Composite Nanofibers Research Articles

Improving passive daytime radiative cooling via incorporation of composite nanoparticles into sheath of PU-PVDF core-sheath nanofiber film

Climate change has recently caused more severe temperatures, increasing demand for personal thermal management outdoors. Radiative cooling fabrics, known for their potent cooling ability, play a crucial role in regulating the thermal balance of the human body in high-temperature environments. In this study, an innovative PU (polyurethane)-SiO2/TiO2@PVDF (polyvinylidene fluoride) core-sheath nanofiber film was developed by incorporating SiO2/TiO2 composite nanoparticles (STNs) into the sheath of the nanofibers through coaxial electrospinning. The PU-STNs@PVDF composite nanofiber film with thickness of ∼100 μm achieved a reflectance of 92 % in the visible to near-infrared spectral range and an emittance of 91 % within the atmospheric transparent window. The temperature of the PU-STNs@PVDF core-sheath nanofiber film was reduced by 6.9 °C and 4.7 °C compared with that of the cotton fabric and PU-PVDF nanofiber film, respectively. Under direct solar radiation in summer, the temperature of the PU-STNs@PVDF core-sheath nanofiber film was 7.7 °C lower than that of cotton fabric. The PU-STNs@PVDF core-sheath nanofiber film elongated at a break of 127.5 % and a tensile strength of 4.3 MPa, implying it promising flexibility. The PU-STNs@PVDF core-sheath nanofiber film possesses huge potential in personal thermal management.

Optimization of Biologically Inspired Electrospun Scaffold for Effective Use in Bone Regenerative Applications.

Human bone is composed of organic and inorganic composite materials, contributing to its unique strength and flexibility. Hydroxyapatite (HAP) has been extensively studied for bone regeneration, due to its excellent bioactivity and osteoconductivity, which makes it a highly valuable biomaterial for tissue engineering applications. For better therapeutic effects, composite nanofibers containing polyvinyl alcohol (PVA) and polyvinyl Pyrrolidone (PVP) were developed using an electrospinning technique in this study. Herein, hydroxyapatite (a major inorganic constituent of native bone) concentrations varying from 5 to 25% were reinforced in the composite, which could alter the properties of nanofibers. The as-prepared composite nanofibers were characterized by SEM, TEM, XRD, and FT-IR spectroscopy, and a bioactivity assessment was performed in simulated body fluid (SBF). The ICP-OES analysis was used to determine the concentration of Ca2+ and PO42- ions before and after SBF immersion. To optimize the material selection, the nanofibrous scaffolds were subjected to cell proliferation and differentiation in MG-63 osteoblast cell lines, but no significant toxicity was observed. In conclusion, HAP-PVA-PVP scaffolds exhibit unique physical and chemical properties and ideal biocompatibility, with great promise to serve as effective candidates for bone tissue applications.

Bridging dielectric-magnetic synergistic units with MOFs on fibers structure for high-efficient microwave absorption at low filler loading

Metal-organic framework (MOF) capable of magnetic-dielectric synergy loss mechanisms shine in the field of electromagnetic wave (EMW) absorption, whereas their high filler loading in the matrix remains a challenge and limit their practical application. Here, we mono-disperse bimetallic CoZn-MOF on conductive carbon nanofibers precursor via electrospinning technique and a following heat-treatment was employed to construct a Co–ZnO@NC carbon nanofiber (CNF) composites. The Co–ZnO particles with a size of 2 μm are evenly distributed within the carbon fibers, forming a unique structure resembling a “pearl necklace”. The introduction of one-dimension (1D) CNF can prolong the electron transport path and effectively reduces the percolation threshold of the composites. The composites are endowed with abundant heterogeneous interfaces, excellent magnetic-dielectric synergy and improved impedance matching, benefiting from which the obtained Co–ZnO@NC CNF composites demonstrate a maximum reflection loss (RLmin) of −54.5 dB at a thickness of 2.3 mm and an effective absorption bandwidth (EAB) of 8.12 GHz at a filler loading of merely 10 %. This study provides a feasible strategy for the design of MOF-derived absorbers with enhanced microwave absorption capacity at low filler loading.

