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Multifunctional hydrogels with transparency, ultraviolet (UV)-blocking, stretchable, self-healing, adhesive, antioxidant and antibacterial properties are promising materials for biomedical and relevant applications. However, preparation of these hydrogels at ambient environment without stimuli is still a challenge. Here, a series of hydrogels possessing ultrashort gelation time (~30 s) at room or cold temperature were fabricated based on self-catalytic Fe3+/Tannic acid-cellulose nanofiber (Fe3+/TA-CNF). Fe3+/TA-CNF formed stable redox pairs to activate ammonium persulfate (initiator), generating abundant free radicals to trigger the ultrafast polymerization of acrylic acid (AA). To improve the antibacterial ability of hydrogel, a bilayer hydrogel composite (NF@HG) composed of tetracycline hydrochloride (TH)-loaded electrospun nanofibers and hydrogel layer was fabricated via a mild casting method. The NF@HG exhibited enhanced antibacterial ability and the sustained release of TH can provide long-term antibacterial activity. Besides, cell viability results demonstrated that NF@HG was non-cytotoxic. Taken together, this strategy based on self-catalytic Fe3+/TA-CNF system may inspire new aspects on fast and economical preparation of multifunctional hydrogels or composites, which have attractive industrial applications for biomedical materials.

The zinc-air battery (ZAB) is a promising candidate for powering wearable electronic devices. Unfortunately, traditional ZAB hydrogel electrolytes dehydrate at room temperature and freeze at extreme cold temperatures, limiting their working life and ability to adapt to the extreme cold polar environment. Herein, the fabrication of alkaline double-network hydrogel electrolytes is made simple using in-situ polymerization of acrylamide (AM) and cellulose nanofibers (CNF), followed by immersion in a solution containing KOH and KI reaction modifier. The anti-dehydration and anti-freezing properties of the prepared hydrogel electrolyte are greatly improved. Furthermore, by altering the conventional discharge/charge reaction paths, the addition of KI significantly improves the energy efficiency of ZABs. The ZAB based on the hydrogel electrolyte not only has excellent discharge/charge performance and cycling life at room temperature, but it can also operate in extremely cold temperatures (-40 °C). The ZABs are connected to power a variety of electronic devices, indicating that they could be used as wearable energy storage devices.

To understand the properties of polyaniline (PANI), aim gas, and the interaction between them in PANI-based gas sensors and help us to design sensors with better properties, direct calculations with molecular dynamics (MD) simulations were done in this work. Polyamide 6/polyaniline (PA6/PANI) nanofiber ammonia gas sensors were studied as an example here, and the structural, morphological, and ammonia sensing properties (to 50–250 ppm ammonia) of PA6/PANI nanofibers were tested and evaluated by scanning electron microscopy, Fourier transform infrared spectroscopy, and a homemade test system. The PA6/PANI nanofibers were prepared by in situ polymerization of aniline with electrospun PA6 nanofibers as templates and hydrochloric acid (HCl) as a doping agent for PANI, and the sensors show rapid response, ideal selectivity, and acceptable repeatability. Then, complementary molecular dynamics simulations were performed to understand how ammonia molecules interact with HCl-doped PANI chains, thus providing insights into the molecular-level details of the ammonia sensing performances of this system. Results of the radial distribution functions and mean square displacement analysis of the MD simulations were consistent with the dedoping mechanism of the PANI chains.

In this study, a necklace-like NiCo2O4@carbon composite nanofiber (NCO@CNF) anode composed of a metal–organic framework, featuring low volume expansion and high rate properties, was prepared as an anode for lithium-ion batteries. By tuning the ratio of the ZIF-67 precursor and growth time, unique necklace-like NCO@CNFs were synthesized for the first time. The novel necklace-like NCO@CNFs presented an interconnected architecture with a large specific surface area (194.2 m2 g−1), robust pore structures and superior mechanical strength. Benefiting from the abovementioned excellent physical properties, the issue of volume expansion derived from Li+ insertion/extraction during cycling was effectively mitigated by improved ionic transportation kinetics when the prepared NCO@CNFs were applied as an anode in a lithium-ion battery. Through a series of electrochemical measurements, the NCO@CNF electrode exhibited a high specific capacity of 1953 mA h g−1 at the current density of 0.3 A g−1, prolonged cycling stability with a reversible capacity of 1388 mA h g−1 after 500 cycles and good rate capability with a reversible capacity of 652 mA h g−1 at a high current density of 2 A g−1. Moreover, its excellent stability was revealed by the sustained integrity of its necklace structure, similar to that of the fresh electrode, without significant volume expansion or pulverization even after 500 cycles.

Bacterial cellulose is the three-dimensional network structure of nanofibers. The bacterial cellulose materials have outstanding characteristics of high surface area and high crystallinity (84%–89%). It has greater compatibility with the degree of polymerization and has excellent mechanical properties. The water-holding capacity of bacterial cellulose (over 100 ti) makes it stand out from other cellulose materials. This is because bacterial cellulose has high purity due to a lack of lignin and hemicellulose. Bacterial cellulose is considered as a non-cytotoxic, non-genotoxic, and highly biocompatible material, which has broad appeal in the medical field and has attracted widespread attention. The proposed review summarizes the microbial effects of enlisting bacterial strains with carbon sources, and culture media on bacterial cellulose production. In addition, it provides a variety of physical and chemical methods that can be used to modify bacterial cellulose with metal and metal oxide nanoparticles; like the common structure of zinc oxide/bacterial cellulose represent antibacterial characteristics against C.freundii, S.aureus, E.coli, and P.aeruginosa with 90.9%, 94.3%, 90.0%, and 87.4% strength respectively. The wound healing properties of such metallic oxide structure with bacterial cellulose presents the characteristics, which confirms its application in 66% of strength, especially for bionic designs for medical applications, including wound healing and artificial skin, vascular and neurosurgical covering materials, dural prosthesis, arterial stent coating, cartilage, bone repair grafts, and biomedicines. Because of the further exposure of value-added medical material application, our review ends with challenges and perspectives in the production of bacterial cellulose nanocomposite.

