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Summary: Among various electrocatalysts, high-entropy alloys (HEAs) have gained significant attention for their unique properties and excellent catalytic activity in the hydrogen evolution reaction (HER). However, the precise synthesis of HEA catalysts in small sizes remains challenging, which limits further improvement in their catalytic performance. In this study, boron- and nitrogen-doped HEA porous carbon nanofibers (HE-BN/PCNF) with an in situ–grown dendritic structure were successfully prepared, inspired by the germination and growth of tree branches. Furthermore, the dendritic fibers constrained the growth of HEA particles, leading to the synthesis of quantum dot-sized (1.67 nm) HEA particles, which also provide a pathway for designing HEA quantum dots in the future. This work provides design ideas and guiding suggestions for the preparation of borated HEA fibers with different elemental combinations and for the application of dendritic nanofibers in various fields.

High temperatures and particulate matter (PM) pollution can make environments uninhabitable. Using air conditioners to cool rooms and air filters to remove PM is effective, but it consumes lots of energy. To save energy, a novel curtain made of polyvinylidene fluoride–hexafluoropropylene (PVDF-HFP) nanofiber membrane has successfully been produced by simple electrospinning technology, which could block PM from outside through natural ventilation and also cool the room by reflecting and scattering sunlight and radiating energy to the outside. The results showed that the curtain was able to effectively reflect sunlight and reduce the subambient temperature by about 10 °C, achieving effective passive radiative cooling. Moreover, the electrospun PVDF-HFP with good piezoelectric properties could be used as a nano-generator to collect the mechanical energy of the wind, and the PVDF-HFP nanofiber films were used as efficient air filtration curtains with 98% filtration efficiency and 64 Pa pressure drop. This simple method to fabricate double energy-saving curtains is more conducive to dissemination.

Herein, the preparation process, morphology, structure, and magnetic properties of La1.85Sr0.15CuO4 (LSCO) cobweb-like nanofibers are reported. LSCO nanofibers with a regular grain size distribution are successfully prepared via electrospinning, followed by calcination. We conducted morphology analysis and elemental distribution using electron microscopy and energy-dispersive X-ray spectroscopy (EDS), respectively. Additionally, magnetic property testing was performed using a vibrating sample magnetometer (VSM) to confirm the superconducting properties of the samples. Interestingly, our samples exhibited a superconducting transition temperature, Tc, of 25.21 K, which showed some disparity compared to similar works. Furthermore, we observed a ferromagnetic response at low temperatures in the superconducting nanofibers. We attribute these phenomena to the effects generated by surface states of nanoscale superconducting materials.

Abstract Magnetic materials are of increasing importance for many essential applications due to their unique magnetic properties. However, due to the limited fabrication ability, magnetic materials are restricted by simple geometric shapes. Three-dimensional (3D) printing is a highly versatile technique that can be utilized for constructing magnetic materials. The shape flexibility of magnets unleashes opportunities for magnetic composites with reducing post-manufacturing costs, motivating the review on 3D printing of magnetic materials. This paper focuses on recent achievements of magnetic materials using 3D printing technologies, followed by the characterization of their magnetic properties, which are further enhanced by modification. Interestingly, the corresponding properties depend on the intrinsic nature of starting materials, 3D printing processing parameters, and the optimized structural design. More emphasis is placed on the functional applications of 3D-printed magnetic materials in different fields. Lastly, the current challenges and future opportunities are also addressed.

Electrospinning (e-spinning) is famous for the construction and production of ultrafine and continuous micro-/nanofibers. Then, the alignment of electrospun (e-spun) nanofibers becomes one of the most valuable research topics. Because aligned fibers have more advantages over random fibers, such as better mechanical properties, faster charge transport, more regular spatial structure, etc. This review summarizes various electrospinning techniques of fabricating aligned e-spun nanofibers, such as early conventional methods, near-field e-spinning, and three-dimensional (3D) printing e-spinning. Among them, four auxiliary preparation methods (e.g., auxiliary solid template, auxiliary liquid, auxiliary electromagnetic field and auxiliary airflow), two collection modes (static and dynamic collection), and the controllability of near-field e-spinning and 3D printing e-spinning are highlighted. The representative applications depending on aligned nanofibers are classified and briefly introduced, emphasizing in the fields of 1D applications (e.g., field-effect transistor, nanochannel and guidance carrier), 2D applications (e.g., platform for gas detection, filter, and electrode materials storage), and 3D applications (e.g., bioengineering, supercapacitor, and nanogenerator). At last, the challenges and prospects are addressed.

