Search

[Display omitted] Self-supporting tree skeleton and densely stackable phenolic resin are cleverly coupled together by a "rebar-concrete" structure. The thick electrode as a master of space utilization has extremely high areal and volumetric energy density. This work confirms the effective coupling of the self-supporting skeleton and powder materials, providing novel ideas for the preparation of thick electrodes with high mass loading. • A "rebar-concrete" structure is proposed to facilitate the high space utilization of thick electrodes. • The areal capacitance of the thick electrode reaches an astonishing 11F cm−2. • The assembled SSC device delivers competitive areal energy density of 0.63 mWh cm−2. The thick electrode design with high packing density of active materials can increase the capacity in a limited space. However, the key challenge is still to develop a system with high space utilization and ensure electron/ion transport in thick electrode. This work proposes an interesting "rebar-concrete" structure, which successfully prepared wood/phenolic resin-derived thick electrode with high space utilization by in-situ polymerization of phenolic resin (concrete) in the wood (rebar) channel. The electrode exhibits an excellent three-dimensional interconnected hierarchical pore structure due to the uniform activation of in-situ anchored KOH particles. The mass loading (35 mg cm−2) and areal capacitance (11F cm−2) of the obtained composite electrode are increased to 446 % and 1257 % of the original balsa wood, respectively. The assembled symmetric supercapacitor (SSC) exhibits a high energy density of 0.63 mWh cm−2 (3.91 mWh cm−3) and an excellent cycle stability (95 % retention after 50 000 cycles), showing good practicability in lighting LEDs or driving a fan. This strategy achieves effective coupling of self-supporting skeleton and powder materials, providing more insights and possibilities for the preparation of high energy density thick electrodes. [ABSTRACT FROM AUTHOR]

Polyamide-imides (PAIs) are highly desired in many applications because of their superior thermal and mechanical properties. In this work, PAI was prepared from an amide-containing diamine and dianhydride by polycondensation and thermal treatment. Both PAI films and aligned electrospun nanofibers (ANFs) were fabricated. FT-IR was used to determine the structure formation of PAI at different annealing temperatures. DSC and TGA were used to evaluate the thermal properties of PAI, while tensile test was applied to evaluate the mechanical properties of PAI films and ANFs. The results indicated that the PAI possessed both outstanding thermal stability and mechanical properties, which provide opportunities for applications in gas separation, high temperature filtration, reinforcement, etc. [ABSTRACT FROM AUTHOR]

High mechanical performance carbon nanofibers are highly required for the carbon nanofiber-reinforced composites, and it is necessary to develop novel precursors for the preparation of carbon nanofibers. In this work, blends of poly(acrylonitrile-butyl acrylate mono-butyl itaconate) (co-PAN) and polyamic acid (PAA) were electrospun into aligned nanofibers and the nanofibers were converted to carbon nanofibers by thermal imidization, pre-oxidation and high-temperature carbonization. FT-IR spectroscopy was applied to monitor the chemical structures of the nanofibers before and after pre-oxidation. Tensile tests were used to characterize the mechanical properties of electrospun carbon nanofibers (ECNFs). The microstructures of ECNFs were investigated by high-resolution TEM and Raman spectroscopy. The results indicated that the ECNFs derived from blend of co-PAN/PAA with molar ratio of 6/4 and with carbonization temperature of 1400 °C possessed the highest tensile strength of 1212 MPa, which could be attributed to the ordered graphitic structures in ECNFs. [ABSTRACT FROM AUTHOR]

Achieving a simple and mild preparation method to obtain high performance carbon-based flax fiber electrode for supercapacitor has become particularly important but still challenges. Hence, the excellent electrochemical performance of electrode was constructed by impregnation-heat treatment with ethylenediamine tetraacetic acid disodium zinc (EDTANa 2 Zn) and zinc nitrate (ZnNO 3) as activators. The results show that the decomposed zinc oxide (ZnO) of EDTANa 2 Zn leads to the prominently hierarchical porous structure and abundant nitrogen-doping, which provides more active storage sites for electrolyte. Likewise, the as-prepared electrode by EDTANa 2 Zn treatment exhibits the specific capacitance of 292 F g−1 at the current density of 0.5 A g−1, and keeps up with the capacitance retention of 102 % even after a 10, 000 long-cycles at the high current density of 10 A g−1. Significantly, the suitable zinc salt assisted preparation of high performance flax fiber carbon-based electrode provides a novel idea for future electrochemical energy storage. [Display omitted] • The obtained electrode was constructed by EDTANa 2 Zn and zinc nitrate. • The 950-EA electrode exhibits the specific capacitance of 292 F g−1–0.5 A g−1 • The 950-EA electrode keeps up with the capacitance retention of 102 % after 10,000 cycles. [ABSTRACT FROM AUTHOR]

Abstract: This work highlights the usage of short electrospun fibers for the first time for the preparation of homogeneous polymer nanofiber/polymer composites and the improvement in mechanical properties by an order to magnitude compared to as-electrospun long and continuous nanofibers. Dispersions of short electrospun nanofibers can be processed by liquid processing techniques resulting in nanofiber nonwovens similar to electrospun nonwovens but is independent from the demands of the electrospinning process is one of the emphasis of this work. The re-formation of electrospun fiber nonwovens by dispersion casting of short electrospun polyimide (PI) nanofibers and the preparation of homogeneous polymer/polymer nanofiber composite films were selected as representative examples for showing the versatility of short electrospun fibers. The self-reinforced PI/PI-short nanofiber composite films were obtained from mixtures of short electrospun PI nanofibers and polyamic acid after imidization. Significant improvement of 53% and 87% in mechanical properties like tensile strength and modulus, respectively in comparison to the neat PI film was observed by using just 2wt% of short fibers. Parallel experiments were also carried out with long and continuous electrospun PI fibers and amazingly a huge difference was observed. The amount of continuously long fibers required for achieving almost the same strength was much higher i.e. 38wt% in comparison to the 2wt% required of short fibers. [Copyright &y& Elsevier]

