Porous FeNi Prussian blue cubes derived carbon-based phosphides as superior sulfur hosts for high-performance lithium-sulfur batteries.

In contrast to lithium-ion batteries, lithium-sulfur batteries have higher theoretical energy density and lower cost, so they would become competitive in the practical application. However, the shuttle effect of polysulfides and slow oxidation-reduction kinetics can degrade their electrochemical performance and cycle life. In this work, we have first developed the porous FeNi Prussian blue cubes as precursors. The calcination in different atmospheres was employed to make precursors convert into common pyrolysis products or novel carbon-based phosphides, and sulfides, labeled as FeNiP/A-C, FeNiP/A-P, and FeNiP/A-S. When these products serve as host materials in the sulfur cathode, the electrochemical performance of lithium-sulfur batteries is in the order of S@FeNiP/A-P > S@FeNiP/A-S > S@FeNiP/A-C. Specifically, the initial discharge capacity of S@FeNiP/A-P can reach 679.1 mAh g-1at 1 C, and the capacity would maintain 594.6 mAh g-1after 300 cycles. That is because the combination of carbon-based porous structure and numerous well-dispersed Ni2P/Fe2P active sites contribute FeNiP/A-P to obtain larger lithium-ion diffusion, lower resistance, stronger chemisorption, and more excellent catalytic effect than other samples. This work may deliver that metal-organic framework-derived carbon-based phosphides are more suitable to serve as sulfur hosts than carbon-based sulfides or common pyrolysis products for enhancing Li-S batteries' performance.

Reinforcing oxygen reduction reaction and accelerating charge migration kinetics on In4SnS8 by polypyrrole for photocatalytic hydrogen peroxide production.

Solar light-driven hydrogen peroxide (H2O2) production through the two-electron oxygen reduction reaction (ORR) from the earth-abundant O2 and water is a potential alternative to the energy-consuming anthraquinone oxidation process, although the activity of the common photocatalysts is still insufficient to satisfy the industrial demands. Poor accessibility of O2 to surface/interface and fast carrier recombination is the limiting-factor for catalytic systems. Herein, we develop a nanohybrid photocatalysts by introducing 1D conducting polymer of polypyrrole (PPy) nanotube on In4SnS8 to promote H2O2 evolution under visible light, obtaining up to 254.8 µM in 2 h, which is 2.4- and 13-fold larger than that of individual In4SnS8 and PPy. The detailed characterizations of hybrid structure, O2 adsorption behaviors, charge carrier dynamics over PPy/In4SnS8 in conjunction with computational calculations corroborate that the modification of PPy could enlarge the amount of O2 adsorption amount, expedite the cycle of O2 adsorption/desorption and accelerate the transportation of electrons from In4SnS8 to the interface, eventually speeding up H2O2 photoproduction via indirect 2e- ORR pathway. This work establishes a paradigm of regulating the interfacial microenvironment by polymer for boosting H2O2 photogeneration through high selectivity of ORR.

Core-shell Fe3O4@SnO2 nanochains toward the application of radar-infrared-visible compatible stealth.

Multiband-compatible stealth materials play an increasingly crucial role in the field of modern military defence because they can enable the targeted objects to dodge advance detection technologies. In this study, chain-like Fe3O4@poly(ethyleneglycol dimethacrylate-co-methacrylic acid) nanocomposites were constructed as precursors through the magnetic field-induced distillation precipitation polymerisation. Then, the liquid-phase seed-mediated growth method, together with subsequent calcination, was applied to introduce SnO2 shells and remove poly(ethyleneglycol dimethacrylate-co-methacrylic acid) shells, which led to the successful preparation of innovative core-shell Fe3O4@SnO2 nanochains. The unique microstructure and appropriate components endowed nanochains with multiple functional applications. The minimum reflection loss value was approximately -39.4 dB (5.67 GHz), exhibiting excellent microwave absorption performance. The possible microwave absorption mechanisms involve interfacial polarisation, space charge polarisation, natural resonance, and multiple reflections and scatterings. The optimal infrared reflectivity reached 0.64, 0.51, and 0.37 in three atmospheric windows, indicating outstanding infrared stealth performance, which was attributed to the intense infrared reflection of SnO2 shells. Furthermore, three nanochains showed different colours (dark green, brick red, and bright orange), revealing selection absorption for visible light. This can be attributed to the combined effect of visible responses of SnO2 shells along with Bragg diffraction from the periodic arrangement of Fe3O4 particles in a single nanochain. Thus, core-shell Fe3O4@SnO2 nanochains can be considered as promising radar-infrared-visible compatible stealth materials. This discovery opens a new means to exploit multiband-compatible stealth materials.

One-dimensional Ag-CoNi nanocomposites modified with amorphous Sn(OH)2/SnO2 shells for broadband microwave absorption.

High-performance microwave absorption absorbers play important roles in the fields of radar stealth, electromagnetic protection, and antenna technology. In this work, high aspect-ratio Ag nanowires were decorated with magnetic CoNi nanoparticles via a PVP-induced solvothermal method, and then amorphous Sn(OH)2/SnO2 shells were introduced through an in-situ oxidative hydrolysis method, successfully preparing Ag-CoNi@Sn(OH)2/SnO2 composites. The morphology and ingredient of composites were ascertained by SEM, TEM, XRD, EDX, and XPS. As Ag-CoNi nanocomposites are coated by Sn(OH)2/SnO2 shells, the minimum reflection loss value is decreased from -31.7 dB (10.1 GHz) to -37.8 dB (6.4 GHz), and the maximum effective absorption bandwidth is extended from 3.9 GHz (10.3-14.2 GHz) to 5.8 GHz (10.7-16.5 GHz). Analyses of electromagnetic parameters reveal the possible mechanisms, involving surface plasma resonance, conductive loss, interfacial polarization, dipole polarization, exchange resonance, eddy current effect, multiple reflection and scattering. Thus, Ag nanowires modified with CoNi nanoparticles and amorphous Sn(OH)2/SnO2 shells can effectively balance the impedance matching and attenuation capability. It is a new strategy to achieve broadband microwave absorbers.