Abstract Bacterial infection especially caused by multidrug-resistant bacteria still endangers human life. Photodynamic therapy (PDT) can effectively kill bacteria, and nanofiber-based PDT can effectively reduce damage to normal tissues. However, current photosensitizers coated on the surfaces of fibers would release to the wound, causing some side effects. And nanofibers prepared by traditional method exhibit poor adhesion on the wound, which severely reduces the PDT effect due to its short-range effect. Herein, core–shell curcumin composite nanofibers are prepared by in situ electrospinning method via a self-made portable electrospinning device. The obtained composite nanofibers show superior adhesiveness on different biological surface than that of traditional preparation method. Upon 808-nm irradiation, these composite nanofibers effectively produced singlet oxygen (1O2) without curcumin falling off. After these composite nanofibers’ exposure to drug-resistant bacteria, they exhibit dual antibacterial behaviors and efficiently kill the drug-resistant bacteria. These dual antibacterial nanofiber membranes with excellent adhesiveness may benefit the application of wound infection as antibacterial dressing.

Non-calcined petroleum coke can serve as an anode material for lithium-ion batteries (LIBs). Nevertheless, this method results in materials with insufficient conductivities and low Coulombic efficiencies during the initial cycle. To address these challenges, the usage of pre-baked carbon anodes as a material for anodes in LIBs is proposed in this study. The surface features of the pre-baked anode (i.e. wrinkle-like filaments) aid in reducing the volume expansion of the electrode during the lithium-ion insertion–removal process. Furthermore, the treatment increases the particle contact area, improving the conductivity of the pre-baked anode. At a current density of 3 A g ^−1 , the pre-baked anode demonstrated an initial discharge capacity and a stable discharge capacity of 548.7 and 134.5 mAh g ^−1 , respectively, after 100 cycles. The capacity of the anode (after 1000 cycles) consistently varies within a narrow range at a current density of 3 A g ^−1 , indicating the stability of the electrode capacity over extended use. Therefore, this study provides valuable insights into exploring potential applications of pre-baked anode materials.

Abstract Background Electrospun (e-spun) nanofibers for wound dressing have attracted wide attention due to its large specific surface area, large porosity and breathability. Compared with solution electrospinning (e-spinning), melt e-spinning is more bio-friendly without toxic solvent participation, which provides the possibility of in situ e-spinning on wounds directly. However, previously reported melt e-spinning devices were usually bulky and cumbersome due to their necessary heating unit, and different components were separated to avoid electrostatic interference. Results In this article, we report on a self-powered hand-held melt e-spinning gun which can work without any external power supply (outdoors). The problem of electrostatic interference for this integrated device was solved by using a special high heat transfer insulation unit. The apparatus is easy and safe to operate by a single hand due to its small volume (24 × 6 × 13 cm3) and light weight (about 450 g). Some biodegradable polymers, for example, polycaprolactone (PCL) fibers were successful e-spun onto wounds directly by using this dressing gun. Conclusions PCL fibrous membrane has good biocompatibility and can be in situ electrospun to wound surface as a wound dressing by the portable melt e-spinning gun. Besides wound dressing, this hand-held melt e-spinning gun may be used in 3D printing and experimental teaching demonstration aids.

Though stretchable strain sensors are attractive for next-generation applications due to their high sensitivity, heat generated in these devices limits their reliability. Here, the authors report boron nitride nanosheet-based stretchable strain sensors with enhanced thermal management.