In order to study the influence of substrates on the structure and properties of deposited functional nanocomposite film, polyester fabrics with different structures were used as substrates, metal ...

A novel solid bacterial cellulose/cotton fibers (BCF) composite with a sandwich-like structure as active and intelligent food packaging was formed in situ. BCF or bacterial cellulose (BC) films were vacuum dried and different concentrations of curcumin were absorbed in the films. Scanning electron microscopy showed cotton fibers were combined with BC, and formed a sandwich-like structure. The elongation at break, water solubility, swelling degree, thermal stability, UV barrier property and antioxidant property of films were increased with the cotton fibers in the films. For studying the interaction between solid support and curcumin, Fourier-transform infrared spectroscopy and X-ray diffraction spectroscopy were conducted. Curcumin was successfully doped into solid support films. With the addition of curcumin, the water solubility, tensile strength and swelling degree of films decreased, while elongation at break, thermal stability and UV barrier property increased. When the concentration of curcumin was the same, BCF based films presented improved antioxidant property and more visible color changes than BC based films. The BCF-curcumin films exhibited a color change from bright yellow to brownness with pH variations ranging from 7 to 10. These results indicated that BCF-curcumin films have the ability to be utilized as an active and intelligent food packaging.

Polylactic acid-based membranes received considerable attention due to its novel biocompatibility, renewability, and biodegradability. In this study, PLA electrospun nanofibrous membrane was prepared and 2-dimethylaminoethyl methacrylate (DMAEMA) was used as a monomer for surface grafting of polymer chains via the atom transfer radical polymerization method. Then the PLA nanofibers were quaternized by using bromoethane. The characterization of poly(DMAEMA) graft PLA nanofiber (poly(DMAEMA)-g-PLA) membranes was done by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. The results showed that the diameter of PLA nanofibers increased 15% as the concentration increased from 10% to 12% and then increased 23% as the concentration of PLA solution increased from 10% to 15%. But the regularity of average diameters is best achieved at 12% concentration.

This work describes that bacterial cellulose was successively modified by copper/zinc nanoparticles with the help of direct current and radio frequency magnetron sputter-coating method for electromagnetic interference shielding to enhance its hydrophobic, mechanical, and conductive properties. The surface morphology and properties of bacterial cellulose/copper/zinc nanocomposite were analyzed by various testing methods (X-ray photoelectron spectroscopy, X-ray diffraction) and instruments to analyze smooth deposition of metallic nanoparticles. The conductive and shielding effects were examined by a four-point probe and vector analyzer. The mechanical properties were investigated by a uniaxial testing machine. The combined structure of bacterial cellulose, copper, and zinc nanoparticles (Zn–Np) improves the surface hydrophobicity, mechanical strength, as well as electromagnetic interference shielding effectiveness, while zinc nanoparticles act as a protective layer over the surface of bacterial cellulose/copper nanocomposite. So, the findings revealed that the bacterial cellulose/copper/zinc nanocomposite has excellent hydrophobic ( θ; 143.7°), good mechanical (T.F; 39.67 MPa, elongation; 13.1%, Y.M; 5.90 MPa), conductive (50 W; 0.0323 S/m), and electromagnetic interference shielding (28.54 dB) properties.

Molybdenum disulfide (MoS2), although it has shown great potential use in electrocatalysis, owns inert basal planes and the low electrical conductivity that limit its effective application. In this...

A facile strategy for synthesizing MnCo2O4/carbon (MCO/C) composite nanofibers is introduced in this work, in which MCO nanoparticles with an average size of about 40 nm are distributed uniformly in carbon nanofiber matrix by electrospinning and subsequent heat treatment. When adopted as anode for lithium-ion batteries (LIBs), MCO/C exhibits better lithium storage capabilities in comparison with bare MCO. The initial discharge/charge capacity of MCO/C is up to 1484/1140 mAh g−1 and can maintain a stable capacity of 933 mAh g−1 at 100 mA g−1 over 200 cycles. Meanwhile, a reversible capacity of 500 mAh g−1 can be retained even at a high current density of 2 A g−1 after 1000 long cycles. The superior electrochemical properties are mainly resulted from the conductive carbon matrix which can not only promote electron transfer but also act as a buffer to alleviate volume change of MCO during the lithiation/delithiation process. It is demonstrated that MCO/C nanofiber can be used as prospective anode materials for LIBs.

A novel form-stable phase change material (FSPCM) with remarkable improvement in thermal properties was fabricated by incorporating ternary fatty acid eutectics with graphene sheetconnected electrospun carbon nanofibers (GCNFs). The GCNFs possessed three-dimensional (3D) porous architecture and large specific surface area while provided mechanical support for FSPCM and effectively prevented flow/leakage of molten fatty acid. The GCNF based FSPCM exhibited desire structural morphology with lauric-myristic-stearic acid (LA-MA-SA) eutectic mixture being well dispersed in a 3D porous architecture. This novel FSPCM demonstrated superior thermal storage/retrieval capability and temperature regulation ability as well as good shape stability and thermal cycling stability. The melting and crystallization enthalpies of the fabricated FSPCMs were up to 120.4 and 120.1 kJ/kg, respectively. The thermal conductivity of the fabricated FSPCMs was 337% and 188% higher than that of LA-MA-SA eutectic mixture and a control sample without graphene, respectively, which ranked the top among the literature about LA-MA-SA eutectic mixture derived composite FSPCMs. Furthermore, the heating/cooling efficiency of the prepared FSPCMs was 45.7/64.9% higher than that of LA-MA-SA eutectic mixture.

