesis. ZIF-8 can be immobilized on the surface of the nanofibers with Zn(NO3)2 solution flowing through the 2-MI/PAN nanofiber membrane and Ag nanoparticles can be immobilized on the nanofibers with Zn2+ in ZIF-8 exchanged by Ag+ followed with reduction reaction. The characteristics of XRD, XPS, FTIR, TGA, HRTEM, and BET proved the successful immobilization of Ag nanoparticles derived from ZIF-8 on PAN nanofiber. The permeance of the Ag@PAN catalytic nanofiber composite membrane can reach 19,227 L m−2 h−1 bar−1 with Ag nanoparticles immobilization amount of 49.64%. The p-NP conversion reaction is addressed for the catalytic performance of the Ag@PAN catalytic nanofiber composite membrane. The conversion rate of 99% can be achieved under the condition of p-NP concentration of 0.025 mM and membrane flux of 300 L m−2 h−1. The apparent reaction rate constant of 236.63 min−1 can be achieved by flowing through mode, which is 4-5 orders of magnitude higher than that in a stirred tank reactor with Ag powders as the catalyst. The catalytic performance of the composite membranes has not declined significantly after ten cycles of the catalysis experiment, implied the good repeatability of the Ag@PAN catalytic nanofiber composite membranes.

Preparation of zinc oxide loaded polyurethane/polysulfone composite nanofiber membrane and study on its waterproof and moisture permeability properties

Herein, zinc oxide Nanoparticles (ZnO-NPs) were bonded to the surface of polyurethane/polysulfone (PU/PSF) electrospun nanofiber membrane, it was then hydrophobically modified with Hexadecyltrimethoxysilane (HDTMS), and a new waterproof and moisture permeable composite nanofiber membrane with excellent ultraviolet (UV) resistant function was finally prepared. In this study, the effects of different PU/PSF mass ratio on the waterproof, moisture permeability and thermodynamic properties of nanofiber membrane were discussed. According to the static water contact angle, air permeability and moisture permeability, the effects of ZnO and HDTMS on the waterproof properties of composite nanofiber membrane were analyzed. The results have revealed that when the mass ratio of PU to PSF was 7:3, PU/PSF composite membrane has the best fiber morphology, thermal stability and waterproof and moisture permeability properties. After the surface of the composite film was successfully loaded with ZnO-NPs and treated with 2 wt% HDTMS, its contact angle reached 149°, the moisture permeability was 9.6 kg/m 2 /d and UPF value up to 1117.67 which shows excellent UV resistance.

Fabrication of polyphenylene sulfide nanofibrous membrane via sacrificial templated-electrospinning for fast gravity-driven water-in-oil emulsion separation

• A new strategy in the study is proposed for preparing PPS membrane. • This process was simple and required fewer organic solvents. • The prepared PPS membrane had good hydrophobicity and chemical stability. • The PPS membrane can efficiently separate surfactant-stabilized water–oil emulsion. Polyphenylene sulfide (PPS) has excellent hydrophobicity and stability, making it an ideal material for preparing water-in-oil separation membranes. PPS membranes are mainly fabricated via thermally induced phase separation which requires a certain amount of solvent. The electrospinning technique is relatively simple and requires little solvent, and it has become a research hotspot in recent years. This study proposes a new strategy for preparing a PPS membrane for water-in-oil emulsion separation in harsh environments. Here, we prepared PPS composite nanofiber membranes via electrospinning and sintering technology. The membrane was formed using polyvinyl alcohol (PVA) as the sacrificial template and polyacrylonitrile as the supporting substrate. By studying the effects of the PPS/PVA mass ratio and sintering temperature on the PPS composite nanofiber membrane structure and performance, the optimum PPS membrane was selected for subsequent water-in-oil emulsion separation. The results show that the water contact angle of the PPS membrane was above 150°; the maximum pure oil flux was 1707 L/ (m 2 h) for the surfactant-stabilized water-in-oil emulsion separation under gravity; and the separation efficiency was around 99%. Moreover, the membrane maintained good chemical resistance after immersion in an organic mixed or acid-base solutions for 5 days.

Copolyamide-Clay Nanotube Polymer Composite Nanofiber Membranes: Preparation, Characterization and Its Asymmetric Wettability Driven Oil/Water Emulsion Separation towards Sewage Remediation.

To address the problem of ever-increasing oily wastewater management, due to its directional liquid transport property, membranes with asymmetric wettability can be effectively used for emulsion separation. This study reports the synthesis of electrospun polymer–clay nanocomposite nanofibers, using co-polyamide polymer (COPA) and halloysite nanotubes (HA) as filler. The influence of clay content on the morphological, thermal and dielectric properties of the polymer composite nanofiber was investigated comprehensively to address the material characteristics of the developed system. The surface structure analysis and contact angle measurements of the electrospun composite nanofibers confirms the change in surface roughness and wettability when the fillers are added to the polymer. The porosity of the composite electrospun nanofiber membrane was found to be 85% with an oil adsorption capacity of 97% and water permeability of 6265 L/m2 h. Furthermore, the asymmetric wettability-driven oil/water emulsion separation abilities of the as-synthesized membranes shows that the separation efficiency of the composite fiber membrane is 10% improved compared to that of the neat fiber membrane, with improved separation time.

Preparation of sodium alginate/polyvinyl alcohol composite nanofiber membranes for adsorption of dyes

In this research, electrospinning was used to prepare sodium alginate (SA)/polyvinyl alcohol (PVA) composite nanofiber membranes. Effects of electrospinning parameters on the morphology and fiber diameter were investigated, and an orthogonal design was chosen to optimize the parameters. The optimized nanofiber membranes were applied as an adsorbent for the removal of methylene blue (MB), basic fuchsin (BF), and methyl orange (MO). Kinetic and isotherm of adsorption and effects of different experimental conditions such as pH, contact time, and initial dye concentration on adsorption capacity were investigated. It was found that the optimum parameters for the nanofiber membranes were SA/PVA blend ratios (3:7), electric field strength (20 kV), flow rate (0.05 mL/h), and distance (12.5 cm) between the syringe needle and collector, and the mean fiber diameter of the optimized membranes was 99.58 nm. The adsorption of nanofiber membranes was well described by the pseudo-second-order adsorption kinetic model and the Langmuir model, indicating that the adsorption mechanism was chemisorption by a monolayer. Based on the Langmuir model, the adsorption capacities for MB, BF, and MO were 9.25 mg/g, 9.02 mg/g, and 7.35 mg/g, respectively.