CsPbBr3 perovskite quantum dots-based Janus membrane with multifunction of luminescence, magnetism and aeolotropic electroconductivity.

Lead halide perovskite quantum dots (QDs) are promising semiconductors for next-generation photoelectric devices. However, the development of perovskite QDs-based multifunctional materials still needs to be addressed in order to further advance the application of perovskite QDs. Herein, a successful synthesis of Janus microfibers array Janus membrane (JMAJM) with up-down structure and multifunction of luminescence, magnetism and electroconductivity is firstly achieved based on CsPbBr3 QDs through a parallel electrospinning. JMAJM comprises up-down two layers tightly bonded together. The up-layer of JMAJM is luminescence/magnetism Janus microfibers array (L/M-JMAJM) constructed by [CsPbBr3/polymethyl methacrylate (PMMA)]//[CoFe2O4/PMMA] Janus microfibers as building elements. The down-layer of JMAJM is luminescence/electroconductivity Janus microfibers array (L/E-JMAJM) fabricated by [CsPbBr3/PMMA]//[polyaniline (PANI)/PMMA] Janus microfibers as building elements. Two independent microcosmic regions are designed and realized in a Janus microfiber, confining luminescence with magnetic or conductive substances into their respective regions, thus minimizing adverse effects of other dark-colored functional substances on the fluorescence of CsPbBr3 QDs. This peculiar Janus microfiber enables the effective separation and high integration of CsPbBr3 QDs with other functional substances. The up-down structure of JMAJM ensures a high integration of luminescence, magnetism and conductivity. Meanwhile, JMAJM addresses the environmental instability of CsPbBr3 QDs while simultaneously endows perovskite QDs-based materials with additional functions to realize multifunction. Under ultraviolet excitation, fluorescence characteristics of the CsPbBr3 QDs in JMAJM are maintained, exhibiting a vibrant green emission at 517 nm. Meanwhile, JMAJM achieves a maximum saturation magnetization of 20.32 emu·g-1, high conductance of 10-2 S and aeolotropic electroconductivity degree of 107. The combination of micro-partition with macro-partition in JMAJM receives superior concurrent luminescence-magnetic-conductive multifunction. This work provides a novel idea and strategy for advancing perovskite QDs-based multifunctional materials.

Dual-Confinement Effect of Nanocages@Nanotubes Suppresses Polysulfide Shuttle Effect for High-Performance Lithium-Sulfur Batteries.

The shuttle effect of lithium polysulfides (LiPSs) severely hinders the development and commercialization of lithium-sulfur batteries, and the design of high-conductive carbon fiber-host material has become a key solution to suppress the shuttle effect. In this work, a unique Co/CoN-carbon nanocages@TiO2-carbon nanotubes structure (NC@TiO2-CNTs) is constructed using an electrospinning and nitriding process. Lithium-sulfur batteries using NC@TiO2-CNTs as cathode host materials exhibit high sulfur utilization (1527 mAh g-1 at 0.2 C) and can still maintain a discharge capacity of 663 mAh g-1 at a high current density of 5 C, and the capacity loss is only 0.056% per cycle during 500 cycles at 1 C. It is worth noting that even under extreme conditions (sulfur-loading = 90%, surface-loading = 5.0 mg cm-2 (S), and E/S = 6.63 µL mg-1), the lithium-sulfur batteries can still provide a reversible capacity of 4 mAh cm-2. Throughdensity functional theory calculations, it has been found that the Co/CoN heterostructures can adsorb and catalyze LiPSs conversion effectively. Simultaneously, the TiO2 can adsorb LiPSs and transfer Li+ selectively, achieving dual confinement for the shuttle effect of LiPSs (nanocages and nanotubes). The new findings provide a new performance enhancement strategy for the commercialization of lithium-sulfur batteries.

Pseudo-tricolor typed nanobelts and arrays simultaneously endowed with conductive anisotropy, magnetism and white fluorescence.