To protect the structure of MoS2 from collapse, a strong skeleton is expected to help maintain the integrity. In this study, cotton linters burdened with hollow C@MoS2 nanocapsules are added into nutrient medium for the growth of a bacterial cellulose membrane. Benefitting from good conductivity and structural integrity, the resultant fibrous membrane anode gives reversible capacities of 559 and 155 mAh g-1 for Li-ion batteries and Na-ion batteries after 100 cycles, respectively. The structural transformation and component evolution in lithiation-delithiation and sodiation-desodiation was elucidated by in situ Raman spectroscopy. After sodiation, the Na2 S did not transform back into MoS2 but was more likely converted into elemental sulfur during the conversion reaction. Layered semiconducting transition metal chalcogenides, such as molybdenum disulfide (MoS2 ), feature open 2 D ion-transport channels amenable to receive various guest ions with high theoretical capacities.[2] One serious challenge curtailing the applicability of such materials is their volume changes during discharge-charge processes.[3, 4] However, particular morphologies of MoS2 are proposed to improve the specific capacity.[5,6,7] Many works have focused on core-shell and hollow MoS2 micro- and nanostructures, and the results validate the advantages of shortening the lithium-ion diffusion distance and enhancing specific capacity.[8,9] Unfortunately, the issue of inferior capacity stability is not resolved, because the structure is not effectively protected and is prone to collapse.

This study investigates the biosynthesis of microbial cellulose–electrospun nano-fibrous membrane hybrid nano-fabric via the use of a modified bioreactor. Microbial cellulose is known for its high liquid absorbency and hygienic nature. Electrospun nano-fibrous membranes, on the other hand, exhibit excessive surface hydrophobicity in typical conditions. As such, this research intends to improve the hydrophilic property of electrospun membranes through in situ self-assembly of microbial cellulose nano-fibrils on membrane’s surface. Scanning electron microscopy showed successful growth of microbial cellulose nano-fibrils on the surface and within the structure of electrospun membranes which could possibly contribute toward improved tensile properties. Some functional properties of hybrid nano-fabric, including water absorbency, drying time, and amount of vertical wicking, were determined and compared with pure electrospun membrane samples. Results showed that water absorbency, wicking ability, and drying time increased, as a result of microbial cellulose reinforcement. The average increase in water absorption capability and water-holding time was 72.8 and 32.65%, respectively, whereas wicking ability increased up to 16.5%. In conclusion, the results demonstrate that microbial cellulose contribution has importance for hybrid nano-fabric in terms of key material characteristics that are appropriate for wound dressing and related applications.

For overcoming the fragility of inorganic supporting materials as form-stable phase change materials (FSPCMs), flexible and soft SiO₂ nanofibrous mats were applied as supporting materials of FSPCMs for storage/retrieval of thermal energy. Quaternary fatty acid eutectics were incorporated into SiO₂ nanofibrous mats as representative phase change materials. Flexible SiO₂ nanofibrous mats were prepared by electrospinning combined with annealing. The thermal energy storage capability, surface morphology and thermal energy storage/retrieval rate of FSPCMs were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and laboratorymade thermal performance measurement device. The results indicated that the resultant SiO₂ nanofibrous mats were soft and free-standing. Quaternary fatty acid eutectics were distributed uniformly in the three-dimensional (3D) network structure of the SiO₂ nanofibrous mats, thereby effectively preventing fatty acid leakage. The absorption capacities of five types of quaternary fatty acid eutectics varied from 85.1% to 88.9%. Moreover, after 20 cycles, the phase change temperature and enthalpy of FSPCMs did not change significantly, suggesting that ideal thermal stability was achieved. The time for thermal energy storage/retrieval taken by FSPCMs was shortened by 23.1% at minimum from that for pure quaternary fatty acid eutectics. Therefore, the fabricated FSPCMs offer promising application prospects in a wide variety of fields, including solar energy utilization, temperature-regulating textiles and air-conditioning systems.

Purpose The purpose of this paper is to prepare structural colors of fabrics coated with Silver/Zinc Oxide (Ag/ZnO) composite films by magnetron sputtering and analyze the relationship between the colors and the thickness of Zinc Oxide (ZnO) film in Ag/ZnO composite film and the photocatalytic property of the fabrics coated with Ag/ZnO composite film. Design/methodology/approach Ag/ZnO composite films deposited on polyester fabrics were prepared by magnetron sputtering technology. The structural colors of textiles coated with Ag/ZnO composite films and the relationship between the colors and Ag/ZnO composite films were analyzed, and the photocatalytic property of Ag/ZnO composite films was also discussed. Findings The results indicated that the colors varied with the thicknesses of the ZnO film in Ag/ZnO composite films. The reactive sputtering time of ZnO film was 5, 8, 10 and 14 min, respectively, and the colors of the corresponding fabrics were purple, blue, blue-green and yellow. Meanwhile, the polyester fabrics coated with Ag/ZnO composite films showed the excellent photocatalytic properties, and silver (Ag) films deposited under the ZnO films in Ag/ZnO composite films could also improve the photocatalytic activities of ZnO films, and the formaldehyde degradation rates was 77.5%, which was higher than the 69.9% for the fabrics coated only with the ZnO film. Originality/value The polyester fabrics coated with Ag/ZnO composite films not only created various structural colors using change the thicknesses of the ZnO film, but also achieved the multifuctionality, which will have a broad application prospect in textile fields.

Nickel hydroxide as a potential electrode material was widely used in supercapacitor, but its electrochemical performance is limited due to its low conductivity, insufficient structure and weak stability. In this work, we reported a simple “one-pot” hydrothermal method of vertically growing cobalt-nickel hydroxide (Co-Ni-OH) and rGO nanosheets on conductive carbon cloth (Co-Ni-OH/rGO/CC). We demonstrated that the capacitive performance of Co-Ni-OH electrode could be significantly improved by adding rGO with uniform vertically growing nanostructure, which shortened ion diffusion paths and avoided the interface resistance. As pseudocapacitors, the as-prepared Co-Ni-OH/rGO/CC electrode showed a notable enhanced specific capacitance (151.46 F g−1 at 2.5 A g−1) and a good cycling stability (88.0% after 1000 cycles). Moreover, the symmetric supercapacitor composed of two as-prepared Co-Ni-OH/rGO/CC electrodes achieved a high energy density of 30.29 W h kg−1 at a power density of 1500 W kg−1 (based on active materials) and remarkable cycling stability (85.6% after 3000 cycles). This finding provides a simple and effective way to fabricate a promising electrode material for high-performance supercapacitor and other energy storage device.