Electrospinning is an effective and versatile method to prepare continuous polymer nanofibers and nonwovens that exhibit excellent properties such as high molecular orientation, high porosity and large specific surface area. Benefitting from these outstanding and intriguing features, electrospun nanofibers have been employed as a promising candidate for the fabrication of food packaging materials. Actually, the electrospun nanofibers used in food packaging must possess biocompatibility and low toxicity. In addition, in order to maintain the quality of food and extend its shelf life, food packaging materials also need to have certain functionality. Herein, in this timely review, functional materials produced from electrospinning toward food packaging are highlighted. At first, various strategies for the preparation of polymer electrospun fiber are introduced, then the characteristics of different packaging films and their successful applications in food packaging are summarized, including degradable materials, superhydrophobic materials, edible materials, antibacterial materials and high barrier materials. Finally, the future perspective and key challenges of polymer electrospun nanofibers for food packaging are also discussed. Hopefully, this review would provide a fundamental insight into the development of electrospun functional materials with high performance for food packaging. [ABSTRACT FROM AUTHOR]

Coaxial electrospinning is an attractive technology to produce core/sheath and hollow fibers. However, until now, the relatively low productivity has limited its broad applications. In this work, coaxial electrospinning with air‐blowing‐assistance is applied to improve the productivity of core/sheath and hollow fibers. Different core and shell materials are used for this electrospinning. The flow rate and air‐blowing rate during electrospinning are optimized. SEM and TEM are used to confirm the core/sheath and hollow structure of fibers. The results show that air‐blowing‐assisted electrospinning technology can be successfully applied for the large‐scale production of core/sheath and hollow fibers which open the path to new applications of this promising class of materials. [ABSTRACT FROM AUTHOR]

Electrospun polyimide (PI) nanofiber nonwovens with excellent mechanical and thermal performance are highly required in many applications. The addition of phosphorus-containing compounds could be used as plasticizer to achieve this purpose. Herein, different amounts of trace diphenyl phosphate (DPhP) as plasticizer are added into the PI's precursor for electrospinning. After imidization, phosphorous-containing electrospun PI nonwovens (PI-PX) are produced. The results indicate that the addition of DPhP significantly enhanced the thermal and mechanical properties of PI-PX. PI-P0.6 (0.6 wt% DPhP) shows a T5% of 510 °C in air and 561 °C in Ar, 29 °C and 40 °C higher than those of pure PI. PI-P0.6 also shows the highest tensile strength/modulus/toughness of 44 MPa/2.0 GPa/8.5 MPa, 208 MPa/9.7 GPa/40.7 MPa, and 123 MPa/3.3 GPa/25.1 MPa, respectively, when applying different thickness determinations. In addition, PI-P0.6 also exhibited much higher puncture strength than other Li-ion battery separators. Such PI-PX composite nonwovens would be good candidates for various applications, especially for Li-ion battery separators. [ABSTRACT FROM AUTHOR]

Due to the rapid development of intelligent technology and the pursuit of green environmental protection, responsive materials with single response and actuation can no longer meet the requirements of modern technology for intelligence, diversification, and environmental friendliness. Therefore, intelligent responsive materials have received much attention. In recent years, with the development of new materials and technologies, cellulose materials have become increasingly used as responsive materials due to their advantages of sustainability and renewability. This review summarizes the relevant research on cellulose-based intelligent responsive materials in recent years. According to the stimuli responses, they are divided into temperature-, light-, electrical-, magnetic-, and humidity-responsive types. The response mechanism, application status, and development trend of cellulose-based intelligent responsive materials are summarized. Finally, the future perspectives on the preparation and applications of cellulose-based intelligent responsive materials are presented for future research directions. [ABSTRACT FROM AUTHOR]

Compared with traditional metal materials, carbon-based materials have the advantages of low density, high conductivity, good chemical stability, etc., and can be used as reliable alternative materials in various fields. Among them, the carbon fiber conductive network constructed by electrospinning technology has the advantages of high porosity, high specific surface area and rich heterogeneous interface. In order to further improve the conductivity and mechanical properties of pure carbon fiber films, tantalum carbide (TaC) nanoparticles were selected as conductive fillers. The crystallization degree, electrical and mechanical properties of electrospun TaC/C nanofibers at different temperatures were investigated. As the carbonization temperature increases, the crystallization degree and electrical conductivity of the sample also increases, while the growth trend of electrical conductivity is markedly slowed. The best mechanical properties of 12.39 MPa was achieved when the carbonization temperature was 1200 °C. Finally, through comprehensive analysis and comparison, it can be concluded that a carbonization temperature of 1200 °C is the optimum. [ABSTRACT FROM AUTHOR]

Polyelectrolyte has wide applications in biomedicine, agriculture and soft robotics. However, it is among one of the least understood physical systems because of the complex interplay of electrostatics and polymer nature. In this review, a comprehensive description is presented on experimental and theoretical studies of the activity coefficient, one of the most important thermodynamic properties of polyelectrolyte. Experimental methods to measure the activity coefficient were introduced, including direct potentiometric measurement and indirect methods such as isopiestic measurement and solubility measurement. Next, progress on the various theoretical approaches was presented, ranging from analytical, empirical and simulation methods. Finally, challenges for future development are proposed on this field. [ABSTRACT FROM AUTHOR]

Heavy metal ions in industrial sewage constitute a serious threat to human health. Nanocellulose-based adsorbents are emerging as an environmentally friendly material platform for heavy metal ion removal based on their unique properties, which include high specific surface area, excellent mechanical properties, and biocompatibility. In this review, we cover the most recent works on nanocellulose-based adsorbents for heavy metal ion removal and present an in-depth discussion of the modification technologies for nanocellulose in the process of assembling high-performance heavy ion adsorbents. By introducing functional groups, such as amino, carboxyl, aldehyde, and thiol, the assembled nanocellulose-based adsorbents both remove single heavy metal ions and can selectively adsorb multiple heavy ions in water. Finally, the remaining challenges of nanocellulose-based adsorbents are pointed out. We anticipate that this review will provide indispensable guidance on the application of nanocellulose-based adsorbents for the removal of heavy metal ions. [ABSTRACT FROM AUTHOR]