A novel [uniaxial needle]//[coaxial needle]//[uniaxial needle] parallel spinneret is first innovatively designed and manufactured by inserting a coaxial needle into the middle of a bi-axial parallel needle, and the corresponding spinning device is established. With the aid of the distinctive-structured spinneret and the spinning device, a novel and brand-new flexible one-dimensional nanobelt//coaxial nanobelt//nanobelt tri-strand parallel nanobelt, very much like a tricolor flag and named a pseudo-tricolor typed nanobelt, is successfully prepared by electrospinning technology for the first time. Microscopically, partition of four independent domains in the pseudo-tricolor typed nanobelt is realized, and such a partitioned structure can assemble various functions and helps reduce detrimental interactions among various functions to acquire excellent poly-functions of multifunctional nanomaterials. As a case study, {anthracene/Eu(2-thenoyltrifluoroacetone)3(triphenylphosphine oxide)2 [Eu(TTA)3(TPPO)2]/polymethylmethacrylate (PMMA)}//{[CoFe2O4/PMMA]@[polyaniline (PANI)/PMMA]}//{coumarin-6/PMMA} pseudo-tricolor typed nanobelts and arrays (abbreviated as [B + R]//[M@C]//[G] PNA) are designed and constructed via electrospinning. Each pseudo-tricolor typed nanobelt is composed of left and right sides of blue and red fluorescent [anthracene/Eu(TTA)3(TPPO)2/PMMA] nanobelts and green fluorescent [coumarin-6/PMMA] nanobelts, respectively, and the middle of the [CoFe2O4/PMMA]@[PANI/PMMA] coaxial nanobelt with magnetic-conductive bifunctionality using the CoFe2O4/PMMA nanobelt as the core and PANI/PMMA as the shell. Luminescence-magnetic-conductive polyfunctionalities are highly integrated but also mutually separated in the pseudo-tricolor typed nanobelt, and thus, both segregation and integration of the functions are actualized in the pseudo-tricolor typed nanobelt. A pseudo-tricolor typed nanobelt as the building unit ensures strong fluorescence and high conductive anisotropy of the array. Moreover, energy transfer between dyes is controlled by the special structure of the nanobelt and thus white light emission is realized by the combination of europium complexes with the dyes. The conductive anisotropy and magnetism of the array are tuned by changing the content of PANI and CoFe2O4, respectively. The formation mechanism of the pseudo-tricolor typed nanobelt is proposed, and new techniques for constructing nanobelts and arrays are established. This kind of pseudo-tricolor typed nanobelt with four functional subareas possesses important implications as a building unit to construct other polyfunctional nanostructures. More importantly, the design philosophy and the construction techniques for the novel pseudo-tricolor typed nanobelt and array afford some guidance for the development of other multifunctional materials.

Tri-functional aerogel photocatalyst with an S-scheme heterojunction for the efficient removal of dyes and antibiotic and hydrogen generation.

A novel three-dimensional (3D) S-scheme S-gC3N4/TiO2/SiO2/PAN aerogel heterojunction photocatalyst (denoted as S-gTAHP) is rationally devised and manufactured by combining electrospinning, calcination, hydrothermal and freeze-drying techniques. The synthesized S-gC3N4 molecule is different from traditional g-C3N4, which has a small molecular structure similar to melamine. S-gC3N4 is embedded in the interwoven network structure of TiO2/PAN short fibers, and the catalytic system of the S-scheme heterojunction is formed with SiO2 as a crosslinking agent. S-gTAHP achieves perfect tri-functional photocatalytic capability, including remarkable hydrogen release capacity (806.7 µmol∙h-1∙g-1), efficient removal of three colored dyes with removal efficiencies up to 99.43% (MB, 15 min), 96.13% (RhB, 30 min) and 91.32% (MO, 40 min), and a degradation rate of the colorless antibiotic TCH reaching 84.20% in 40 min driven by simulated sunlight. Meanwhile, the effects of pH values and concentrations of contaminant solutions on the removal rates are explored, and the S-scheme mechanism of S-gTAHP strengthening photocatalytic activity is elucidated. The apparently heightened photocatalytic activities of S-gTAHP can be ascribed to the fact that the 3D hierarchical porous structure of the aerogel endows more active centers and enhanced light-harvesting capacity, and the S-scheme heterojunction supplies effective charge migrating channels, thereby affording the carriers with strong redox capability. Furthermore, S-gTAHP holds prominent reusability and is light weight. Hence, efficient and recyclable 3D aerogel photocatalysts with S-scheme heterojunctions have broad application prospects in practical sewage treatment and energy conversion fields.

Distinctive Sandwich-Type Composite Film and Deuterogenic Three-Dimensional Triwall Tubes Affording Concurrent Aeolotropic Conduction, Magnetism, and Up-/Down-Conversion Luminescence.