Electrospun SiO2 nanofibrous mats have been widely utilized as substrate of form-stable phase change materials due to large specific surface area and high convection coefficient. In order to overcome the brittleness and enhance the absorption capacity of SiO2 nanofibrous mats as substrate, flexible and hollow SiO2 nanofibrous mats were prepared by single-spinneret electrospinning which eliminated complicated spinneret and unstable structure compared with coaxial electrospinning. Quinary fatty acid eutectics were chosen as representative fatty acid which were adsorbed in SiO2 nanofibrous mats to form form-stable phase change materials. The results showed that hollow structure can be observed as the content of paraffin oil decreased from 1.67 to 0.70 g, and as-prepared hollow nanofibrous mats displayed favorable flexibility. DSC results demonstrated that the largest melting/crystallization enthalpy supported by hollow SiO2 nanofibrous mats was approximately 123.80/120.50 J g−1, which was much higher than solid SiO2 nanofibers. More importantly, after 30 cycles, there was no obvious change for phase change temperature and enthalpy. The thermal conductivity of representative form-stable phase change materials was over three times than that of quinary fatty acid eutectics. Hence, flexible and hollow SiO2 nanofibrous mats were excellent substrate in form-stable phase change materials and would have wide application prospects.

Improvement in thermal conductivity and shape-stabilization of lauric-myristic-stearic acid (LA-MA-SA) ternary eutectic mixture phase change materials by incorporating with reduced graphene oxide/carbon nano-felts (RGO/CNFs) were investigated. The RGO/CNFs Supporting Materials were facilely made from amidoxime surface-functionalized polyacrylonitrile (ASFPAN) nano-felts immersed in graphene oxide aqueous through stabilization in air followed by carbonization in argon. Various analytical techniques were employed to reveal the morphological structure and thermal properties of fabricated form-stable phase change materials (FSPCMs). FT-IR, SEM, TEM, XRD, EDS and BET characterizations indicated that the RGO/CNFs matrix possessed excellent morphological structure and large specific surface area, so that LA-MA-SA could well dispersed in its 3D porous architecture and well-retain their overall shapes. DSC results showed that the maximum loading capacity of LA-MA-SA reached 73.5%, and the highest melting/crystallization enthalpies of fabricated FSPCMs were 128.1/127.9 kJ/kg, respectively. Hot disk thermal constant analyzer suggested that thermal conductivity of the FSPCMs was 1.88 W/m K, approximately 583% higher than that of neat LA-MA-SA. Temperature-time curves for melting/freezing process indicated that compared with melting/freezing times of LA-MA-SA, the melting/freezing time of fabricated FSPCMs decreased about 55.1/62.7%. The RGO/CNFs might afford a lot of conductive pathways for heat transfer and/or conversion. The FSPCMs exhibited superior shape-stabilization owing to capillary force and surface tension induced by interconnected netlike RGO/CNFs composites. Hence, they can be considered as more promising thermal energy storage material in advanced energy-related devices and building energy conservation applications.

As the most widely used metal oxide catalysts in photocatalytic degradation, the fast recombination of charge carriers limits the photocatalytic performance of multiform TiO2, resulting from its direct-band-gap property. In the present work, we designed C-doped coupled TiO2/ZnO nanofibrous membrane based on the derivation of ZnO from the metal organic framework (MOF). The morphology and catalytic properties of the composite membrane could be manipulated by the growth of ZIF-8 crystals. Compared to pristine TiO2 nanofibers (11.4341 m2 g−1), the composite membrane with an optimized ZnO cubes exhibited larger specific surface area (30.2475 m2 g−1) after introducing ZnO cubes. Furthermore, the crossed-network connection between TiO2 and ZnO cubes is propitious to increase the synergy of the heterojunction, subsequently effectively inhibiting the recombination of photogenetrated holes and electrons. Benefitting from the trinomial synergistic effect of carbon doping, ZnO and TiO2, the as-designed composite membrane exhibited excellent photocatalytic performance to Rhodamine compared to pure TiO2 nanofibers. This study not only presents the strategy of preparing a C-doped coupled TiO2/ZnO composites with crossed network connection for effective photocatalysis, but also exploit the application of MOFs.

Poly(lactic acid)/hexadecyl trimethyl ammonium chloride-modified montmorillonite clay nanofiber membranes have been fabricated by the electrospinning technique. The nanofiber membranes were then characterized by scanning electron microscopy and Fourier transform-infrared spectroscopy. Nanofiber membranes with different ratios of Poly(lactic acid) and hexadecyl trimethyl ammonium chloride-modified montmorillonite have been spun by varying voltage supply during electrospinning. These parameters were found to have a substantial effect on the morphologies of these membranes. It was found that 8% (w/w) Poly(lactic acid)/hexadecyl trimethyl ammonium chloride-modified montmorillonite concentration is an ideal condition to obtain thinner and uniform Poly(lactic acid) fibers. The results also suggested the coexistence of exfoliated hexadecyl trimethyl ammonium chloride-modified montmorillonite layers over the studied hexadecyl trimethyl ammonium chloride-modified montmorillonite contents. Fourier transform-infrared spectroscopy revealed that there might be possible interactions between the hexadecyl trimethyl ammonium chloride-modified montmorillonite clay and Poly(lactic acid) matrix.

In this research work, in-situ self-assembly approach was used the first time, to cultivate bacterial cellulose on the surface of fibers, extracted from banana peels. The characterization was perfo...