Abstract Fine particulate matter (PM) has seriously affected human life, such as affecting human health, climate, and ecological environment. Recently, many researchers use electrospinning to prepare nanofiber air filters for effective removal of fine particle matter. However, electrospinning of the polymer fibers onto the window screen uniformly is only achieved in the laboratory, and the realization of industrialization is still very challenging. Here, we report an electrospinning method using a rotating bead spinneret for large-scale electrospinning of thermoplastic polyurethane (TPU) onto conductive mesh with high productivity of 1000 m2/day. By changing the concentration of TPU in the polymer solution, PM2.5 removal efficiency of nanofiber-based air filter can be up to 99.654% with good optical transparency of 60%, and the contact angle and the ventilation rate of the nanofiber-based air filter is 128.5° and 3480 mm/s, respectively. After 10 times of filtration, the removal efficiency is only reduced by 1.6%. This transparent air filter based on TPU nanofibers has excellent filtration efficiency and ventilation rate, which can effectively ensure indoor air quality of the residential buildings.

Abstract CuS nanoflowers were loaded on anatase TiO2/polyvinylidene fluoride (PVDF) fibers by hydrothermal treated electrospun tetrabutyl orthotitanate (TBOT)/PVDF fibers at low temperature. The results indicated that the amount of copper source and sulfur source determined the crystallization and morphology of the resultant products. It was found that the composite of CuS narrowed the band gap energy of TiO2 and enhanced the separation efficiency of the photogenerated electron-hole pairs of TiO2. The photocatalytic reaction rate of CuS/TiO2/PVDF fibers to rhodamine B was 3 times higher than that of TiO2/PVDF fibers under visible light irradiation. Besides, owing to the preparation process was carried out at low temperature, the flexibility of CuS/TiO2/PVDF fibers was ensured. In addition, the self-cleaning performance of the dye droplets on the resultant product surface was demonstrated under visible light. Meanwhile, the resultant product can automatically remove dust on the surface of the material under the rolling condition of droplets due to its hydrophobicity. Therefore, the as-prepared CuS/TiO2/PVDF fibers can not only degrade the contaminated compounds, but also depress the maintenance cost owing to its self-cleaning performance, which means a very practical application prospect.

Abstract For effective application of electrospinning and electrospun fibrous meshes in wound dressing, we have in situ electrospun poly(vinyl pyrrolidone)/iodine (PVP/I), PVP/poly(vinyl pyrrolidone)-iodine (PVPI) complex, and poly(vinyl butyral) (PVB)/PVPI solutions into fibrous membranes by a handheld electrospinning apparatus. The morphologies of the electrospun fibers were examined by SEM, and the hydrophobicity, gas permeability, and antibacterial properties of the as-spun meshes were also investigated. The flexibility and feasibility of in situ electrospinning PVP/I, PVP/PVPI, and PVB/PVPI membranes, as well as the excellent gas permeabilities and antibacterial properties of the as-spun meshes, promised their potential applications in wound healing.

Abstract Precise deposition of nanofibers is still an important issue in the applications of electrospinning (e-spinning), especially in rapid hemostasis of organs such as the liver, lung, and kidney. In this study, we propose an electric field-modified e-spinning technique with a metal cone attached to the spinning nozzle to realize controllable precise deposition of fibers. The deposition range of the e-spun fibers is tunable by changing the size of the metal cone, and the mechanism is attributed the focused electric field verified by theoretical simulations. This electric field-modified e-spinning method was further used to in situ precisely deposit medical glue N-octyl-2-cyanoacrylate (NOCA) fibers onto the resection site of rat liver to realize rapid hemostasis within 10 s. Postoperative pathological results indicate that less inflammatory response and tissue adhesion are observed in this electric field-modified e-spinning group compared with that of traditional airflow-assisted group. This technique combined with our designed handheld e-spinning device could be used in emergency medical treatment, clinics, field survival, and home care for its portability and precise deposition characteristics.

Abstract A facial electrospinning method of in situ precise fabricating magnetic fibrous membrane composed of polyurethane (PU) nanofibers decorated with superparamagnetic γ-Fe2O3 nanoparticles with simultaneous heat generation in response to alternating magnetic field (AMF) is reported. In this method, a conical aluminum auxiliary electrode is used to regulate the electrostatic field and affect the process of electrospinning for the in situ rapid and precise deposition of electrospun γ-Fe2O3/PU fibers. The auxiliary conical electrode can extend the jet stabilization zone of the precursor solution four times longer than that of without auxiliary electrode, which can achieve the precise control of the fiber deposition area. Moreover, the electrospun composite fibrous membranes show a rapid temperature increase from room temperature to 43 °C in 70 s under the AMF, which exhibits faster heating rate and higher heating temperature compared to the samples fabricated without the assist of the auxiliary electrode. The present results demonstrate that the in situ precise electrospinning with the help of an auxiliary conical electrode has the potential as a manipulative method for preparing magnetic composite fibers as well as magnetic hyperthermia of cancer therapy.