Stimulus-responsive hydrogels are an important member of smart materials owing to their reversibility, soft/wet properties, and biocompatibility, which have a wide range of applications in the field of intelligent actuations. However, poor mechanical property and complicated fabrication process limit their further applications. Herein, we report a light-responsive tissue paper/hydrogel composite actuator which was developed by combining inkjet-printed tissue paper with poly(N-isopropylacrylamide) (PNIPAM) hydrogel through simple in situ polymerization. Due to the high strength of natural tissue paper and the strong interaction within the interface of the bilayer structure, the mechanical property of the composite actuator was highly enhanced, reaching 1.2 MPa of tensile strength. Furthermore, the light-responsive actuation of remote manipulation can be achieved because of the stamping graphite with high efficiency of photothermal conversion. Most importantly, we also made a few remotely controlled biomimetic actuating devices based on the near-infrared (NIR) light response of this composite actuator. This work provides a simple strategy for the construction of biomimetic anisotropic actuators and will inspire the exploration of new intelligent materials. [ABSTRACT FROM AUTHOR]

In this study, ZnO nanoparticles were prepared by a hydrothermal method with varying the reaction times, material ratios and reaction temperatures. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray Diffraction (XRD) and Fourier infrared spectroscopy (FTIR). It was shown that the material ratio significantly affected the structure and morphology of the synthesized ZnO nanoparticles, and then the uneven nano-octahedral structure, uniform nano-octahedral structure, nano-tubular structure, and nano-sheet structure could be obtained successively. The synthesized ZnO nanoparticles as mordant were used for the dyeing of silk fabrics with different natural dyes (tea polyphenols and hematoxylin). Moreover, they could improve the dyeing properties and fastness (wash and light) on silk fabrics to a certain extent. [ABSTRACT FROM AUTHOR]

Highlights: [•] Heat-resistant electrospun PBO nanofibers were prepared from precursor OH-PAA. [•] The obtained PBO nanofibers are thermally stable up to 643°C. [•] The obtained PBO nanofibers have excellent mechanical properties. [•] PBO nanofibers have retention of tensile strength and modulus over 80% at 350°C. [•] Such heat-resistant PBO nanofibers could be used in high temperature fields. [ABSTRACT FROM AUTHOR]

[Display omitted] • This review focuses on recent development of carbon dots/porous materials composites. • Preparation, structures, and properties of carbon dots/porous materials composites are discussed. • Challenges and future development of carbon dots/porous materials composites are described. Carbon dots (CDs), an emerging fluorescent carbon nanomaterial, have attracted great attention in recent year due to their features such as unique optical property, good biocompatibility and low cost and easy synthesis. When CDs are integrated with porous materials, it not only compensates for the shortcomings of monocomponent CDs in applications, but also produces new functionalities through synergistic interactions to extend new applications. At present, CDs have been assembled with various porous materials such as zeolites, carbonaceous porous materials, porous graphitic carbon nitride (g-C 3 N 4), mesoporous SiO 2 , porous metallic compounds and metal-organic frameworks (MOFs), which exhibit excellent performance and a wide range of applications. Therefore, recent research advances in CDs/porous materials composites should be presented to facilitate further development of the field. In this article, the preparation methods, porous structures, and properties of CDs/porous materials composites are classified and presented. Then, the applications of CDs/porous materials composites in optics, biomedicine, sensing, electrochemistry, and photocatalysis are also discussed. Finally, current challenges and future directions are briefly discussed to facilitate the next development of CDs/porous materials composites. [ABSTRACT FROM AUTHOR]

[Display omitted] • This review focuses on recent development of carbon dots/porous materials composites. • Preparation, structures, and properties of carbon dots/porous materials composites are discussed. • Challenges and future development of carbon dots/porous materials composites are described. Carbon dots (CDs), an emerging fluorescent carbon nanomaterial, have attracted great attention in recent year due to their features such as unique optical property, good biocompatibility and low cost and easy synthesis. When CDs are integrated with porous materials, it not only compensates for the shortcomings of monocomponent CDs in applications, but also produces new functionalities through synergistic interactions to extend new applications. At present, CDs have been assembled with various porous materials such as zeolites, carbonaceous porous materials, porous graphitic carbon nitride (g-C 3 N 4), mesoporous SiO 2 , porous metallic compounds and metal-organic frameworks (MOFs), which exhibit excellent performance and a wide range of applications. Therefore, recent research advances in CDs/porous materials composites should be presented to facilitate further development of the field. In this article, the preparation methods, porous structures, and properties of CDs/porous materials composites are classified and presented. Then, the applications of CDs/porous materials composites in optics, biomedicine, sensing, electrochemistry, and photocatalysis are also discussed. Finally, current challenges and future directions are briefly discussed to facilitate the next development of CDs/porous materials composites. [ABSTRACT FROM AUTHOR]

Carbon nanotubes microspheres (CNTsM) with porous skeleton and net structure were successfully prepared by a facile method of ultrasonic atomization combined with heat treatment. Dielectric characteristics and electromagnetic wave (EMW) absorption properties within the frequency range of 2–18 GHz of CNTsM were studied. Owing to increased multiple reflection/scattering, enhanced interfacial polarization and optimized impedance matching, an excellent EMW absorption performance is therefore obtained for CNTsM. The maximum reflection loss (RL) reaches −35 dB at the thickness of 4.6 mm, and a wide effective absorption bandwidth (EAB, RL < −10dB) of 4.4 GHz is achieved with a thickness of 1.5 mm. CNTsM can be regarded as a brand-new competitive candidate for EMW absorption materials. [ABSTRACT FROM AUTHOR]