Coaxial electrospinning of Au@silicate/poly(vinyl alcohol) core/shell composite nanofibers with non-covalently immobilized gold nanoparticles for preparing flexible, freestanding, and highly sensitive SERS substrates amenable to large-scale fabrication

Coaxial electrospinning of Au@silicate/poly(vinyl alcohol) core/shell composite nanofibers with non-covalently immobilized gold nanoparticles for preparing flexible, freestanding, and highly sensitive SERS substrates amenable to large-scale fabrication

Fabrication of Sustainable Sodium Alginate/Polyethyleneimine/Polyvinyl Alcohol Multilayer Composite Electrospun Nanofiber Membrane for Efficient Cu2+ Removal

In pursuit of sustainable solutions for water pollution mitigation, we have successfully employed electrospinning technology to fabricate a multilayered sodium alginate (SA)/polyethyleneimine (PEI)/polyvinyl alcohol (PVA) nanocomposite fiber membrane, with a focus on enhancing its adsorption capacity for Cu2+ ions in wastewater. Our research underscores the potential of this novel membrane, characterized by its small diameter, high uniformity, and expansive surface area, in effectively filtering heavy metal ions. By optimizing critical electrospinning parameters such as a voltage of 19.5 KV, a collector distance of 8 cm, a specific mass ratio of SA:PEI: PVA (1:2:6), and an injection rate of 8 μL/min, we achieved a nanofiber membrane with an average diameter of 112.5 nm, exhibiting exceptional morphological characteristics and high efficiency. Notably, the membrane exhibited an adsorption capacity of over 85% for Cu2+ during initial testing, maintaining over 80% efficiency throughout four consecutive filtration cycles. This work not only advances the field of nanocomposite membranes for water purification but also contributes significantly to the broader goal of achieving environmental sustainability by mitigating the impact of heavy metal contamination in water bodies.

Improvement of water resistance for natural rubber/nanocellulose composites

Natural rubber/cellulose nanofiber (NR/CNF) composites exhibit improved dry tensile properties compared with neat NR sheets. However, the presence of hydrophilic CNFs in the composites causes low water resistance, resulting in high water content and low tensile strength when the composites are soaked in water at 70 °C for 7 d. Herein, water-resistant NR/CNF composites were developed by adding zinc methacrylate or aluminum acrylate, and the oven-dried NR/CNF/additive materials were counterion-exchanged with 0.1 M NH4OH. X-ray fluorescence analysis of the composite sheets indicates the reasons and mechanisms for the improved water resistance of the composites prepared with the tested additives by post-counterion exchange.

Preparation and Structure-Property Relationship Study of Piezoelectric-Conductive Composite Polymer Nanofiber Materials for Bone Tissue Engineering.

This study aimed to develop Janus-, cross-network-, and coaxial-structured piezoelectric-conductive polymer nanofibers through electrospinning to mimic the piezoelectricity of bone and facilitate the conduction of electrical signals in bone tissue repair. These nanofibers were constructed using the piezoelectric polymer polyvinylidene fluoride, and the conductive fillers reduced graphene oxide and polypyrrole. The influence of structural features on the electroactivity of the fibers was also explored. The morphology and components of the various structural samples were characterized using SEM, TEM, and FTIR. The electroactivity of the materials was assessed with a quasi-static d33 meter and the four-probe method. The results revealed that the piezoelectric-conductive phases were successfully integrated. The Janus-structured nanofibers demonstrated the best electroactivity, with a piezoelectric constant d33 of 24.5 pC/N and conductivity of 6.78 × 10-2 S/m. The tensile tests and MIP measurements showed that all samples had porosity levels exceeding 70%. The tensile strength of the Janus and cross-network structures exceeded that of the periosteum (3-4 MPa), with average pore sizes of 1194.36 and 2264.46 nm, respectively. These properties indicated good mechanical performance, allowing material support while preventing fibroblast invasion. The CCK-8 and ALP tests indicated that the Janus-structured samples were biocompatible and significantly promoted the proliferation of MC3T3-E1 cells.