A simple and novel strategy of superhydrophilic-superhydrophobic Janus membrane was provided here to deal with the increasingly serious oil-water separation problem, which has a very bad impact on environmental pollution and resource recycling. The Janus membrane of cPVA-PVDF/PMMA/GO with opposite hydrophilic and hydrophobic properties was prepared by layer-by-layer electrospinning. The structure of the Janus membrane is as follows: firstly, the mixed solution of polyvinylidene fluoride (PVDF), polymethylmethacrylate (PMMA) and graphene oxide (GO) was electrospun to form a hydrophobic layer, then polyvinyl alcohol (PVA) nanofiber was coated onto the hydrophobic membrane by layer-by-layer electrospinning to form a composite membrane, and finally, the composite membrane was crosslinked to obtain a Janus membrane. The addition of GO can significantly improve the hydrophobicity, mechanical strength and stability of the Janus membrane. In addition, the prepared Janus membrane still maintained good oil-water separation performance and its separation efficiency almost did not decrease after many oil-water separation experiments. The flux in the process of oil-water separation can reach 1909.9 L m−2 h−1, and the separation efficiency can reach 99.9%. This not only proves the separation effect of the nanocomposite membrane, but also shows its high stability and recyclability. The asymmetric Janus membrane shows good oil-water selectivity, which gives Janus membrane broad application prospects in many fields.

In some cases, we hope to remove the electrospun nanofibrous mesh from the collector easily. But in some cases such as wound dressing, we observe that the in situ electrospun nanofibers can stick to the collector (e.g., skin). Therefore, the adhesion between the in situ electrospun web and the substrate becomes important in the performance and practical application of the electrospun material. In this paper, we reported a direct pulling method to measure the adhesion and understand the adhesion mechanism. In this method, we used gravity to pull the fiber directly from the substrate and then measured the gravity to calculate the adhesion. This new test method is more convenient and practical than the previously reported methods. In addition, the adhesion of the in situ electrospun web on different substrates (e.g., aluminium foil, wood pulp paper, and silicon paper) was also studied by this method. The adhesion was influenced by spinning voltage, electrical conductivity, and surface roughness of the substrates.

In order to improve the performance and endurance of steel rings used for twisting and winding yarns in the textile industry, a more wear-resistant ceramic version is studied and examined by conducting multiple simulations combined with microwave sintering experiments of the ring preparation process, aiming to reduce manufacturing costs and improve efficiency. The three-dimensional (3D) electromagnetic field simulation software HFSS is used to simulate the electromagnetic field distribution in the microwave sintering cavity and to determine the electromagnetic region with the most uniform electromagnetic field to guide the microwave sintering experiments. The 3Y-TZP ceramic rings are shaped by gel-casting. The effect of presintering on the performance of ceramic rings is investigated by applying conventional sintering and microwave sintering methods. The experimental results show that the simulation-guided microwave sintering process can resolve the deficiency of uneven microwave sintering at low temperatures. Comparing the final sintering temperatures and mechanical properties of the final ceramic-sintered rings obtained by microwave presintering to those obtained by conventional presintering, microwave presintered sample has a final temperature of 1400°C, which is 100°C lower than that of conventional presintering, which is 1500°C; its average grain size of 0.18 μm is dramatically smaller than that of conventional presintering, which is 0.24 μm, with about 80% of the grain sizes present in the range of 0.1-0.2 μm and a relative density of about 99%, as opposed to conventional presintering’s 70% falling between 0.2 and 0.3 μm and relative density of about 98%; the Vickers hardness and fracture toughness for microwave presintered sample reach 1550 kg·f·mm−2 and 9.05 MPa m1/2, respectively, which are both greater than 1431 kg·f·mm−2 and 8.86 MPa m1/2 in the conventional samples.