• A green and common method was proposed to prepare biomimetic actuators. • The PNPB actuator showed excellent multi-stimulus response and synergistic effect. • Anisotropic natural bamboo endowed the PNPB actuator programmable performance. • The PNPB actuator had application potential in complex environment. Hydrogel actuators with controllable deformation and excellent biocompatibility are widely used in soft robot, valve, drug delivery and lenses. However, the stimulation response performance of existing hydrogel actuators mostly focuses on a single active layer, which greatly affects its driving performance and service life. In this work, we integrate temperature-responsive hydrogel (Poly (N-isopropyl acrylamide), PNIPAM) and pH-responsive hydrogel (polyacrylic acid, PAAc) into one system to fabricate a dual active layer composite hydrogel actuator with high performance. Based on the PAAc hydrogels achieving contract or expand at different pH values, the obtained actuator exhibits admirable bidirectional bending characteristics. In addition, the anisotropic bamboo sheet endows the hydrogel actuator with programmable 3 D complex deformation. Benefitting from the synergy and different responsiveness between the two active layers, the hydrogel actuator not only has multiple response performance, but also greatly improves its deformation degree and response speed. More importantly, these promising properties of the actuator have broad application prospects in the development of pattern design and intelligent switch. This work proposes a promising strategy for the structural design of hydrogel actuators with excellent performance, and encourages more exploration of the application range of the actuator. [ABSTRACT FROM AUTHOR]

Increased energy consumption stimulates the development of various energy types. As a result, the storage of these different types of energy becomes a key issue. Supercapacitors, as one important energy storage device, have gained much attention and owned a wide range of applications by taking advantages of micro-size, lightweight, high power density and long cycle life. From this perspective, numerous studies, especially on electrode materials, have been reported and great progress in the advancement in both the fundamental and applied fields of supercapacitor has been achieved. Herein, a review of recent progress in carbon materials for supercapacitor electrodes is presented. First, the two mechanisms of supercapacitors are briefly introduced. Then, research on carbon-based material electrodes for supercapacitor in recent years is summarized, including different dimensional carbon-based materials and biomass-derived carbon materials. The characteristics and fabrication methods of these materials and their performance as capacitor electrodes are discussed. On the basis of these materials, many supercapacitor devices have been developed. Therefore, in the third part, the supercapacitor devices based on these carbon materials are summarized. A brief overview of two types of conventional supercapacitor according to the charge storage mechanism is compiled, including their development process, the merits or withdraws, and the principle of expanding the potential range. Additionally, another fast-developed capacitor, hybrid ion capacitors as a good compromise between battery and supercapacitor are also discussed. Finally, the future aspects and challenges on the carbon-based materials as supercapacitor electrodes are proposed. [ABSTRACT FROM AUTHOR]

To ensure water safety, fluoride elimination from aqueous environment is an urgent affair. In this study, a series of La-modified ZIF-8 (denoted as La-ZIF-8) hybrids with different contents of La were fabricated via a solvothermal reaction and used for fluoride recovery from wastewater. The structure and morphology of the fabricated La-ZIF-8 hybrid were confirmed by various techniques (SEM, XRD, BET, FTIR, and XPS). The specific surface area along with the pore volume of La-ZIF-8 hybrid was 121 m2 g−1 and 0.816 cm3 g−1, respectively. The defluoridation performance of La-ZIF-8 under different conditions was assessed by static batch trials. The optimized La-ZIF-8 with a La/Zn molar ratio of 4:1 achieved the supreme defluoridation performance. The fluoride uptake was greatly enhanced from 1.85 mg g−1 for pure ZIF-8–49.5 mg g−1 for La-ZIF-8 at C 0 = 10 mg L−1. The results revealed that La-ZIF-8 had a maximal fluoride uptake of 224.72–230.95 mg g−1 at 30–50 °C, pH 4, and C 0 = 80 mg L−1. Adsorption of fluoride on La-ZIF-8 obeyed to the Langmuir isotherm (R 2 > 0.99) and pseudo-second order model (R 2 > 0.999), reflecting a single-layer chemical adsorption process. Δ H 0 (36.38 kJ mol−1) > 0, Δ S 0 (155.36 J mol−1 K−1) > 0, and Δ G 0 < 0 stated that the defluoridation by La-ZIF-8 is an endothermic nature, random state, highly feasible and spontaneous process. The co-existing of cations and anions effect inferred that Mg2+, Ca2+, SO 4 2–, Cl–, and NO 3 – only had a trivial impact on fluoride removal performance, illustrating the high selectivity for F–. The La-ZIF-8 can be deemed to be a candidate adsorbent for tackling F− pollution. [Display omitted] • La-ZIF-8 hybrids were successfully fabricated by a solvothermal method. • The optimal La-ZIF-8 hybrids possessed excellent fluoride removal efficiency. • The maximum uptake derived from Langmuir isotherm at 50 ℃ was 230.95 mg g−1. • The defluoridation by La-ZIF-8 is controlled by chemical adsorption. [ABSTRACT FROM AUTHOR]

• The morph-genetic method was innovatively used to fabricate the ABH actuator. • The ABH actuator exhibits promising comprehensive performance. • The assembled biomimetic actuators show excellent synergistic performance. • The biomimetic actuator shows potential for a variety of applications. Stimuli-responsive hydrogels are most promising for the fabrication of autonomous bio-mimetic soft actuators. However, their weak actuation forces and isotropic volume change hinder their practical utilization as versatile actuators, owing to their fragility. Herein, we used the morph-genetic method to fabricate anisotropic bamboo/poly(N-isopropylacrylamide) hydrogel (ABH) complex for use as soft actuator. First of all, the bamboo fiber structure provides an anisotropic framework for the ABH actuator to achieve precise deformational programmability. Secondly, benefiting from the ultra-high directional strength (110 MPa) of bamboo, ABH actuator exhibits sufficiently robust mechanical property, which generates a powerful actuating force. Lastly, owing to the regulation of bamboo sheet and PNIPAM hydrogel, the ABH actuator not only achieves ultra-fast response speed (825°/s of the bending speed), but also has excellent synergetic performance. We demonstrate several bio-mimetic actuating devices based on ABH actuator, inspired by the intricate motions of natural organisms, to highlight how the specific materials properties and their synergy can be systematically exploited for the rational design of soft actuators. Henceforth, it is anticipated that the development of hydrogel actuators could continue to benefit from the use of various naturally-anisotropic materials, such as shape-memory polymers or liquid crystals, for the preparation of further advanced hydrogel actuators by the morph-genetic method. [ABSTRACT FROM AUTHOR]