Electrospinning mediated solvothermal preparation of hierarchical MGa2O4/ZnIn2S4 (M = Ni, Co) hollow nanofibers with p-n heterojunction for boosting photocatalytic H2 evolution

ZnIn2S4 has been extensively studied in the field of photocatalytic hydrogen evolution (PHE), but its bulky structure often results in high charge carrier recombination and low light harvesting capability. Herein, efficient hierarchical MGa2O4/ZnIn2S4 (M = Ni, Co) hollow nanofiber photocatalysts with p-n heterojunction were fabricated by an electrospinning-solvothermal method. The hierarchical structure of MGa2O4/ZnIn2S4 composites has facilitated p-n heterojunction formation, promoted the charge separation efficiency, enhanced light harvesting capability, and provided abundant reactive sites. The synergistic effects of MGa2O4 and ZnIn2S4 accelerated the PHE rate by reducing the *H reaction intermediates energy barrier. Under simulated solar light, the NiGa2O4/ZnIn2S4 and CoGa2O4/ZnIn2S4 with optimal proportions delivered outstanding PHE rate of 9292 and 6283 µmol·g−1·h−1, which was 5 and 3 times higher than that of pure ZnIn2S4, respectively. This work opens up an efficient electrospinning-mediated solvothermal strategy for constructing hierarchical ZnIn2S4-based nanofiber composites with excellent PHE performance.

Centrifugally spun hydroxyapatite/carbon composite nanofiber scaffolds for bone tissue engineering

In recent years, advancements in tissue engineering have demonstrated the potential to expedite bone matrix formation, leading to shorter recovery times and decreased clinical challenges compared to conventional methods. Therefore, this study aims to develop composite carbon nanofibers (CNFs) integrated with nano-hydroxyapatite (nHA) particles as scaffolds for bone tissue engineering applications. A key strategy in achieving this objective involves harnessing nanofibrous structures, which offer a high surface area, coupled with nHA particles expected to accelerate bone regeneration and enhance biological activity. To realize this, polyacrylonitrile (PAN)/nHA nanofibers were fabricated using the centrifugal spinning (C-Spin) technique and subsequently carbonized to yield CNF/nHA composite structures. Scanning Electron Microscopy (SEM) confirmed C-Spin as a suitable method for PAN and CNF nanofiber production, with nHA particles uniformly dispersed throughout the nanofibrous structure. Carbonization resulted in reduced fiber diameter due to thermal decomposition and shrinkage of PAN molecules during the process. Furthermore, the incorporation of nHA particles into PAN lowered the stabilization temperature (by 5 °C–20 °C). Tensile tests revealed that PAN samples experienced an approximately 80% increase in ultimate tensile strength and a 187% increase in modulus with a 5 wt.% nHA loading. However, following carbonization, CNF samples exhibited a 50% decrease in strength compared to PAN samples. Additionally, the addition of nHA into CNF improved the graphitic structure. The incorporation of nHA particles into the spinning solution represents a viable strategy for enhancing CNF bioactivity.

Electrospun chitosan/polymethyl methacrylate nanofiber membranes integrated with polyethyleneimine for enhanced removal of chromium(VI) ions