Abstract Electrospinning provides an effective method for generating nanofibers from solution of carboxymethyl chitosan/polyoxyethylene oxide (CMCS/PEO). The goal of this work is to explore the potential application of electrospun CMCS/PEO nanofiber membrane in fruit fresh-keeping. The microstructure, antibacterial activity, hydrophilia, and air permeability of the nanofiber membrane have been tested. For comparison, the fresh-keeping effects of commercial cling wrap and CMCS/PEO nanofiber membranes on strawberries’ rotting rate and weight loss rate have been studied. The results indicate that the electrospun CMCS/PEO membrane could effectively avoid water loss in strawberries and has a remarkable effect to prolong strawberries’ shelf life due to its breathability and antibacterial activity. In addition, the composite CMCS/PEO, nanofiber membrane is non-poisonous and edible, which can be used in food industry.

Abstract Highly stretchable and electrically conductive thermoplastic polyurethane (TPU) nanofibrous composite based on electrospinning for flexible strain sensor and stretchable conductor has been fabricated via in situ polymerization of polyaniline (PANI) on TPU nanofibrous membrane. The PANI/TPU membrane-based sensor could detect a strain from 0 to 160% with fast response and excellent stability. Meanwhile, the TPU composite has good stability and durability. Besides, the composite could be adapted to various non-flat working environments and could maintain opportune conductivity at different operating temperatures. This work provides an easy operating and low-cost method to fabricate highly stretchable and electrically conductive nanofibrous membrane, which could be applied to detect quick and tiny human actions.

Abstract A multi-hierarchical porous polyaniline (PANI) composite which could be used in good performance pressure sensor and adjustable sensitivity gas sensor has been fabricated by a facile in situ polymerization. Commercial grade sponge was utilized as a template scaffold to deposit PANI via in situ polymerization. With abundant interconnected pores throughout the whole structure, the sponge provided sufficient surface for the growth of PANI nanobranches. The flexible porous structure helped the composite to show high performance in pressure detection with fast response and favorable recoverability and gas detection with adjustable sensitivity. The sensing mechanism of the PANI/sponge-based flexible sensor has also been discussed. The results indicate that this work provides a feasible approach to fabricate efficient sensors with advantages of low cost, facile preparation, and easy signal collection.

Abstract Humidity indicators based on composite polyamide 66/cobalt chloride (PA66/CoCl2) nanofibrous membranes (NFMs) were successfully fabricated by electrospinning. A series of NFMs with various weight percentage of CoCl2 to PA66 were prepared, and their humidity sensitivity based on color changing and quartz crystal microbalance (QCM) were studied. Due to the color change property of cobalt chloride, the as-spun composite NFMs show obviously macroscopic color change from blue to pink as relative humidity (RH) increasing from 12.4 to 97.2%. Moreover, the QCM detection showed a linear dependence on the RH changing and exhibited short response/recovery time (less than 65.4 s/11 s), small hysteresis (less than 11%), good reproducibility, and stability. Owing to the above double sensitive mechanism on RH, the PA66/CoCl2 composite NFM may show great potential applications from meticulous to coarse.

Wearable electronics, such as sensors, actuators, and supercapacitors, have attracted broad interest owing to their promising applications. Nevertheless, practical problems involving their sensitivity and stretchability remain as challenges. In this work, efforts were devoted to fabricating a highly stretchable and sensitive strain sensor based on dip-coating of graphene onto an electrospun thermoplastic polyurethane (TPU) nanofibrous membrane, followed by spinning of the TPU/graphene nanomembrane into an intertwined-coil configuration. Owing to the intertwined-coil configuration and the synergy of the two structures (nanoscale fiber gap and microscale twisting of the fiber gap), the conductive strain sensor showed a stretchability of 1100%. The self-inter-locking of the sensor prevents the coils from uncoiling. Thanks to the intertwined-coil configuration, most of the fibers were wrapped into the coils in the configuration, thus avoiding the falling off of graphene. This special configuration also endowed our strain sensor with an ability of recovery under a strain of 400%, which is higher than the stretching limit of knees and elbows in human motion. The strain sensor detected not only subtle movements (such as perceiving a pulse and identifying spoken words), but also large movements (such as recognizing the motion of fingers, wrists, knees, etc.), showing promising application potential to perform as flexible strain sensors.