Electrospun polyacrylonitrile/sliver nanoparticles (PAN/Ag-NPs) nanofibrous membranes were fabricated as supporting materials by direct dispersing Ag-NPs additives into PAN solutions. And then a series of form-stable phase change composite fibrous membranes (PCCFMs) were developed by physical adsorbing three different kinds of solid-liquid phase change materials (PCMs) with the melting temperatures of about 20–33 °C including butyl stearate (BS), capric-myristic acid binary eutectic (CA-MA), capric- palmitic-stearic acid ternary eutectic (CA-PA-SA) into electrospun PAN/Ag-NPs supporting membranes. The morphology and thermal properties were characterized by scanning electron microscopy, thermogravimetric analysis, differential scanning calorimeter and measurement of melting and freezing times, respectively. DSC curves suggested that melting peak temperatures and enthalpies of the PAN/Ag-NPs-based form- stable PCCFMs were in the range of about 23.47–29.31 °C and 138.1–156.7 kJkg −1 , respectively. Melting/freezing times were significantly shorten by about 29%/32% and 44%/52% for the BS/PAN/Ag-NPs5 and BS/PAN/Ag-NPs10 form-stable PCCFMs owing to the addition of Ag- NPs.

In this study, the NiCo2O4 nanofibers derived from metal-organic frameworks (MOFs) are produced through electrospinning, in situ growth with following calcination. The electrode materials with various morphologies are developed by adjusting the in situ growth duration. The NiCo2O4-6 (NCO-6) nanofibers grown for 6 h exhibit large specific surface area (SSA, 151 m2 g−1) and massive pore structures. Upon applying as anode for LIBs, high discharge capacities of 1584 and 877 mAh g−1 are delivered in the first and 300th cycle at 0.3 A g−1. After cycling at different current densities ranging from 0.3 to 1.2 A g−1, the reversible capacity of 970 mAh g−1 is sustained once the current density is reversed to 0.3 A g−1. Such an excellent cycle and rate stability of the prepared NCO-6 electrode is attributed to its distinct structure which significantly reliefs the volume expansion and consequently improves lithium-ion intercalation/deintercalation efficiency.

Long-lasting and reusable adhesive hydrogels are highly desirable in biomedical and relevant applications, however, its design still remains challenge. Here, a series of plant-inspired adhesive hydrogels were prepared based on Ag/Tannic acid-Cellulose nanofibers (Ag/TA-CNF) triggered reversible quinone/catechol chemistry, which mimicked the long-lasting reductive/oxidative balance in mussels. The dynamic redox system generated catechol groups inner the hydrogel continuously, imparting hydrogels with high and repeatable adhesiveness. Besides, the hydrogel still maintained its high adhesiveness after storing at extreme temperatures for 30 days. Furthermore, to broaden the biomedical applications of the hydrogels, the pre-gel solution with optimal composition was cast onto the surface of vaccarin-loaded electrospun nanofibers to form the bilayer nanocomposite hydrogel (NF@HG) in situ. The NF@HG with the intrinsic properties of the hydrogel layer (e.g. stretchable, adhesive, antioxidant, antifreezing, antidrying, photothermal and antibacterial) exhibited enhanced mechanical properties, sustained drug release and good cytocompatibility, which could be an attractive candidate for wound healing material. Taken together, this study may inspire new aspects for designing reusable and long-lasting adhesive hydrogels according to dynamic catechol chemistry.

Developing multifunctional hydrogels with good mechanical properties, tissue-adhesiveness, self-healing properties and antioxidant, blood clotting and antibacterial properties is highly desirable for biomedical applications. In this study, a series of multifunctional chitosan-based double cross-linked hydrogels were prepared using a facile method based on quaternized chitosan (QCS) and polyacrylamide (PAM) using polydopamine (PDA) as a novel connecting bridge. Investigation on the content of dopamine (DA) and QCS revealed that the catechol-mediated interactions played an important role in the hydrogel properties. Results showed that the hydrogel exhibited the best mechanical properties when QCS = 12 wt% and DA = 0.4 wt%. Tensile and compressive strength was 13.3 kPa and 67.8 kPa, respectively, and the hydrogel presented strong and repeatable tissue-adhesiveness (27.2 kPa) to porcine skin, as well as good stretchability (1154%). At room temperature, the hydrogel exhibited high self-healing efficiency (90% after 2 h of healing). Antibacterial test results showed that the hydrogel killed 99.99% S. aureus and E. coli. Moreover, the vaccarin-loaded hydrogel exhibited a pH-responsive drug release profile with superior cytocompatibility compared to the pure hydrogel. In summary, this strategy combined double cross-linking and catechol-mediated chemistry to shed new light on the fabrication of novel multifunctional hydrogels with desirable mechanical properties, strong tissue adhesiveness and self-healing abilities.

Metal-organic frameworks (MOFs) can act as precursors or templates to a myriad of nanostructured materials that are difficult to prepare. In this study, Co-MOF nanorods (NRs) were prepared at room temperature followed by a calcination and hydrothermal sulfurization strategy to transform the MOF into CoS NRs on carbon cloth (CoS/CC). Intriguingly, the resultant 3D sulfide NRs can serve as scaffolds to electrodeposit layered double hydroxides (LDHs) on the surfaces. Through combining the advantages of structure and composition, the as-fabricated CoS@CoNi-LDH/CC exhibits remarkable electrocatalytic activity for the hydrogen evolution reaction (HER). An overpotential of 124 mV is needed to reach a current density of 10 mA cm-2 with a Tafel slope of only 89 mV dec-1, which is superior to that of pure CoS/CC (141 mV along with 103 mV dec-1) and other reported cobalt-based catalysts. Notably, after the chronopotentiometry test for 50 h, the overpotential of CoS@CoNi-LDH/CC increased by 17 mV only.

An Enzyme (glucose/O2) BioFuel Cell (EBFC) was developed using glucose oxidase (GOx)-based bioanode and a laccase (Lac)-based biocathode with carboxylic multi-walled carbon nanotubes (c-MWCNTs) and gold nanoparticles (AuNPs)-modified bacterial cellulose (BC) electrode as the substrate. The open circuit potential (OCP) of the EBFC was inhibited and later activated by the self-powered electrochemical device. The device not only provided high power density (345.14 µW cm−3), but also exhibited an unprecedented broad linear dynamic range from 0 to 50 mM with a lower detection limit of 2.874 μM for glucose concentrations in biological media. This result was attributed to a synergistic mechanism between the enzymes, c-MWCNTs, and AuNPs in which direct electron transfer (DET) was facilitated from the catalytic centers of enzymes to the electrode surface. The BC-based nanocomposites may have great promise as flexible electrodes in the field of self-powered biosensors.