AbstractThis study demonstrates the preparation of a unique chitosan (CS)/polymethyl methacrylate (PMMA)/polyethyleneimine (PEI) nanofiber (NF) membrane using PMMA as the composite skeleton through an electrospinning method. The chemical and mechanical properties, chromium (Cr) adsorption capabilities, and mass transfer mechanisms of the NF membrane were thoroughly investigated. The findings indicate that the CS/PMMA/PEI NF membranes, with an average diameter of approximately 856.2 nm, exhibits favorable hydrophilicity, effective Cr(VI) adsorption (first adsorption capacity of 226.5 mg g−1), and robust mechanical properties (tensile strength of 1.58 ± 0.092 Mpa), which is superior to most reported adsorbents. Moreover, the composite NF membranes exhibit a second adsorption capacity of 194.4 mg g−1 and a tensile strength of 0.739 ± 0.072 Mpa after the second adsorption, indicating a remarkable level of reusability and cycle stability. Additionally, x‐ray photoelectron spectroscopy, and structural tests reveal the presence of abundant amino (NH2) and hydroxyl (OH) groups in the CS/PMMA/PEI NF membranes, suggesting potential sites for complexation reactions and the reductions of Cr(VI) ions, thereby facilitating effective adsorption and removal of heavy metals. This study introduces a novel and straightforward approach for synthesizing highly effective adsorbents, with have potential implications for the removal of heavy metal ions from wastewater.

Gallium and magnesium substituted hydroxyapatite/carbon nanofiber composite: Improved mechanical and bioactivity for biomedical implant applications

Abstract The primary goal of this effort is to develop an appropriate bone replacement material that exhibits superior biological, mechanical, and antimicrobial properties for potential use in the orthopedics field. For this purpose, the present work focuses on the development of gallium (Ga) and magnesium (Mg) substituted hydroxyapatite (Ga,Mg-HAP)/carbon nanofiber (CNF) composite coating on Ti6Al4V alloy. A number of methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR), were used to assess the mechanical, morphological, and structural characteristics of the Ga,Mg-HAP/CNF composite coated Ti6Al4V. Additionally, the composite’s antibacterial activity is evaluated against E. Coli and S. aureus. On various incubation days, the HOS MG63 cell’s viability on the composite coating was evaluated. The obtained result clearly shows that while the substitution of minerals would improve the biological features of the composite sample, the reinforcement of the CNF in Ga,Mg-HAP increases the mechanical strength of the composite. Therefore, the Ga,Mg-HAP/CNF composite coated Ti6Al4V will be a viable implant for applications involving biological implants.

Self-Poled Piezoelectric Nanocomposite Fiber Sensors for Wireless Monitoring of Physiological Signals.

Self-powered sensors have the potential to enable real-time health monitoring without contributing to the ever-growing demand for energy. Piezoelectric nanogenerators (PENGs) respond to mechanical deformations to produce electrical signals, imparting a sensing capability without external power sources. Textiles conform to the human body and serve as an interactive biomechanical energy harvesting and sensing medium without compromising comfort. However, the textile-based PENG fabrication process is complex and lacks scalability, making these devices impractical for mass production. Here, we demonstrate the fabrication of a long-length PENG fiber compatible with industrial-scale manufacturing. The thermal drawing process enables the one-step fabrication of self-poled MoS2-poly(vinylidene fluoride) (PVDF) nanocomposite fiber devices integrated with electrodes. Heat and stress during thermal drawing and MoS2 nanoparticle addition facilitate interfacial polarization and dielectric modulation to enhance the output performance. The fibers show a 57 and 70% increase in the output voltage and current compared to the pristine PVDF fiber, respectively, at a considerably low MoS2 loading of 3 wt %. The low Young's modulus of the outer cladding ensures an effective stress transfer to the piezocomposite domain and allows minute motion detection. The flexible fibers demonstrate wireless, self-powered physiological sensing and biomotion analysis capability. The study aims to guide the large-scale production of highly sensitive integrated fibers to enable textile-based and plug-and-play wearable sensors.