The exploration of a new family of flexible and high-performance electromagnetic shielding materials is of great significance to the next generation of intelligent electronic products. In this paper, we report a simple magnetic-electrospinning (MES) method for the preparation of a magnetic flexible film, γ-Fe2O3 nanoparticle-embedded polymeric nanofibers. By introducing the extra magnetic field force on γ-Fe2O3 nanoparticles within composite fibers, the critical voltage for spinning has been reduced, along with decreased fiber diameters. The MES fibers showed increased strength for the magnetic field alignment of the micro magnets, and the attraction between them assisted the increase in fiber strength. The MES fibers show modifications of the magnetic properties and electrical conductivity, thus leading to better electromagnetic shielding performance.

Stretchable nano-fibers have attracted dramatic attention for the utility in wearable and flexible electronics. In the present case, Ag nanowires (AgNWs)-intertwined thermoplastic polyurethanes (TPU) unwoven nano-membrane is fabricated by an electrospinning method and dip coating technique. Then a strain sensor with a spring-like configuration is fabricated by a twisted method. The sensor exhibits superior electrical conductivity up to 3990 S·cm−1 due to the high weight percentage of the Ag nanowires. Additionally, thanks to the free-standing spring-like configuration that consists of uniform neat loops, the strain sensor can detect a superior strain up to 900% at the point the sensor ruptures. On the other hand, the configuration can mostly protect the AgNWs from falling off. Furthermore, major human motion detection, like movement of a human forefinger, and minor human motion detection, such as a wrist pulse, show the possible application of the sensor in the field of flexible electronics.

Piezoelectric materials such as ZnO semiconductors and polyvinylidene fluoride (PVDF) have been extensively studied to produce flexible wearable devices, providing a viable method for energy collection. In this study, PVDF was mixed with ZnO nanoparticles to prepare PVDF/ZnO devices by electrospinning. The composite ZnO affects the diameter of electrospun fibers and the output performance of the devices. As ZnO was added, the diameter of the fibers decreases, but the output current of the devices increases. Moreover, compared with pristine PVDF, the bending output current and pyroelectric current of the devices were improved after mixed with ZnO. The results indicated that PVDF/ZnO composite was a promising flexible device that can provide power for small electronic devices.

We report the fabrication of polyvinylidene fluoride (tetrabutyl titanate)/polyvinyl pyrrolidone ((tetrabutyl titanate))-graphene quantum dots [PVDF(TBT)/PVP(TBT)-GQDs] film photocatalyst with enhanced photocatalytic performance. The polyvinylidene fluoride (tetrabutyl titanate)/polyvinyl pyrrolidone ((tetrabutyl titanate)) [PVDF(TBT)/PVP(TBT)] film was first prepared with a dual-electrospinning method and then followed by attaching graphene quantum dots (GQDs) to the surface of the composite film through a hydrothermal method. Later, part of the PVP in the composite film was dissolved by a hydrothermal method. As a result, a PVDF(TBT)/PVP(TBT)-GQDs film photocatalyst with a larger specific surface area was achieved. The photocatalytic degradation behavior of the PVDF(TBT)/PVP(TBT)-GQDs film photocatalyst was examined by using Rhodamine B as the target contaminant. The PVDF(TBT)/PVP(TBT)-GQDs photocatalyst showed a higher photocatalytic efficiency than PVDF(TBT)-H2O, PVDF(TBT)/PVP(TBT)-H2O, and PVDF(TBT)-GQDs, respectively. The enhanced photocatalytic efficiency can be attributed to the broader optical response range of the PVDF(TBT)/PVP(TBT)-GQDs photocatalyst, which makes it useful as an effective photocatalyst under white light irradiation.

