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Hollow porous fibers with low emissivity and conductivity aluminum platelets skin for thermal insulation.

Both sweat drainage and evaporation play important roles in achieving personal moisture and thermal management during sweat-producing exercises. However, it remains a great challenge to simultaneously realize thermal management through radiative cooling for human body without perspiration. Herein, we report a bilayer nanoporous polyethylene membrane with anisotropic wettability, which possesses superior radiative cooling ability (∼2.6 °C lower than that of cotton) without perspiration. Meanwhile, it realizes efficient sweat drainage and good evaporation cooling property (∼1.0 °C lower than that of cotton) in perspiration to avoid sticky and hot sensation. In addition, it can also block water and fine particulate matter owing to the hydrophobic nanoporous structure. By virtue of the outstanding personal thermal and moisture management performance, it is expected that this study provides inspiration for designing new clothing and medical protective suits with more comfortable microclimates and reducing energy consumption for global sustainability.

Owing to the low cost, high energy density, and high theoretical specific capacity, lithium-sulfur batteries have been deemed as a potential choice for future energy storage devices. However, they also have suffered from several scientific and technical issues including low conductivity, polysulfides migration, and volume changes. In this study, CoS2-TiO2@carbon core-shell fibers were fabricated through combination of coaxial electrospinning and selective vulcanization method. The core-shell fibers are able to efficiently host sulfur, confine polysulfides, and accelerate intermediates conversion. This electrode delivers an initial specific capacity of 1181.1 mAh g-1 and a high capacity of 736.5 mAh g-1 after 300 cycles with high coulombic efficiency over 99.5% (capacity decay of 0.06% per cycle). This strategy of isolating interactant and selective vulcanization provides new ideas for effectively constructing heterostructure materials for lithium-sulfur batteries.

As the desired sulfur host of lithium-sulfur battery, the strong polarity and fast electron migration capability are indispensable for achieving effective adsorption and conversion of lithium polysulfides (LiPSs), that is, restricting the shuttle effect. Herein a porous microdisk Ti4O7/TiN/C heterojunction with strong polar N-Ti-O covalent bonds is precisely constructed. Compared with O-Ti-O or N-Ti-N bond in single Ti4O7 or TiN, the N-Ti-O bond with stronger polarity could adsorb and bond with S and Li atoms in LiPSs, which is beneficial for LiPSs adsorption. Beside, the Ti4O7/TiN heterostructure favors the electron transfer, which could promote the conversion of LiPSs. The design strategy is to construct abundant polar N-Ti-O bonds at Ti4O7/TiN heterogeneous interface that would realize the associative process of LiPSs adsorption, trapping, and conversion, thereby restraining the shuttle effect efficiently. In the current study, as the host of the sulfur cathode, the porous microdisk TiN/Ti4O7/C heterojunction exhibits a high specific capacity of 1204.5 mAh g−1 at 0.2 C, and a high specific capacity of 616.5 mAh g−1 at an ultrahigh current density of 4 C. In addition, 86.4% and 116.9% capacity are retained over 1000 cycles at 1 C and 2 C, respectively. This strategy provides an insight into developing lithium-sulfur battery with extraordinary performance, and opens promising routes to design the next-generation electrochemical energy storage devices.

TiO2@g-C3N4 core/shell fibers with a continuous g-C3N4 layer packing around exhibit high photocatalytic efficiency toward H2 production and RhB degradation due to the intimate core/shell structure with a high-quality TiO2/g-C3N4 heterojunction.

Electrospinning is a popular method for generating long and continuous nanofibers due to its simplicity and versatility. However, conventional electrospun products have weak strength and low availability, which restrict their functionality in complex applications. Hierarchical morphology introduces additional and distinctive structural layers onto electrospun fibers. This requires either an extra fabrication step or controlling electrospinning parameters to achieve the desired morphology. Hierarchical morphology can improve the properties of electrospun nanofibers while also mitigating the undesired characteristics. This review discusses the primary and secondary hierarchical structures of electrospun nanomaterials. Hierarchical structures were found to enhance the functionality of nanomaterials and improve pore connectivity and surface areas of electrospun nanofibers. A further advantage is the ability to impart multiple functionalities on nanostructures. With a better understanding of some of the dominant hierarchical structures, nanomaterials applications in drug delivery, tissue engineering, catalysis, and energy devices industries can be improved.