Two-dimensional (2D) MoS2-nanosheet (NS) incorporated within electrospun PVA nanofibers: Fabrication and characterization study

In this study, with the help of grinding and sonication, the bulk state of molybdenum disulfide was transformed into a two-dimensional sheet, and composite nanofiber consisting of molybdenum disulfide MoS2/polyvinyl alcohol (PVA) has been successfully developed via electrospinning process. X-ray diffraction (XRD) pattern showed the preferred orientation along the (002) plan of The MoS2 nanosheet. Rietveld refinement was applied to obtain the microstructure parameters of the MoS2. The formation of S-S and Mo-S bonds in MoS2 was confirmed by the Fourier-transform infrared spectroscopy (FTIR). FE-SEM images reveal the surface morphology of MoS2 nanosheets, which typically exhibit a flat and layered structure resembling stacked atomic layers of MoS2 two-dimensional nature.In contrast, the MoS2/PVA fibers display a uniform, interconnected nanofiber network with a distinct random formation. Also, Atomic Force Microscopy (AFM) images show the formation of the uniform MoS2/PVA nanofibers, and the evaluated root mean square (RMS) roughness values for PVA and MoS2/PVA fibers are 250 nm and 277 nm, respectively. To elucidate the elemental composition of the MoS2 nanofibers, Energy Dispersive X-ray Spectroscopy (EDX) analysis was performed, confirming the presence of molybdenum and sulfur in the compound. Finally, diffuse reflectance spectroscopy (DRS) was applied to study the optical properties of the MoS2/PVA composite. In addition, the measurement of the contact angle shows that the surface of the nanofibers is hydrophilic, and the amount of hydrophilicity decreases by adding MoS2 nanosheets.

Synthesis of copper/carbon nanofibers by electrostatic spinning toward persulfate activation for treatment of antibiotic wastewater

ABSTRACT Antibiotics in water will cause serious harm to human health and ecosystem. Carbon-based materials and transition metals activated peroxodisulfate (PDS) to produce active species, which can degrade residual antibiotics in water. In this paper, Cu/CNF (carbon nanofibers) composites were first prepared by introducing Cu into CNF using electrostatic spinning technology, which was used to activate PDS to degrade tetracycline (TC). The degradation efficiency of Cu/CNF/PDS was 36.23% higher than that of CNF/PDS. The reason is that introducing Cu can increase the number of surface functional groups and specific surface area of CNF, and then improve the catalytic performance. The functional groups and Cu species are the active sites for catalytic PDS. Moreover, the main ways to degrade TC in the Cu/CNF/PDS system are singlet oxygen (1O2) and electron transfer. Based on the above analysis, we modified CNF with transition metal salts, prepared efficient environmental functional materials, and used them for PDS activation, providing a theoretical basis and technical support for the degradation of antibiotic pollutants and creating new ideas for other research.

Tuning a Superhydrophobic Surface on an Electrospun Polyacrylonitrile Nanofiber Membrane by Polysulfone Blending.

Nanofibers made of different materials have been continuously studied and widely used as membranes due to their simple fabrication techniques and tunable surface characteristics. In this work, we developed polyacrylonitrile (PAN) nanofiber membranes by the electrospinning method and blended them with polysulfone (PSU) to obtain superhydrophobic surfaces on the fiber structures. The scanning electron microscopy (SEM) images show that the fabricated nanofibers have smooth and continuous morphology. In addition, to observe the effect of the PSU-based blending material, Fourier-transform infrared (FTIR) spectra of the samples were acquired, providing chemical compositions of the bare and PSU-blended PAN nanofibers. The fabricated PSU/PAN composite nanofibers have a diameter range of 222-392 nm. In terms of the wettability, the measured water contact angle (WCA) value of the PAN nanofibers was improved from (14 ± 1)° to (156 ± 6)°, (160 ± 4)°, (156 ± 6)°, and (158 ± 4)° after being blended with PSU solutions having concentrations of 0.5, 1, 1.5, and 2 wt %, respectively. This result has proven that the PAN nanofiber surfaces can be tuned from hydrophilic to superhydrophobic characteristics simply by introducing PSU into the PAN solution prior to electrospinning, where a small PSU concentration of 0.5% has been sufficient to provide the desired effect. Owing to its low-cost and highly efficient process, this strategy may be further explored for other types of polymer-based nanofibers.