As the world faces water shortage and pollution crises, the development of novel visible light photocatalysts to purify water resources is urgently needed. Over the past decades, most of the reported photocatalysts have been in powder or granular forms, creating separation and recycling difficulties. To overcome these challenges, a flexible and recyclable heterostructured TiO2/polyvinylidene fluoride/graphitic carbon nitride (TiO2/PVDF/g-C3N4) composite was developed by combining electrospinning, sintering and hydrothermal methods. In the composite, PVDF was used as a support template for removing and separating the photocatalyst from solution. Compared with pure TiO2, the TiO2/PVDF/g-C3N4 composite exhibited the extended light capture range of TiO2 into the visible light region. The photogenerated carriers were efficiently transferred and separated at the contact interface between TiO2 and g-C3N4 under visible light irradiation, which consequently increased the photocatalytic activity of the photocatalyst. In addition, the flexible composites exhibited excellent self-cleaning properties, and the dye on the photocatalysts was completely degraded by the as-prepared materials. Based on the intrinsic low cost, recyclability, absorption of visible light, facile synthesis, self-cleaning properties and good photocatalytic performances of the composite, the photocatalyst is expected to be used for water treatment.

Self-powered nanogenerators composed of poly(vinylidene fluoride) (PVDF) have received much attention. Solution blow spinning (SBS) is a neoteric process for preparing nanofiber mats with high efficiency and safely, and SBS is a mature fiber-forming technology that offers many advantages over conventional electrospinning methods. Herein, we adopted the SBS method to prepare independent PVDF nanofiber membranes (NFMs), and successfully employed them as nanogenerators. Finally, we tested the change in the output current caused by mechanical compression and stretching, and studied its durability and robustness by charging the capacitor, which can drive tiny electronic devices. The results show that the PVDF nanogenerators by using this SBS equipment can not only be used in wearable electronic textiles, but are also suitable for potential applications in micro-energy harvesting equipment.

Paper-based relics, which are an important part of cultural heritage worldwide, are at risk of imminent damage from various environmental sources. To protect them, the atmospheric pressure plasma polymerization of hexamethyldisiloxane (HMDSO) precursor has been explored on paper-based relics in situ. The macro and micro images taken during this process suggest that the in situ plasma treatment does not change the macro morphology and the micro structure of the treated paper-based relic samples. On the other hand, plasma treatment causes the polymerization of the HMDSO which then produces nanoparticles deposited onto the paper-based relics. These nanoparticles provide good waterproof properties with large static water contact angles and smaller rolling angles, which protect the paper-based relics from water penetration. Moreover, since the nanoparticles are deposited onto the fibers, waterproof fastness is ensured. Also, the examined mechanical properties of the treated and untreated paper-based relics indicate that the atmospheric pressure plasma treatment does not affect the strength of the paper very much. The results in this study show that atmospheric pressure plasma treatment with the use of HMDSO precursor is a good method to preserve paper-based relics.

This study shows the feasibility of using electrospinning technique to prepare polytetrafluoroethylene/poly (vinyl alcohol) (PTFE/PVA) nanofibers on PTFE microfiber membrane as substrate. Then, PVA in the fiber membrane was removed by thermal treatment at about 350 °C. Compared to PTFE microfiber substrates, the composite PTFE fiber membranes (CPFMs) have improved filtration efficiency by 70% and water contact angle by 23°. Experimental test data showed that the water contact angle of the sample increased from about 107° to 130°, the filtration efficiency of PM2.5 increased from 44.778% to 98.905%, and the filtration efficiency of PM7.25 increased from 66.655% to 100% due to the electrospun PTFE nanofiber layer. This work demonstrates the potential of CPFMs as a filter for the production of indoor or outdoor dust removal and industrially relevant gas filtration.