Janus membrane with opposite wettability on its two sides has witnessed an explosion of interest in the field of liquid spontaneous and directional transport for their promising prospect. The advances in fabrication technology and natural bionics have brought remarkable progress for the development of Janus materials. Among the exciting progress, the micro/nanofabrication technique of electrospinning shows advantages in constructing thin porous fibrous membrane materials with controllable surface wettability and hierarchical structures. Here, a brief review of bioinspired Janus membrane for unidirectional liquid penetration fabricated by electrospinning is presented, and the underlying scientific mechanism is discussed with an emphasis on the materials design involving asymmetric surface wettability and micro-topology structure. An overview of recent emerging applications is also reviewed, with special attentions to liquid separation, water collection, distillation, and smart textile, etc. As researchers keep to develop more efficient strategies on designing new Janus membrane with higher performances, it has become increasingly important to understand the mechanism of liquid moving dynamics at the asymmetric interface in order to better recognize the scientific limitations currently hindering the field development. At last, the challenges currently faced and possible strategies on developing new Janus membranes for optimization and engineering in the future are proposed.

Hydrogen evolution and dye degradation catalyzed by environmentally benign and inexpensive photocatalyst in aqueous solution is regarded as a promising avenue to effectively address the global energy and environmental crisis. It is difficult for traditional photocatalysts to perform efficient light harvesting, with conducive recycling and promoted charge separation and transport, which limit practical applications in photocatalytic conversion. In this study, a facile template-assisted coaxial electrospinning approach was explored to successfully build close contacted heterojunctions within the interface of g-C3N4 nanosheets and hollow porous TiO2 nanofibers, which significantly increased the separation efficiency of photo-induced electron–hole pairs in the visible-light region. A hollow and porous structure with abundant surface-active sites assisted in inducing multiple light reflection for more efficient light harvesting. Moreover, one dimensional TiO2/g-C3N4 composite nanofibers with a large length-to-diameter ratio would be more attractive for recovery. At the optimal g-C3N4 loading, hollow porous TiO2/g-C3N4-50% nanofibers exhibited the highest rate of hydrogen evolution and RhB degradation. The enhanced photocatalytic performance of hollow porous TiO2/g-C3N4 composite photocatalysts was mainly attributed to the synergistic effect of the hollow porous architecture and heterojunction. This work might make a significant contribution to insight into preparing hollow structure heterogenous nanofiber photocatalysts with improved activities in hydrogen generation and pollutant degradation.

The rapid response movement caused by the Marangoni effect, a surface tension gradient-induced mass transfer behavior, has spurred considerable promise for diverse applications from microrobots and microreactors to smart drug delivery. Herein, we fabricated an aligned hollow fiber swimmer that showed self-propel movement on a water surface based on the Marangoni effect. By rational designing of an aligned hollow microstructure and an optimized geometrical shape, this swimmer can move continuously for more than 600 s and the maximum angular velocity can reach 22 rad·s

TiO

Wearable and stretchable electronics including various conductors and sensors are featured with their lightweight, high flexibility, and easy integration into functional devices or textiles. However, most flexible electronic materials are still unsatisfactory due to their poor recoverability under large strain. Herein, we fabricated a carbon nanotubes (CNTs) and polyurethane (PU) nanofibers composite helical yarn with electrical conductivity, ultrastretchability, and high stretch sensitivity. The synergy of elastic PU molecules and spring-like microgeometry enable the helical yarn excellent stretchability, while CNTs are stably winding-locked into the yarn through a simple twisting strategy, making good conductivity. By virtue of the interlaced conductive network of CNTs in microlevel and the helical structure in macrolevel, the CNTs/PU helical yarn achieves good recoverability within 900% and maximum tensile elongation up to 1700%. With these features, it can be used as a superelastic and highly stable conductive wire. Moreover, it also can monitor the human motion as a rapid-response strain sensor by adjusting the content of the CNTs simply. This general and low-cost strategy is of great promise for ultrastretchable wearable electronics and multifunctional devices.

Multi-wall Sn/SnO2 @carbon hollow nanofibers evolved from SnO2 nanofibers are designed and programable synthesized by electrospinning, polypyrrole coating, and annealing reduction. The synthesized hollow nanofibers have a special wire-in-double-wall-tube structure with larger specific surface area and abundant inner spaces, which can provide effective contacting area of electrolyte with electrode materials and more active sites for redox reaction. It shows excellent cycling stability by virtue of effectively alleviating pulverization of tin-based electrode materials caused by volume expansion. Even after 2000 cycles, the wire-in-double-wall-tube Sn/SnO2 @carbon nanofibers exhibit a high specific capacity of 986.3 mAh g-1 (1 A g-1 ) and still maintains 508.2 mAh g-1 at high current density of 5 A g-1 . This outstanding electrochemical performance suggests the multi-wall Sn/SnO2 @ carbon hollow nanofibers are great promising for high performance energy storage systems.