S-doped MXene@porous carbon nano-fiber composite for improved sodium storage performance

Sodium-ion batteries have attracted considerable interest of many scholars due to their low cost and similar energy storage mechanism to lithium-ion batteries. Considering the poor electrochemical redox reaction kinetics and low structural stability resulting from the larger radius of Na+ (0.102 nm), we have elaborately designed novel sulfur-doped MXene/porous carbon nano-fiber composites (S-MX@CNF) as anodes for SIBs via a synergistic assembly and sulfidation treatment approach. The S-MX@CNF composites have a multi-layered structure, which not only prevents restacking of MXene layers and increases accessible active sites, but also enhances the overall electrode conductivity. The composites exhibit a unique interconnected conductive network frame structure and increased interlayer spacing, which facilitates fast ionic and electronic transport rates. Additionally, the robust composites exhibit high chemical stability, enabling it to tolerate volume changes during the rapid charge/discharge process. As a result of these synergistic effects, the S-MX@CNF displays a high reversible capacity of 304 mAh/g (0.5 A/g) after 1000 cycles and long cycle stability of 170 mAh/g (3 A/g) with only 0.1 % degradation per cycle within 4900 cycles. This work opens up new opportunities for further advances in synergistic assembly and heteroatom doping strategies for composites in energy storage devices.

Enhanced Photodegradation of Acetaminophen Using Efficient ZnO-NiO Nanofibers

The increasing presence of pharmaceutical pollutants, such as acetaminophen, in water bodies poses a significant environmental challenge due to their persistence and potential toxicity. This study investigated the enhanced photodegradation of acetaminophen using ZnO-NiO nanofibers as superior photocatalysts. The nanofibers synthesized with varying NiO contents (designated as ZN0.5, ZN1, ZN1.5, and ZN2), were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, FTIR, Brunauer–Emmett–Teller (BET) analysis, and diffuse reflectance spectroscopy (DRS) to elucidate their structural, morphological, and optical properties. Thermogravimetric analysis (TGA) indicated that the nanofibers exhibit high thermal stability, with major weight loss attributed to the decomposition of the polymer matrix and residual organics. The BET analysis revealed that the specific surface area remains stable after increasing the NiO content up to a certain ratio. This stability correlates with the enhanced photocatalytic performance due to increased light absorption and improved charge separation. The diffuse reflectance spectra and Kubelka–Munk plots demonstrated a reduction in bandgap energy with higher NiO content, facilitating greater visible light absorption. Photocatalytic experiments under visible light irradiation, in the presence of peroxymonosulfate (PMS), showed that the ZN1.5 nanofibers achieved the highest acetaminophen degradation rate, i.e., 92%, within 3 h. Mechanistic studies, supported by radical trapping experiments, revealed that the improved photocatalytic efficiency is due to the synergistic effects of ZnO and NiO heterojunctions, which enhance charge separation and reactive oxygen species (ROS) generation. This research highlights the potential of ZnO-NiO nanofibers as effective photocatalysts for the degradation of pharmaceutical pollutants. The findings demonstrate that optimizing the composition and structure of nanofibers can significantly improve their environmental remediation capabilities, providing a promising solution for sustainable water treatment.

Electrospinning of fluorescent-magnetic-conductive tri-functional nanofibrous yarns