Compared to single functional materials, multifunctional materials with electrical conduction, magnetism, and luminescence are more attractive and promising, so it has become an important subject. A distinctive sandwich-type composite film (STCF) with dual-color up- and down-conversion luminescence, magnetism, and aeolotropic conduction is prepared by layer-by-layer electrospinning technology. Macroscopically, STCF is assembled by three tightly bonded layers, including a [polypyrrole (PPy)/poly(methyl methacrylate) (PMMA)]//[NaYF4:Yb3+, Er3+/PMMA] Janus nanobelt array layer as the first layer, a CoFe2O4/polyacrylonitrile (PAN) nanofiber nonarray layer as the second layer, and a Na2GeF6:Mn4+/polyvinylpyrrolidone (PVP) nanofiber nonarray layer as the third layer. This unique macropartition effectually confines conductive aeolotropy, magnetism, and luminescence in different layers. Microscopically, a Janus nanobelt is used as a construction unit to restrict the luminescent and conductive materials to their microregions, thus achieving highly conductive aeolotropy and green luminescence. The high integration of the micro-subarea and macro-subarea in the STCF can efficaciously avoid the mutual disadvantageous effects among different materials to obtain splendid polyfunctional performance. The conductive anisotropy and magnetism of the STCF can be adjusted by changing the contents of PPy and CoFe2O4. When the PPy content reaches 70%, the conductance ratio in the conductive direction to insulative direction is 108. The 2D STCF can be crimped by four different methods, and the 3D TWTs have the same excellent polyfunctional performances as 2D STCF. This unique design idea and construction technology can be applied to the preparation of other multifunctional materials to avoid harmful interference among various functions.

A fluorescent triboelectric nanogenerator manufactured with a flexible janus nanobelt array concurrently acting as a charge-generating layer and charge-trapping layer.

Triboelectric nanogenerators (TENGs) have opened a new direction in the field of flexible devices. Here, a fluorescent TENG-JNA constructed with a flexible Janus nanobelt array (JNA) and PVDF/PVP nanofibers membrane by electro-spinning is reported for the first time. The building unit of JNA is the [PANI/CNTs/PMMA]//[Tb(BA)3phen/PMMA] Janus nanobelts, which demonstrate green fluorescence and electrical conduction bi-function, where two independent partitions are microscopically realized in the Janus nanobelts. In TENG-JNA, JNA concurrently gains excellent charge-trapping ability and charge-generating capability by optimizing the PANI content; therefore, JNA serves as both a charge-generating layer and charge-trapping layer. The interface between TB(BA)3phen and PMMA, the existence of aromatic ring structures in the PANI main chain and the interface between PANI and PMMA are conducive to trap a large number of triboelectric charges in time to prevent the triboelectric charges from combining with induced charges, which can significantly improve the output performance of TENG-JNA. The maximum output current and voltage of TENG-JNA are 6.20 µA and 155 V, respectively. The introduction of Tb(BA)3phen ensures the strong fluorescence of TENF-JNA, and this fluorescence can be used to judge whether TENF-JNA works normally or is out of order in a dark environment. TENG-JNA possesses other compelling features, such as prominent flexibility, good hydrophobicity, durability and light weight, which provides the premise for TENG-JNA to be used as a flexible device in a wet environment or for warning functions. The Janus nanobelt was firstly used to assemble a TENG, which provides theoretical, material and technical support for the development of new building units of TENGs and paves a pathway for designing and assembling new TENGs.

Novel photosensitive dual-anisotropic conductive Janus film endued with magnetic-luminescent properties and derivative 3D structures.

A new photosensitive dual-anisotropic conductive Janus film (PDCJF) is proposed for the first time. It is rationally designed and manufactured by facile electrospinning. PDCJF is firstly constructed using 2,7-dibromo-9-fluorenone (DBF) with photoconductive and luminescent properties. Janus nanofibers are respectively used as the building units to construct the top layer (T-PDCJF) and the bottom layer (B-PDCJF) of PDCJF. The two layers are tightly bonded to form PDCJF. Under light irradiation, there is photosensitive dual-anisotropic conduction in PDCJF, but there is no anisotropic conduction without light. Thus, the transition of PDCJF from mono-functional magnetism to tri-functionalities is realized under light and without light. The luminescence color of PDCJF is tunable and it emits white-light. This is made possible by modulating the amounts of luminescent substances and excitation wavelength. The microscopic Janus nanofibers used as building units and macroscopic Janus film structure ensure high photosensitive dual-anisotropic conduction and excellent fluorescence in PDCJF. The two-dimensional (2D) PDCJF is rolled to obtain three-dimensional (3D) Janus-type tubes and 2D plus 3D complete flag-like structures with exceptional multi-functionalities. The new findings can strongly guide in developing advanced multi-functional nanostructures.

Preparation and Properties of Novel Cross-Linked Fluorinated Poly(aryl ether) with Low Dielectric Constant and High Thermal Stability.