In this work, bacterial cellulose/electrospun membrane three-dimensional (BC/ENM 3D) hybrid structures were fabricated using in-situ self-assembly and characterized by SEM and FTIR. SEM showed as the bacterium extrudes cellulose nanofibrils; they gradually self-assemble to form a unified network on membrane surface and also penetrate into its structure, hence securely binding electrospun nanofiber and interlocking multiple membrane layers to form a stable 3D hybrid scaffold. FTIR results confirmed the presence of BC in the resulting nanocomposites. The permeability and porosity of the scaffold decreased with prolonged fermentation and with increased oxygen ratio as the cellulose grew more quickly.

A novel graphene oxide/polyester (GO/PET) composite fabric as a recyclable adsorbent was prepared via electrostatic self-assembly. The structure, morphology, and properties of the GO/PET composite fabrics were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and contact angle (CA), respectively. The absorption property was evaluated by the absorption amount and removal efficiency of methylene blue (MB) solution on the GO/PET composite fabric. The results indicated that the absorption amount was found to be 21.80 mg/g and the removal efficiency reached 99.93 % under the experimental conditions of GO concentration of 2 mg/ml, initial concentration of 50 mg/l, and area of 64 cm2. The experimental parameters were investigated including the concentration of GO, the initial concentration of MB solutions, and adsorbent area. Simultaneously, according to a series of dynamic analysis, the absorption process revealed that the kinetics was well-described by pseudo-second-order model. This study showed that the GO/PET composite fabric could be a recyclable, efficient adsorbent material for the environmental cleanup.

In this work, porous electrospun polylactic acid (PLA) fibers with high specific surface area and excellent biodegradability were examined as the support of titanium dioxide (TiO2) nanoparticles (NPs). The deposition of TiO2 NPs on porous electrospun PLA fibrous substrates was accomplished through the hydrolysis of titanium tetra isopropoxide (TTIP) under ultrasonic irradiation, and the effects of the TTIP concentrations on structure and property of composite fibers was also investigated. The prepared TiO2-deposited PLA composite fibers were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) and thermogravimetric analyzer (TGA). The results indicated that the anatase TiO2 NPs with an average size of about several tens of nanometers to 200 nm were successfully loaded onto surface of porous PLA fibrous substrates. Meanwhile, the TiO2 NPs liked a "double-edged sword," overfull deposition of TiO2 NPs had negative effect on the properties of composite fibers. Under the optimized condition, the TiO2 NPs deposited dispersedly on the surface of PLA fibers without severe agglomeration and this structure performed with a high specific surface area of 64.8 m2/g, which was 5 times as large as pure PLA nanofibers (12.9 m2/g). In addition, the prepared TiO2-loaded composite fibers showed satisfactory removal efficiency on MB, the MB concentration decreased about 75%, which was remarkably higher than that of pure PLA fibers. Compared with powdery TiO2, TiO2-loaded composite fibers showed considerable photocatalytic activity, as well as easier operation, confirming this hybrid composite fibers was suitable for the easier operated application of TiO2.

The development of cost-effective electrocatalysts for both hydrogen and oxygen evolution reactions (HER and OER) in alkaline media is crucial in renewable energy conversion technologies. Metal–organic frameworks (MOFs) can act as precursors to the design and construct of varied nanostructured materials which may be difficult to produce in other ways. Herein, we put forward a serial ion-exchange reaction and selenation strategy to prepare novel yolk–shelled Ni–Co–Se dodecahedral nanocages on carbon fiber paper (Y–S Ni–Co-Se/CFP). ZIF-67@LDH/CFP was first synthesized by a simple ion-exchange reaction, followed by a hydrothermal selenation process to form Y–S Ni–Co-Se/CFP. Moreover, the composition of the as-prepared yolk–shelled Ni–Co–Se nanocages was a mixture of Co0.85Se and Ni0.85Se (Co/Ni atomic ratio of about 2.42). Due to their structural and compositional merits, the as-prepared Y–S Ni–Co-Se/CFP exhibited remarkable electrocatalytic activity and long-term stability (over 80% current retention for at...

Chitosan/polyaniline (CTS/PANI) were deposited onto the surface of wool fabric in one step by in-situ polymerization method, carboxylic acid and hydrochloric acid as doping acid and chitosan exited. Oxygen plasma pretreatment was used to etch the scale layer of wool and to introduce active free radicals which can form hydrogen bonds with the -OH of CTS, and this was beneficial to improve the binding force and fastness among CTS, PANI and wool, and form a more uniform conductive layer. Various characterizations were chosen to evaluate the performances of the fabrics, including field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), resistance measurement and antibacterial test. The prepared PANI/CTS/Wool composite conductive fabric showed high conductivity up to 11.32 S/cm, homogeneous color as well as good antibacterial properties. The antibacterial effect of Escherichia coli and Staphylococcus aureus was more than 99.99% even after 10 washes.

One-dimension mesoporous cobalt ferrite (CoFe2O4) nanofibers were prepared by a facile single-nozzle electrospinning technique followed by calcination. The lithium storage properties show that the CoFe2O4 nanofibers obtained at 800 °C deliver an initial discharge capacity of 1888 mAh g−1 and a reversible capacity as high as 942 mAh g−1 after 80 cycles, much higher than those of the samples obtained at 600 °C (1193 and 701 mAh g−1, respectively). The CoFe2O4 nanofibers obtained at 800 °C also demonstrate an excellent rate capability. The improved lithium storage properties of CoFe2O4 nanofibers obtained at 800 °C can be attributed to the unique mesoporous and fibrous structures, as well as the high crystallinity, which provide an easy Li+ diffusion path promote electron transfer, meanwhile preventing volume expansion/contraction during discharge/charge processes.