To achieve a high integration of fluorescence, conductivity and magnetism in the yarn structure while completely avoiding direct contact of different functional substances, three types of nanofibers with different functions are integrated into a yarn to achieve enhanced perovskite quantum dots (PQDs) fluorescence, intensified conductivity and adjustable magnetism. As a case study, [CsPbBr3 PQDs/polyacrylonitrile (PAN)]//[CoFe2O4/PAN]//[polyaniline (PANI)/PAN] triple-strand nanofibers yarns (TSNYs) were innovatively designed and constructed. We also advance a facile triple-strand conjugate electrospinning technology for the first time to create this specialized nanofiber yarn. The mechanical properties of the TSNYs are controllable by adjusting the twist. TSNYs emit strong green fluorescence excited by 365-nm ultraviolet (UV) light. The magnetism and conductivity of TSNYs are respectively tunable by regulating the contents of CoFe2O4 MNPs and PANI. With the aid of the peculiar structure of TSNYs, various substances are evenly distributed in the respective nanofibers avoiding direct contact. TSNY effectively prevents the adverse effects of dark-colored magnetic and conductive substances on the fluorescent properties, and the decrease in conductivity caused by mixing insulating substances with PANI is also avoided. TSNYs exhibit 33 times higher fluorescence intensity and two orders of magnitude higher conductivity than the composite nanofibers yarns. The formation mechanism of the TSNYs is elucidated, and triple-strand conjugate electrospinning technique is established. The design ideas and fabricating techniques are instructive for fabricating poly-functional yarns. The fluorescence-magnetic-conductive yarns are potential candidates in lighting devices, biomedical imaging and electromagnetic shielding.

Electrospun rGO-PVDF/WO3 composite fibers for SO2 sensing

Developing highly selective and sensitive SO2 sensors is essential due to the excessive presence of SO2 in the environment which can cause respiratory illness and acid rain. Semiconducting metal oxides are the materials most used for the development of SO2 sensors; however, they still suffer from sensitivity, selectivity, low-temperature operation, low detection limit, and slow response/recovery time for real-field applications. In this work, rGO-PVDF/WO3 composite fibre-based sensors are developed via electrospinning technique. The electrospun rGO-PVDF/WO3 were characterized for their structural morphology, thermal stability, crystal structure, and their SO2 sensing capability. The results show that the electrospun rGO-PVDF/WO3 sensor (containing 10 mL GO) leads the most improved SO2 sensing performance of all tested sensors in this work, with a response of 11.08 and 22.06 at SO2 concentrations of 60 and 80 ppm, respectively. The 10 mL-rGO-PDVF/WO3 composite nanofibers also demonstrated good selectivity and stability for SO2. The improvement in gas sensitivity is due to the synergistic effect of forming an ohmic contact between the rGO nanosheets, PVDF fibers, and the WO3 nanograins. The good surface properties such as high surface area (10.64 m2/g) and porous structure of 10 mL-rGO-PDVF/WO3 composite nanofibers have also contributed to the SO2 gas sensing performance. The results show that the composite nanofibers rGO-PVDF/WO3 can be used to detect low concentrations of SO2 and could be used to monitor the environment.

SnO2 induced electrostatic polarization PVDF composite nanofibers for efficient energy harvesting and self-powered wireless monitoring /motion recognition systems

With the rapid development of the Internet of Things and flexible electronics, piezoelectric nanogenerators (PENGs) based on polyvinylidene fluoride (PVDF) have demonstrated a wide range of potential applications in wearable devices. However, there are still challenges in developing high-performance PENGs, which affect their potential applications in more scenarios. Herein, we propose a SnO2-PVDF (SP)-PENG based on low-cost and environment-friendly SnO2 nanoparticles modulated via electrospinning, achieving outstanding piezoelectric output performance. The piezoelectric output of SP-PENG is up to 49.2 V, which is 11.7 times higher than that of pure PVDF-PENG. From the theoretical perspective, the enhanced electrostatic polarization is achieved by the strengthened local electric field due to the presence of low-resistivity SnO2 in the SP fibers. The mechanism of enhanced electrostatic polarization is also declared by COMSOL simulation. Moreover, the SP-PENG exhibits excellent durability (41,600 cycles) and long-term stability (8 months). A self-powered wireless sensing-monitoring system is realized by combining SP-PENG with circuit design. The motion recognition system is accomplished by integrating an assistance of a 1D CNN-LSTM joint learning model, which is verified by an alphabetic handwriting recognition with a classification accuracy up to 100 %. This study provides significant insights for enhancing the performance of PENGs and offers valuable guidance for exploring the application of PENGs in flexible electronics and artificial intelligence.