• PPy-coated P(NIPAM-ABP) electrospun nanofiber can provide high strength. • PPy-coating by in situ polymerization can provide high light-responsive. • The actuator owns ultrafast deformation and rapid recovery. • The actuator can realize various 3D programmable complex deformations. • We have explored new biomimetic devices based on the advantages of the actuator. Intelligent hydrogels are promising for biomimetic actuators, but acquiring actuations with both high speed and powerful force is still extremely difficult. Herein, a new robust polypyrrole (PPy)-coated copoly(isopropylacrylamide-4-benzoylphenyl acrylate) [P(NIPAM-ABP)] electrospun light-responsive hydrogel is explored. The (PPy)-coated P(NIPAM-ABP) hydrogel can be obtained via in-situ polymerization of pyrroles on the nanofiber-oriented electrospun P(NIPAM-ABP) hydrogel. Compared with original P(NIPAM-ABP) hydrogel, this PPy-coated P(NIPAM-ABP) hydrogel can integrate highly-enhanced mechanical strength (from 1.21 to 5.12 MPa of tensile strength) and ultrahigh-efficiency of photothermal conversion together. In addition, the orientation of P(NIPAM-ABP) nanofibers can still maintain well for programmable complex deformations. Consequently, the as-prepared robust bi-hydrogel actuator with ultrafast and complex deformations has been achieved, through bonding the PPy-P(NIPAM-ABP) hydrogel membrane with a polyethylene glycol diacrylate-cellulose nanofiber (PEGDA-CNF) composite hydrogel membrane via interfacial ultraviolet (UV) polymerization of PEGDA monomers. Several light-responsive biomimetic actuating devices have been achieved, which owning powerful force (can grab up 100 times of self-weight), rapid speed (1285.71°/s of folding) or precisely programmable complex deformations. Furthermore, two biomimetic devices with synergistic functions of the three advantages above have been explored, which can mimic the child's sit-up and the starfish's continuous crawling movement respectively. This work provides a robust remotely-controlled light-responsive hydrogel actuator with powerful force, ultrafast speed and programmable complex actuations, which will inspire the design and fabrication of novel soft biomimetic actuating materials and systems. [ABSTRACT FROM AUTHOR]

Electrospinning is a common method for preparing nanomaterials. Among many electrospinning materials, electrospun carbon nanofibers (CNFs) have become one of the hot research directions for advanced functional materials owing to their good mechanical properties, high surface area, excellent flexibility, physical and chemical stability. Particularly, significant progress has been made in the engineering advancement of electrospinning, electrospun CNFs and their derived reinforced composites to fulfill various applications. This review aims to afford a comprehensive overview of electrospun CNF reinforced composites. Firstly, the different precursors, the correlative properties, and surface modification strategies (e.g. , physical modification and chemical modification) of electrospun CNFs are introduced. Secondly, the preparation methods of reinforced composites based on electrospun CNFs are described in detail. Then, the functional applications of electrospun CNF reinforced composites are discussed. Finally, the challenges and future solutions of electrospun CNF reinforced composites are also prospected. This review is expected to offer a basic but deep understanding of modification strategies to heighten the surface performances of CNFs for the future development of high-performance electrospun CNF reinforced composites in the composite industry, defense, and aerospace applications. [Display omitted] • Electrospun CNF reinforced composites are widly used in engineering materials. • The precursors and modification strategies of electrospun CNFs are detailly reviewed. • Diverse preparation and application of CNF reinforced composites are summarized. • The current challenges of electrospun CNF reinforced composites are discussed. • The future prospects of CNF-based composites in advanced engineering are proposed. [ABSTRACT FROM AUTHOR]

In recent years, various biomasses (such as coconut, cotton, wheat straw, basswood, bamboo, etc.) have been utilized to prepare porous carbon materials (PCMs) through carbonization and/or physical/chemical activation. Most of these carbon materials are limited by the electric double-layer capacitance, resulting in a limited specific capacitance. Moreover, the preparation processes are often complicated and the carbon yield is low. Therefore, from the perspective of green and sustainable preparation of PCMs with high carbon yield and high performance, in this study, N-doped porous carbon electrodes were prepared by one-step activation carbonization method using camellia oleifera branches as raw material and NH 4 Cl as the activator. The N-doped NCW-2 sample has a rational hierarchical porous structure and high N doping amount (3.35 at. %) and exhibited optimal rate performance with a specific capacitance of 250 F g−1 at 50 A g−1. The symmetrical device also presented excellent performance with a capacitance retention of 93.7 % after cycling 30,000 times at 20 A g−1 and delivered superior rate performances of 22.3 W h kg−1@100 W kg−1 to 11.8 W h kg−1@4800 W kg−1. This work may provide a certain reference for the preparation of N-doped biomass-derived PCMs and widen its practical application in supercapacitor devices. [Display omitted] • The self-supporting N-doped porous carbon can be directly used without posttreatment. • The mechanism of doping and activation are preliminarily proposed. • The as-prepared material has a high nitrogen doping of 3.35 at. %. • Electrodes exhibited a high specific capacitance of 250 F g−1 even at 50 A g−1. • The symmetrical device showed a capacitance retention of 93.7 % after 30,000 cycles. [ABSTRACT FROM AUTHOR]