We successfully combined electrospinning with in situ polymerization methods to synthesize the PANI-coated ZnFe2O4 nanofibers which possess the abundant pore structure. The lithium storage properties of PANI-coated ZnFe2O4 nanofibers as anode materials for lithium-ion batteries have been discussed for the first time. PANI nanoparticles were directly coated on the surface of the ZnFe2O4 nanofibers, increasing the electrical conductivity, and also acting as the protect shell to enhance the mechanical strength of material. The electrochemical performance showed that 15% PANI incorporated ZnFe2O4 composite nanofibers (ZP-15) exhibited the highest reversible capacity of 1142 mAhg−1 after 50 cycles, which was much higher than that of pure ZnFe2O4 nanofibers (628 mAhg−1), 10% PANI incorporated ZnFe2O4 composite nanofibers (ZP-10, 975 mAhg−1), and 20% PANI incorporated ZnFe2O4 composite nanofibers (ZP-20, 536 mAhg−1). Additionally, the ZP-15 composite nanofibers achieved outstanding cycling rate capacity of 852, 738, 609 and 539 mAhg−1 with current densities range from 500 to 5000 mA g−1, and exhibited a specific capacity of 1082 mAhg−1 when the current reverted to 50 mA g−1 from the high rate charge-discharge cycles. The enhanced electrochemical performance of PANI-coated ZnFe2O4 nanofibers can be attributed to the PANI providing a highly electrical conductive medium, which can promote electron transfer and facilitate the Li+ transport in the lithiation/delithiation process, also can reduce self-discharge; moreover, the PANI layer covered on the surface of ZnFe2O4 nanofibers can be as buffer matrix to restrain the stress of volume expansion to get stable structure.

In order to solve the complex spinneret and unstable structure of multifludic electrospinning and side-by-side electrospinning, TiO2 nanofibers with hierarchical porosity were fabricated via microemulsion electrospinning, which can be realized just by single-spinneret electrospinning. The morphology, crystal, and specific surface area of the TiO2 nanofibers were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and physisorption analyzer. The photocatalytic activities of TiO2 nanofibers calcined at 500, 700, and 900 °C were examined. The experimental results indicated that TiO2 nanofibers were hollow, and the wall of nanofibers possessed abundant mesopores. The specific surface area of TiO2 nanofibers calcined at 500 °C was approximately 41.4 m2/g, which was favorable for increasing the photocatalytic reaction sites and the separation efficiency of electron–holes. The photocatalytic results demonstrated that compared with solid TiO2 nanofibers, the photocatalytic activities of t...

Novel hierarchically structured fabrics were successfully fabricated by coating graphene oxide (GO) and depositing polytetrafluoroethylene (PTFE) nanoparticles on the surface of polyester (PET) fib...

Heteroatom doping is a feasible approach to adjust catalytic performance of the HER catalysts. In this work, we report a design of Fe-doped Co9S8 nanosheets grown on carbon cloth (Fe-Co9S8 NSs/CC) as a hydrophilic 3D monolithic electrocatalyst for efficient hydrogen evolution under all pH. The water contact angle and electrochemical measurements proved that the resultant material was hydrophilic for its nano hierarchitectures and dopant Fe enhanced the catalytic capability of singular Co9S8. In 1.0 M KOH, the Fe-Co9S8 NSs/CC possessed a relatively small Tafel slope (95.3 mV dec−1) and required the overpotential of 83 mV to achieve 10 mA cm−2. To drive the same current density, the overpotentials were 65 and 192 mV in 0.5 M H2SO4 and 1.0 M PBS, respectively. Meanwhile, it showed good cycle stability and durability over 20 h static test at alkaline and neutral condition. The flexible freestanding catalyst has great potential in practical applications.

Freestanding N-doped carbon coated Fe3O4 particles nanocomposites with three dimensional (3D) carbon fibers network (NC@Fe3O4/CF) derived from bacterial cellulose (BC) was fabricated by simple hydrothermal and carbonization. This self-supporting structure, as promising electrode without current collector or conductive additive, showed high area capacitance and volume capacitance (1.36 F·cm− 2, 2300 F·cm− 3 at 3 mA·cm− 2). Simultaneous, the electrode showed good cycle life (88.5% capacitance retention over 4000 cycles) and wide potential window (− 1.2 to 0 V), possessed the property of pseudo and carbon materials. This low-cost, non-toxic and high capacity freestanding electrode is a potential candidate for supercapacitor applications.

Herein, we report a novel ammonia (NH3) sensor material with outstanding sensing performance based on free-standing polyaniline (PANI) coated inorganic silica (SiO2) nanofibers (SNF) membranes, which could work well at room temperature. SNF membranes were prepared by the combination of sol-gel, electrospinning and calcination methods It was realized per the results that the flexibility of SNF membranes could be considerably controlled by calcination temperature. SNF were diverted from flexible to brittle as the temperature increased from 600 °C to 1000 °C. In order to adapt to wearable gas senor demands, flexible SNF membranes obtained from heat-treated at 600 °C and 800 °C were used as templates for in-situ polymerization of aniline. The gas sensing behavior of PANI coated SNF of 10 ppm to 300 ppm NH3 were operated at room temperature. Gas sensing tests revealed that the SNF/PANI composite nanofibers had high response values. Additionally, the gas sensing abilities of PANI coated on SNF annealed at 800 °C was much higher than SNF treated at 600 °C. Moreover, the PANI coated SNF (annealed at 800 °C) could detect NH3 to 400 ppb, as well as showed excellent selectivity, repeatability and reversibility. The flexible SNF/PANI membranes were easy to prepare and it obtained ideal flexibility, which exhibited their potential for applying as wearable gas senor.