Fabrication of one-dimensional ZnFe2O4@carbon@MoS2/FeS2 composites as electromagnetic wave absorber.

In this work, one-dimensional (1D) ZnFe2O4@carbon@MoS2/FeS2 composites were synthesized by hydrothermal method, magnetic-field-induced distillation-precipitation polymerization and high-temperature carbonization. The structure, morphology, composition, magnetic performance and electromagnetic (EM) wave absorbing properties of the composites were systematically studied. The composites show strong microwave absorption (MA) capacity with a minimum reflection loss (RLmin) value of -52.5 dB at 13.2 GHz, and have an effective absorption frequency range of 10.10-15.08 GHz with a bandwidth of 4.98 GHz when the thickness is 2.23 mm. It is expected that as-synthesized 1D ZnFe2O4@carbon@MoS2/FeS2 composites can be a promising EM wave absorption material.

Fabrication of one-dimensional CoFe2/C@MoS2 composites as efficient electromagnetic wave absorption materials.

New types of electromagnetic (EM) wave absorption materials with a light weight, strong absorption ability and wide absorption frequency have been widely explored. Nevertheless, it is still an intractable challenge to design the structure of the materials and rationalize multiple components. In this work, one-dimensional (1D) CoFe2/C@MoS2 composites were prepared via electrospinning technology, high-temperature carbonization and hydrothermal method. SEM and TEM images reveal that the as-prepared CoFe2/C fibers with a 1D structure are well coated with MoS2. The excellent absorption performance of the composites is mainly attributed to the 1D structure and the ideal impedance matching. CoFe2/C@MoS2 composites show strong absorption ability with an optimal reflection loss (RL) of -66.8 dB (13.28 GHz) at a matching thickness of 2.12 mm. Meanwhile, the composite possesses an effective absorption frequency range between 10.70 and 16.02 GHz with a bandwidth of 5.32 GHz. These results indicate that CoFe2/C@MoS2 composites will become promising lightweight and highly efficient MA materials.

Novel reusable porous polyimide fibers for hot-oil adsorption.

The development of oil sorbents with high thermal stability, adsorption capacity, reusability and recoverability is of great significance for hot oil leakage protection, especially for oil spillage of oil refinery, petrochemical industry and cars. In our work, highly efficient hot oil adsorption of polyimide (PI) fibers with excellent thermal stability was successfully prepared by a facile electrospinning method followed by post-treatment. The corresponding morphologies, structures and oil adsorption properties of as-prepared PI fibers at different temperatures were analyzed and characterized. Results showed that PI fibers presented a stable morphology and pore structure at 200°C. The oil adsorption capacity of porous PI fibers for hot motor oil (200°C) was about 57.4gg-1, higher than that of PI fibers (32.7gg-1) with non-porous structure for the motor oil at room temperature. Even after ten adsorption cycles, porous PI fibers still maintained a comparable oil sorption capacity (oil retention of 4.2%). The obtained porous PI fibers exhibited excellent hot oil adsorption capacity, reusability and recoverability, which would broaden the application of electrospun fibers in oil spill cleanup and further provide a versatile platform for exploring the technologies of nanofibers in hot oil adsorption field.

Fabricating and Tailoring Polyaniline (PANI) Nanofibers with High Aspect Ratio in a Low-Acid Environment in a Magnetic Field.

In a 0.010 m HCl solution, we successfully transformed irregular polyaniline (PANI) agglomerates into uniform PANI nanofibers with a diameter of 46-145 nm and a characteristic length on the order of several microns by the addition of superparamagnetic Fe3 O4 microspheres in a magnetic field. The PANI morphological evolution showed that the PANI nanofibers stemmed from the PANI coating shell synthesized on the surface of the Fe3 O4 microsphere chains. It was found that the magnetic field could optimize the PANI nanofibers with a narrow diameter size distribution, and effectively suppressed secondary growth. When compared with other microspheres (like silica and polystyrene), only the use of superparamagnetic Fe3 O4 microspheres resulted in the appearance of PANI nanofibers. Attempts to form these high-quality PANI nanofibers in other concentrations of HCl solution were unsuccessful. This deficiency was largely attributed to the inappropriate quantity of aniline cations.

Amino-Fe3O4 Microspheres Directed Synthesis of a Series of Polyaniline Hierarchical Nanostructures with Different Wettability.

We demonstrated polyaniline (PANI) dimensional transformation by adding trace amino-Fe3O4 microspheres to aniline polymerization. Different PANI nanostructures (i.e., flowers, tentacles, and nanofibers) could be produced by controlling the nucleation position and number on the surface of Fe3O4 microspheres, where hydrogen bonding were spontaneously formed between amino groups of Fe3O4 microspheres and aniline molecules. By additionally introducing an external magnetic field, PANI towers were obtained. These PANI nanostructures displayed distinctly different surface wettability in the range from hydrophobicity to hydrophilicity, which was ascribed to the synergistic effect of their dimension, hierarchy, and size. Therefore, the dimension and property of PANI nanostructures can be largely rationalized and predicted by adjusting the PANI nucleation and growth. Using PANI as a model system, the strategies presented here provide insight into the general scheme of dimension and structure control for other conducting polymers.