A fast neutron has strong penetration ability through dense and bulky objects, which makes it an ideal nondestructive technology for detecting voids, cracks, or other defects inside large equipment. However, the lack of effective fast neutron detection materials limits its application. Perovskites have shown excellent optical properties in many areas, but they are absent from fast neutron detection imaging because they cannot directly absorb fast neutrons and emit luminescence. Here, we demonstrate a hydrogen-rich long-chain organic amine modified two-dimensional (2D) perovskite fast neutron scintillator, Mn-(C

Owing to the low cost, high energy density, and high theoretical specific capacity, lithium-sulfur batteries have been deemed as a potential choice for future energy storage devices. However, they also have suffered from several scientific and technical issues including low conductivity, polysulfides migration, and volume changes. In this study, CoS

Hierarchically structured nanomaterials are critical for the catalysis and energy storage to make full use of the surfaces and space to elevate activities. Electrospinning is a very convenient technique for programmable fabrication of different kinds of nanofibers with diverse compositions as well as complex internal and external structures for various demands in application of catalysis and energy storage fields. In this review, some effective electrospinning strategies for constructing various nanofibrous materials with multilevel structures are presented. Firstly, hierarchically hollow structured nanofibers are described and categorized including hollow fibers, wire-in-tube fibers, tube-in-tube fibers, peapod-like fibers, multichannel fibers and outer branched fibers etc. The unique properties arose from the special hierarchical structures effect such as multiple heterogeneous interfaces, confined space and large specific area are discussed and some representative applications in catalysis and energy storage are presented. Finally, the challenges and perspectives of future researches on the electrospinning hierarchically structured nanofibers for various applications are highlighted.

One-dimensional (1D) hollow nanomaterials were widely used in the catalysis field. However, the inner surfaces of 1D hollow nanostructures could not be effectively utilized in liquid reaction because of diffusional limitation caused by the large ratio of length to diameter. In this work, a template-assisted coaxial electrospinning method was developed to prepare TiO2 hollow nanofibers with through-holes which were further employed as a carrier for Au nanoparticles. The Au/TiO2 hollow nanofibers with through-holes showed significant catalytic activity enhancement to the reduction of 4-nitrophenol in aqueous solution compared with solid and hollow nanofiber counterparts. The through-holes which provided unrestricted macropores for mass transfer in liquid solution were studied to be accounted for the catalytic activity enhancement. The through-hole structures can widen the application ranges and increase the efficiencies of zero-dimensional or 1D hollow nanomaterials.

Bio-inspired materials, of whose structures, properties or functions mimic those of natural materials, have provided solutions to many practical problems. While an increasing number of scientists are working to mimic those structures and properties found in nature and selected by evolutions, the complicated multiscale architecture in nature far exceeds the ability of traditional design and fabrication methods. During the past ten years, the electrospinning technique has been emerged as an effective approach to designing and fabricating bio-inspired materials. In this review, we present the interplay between bio-inspired materials and the electrospinning technology, with an emphasis on the structure control to obtain optimized properties for real-world applications. We also provide an overview of recent development in the electrospinning of bio-inspired functional materials, and prospect the next-generation electrospun membrane’ materials in liquid gating systems, and their potential applications for membrane separation, flexible wearable electronics, and 4D printing, etc.

Inspired by the asymmetric microgeometry of cactus spines and the alternate hydrophobic/hydrophilic micropattern of a desert beetle's back, we designed a hybrid membrane with asymmetric microtopology and anisotropic wettability that achieved highly efficient fog collection.

The core-shell NaYF4/Yb/Tm/TiO2 hollow composite fibers were prepared by coaxial electrospinning and high-temperature calcination. The composite fibers exhibit excellent photocatalytic activity under the dual synergistic of regulating the core-shell hollow microstructure and the composition by doping nanoparticles. Compared with commercial P25 and hollow fiber without nanoparticles, the degradation efficiency of rhodamine B using the core-shell composite fiber was significantly improved up to 99%. Moreover, the nanoparticles in the composite fibers can exist stably and maintain good structure and photocatalytic activity after repeated use. Therefore, the composite fiber has a wide application prospect in photocatalytic degradation of organic pollutants.

Oil or chemical purification is significant not only for industrial safety production but also because it conforms to the principle of sustainable development. In this paper, based on the synergistic concept of superwettability and nanopores sieve effect, a superoleophilic and under-oil superhydrophobic carbon nanotube/poly(vinylidene fluoride-co-hexafluoropropylene) nanofiber composite membrane is prepared via electrospinning, pressure-driven filtration, and chemical vapor modification. The as-prepared membrane with durable mechanical and chemical stabilities achieves separation efficiency higher than 99.9% and high flux up to 632.5 L m-2 h-1 bar-1 for different water-in-oil emulsions. This membrane is highly promising for the petroleum and chemical industries for both product quality improvement and green recycling manufacturing processes.

Correction for ‘TiO2/g-C3N4 heterojunction hollow porous nanofibers as superior visible-light photocatalysts for H2 evolution and dye degradation’ by Jing Liu et al., New J. Chem., 2021, 45, 22123–22132, DOI: 10.1039/d1nj04390k.