Near-infrared light-responsive hydrogel actuator with complex deformations and remote precise control is fabricated from the natural bamboo. The resulting biomimetic bamboo/PNIPAM hydrogel actuator can be precisely designed to perform a variety of simulations. [Display omitted] • Biomimetic actuators based on anisotropic natural bamboo were prepared. • Nigrosine was first used to fabricate light-responsive hydrogel actuator. • The actuator exhibits outstanding programmability and remote-control performance. • The actuator can move freely on the water surface based on Marangoni effect. Near-infrared light-responsive hydrogels are one of the most important soft biomimetic actuators owing to their accuracy, remote control performance, and permeability. However, the complex deformations and materials of hydrogel actuators are still a serious challenge. Herein, we have developed a novel composite hydrogel actuator by combining natural bamboo sheet and nigrosine/poly(N-isopropylacrylamide) (PNIPAM) composite hydrogel. The high-efficient photothermal conversion of the nigrosine/PNIPAM composite hydrogel sheet generates light-responsive actuation that is remotely controllable. Furthermore, the bamboo sheet with fiber-oriented structure can be cut at different angles, which facilitates programmable 3D complex deformations in the actuator. Accordingly, we have designed a series of biomimetic actuating devices, including simulations of butterfly antenna, Dendrobium , smart switch, and even a multi-step deformational biomimetic claw. In addition, we also explored a biomimetic insect with precisely-controlled fast movements on the water surface based on Marangoni effect. This work provides a simple but general strategy for fabricating biomimetic actuators and will inspire new designs for intelligent soft actuators. [ABSTRACT FROM AUTHOR]

A reusable magnetic WC-Co composite (Co/C-1000) filter with efficient water treatment was prepared by in-situ growth of ZIF-67 on the inside and outside surface of wood following by carbonization. [Display omitted] • Magnetic WC-Co composite is designed for wastewater treatment. • WC-Co composite has ultra-high dyes adsorption capacity. • The Co/C-1000 filter has good removal efficiency for high dye concentration solution at a higher flux. • The Co/C-1000 filter with excellent thermal stability can be recycled by simple burning method. Organic dye in water is a crucial global environmental problem. Notably, dyes, especially anionic dye Congo red (CR) and cationic dye Methylene blue (MB), have carcinogenic and mutagenic effects on human health. However, the commercial activated carbon with bad reusability is difficult to collect, which results in poor actual adsorption. In this paper, ZIF-67@wood obtained by in situ growth of ZIF-67 on wood is carbonized to prepare magnetic WC-Co composites. The hierarchical porous structure of wood can facilitate the rapid passage of dye solution, and promote full contact between magnetic core–shell Co/C nanoparticles and dyes. The adsorption capacities of CR and MB by Co/C-1000 are 1117.03 and 805.08 mg g−1, respectively. The pH pzc (7.9) of Co/C-1000 is then determined. When the dye concentration reaches 1200 mg L−1, the removal efficiency of Co/C-1000 reaches 99.98% under gravity. With the flux of 1.0 × 104 L m−2h−1 for CR solution (100 mg L−1), the removal efficiency of Co/C-1000 filter connected with peristaltic pump is almost 99.28%. In addition, the Co/C-1000 filter with high reusability and the adsorbed dyes can be removed by simple burning. This economical, recyclable and self-supporting filter with ultra-high adsorption capacity feature has the potential to replace commercial activated carbon and it will be widely used in practical wastewater treatment. [ABSTRACT FROM AUTHOR]

A reusable magnetic WC-Co composite (Co/C-1000) filter with efficient water treatment was prepared by in-situ growth of ZIF-67 on the inside and outside surface of wood following by carbonization. [Display omitted] • Magnetic WC-Co composite is designed for wastewater treatment. • WC-Co composite has ultra-high dyes adsorption capacity. • The Co/C-1000 filter has good removal efficiency for high dye concentration solution at a higher flux. • The Co/C-1000 filter with excellent thermal stability can be recycled by simple burning method. Organic dye in water is a crucial global environmental problem. Notably, dyes, especially anionic dye Congo red (CR) and cationic dye Methylene blue (MB), have carcinogenic and mutagenic effects on human health. However, the commercial activated carbon with bad reusability is difficult to collect, which results in poor actual adsorption. In this paper, ZIF-67@wood obtained by in situ growth of ZIF-67 on wood is carbonized to prepare magnetic WC-Co composites. The hierarchical porous structure of wood can facilitate the rapid passage of dye solution, and promote full contact between magnetic core–shell Co/C nanoparticles and dyes. The adsorption capacities of CR and MB by Co/C-1000 are 1117.03 and 805.08 mg g−1, respectively. The pH pzc (7.9) of Co/C-1000 is then determined. When the dye concentration reaches 1200 mg L−1, the removal efficiency of Co/C-1000 reaches 99.98% under gravity. With the flux of 1.0 × 104 L m−2h−1 for CR solution (100 mg L−1), the removal efficiency of Co/C-1000 filter connected with peristaltic pump is almost 99.28%. In addition, the Co/C-1000 filter with high reusability and the adsorbed dyes can be removed by simple burning. This economical, recyclable and self-supporting filter with ultra-high adsorption capacity feature has the potential to replace commercial activated carbon and it will be widely used in practical wastewater treatment. [ABSTRACT FROM AUTHOR]