Fluorinated poly(aryl ether)s (FPAEs) have attracted much attention due to their high thermal stability, excellent mechanical strength, and low dielectric constant. High-molecular-weight fluorinated poly(aryl ether) containing phenylethynyl (FPAE-PE) is successfully synthesized by nucleophilic substitution between 3-ethynylphenol and FPAE. The cross-linked fluorinated poly(aryl ether) (C-FPAE-PE) is prepared by thermal treatment of FPAE-PE at 300 °C. The thermal stability, dynamic thermomechanical property, and dielectric performance of C-FPAE-PE are systematically studied. C-FPAE-PE has excellent heat resistance with 5% weight loss temperature (Td5% ) at 490 °C in air and high thermomechanical properties with storage modulus retention of 50% at 215 °C. C-FPAE-PE displays low and steady dielectric constant of 2.4 and dielectric loss of 0.004 at 215 °C, exhibiting potential applications in the field of microelectronics, communication technology, and energy storage as high-temperature low dielectric materials.

Utilizing modules of different functions to construct a Janus-type membrane and derivative 3D Janus-type tube displaying synchronous trifunction of conductive aeolotropism, magnetism and luminescence.

The microstructures and macrostructures play a crucial role in the properties and applications of multifunctional materials. Herein, microscopic partition and macroscopic partition are combined by devising and preparing different modules that can be elaborately devised to possess specific performances. A two-dimensional (2D) 3-module Janus-type membrane multifunctionalized by conductive aeolotropism, magnetism and luminescence (defined as 3M-CML Janus-type membrane) is constructed via electro-spinning. The modular structure of 3M-CML Janus-type membrane is obtained by devising and constructing three different modules, including luminescence module (denoted as L module), conductive aeolotropism-luminescence module (marked as C-L module) and magnetism-luminescence module (named as M-L module). The results prove that almost no mutual detrimental influences exist among different modules owing to the macroscopic modular structure and Janus-type structure, which effectively avoids the negative interactions among different materials. Tb(BA)3phen/PVP nanofiber, [PMMA/Eu(BA)3phen]//[PMMA/PANI] Janus-type nanoribbon and [PMMA/Tb(BA)3phen]//[PMMA/Fe3O4] Janus-type nanoribbon are, respectively, selected as building units of the three modules, which further prevents the negative interactions among different materials and improves the versatility of 3M-CML Janus-type membrane. The luminescence, adjustable conductive aeolotropism and variable magnetism of 3M-CML Janus-type membrane are systematically discussed. Meanwhile, novel flexible four types of brand-new three-dimensional (3D) Janus-type tubes are obtained by rolling modularly devised 2D 3M-CML Janus-type membrane with different rolling schemes. As derivatives of the 2D 3M-CML Janus-type membranes, macroscopic 3D Janus-types tubes exhibit similar performances to 2D 3M-CML Janus-type membranes. The 2D Janus-type membrane and 3D Janus-type tube will have momentous applications in flexible electronics and nanodevices in the future.

Electrospun Janus-like pellicle displays coinstantaneous tri-function of aeolotropic conduction, magnetism and luminescence.

A new Janus-like pellicle with top-bottom structure, functionalized by conductive aeolotropism, magnetism and luminescence (defined as a CML Janus-like pellicle), is conceived and constructed via electrospinning by combining microcosmic with macroscopic partitions. [PANI/PMMA]//[Eu(BA)3phen/PMMA] and [Fe3O4/PMMA]//[Tb(BA)3phen/PMMA] Janus-like microribbons are selected as building units to construct a conductive aeolotropism-luminescence layer (CL layer) and magnetism-luminescence layer (ML layer), and the two layers are combined to form a CML Janus-like pellicle. Macroscopic partition is achieved by designing the Janus-like structure of the pellicle, while Janus-like microribbons are used for the microcosmic partition by separating rare earth luminescent compounds from dark-colored magnetic Fe3O4 NPs and conductive PANI. The CML Janus-like pellicle has stronger luminescence compared to the contrast samples. The magnetism of the CML Janus-like pellicle can be adjusted by changing the doping amount of Fe3O4 NPs. The CML Janus-like pellicle can achieve a strong and variable conductive aeolotropism via changing the doping amount of PANI and the highest conductive aeolotropism ratio can reach ca. 108 times when the PANI content is 70%. Microcosmic and macroscopic partitions are simultaneously integrated into the CML Janus-like pellicle, which results in almost no detrimental mutual influences between the two layers, and the overall performances of the CML Janus-like pellicle are greatly improved.