Water pollution is a serious problem around the world. It causes the lack of clean drinking water and brings risks to human health. Membrane technology has become a competitive candidate to treat the contaminated wastewater due to its high separation efficiency and low energy consumption. In this review, we introduce the recent development of several kinds of bioinspired separation membranes, involving the membrane design and applications. We emphasize the multi-phase liquid separation membranes inspired from nature with special wettability applied for oil/water separation, organic liquids mixture separation, and emulsion separation. After separating multi-phase liquids using these membranes, small molecule pollutants still exist in single-phase liquid. Therefore, we also expand the scope to small molecule-scale separation membranes, such as the nacre-like graphene oxide separation membrane and other nanofiltration membranes. Summary and outlook concerning the future development of separation membranes are also introduced briefly.

Smart regulation of substance permeability through porous membranes is highly desirable for membrane applications. Inspired by the stomatal closure feature of plant leaves at relatively high temperature, here we report a nano-gating membrane with a negative temperature-response coefficient that is capable of tunable water gating and precise small molecule separation. The membrane is composed of poly(N-isopropylacrylamide) covalently bound to graphene oxide via free-radical polymerization. By virtue of the temperature tunable lamellar spaces of the graphene oxide nanosheets, the water permeance of the membrane could be reversibly regulated with a high gating ratio. Moreover, the space tunability endows the membrane with the capability of gradually separating multiple molecules of different sizes. This nano-gating membrane expands the scope of temperature-responsive membranes and has great potential applications in smart gating systems and molecular separation., The smart regulation of substance permeability is highly desirable for membrane separation technologies. Here, the authors design a poly(N-isopropylacrylamide)-grafted graphene oxide membrane with temperature tunable lamellar spaces, allowing for water gating and size-variable molecular separations.

Encapsulating ferroelectric ceramic nanofillers into polymer matrix with various architectures has been demonstrated as an effective strategy for ultrahigh energy storage density. Nevertheless, large discrepancy in permittivities between ceramic fillers and polymer requires sophisticated interfacial modification to alleviate local charge concentration. The idea to design graded permittivity from the filler center to surrounding matrix in composites is promising, yet remains a big challenge. Here coaxial electrospinning technique has been employed to control the polarization gradient distribution in TiO2 nanofibers (TOnf) and poly(vinylidene fluoride)/poly(vinylidene fluoride-co-trifluoroethylene) [PVDF/P(VDF-TrFE)] core-shell structured hybrid nanocomposites system where TOnf is fixed at volume fraction 2%, and the polarization gradient of the polymer is adjusted via altering the volume ratios of PVDF and P(VDF-TrFE) in the coaxial electrospun polymer blends in two layers, respectively. Compared with nanocomposites made from mixed solution electrospun randomly and oriented TOnf-PVDF/P(VDF-TrFE) at the same constituent volume fraction, the dielectric losses of coaxial-spun films decrease more than twice, from 0.087 for random nanocomposite film to 0.028, and more intriguingly, the discharged energy storage density (Ue) doubled increasing from 6.5 J cm−3 for random nanocomposite film to 12.7 J cm−3 for coaxial electrospun film with medium polarization gradient. Finite element analyses reveal the polarization and local electric field distribution in the nanocomposites with various polarization gradient design, and the results unambiguously demonstrate that Ue can be significantly boosted via controlled polarization gradient design.

An understanding of the composition, structure and property relationship is essential for engineering high performance polymer nanofibers to meet the ever-increasing demands for various applications. Here, bi-phasic polymeric fibres were prepared using electrospinning followed by thermal bonding. By controlling the softness-stiffness of the composition and configuration, the mechanical properties of bi-phasic fibrous films were improved with the strength up to eight times higher than that of single counterparts. We demonstrate that compatible interfaces, increasing alignment, supramolecular chains and connected bonding points, are jointly responsible for the mechanical enhancement except the diameter previous thought. This strategy provides new ideas and directions to design high-performance materials, especially for polymer-based fibrous material.

A hydrophobic/superoleophilic nanofibrous container was designed for the purpose of collecting oil spills. The device could continuously collect various kinds of oils from the surface of water and retain excellent stability when exposed to corrosive media. This work might provide a new strategy for designing fibrous membranes and applying them to the collection of oil spills.

Strong corrosive emulsion sewage must be properly treated because it is not only very harmful to the environment, but also an enormous waste of chemical resources. Here we fabricated a pine-branch-like TiO2 nanofibrous membrane via an electrospinning and hydrothermal process. Besides neutral emulsions, the obtained membrane could separate various highly corrosive acidic (pH 14), and salty oil-in-water emulsions with efficiencies higher than 99% without extra force assistance, which is highly promising for aquatic environment protection as well as resource recycling.

Multi-wall Sn/SnO