Hierarchical porous carbon-based electrodes, benefiting from their facilitated ion diffusion and electron conduction, have demonstrated enormous potential in supercapacitors. The preparation of hierarchical carbons with uniformity and appropriate porosity, however, still remains a grand challenge, which hinders their widespread applications. Herein, a hierarchical porous polyimide-derived carbon electrode (CPC-Fe/Zn) has been fabricated by employing bimetallic salts (Fe/Zn) as precursor and template to activate the cellulose/polyimide (PI) carbon (CPC). Originating from suitable distribution of mesopores and micropores, the obtained CPC-Fe/Zn delivers a high specific capacitance of 420 F/g at a current density of 1 A/g. Moreover, a symmetric supercapacitor device assembled with CPC-Fe/Zn exhibits delivers an energy density of 35.5 Wh/kg at a power density of 800 W/kg. Even at a larger current density of 20 A/g, the specific capacitance retention of such device still remains 92.5 % after 10,000 cycles, showing the rate performance and stability. This work has proposed a bimetallic salts template-assisted strategy to precisely modulate of the pore structure of carbon electrodes, which provides a promising platform to design superior electrodes for various electrochemical systems. [Display omitted] • The hierarchically porous structure of the material can be modulated precisely. • The symmetric supercapacitor exhibited a remarkable energy density of 35.5 Wh/kg @ 1000 W/kg. • The specific capacitance retention of symmetric supercapacitor reached 92.5 % after 10,000 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • The actuator can achieve synergistic movement of deformation and transportation. • Added Fe 3 O 4 NPs provide both magnetism and high-efficient photothermal conversion. • The hydrogel actuator owns high tensile-strength of 4.59 MPa via electrospinning. • The actuator can provide ultrafast deformational speed of 178°/s. • We have explored new bio-inspired systems with two/multi-step synergic actuation. As a soft/wet intelligent material, hydrogel actuators with multiple stimuli-responsiveness have been widely developed. However, it is still greatly difficult for them to integrate bi/multiple responsiveness together for bio-mimetic synergistic actuation. Here, we have explored a high-strength anisotropic bi-layer hydrogel actuator with P(NIPAM-ABP) layer and Fe 3 O 4 /PAN layer via electrospinning technique, which can provide programmable bi-functional synergistic movement. The Fe 3 O 4 /PAN layer can provide magnetic responsive navigation for long-range transportation on account of the magnetism of the Fe 3 O 4 nanoparticles. Furthermore, the ultrahigh photothermal conversion efficiency of the Fe 3 O 4 nanoparticles in the Fe 3 O 4 /PAN layer, can endow the P(NIPAM-ABP) layer with fast remotely-controlled photothermal-responsive deformation. Most importantly, this hydrogel actuator can achieve complex higher-level programmable movements than before based on the synergy of remotely-controlled deformation and the long-range transportation, which can be utilized to design various novel bio-mimetic soft-robots. Last but not least, the introduction of the electrospinning, not only can achieve high strength (4.59 MPa of tensile strength) of this bi-layer hydrogel, but also can provide both ultrafast (178°/s) and programmable complex photothermal-responsiveness, owing to the ultrahigh specific surface area (ultra-thin and porous structure) and excellent orientation of the thermal-responsive P(NIPAM-ABP) nanofibers respectively. This work will provide a general method via electrospinning for anisotropic hydrogel actuator with bi/multiple-functional synergy and will provide a new strategy for smart actuators and other bio-mimetic intelligent materials/systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • The recent progress of electrospun nanofibers as electrocatalysts for flexible metal-air batteries has been reviewed. • The fundamental principles of electrospinning technique have been introduced. • The importance of bifunctional electrocatalysts for oxygen reduction and oxygen evolution in metal-air batteries has been highlighted. • Future perspectives of novel electrospun nanofibers composite for flexible metal-air batteries have been proposed. Rechargeable metal-air (O 2) batteries have been regarded as the promising candidates for wearable and flexible energy devices owing to their outstanding energy density, low cost, and high safety. Generally, the electrocatalyst at air cathode plays a significant role in various metal-air (O 2) batteries. As a versatile and efficient technique, electrospinning has been considered as a powerful method to fabricate nanofibers, which hold great potential as bifunctional electrocatalysts for such batteries. Although great progresses have been achieved in improving the electrochemical performance of catalysts in recent years, some critical challenges still maintain. In this review, the advanced electrospun carbon nanofiber-based electrocatalysts for flexible metal-air batteries have been summarized. Then, additional discussions have been included focusing on the advantages and characteristics of different nanofibers and some special requirements for various flexible metal-air batteries. Moreover, some current challenges and future prospects in the development of electrospun carbon nanomaterials for flexible metal-air cathode catalysts have been rationally analyzed. [ABSTRACT FROM AUTHOR]

An alternative magnetic field (AMF)-induced electrospun fibrous thermoresponsive composite actuator showing penetrable remote-control ability with fast response is shown here for the first time. The built-in heater of magnetothermal Fe3O4 nanoparticles in the actuator and the porous structure of the fibrous layer contribute to a fast actuation with a curvature of 0.4 mm−1 in 2 s. The higher loading amount of the Fe3O4 nanoparticles and higher magnetic field strength result in a faster actuation. Interestingly, the composite actuator showed a similar actuation even when it was covered by a piece of Polytetrafluoroethylene (PTFE) film, which shows a penetrable remote-control ability. [ABSTRACT FROM AUTHOR]

• A new double-network hydrogel is explored for uranium recovery from seawater. • U-adsorption capacity of the hydrogel is greatly enhanced by added nanoclay. • Mechanical property of the hydrogel is largely improved by th double-network. • Used materials are lowcost and the hydrogel owns good U-adsorption reusability. Massive uranium recovery from seawater is a key project to provide the long-time consumption of global nuclear power, while it is still greatly difficult to achieve high-efficient adsorbents with high mechanical property. In this work, a new nanoclay-poly(amidoxime) (NC-PAO) high-strength double-network (DN) composite hydrogel adsorbent with high-efficient and fast uranium extraction capacity has been explored. The uranium adsorbing performance can be significantly enhanced by the small content of added super-hydrophilic NC (Laponite RDS sheets), because of the largely improved hydrophilicity of the hydrogel. Compared with the blank PAO DN hydrogel without nanoclay, the uranium adsorbing capacity of this NC-PAO DN hydrogel can largely increase 73.4% from 4.97 mg/g to 8.62 mg/g, after in seawater only 25 days. The uranium adsorption rate of this hydrogel from natural seawater, can reached 0.345 mg/(g∙day), which is excellent among existing uranium adsorbents. Furthermore, this hydrogel has high mechanical performance with 2.42 MPa of tensile strength and 16.13 MPa of compressive strength, which can be used in seawater for relatively longer time than traditional low-strength single-network hydrogel, owing to its double network (DN) structure (the weakly crosslinked gelatin soft network and the strongly crosslinked cellulose nanofiber (CNF) hard network). This NC-PAO DN hydrogel adsorbent will be an excellent candidate for fast uranium recovery from seawater in largescale. Most importantly, this work will inspire the development of new hydrogel-based adsorbents and even other type of adsorbents for high-efficient uranium extraction, through compositing various low-cost and super-hydrophilic nanomaterials to significantly improve the hydrophilicity of the adsorbent and designing double-network structure to largely enhance the mechanical property. [ABSTRACT FROM AUTHOR]