Novel flexible and recyclable core-shell heterostructured fibers based on cauliflower-like MoS2 and TiO2/PVDF fibers have been designed through one-step hydrothermal treatment based on electrospun tetrabutyl orthotitanate (TBOT)/PVDF fibers. The low hydrothermal temperature avoids the high temperature process and keeps the flexibility of the as-synthesized materials. The formation mechanism of the resultant product is discussed in detail. The composite of MoS2 not only expands the light harvesting window to include visible light, but also increases the separation efficiency of photo-generated electrons and holes. The as-prepared product has proven to possess excellent and stable photocatalytic activity in the degradation of Rhodamine B and levofloxacin hydrochloride under visible light irradiation. In addition, the TiO2/PVDF@MoS2 core-shell heterostructured fibers exhibit self-cleaning property to dye droplets under visible light irradiation. Meanwhile, due to its hydrophobicity, the resultant product can automatically remove dust on its surface under the rolling condition of droplets. Hence, the as-prepared product cannot only degrade the contaminated compounds on the surface of the material, but also reduce the maintenance cost of the material due to its self-cleaning performance. Therefore, the as-prepared product possesses potential applications in degradation of organic pollutants and water treatment, which makes it a prospective material in the field of environmental treatment.

Electrospinning (e-spinning) is an emerging technique to prepare ultrafine fibers. Polyphenylene sulfide (PPS) is a high-performance resin which does not dissolve in any solvent at room temperature. Commercial PPS fibers are produced mainly by meltblown or spunbonded process to give fibers ~20 μm in diameter. In this research, an in-house designed melt electrospinning device was used to fabricate ultrafine PPS fibers, and the e-spinning operation conducted under inert gas to keep PPS fibers from oxidizing. Under the optimum e-spinning conditions (3 mm of nozzle diameter, 30 kV of electrostatic voltage, and 9.5 cm of tip-to-collector distance), the as-spun fibers were less than 8.0 μm in diameter. After characterization, the resultant PPS fibers showed uniform diameter and structural stability. Compared with commercial PPS staple fibers, the obtained fibers had a cold crystallization peak and 10 times higher storage modulus, thereby offering better tensile tenacity and more than 400% elongation at break.

To meet the urgent need of society for advanced photocatalytic materials, novel visible light driven heterostructured composite was constructed based on graphitic carbon nitride (g-C3N4) and fibrous TiO2. The g-C3N4/TiO2 (CNT) composite was prepared through electrospinning technology and followed calcination process. The state of the g-C3N4 and fibrous TiO2 was tightly coupled. The photocatalytic performance was measured by degrading the Rhodamine B. Compared to commercial TiO2 (P25®) and electrospun TiO2 nanofibers, the photocatalytic performance of CNT composite was higher than them. The formation of CNT heterostructures and the enlarged specific surface area enhanced the photocatalytic performance, suppressing the recombination rate of photogenerated carriers while broadening the absorption range of light spectrum. Our studies have demonstrated that heterostructured CNT composite with an appropriate proportion can rational use of visible light and can significantly promote the photogenerated charges transferred at the contact interface between g-C3N4 and TiO2.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polyvinylpyrrolidone (PEDOT:PSS/PVP) composite nanofibers were successfully fabricated via electrospinning and used as a quartz crystal microbalance (QCM) sensor for detecting CO gas. The electrical property of individual PEDOT:PSS/PVP nanofibers was characterized and the room temperature resistivity was at the magnitude of 105 Ω·m. The QCM sensor based on PEDOT:PSS/PVP nanofibers was sensitive to low concentration (5–50 ppm) CO. In the range of 5–50 ppm CO, the relationship between the response of PEDOT:PSS nanofibers and the CO concentration was linear. Nevertheless, when the concentration exceeded 50 ppm, the adsorption of the nanofiber membrane for CO gas reached saturation and the resonant frequency range had no change. Therefore, the results open an approach to create electrospun PEDOT:PSS/PVP for gas sensing applications.

This paper highlights our work on the recent progress in novel elastico-mechanoluminescence (EML) materials CaZnOS:Mn2+ and CaZr(PO4)2:Eu2+, which can simultaneously "feel" (sense) and "see" (image) the applied mechanical stress as an intense and proportional luminescence. CaZnOS:Mn2+ can sense various types of mechanical stress, including ultrasonic vibration, impact, friction and compression because of the large piezoelectric coefficient. CaZr(PO4)2:Eu2+ with multiple trap levels shows a broad measurement range for dynamic load. Both of CaZnOS:Mn2+ and CaZr(PO4)2:Eu2+ belong to the defect-controlled type piezoelectric phosphors, and their EML mechanisms could be explained using the piezoelectrically induced carrier de-trapping model.