Designing multifunctional medical adhesives with strong adhesiveness under water is of great significance to achieve desirable therapeutic effects for promoting wound healing. However, its design is still challenging since most of existing hydrogel adhesive cannot work in wet environments. Here we proposed a tissue adhesive made from a combination of hydrogel matrix and nanocrystal fillers. The adhesion mechanism of this hydrogel adhesive relies on the absorption of interfacial water from tissue surfaces by hydrophilic hydrogel matrix, while the nanocrystals from the hydration process of calcium sulphoaluminate (CSA) contributes to strong cohesion. Subsequent noncovalent and covalent bonds between amine groups on tissue surfaces and catechol groups on polydopamine-intercalated silicate nanoflakes (PDA-Silicate) further improves the adhesion ability. The hydrogel adhesive with optimal compositions exhibited robust adhesiveness to different surfaces, with over 30 kPa of adhesive strength to porcine skin under water. Furthermore, chopped curcumin-loaded electrospun nanofibers were added into the precursor with optimized formulation to form nanofibers/hydrogel composite (NF-HG) in situ. The obtained NF-HG exhibited enhanced antibacterial activity, sustained drug release and good cytocompatibility. Taken together, this strategy may open new route to design versatile functional underwater adhesives.

Carbon-coated magnesium ferrite composite nanofibers (MFO/C) have been synthesized via a combination of electrospinning and carbonization process. The as-prepared MFO/C with uniform carbon layers were explored as anode material for lithium-ion batteries. Electrochemical results show that benefiting from its appropriate carbon coating, MFO/C-2 can deliver a reversible capacity of 743 mAh g−1 after 200 cycles at 0.1 A g−1 and keep a stable capacity of 451 mAh g−1 at a high current density of 2 A g−1, which indicates MFO/C-2 are very prospective anode materials for high-performance lithium-ion batteries.

A novel ordered mesoporous Co/CMK-3 nanocomposites were successfully fabricated via a facile hydrothermal method. XRD patterns affirmed that the CoCl2 entirely reduced to metal Co. Cobalt particles were well-dispersed and embedded in the mesochannels of the CMK-3 according to the nitrogen adsorption-desorption technique and transmission electron microscopy (TEM) images. Electrochemical test shows that cobalt nanoparticle can significantly promote the electrochemical properties of CMK-3 leading to a remarkable enhancement of the reversible capacity, cyclic stability, and rate capacity. The Co/CMK-3 nanocomposites were delivering a high reversible capacity of 674 mAh g−1 at the current density of 50 mA g−1 after 50 cycles, which was much higher than that of original CMK-3 (400 mAh g−1). The Co/CMK-3 nanocomposites also demonstrate an excellent rate capability. The improved lithium storage properties of ordered Co/CMK-3 nanocomposites can be attributed to the CMK-3 that could restrain the aggregation of Co nanoparticles, the large surface area of the mesopores in which the Co nanoparticles are formed, as well as presence of Co which played the role of catalyst could promote the lithium storage reaction.

Electrospun cellulose acetate (CA) nanofibrous mats incorporated with capric acid was studied to fabricate form-stable phase change materials (PCMs) for storing/retrieving thermal energy. Electrosp...

The innovative form-stable phase change materials (PCMs) were fabricated by incorporating capric-myristic-stearic acid (CMS) ternary eutectic mixture with cellulose acetate (CA) phase inversion membrane. CMS as model PCM, with melting point near ambient temperature as the temperature range was most valuable in practice. Effects of different SiO 2 amounts on surface features, structural morphology and absorption capacity of CA membrane were investigated. The SiO 2 nanoparticles created porous structure and increased CMS incorporation capability of CA membrane, the maximum absorption capacity of CA-SiO 2 membrane was ∼80.3 wt.%. The enthalpies of melting of form-stable PCMs were 76.6 kJ/kg for CA membrane and 99.8 kJ/kg for CA-SiO 2 membrane, respectively. The SiO 2 nanoparticles increased remarkably thermal stability property of form-stable PCMs. As compared to CA-SiO 2 membrane, the control temperature time of CMS/CA-SiO 2 form-stable PCMs was increased by ∼46.8%. The developed form-stable PCMs demonstrated good thermal storage/retrieval property and thermal insulation capability.

A novel ordered Co/CMK-3 nanocomposite was successfully synthesized via the sonochemical method followed by carbonization process. The ordered Co/CMK-3 nanocomposite were characterized by X-ray diffraction, transmission electron microscopy and N2 adsorption–desorption analysis techniques. The lithium storage properties shows that the Co/CMK-3 nanocomposites exhibit a large reversible capacity and good cycle stability with the capacity of 720 mAh g−1 after 50 cycles at a current rate of 50 mA g−1, much higher than that of original CMK-3 electrode. The Co/CMK-3 nanocomposites also demonstrates an excellent rate capability with capacity of 479 mAh g−1 even at a current density of 1000 mA g−1 after 50 cycles. The improved lithium storage properties of ordered Co/CMK-3 nanocomposites can be attributed to the CMK-3 could restrain the aggregation of Co nanoparticles, the large surface area of the mesopores in which the Co nanoparticles are formed, as well as presence of Co which played the role of catalyst could promote the lithium storage reaction.

Carbon coated magnesium ferrite (MgFe2O4@C) nanofibers have been successfully synthesised via electrospinning technology and the subsequent carbonization process using polydopamine (PDA) as carbon precursor. Scanning electron microscopy and transmission electron microscopy results show that nitrogen-doped carbon layers with different thicknesses are uniformly coated on the surface of MgFe2O4 nanofibers. When used as anode materials for lithium-ion batteries (LIBs), MgFe2O4@C nanofibers with a carbon thickness of 7 nm exhibit excellent cycling performance and rate capability compared with pristine MgFe2O4 and MgFe2O4@C nanofibers with carbon thicknesses of 4 nm and 15 nm, respectively. These nanofibers deliver high initial discharge and charge capacities of 1383 and 1044 mAh g-1, respectively, with coulombic efficiency of 75.5%. A reversible capacity of 926 mAh g-1 can be obtained after 200 cycles at 0.1 A g-1. Even at high rate of 1 A g-1 after 500 cycles, they still maintain a stable capacity of 610 mAh g-1 with a capapcity retention of 81.9%. It is, therefore, demonstrated that MgFe2O4@C nanofibers can be used as a potential anode candidate for LIBs.