[Display omitted] • High P-doped (9.24 at%) thick carbon electrodes (CW-P) by phytic acid treatment. • SSC exhibits high capacitance of 4.7F cm−2/206.5F g−1 at 1.0 mA cm−2. • Excellent capacitance retention of 90.5% after 20 000 cycles (@20 mA cm−2). • High energy density up to 0.94 mW h cm−2 (41.2 Wh kg−1). • High power density up to 0.6 mW cm−2 (26.3 W kg−1). Keeping outstanding electrochemical performance under high mass loading is critical to develop functional thick electrodes. Here, we report a high phosphorus-doped wood-derived carbon thick electrode for supercapacitor via phytic acid treatment, which can form hydrogen bonds with cellulose molecules in the wood. The content of phosphorus reaches up to 9.24 at% in carbonized wood with P-doping (CW-P-9.24), higher than most previously reported P-doped carbonaceous materials. CW-P-9.24 electrode (800 μm, 17.17 mg cm−2) exhibits greatly improved electrochemical performance, especially in energy density and cyclic stability. Significantly, the symmetrical supercapacitor device exhibits high areal and specific capacitance of 4.7 F cm−2 and 206.5 F g−1 at 1.0 mA cm−2 with prominent retention of 90.5% through the long-term cycling at 20 mA cm−2 for 20,000 cycles, and 0.94 mW h cm−2 (41.2 Wh kg−1) at power density of 0.6 mW cm−2 (26.3 W kg−1), and possesses excellent volumetric capacitance and energy density of 29.3 F cm−3 and 5.8 Wh cm−3, respectively. The outstanding performance can be attributed to the excellent hierarchical structure, low tortuosity, and high phosphorus doping with fast accessible channels at high current density. The extraordinary performance of CW-P has been elucidated by density functional theory calculations, which confirm the enhanced activity by P-doping. These results demonstrate that the CW-P electrode is promising for practical application in energy storage devices and encourage more investigations for thick electrode. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of electrode thickness on the supercapacitance performance is studied. • Bass wood with hierarchical pores is easy processed to thick electrode. • The thick electrodes have high specific/areal/volumetric energy/power densities. • The SSC shows excellent cycling performance of 81% (20 mA cm−2, 15 000 cycles). The practical application of energy storage device requires high areal/volumetric energy density. One of the strategies is to design bulk electrode with hierarchical porous structure for the application of supercapacitor. Significantly, the energy storage electrochemical performance of the bulk electrode is highly influenced by the pore structure regulation and electrolyte infiltration. Therefore, it is necessary to design thick electrodes with proper pore structures and investigate the effect of thickness on the supercapacitance performance. In this work, bass wood is selected as the carbon source of electrode because of its hierarchical porous structure and easy processing into different thicknesses. The wood-derived carbon thick electrode with a thickness of 1.532 mm (CWT1.532) presents the best supercapacitance performance. Such electrode possesses a high active material loading of 54.75 mg cm−2. The symmetrical supercapacitor from CWT1.532 electrode displays remarkable specific capacitance of 65 F g−1 and areal/volumetric capacitance of 0.846 F cm−2 and 2.67 F cm−3 at 1.0 mA cm−2, respectively. It also exhibits mass/areal/volumetric power densities of 38.47 W kg−1, 500 mW cm2 and 1580 mW cm−3 as well as the corresponding energy densities of 9.04 Wh kg−1, 117.5 mWh cm−2 and 0.374 mWh cm−3, respectively. Moreover, the symmetrical supercapacitor shows an attractive cycling stability with a supercapacitance retention of 81.48% at 20 mA cm−2 even after 15 000 long-term cycles. This work provides an essential understanding about the effect of different thicknesses on the thick electrode-assembled supercapacitance and inspires future practical application in other energy storage areas. [ABSTRACT FROM AUTHOR]

• Single PI/rGO composite nanofiber by in-situ polymerization and in-situ thermal conversion. • Tensile strength of single nanofiber up to 4.2 GPa (PI/rGO-1.0% single nanofiber). • Modulus of single nanofiber up to 121 GPa (PI/rGO-1.2% single nanofiber). • Homogeneous dispersion of rGO by in-situ strategies. • In-situ strategies enhance the interfacial interaction between rGO and PI fibrous matrix. High mechanical performance electrospun polymeric nanofibers are highly desired for practical applications, especially as reinforcements for composites. However, most of the electrospun polymeric nanofibers present tensile strength < 3 GPa. To overcome such limitation, this work successfully prepared single rGO reinforced polyimide composite nanofiber with tensile strength up to 4.2 GPa (PI/rGO-1.0%) and modulus up to 121 GPa (PI/rGO-1.2%) by applying in-situ polymerization, electrospinning, and in-situ thermal conversion. These mechanical properties are higher than other polymer-based electrospun nanofibers, and 45% and 236% higher than those of neat PI single nanofiber, respectively. The in-situ strategies provide the homogeneous dispersion of rGO in single electrospun nanofibers and enhance the interfacial interaction between rGO and PI. In addition, the PI/rGO composite nanofibers also present excellent thermal stability with glass transition temperature (T g) > 295 °C, and the 5% thermal decomposition temperature (T 5%) > 539 °C. This work would open a new route for the preparation of high performance electrospun nanofibers for composites. [ABSTRACT FROM AUTHOR]