One-step wet-spinning assembly of twisting-structured graphene/carbon nanotube fiber supercapacitor

Graphene fiber-based supercapacitors hold great promise as flexible energy-storage devices. However, simultaneously achieving high ion-transport ability in electrode and electrolyte layer, which is crucial for realizing the high electrochemical performance, still remains challenging. Here, a facile and effective strategy to solve the problem was proposed by developing a twisting-structured graphene/carbon nanotube(CNT) fiber supercapacitor via one-step wet-spinning process with customized multi-channel spinneret.The remarkable structure features of the resulting fiber supercapacitor with wrinkled and thin electrolyte layer, and well-developed porosity of fiber electrode favored the rapid infiltration and transport of electrolyte ions inside the electrode, as well as between electrode and electrolyte, thus boosting high specific capacitance of 187.6 mF cm^(-2) and energy density of 30.2 μWh cm^(-2), and featuring long cycling life(93%capacitance retention after 10,000 cycles) and excellent flexibility. Moreover, the specific capacitance and energy density could be further improved to 267.2 m F cm^(-2) and 66.8 μWh cm^(-2), respectively, when Mn O2 was incorporated into the fiber.

Formation and Growth of Silver Nanocubes upon Nanosecond Pulsed Laser Irradiation: Effects of Laser Intensity and Irradiation Time

Silver nanoparticles (AgNPs) were fabricated by repetitive irradiation of near ultraviolet (UV) nanosecond laser pulses (355 nm, 5 ns) in an aqueous solution of silver nitrate in the absence of stabilizing agents. A broad absorption peak was observed in the visible region showing the formation of a variety of AgNPs in the solution. Among the variety of products, it was found that silver nanocubes (AgNCs) grew in size with longer laser irradiation time. The size of AgNCs also increased with higher laser intensity. The average size of AgNCs, investigated by a scanning electron microscope (SEM) was in the range of 75 - 200 nm. The number of reduced atoms in AgNCs as a function of laser intensity showed that the AgNCs are apparently produced by a four photon process, implying that the formation of dimer silver atoms is essential for the formation.

The effect of NiO-Ni_(3)N interfaces in in-situ formed heterostructure ultrafine nanoparticles on enhanced polysulfide regulation in lithium-sulfur batteries

Inhibiting the “shuttle effect” of soluble polysulfides and improving reaction kinetics are the key factors necessary for further exploration of high-performance Li-S batteries. Herein, an effective interface engineering strategy is reported, wherein nitriding of an Ni-based precursor is controlled to enhance Li-S cell regulation. The resulting in-situ formed NiO-Ni_(3)N heterostructure interface not only has a stronger polysulfide adsorption effect than that of monomeric NiO or Ni_(3)N but also has a faster Li ion diffusion ability than a simple physical mixture. More importantly, this approach couples the respective advantages of NiO and Ni_(3)N to reduce polarization and facilitate electron transfer during polysulfide reactions and synergistically catalyze polysulfide conversion. In addition, ultrafine nanoparticles are thought to effectively improve the use of additive materials. In summary, Li-S batteries based on this NiO-Ni_(3)N heterostructure have the features of long cycle stability, rapid charging-discharging, and good performance under high sulfur loading.

Dual-Ion Co-Regulation System Enabling High-Performance Electrochemical Artificial Yarn Muscles with Energy-Free Catch States

Artificial yarn muscles show great potential in applications requiring low-energy consumption while maintaining high performance. However, conventional designs have been limited by weak ion-yarn muscle interactions and inefficient “rocking-chair” ion migration. To address these limitations, we present an electrochemical artificial yarn muscle design driven by a dual-ion co-regulation system. By utilizing two reaction channels, this system shortens ion migration pathways, leading to faster and more efficient actuation. During the charging/discharging process, PF_6~- ions react with carbon nanotube yarn, while Li~+ ions react with an Al foil. The intercalation reaction between PF_6~- and collapsed carbon nanotubes allows the yarn muscle to achieve an energy-free high-tension catch state. The dual-ion coordinated yarn muscles exhibit superior contractile stroke, maximum contractile rate, and maximum power densities, exceeding those of “rocking-chair” type ion migration yarn muscles. The dual-ion co-regulation system enhances the ion migration rate during actuation, resulting in improved performance. Moreover, the yarn muscles can withstand high levels of isometric stress, displaying a stress of 61 times that of skeletal muscles and 8 times that of “rocking-chair” type yarn muscles at higher frequencies. This technology holds significant potential for various applications, including prosthetics and robotics.

Hollow Gradient-Structured Iron-Anchored Carbon Nanospheres for Enhanced Electromagnetic Wave Absorption

In the present paper,a microwave absorber with nanoscale gradient structure was proposed for enhancing the electromagnetic absorption performance.The inorganic-organic competitive coating strategy was employed,which can effectively adjust the thermodynamic and kinetic reactions of iron ions during the solvothermal process.As a result,Fe nanoparticles can be gradually decreased from the inner side to the surface across the hollow carbon shell.The results reveal that it offers an outstanding reflection loss value in combination with broadband wave absorption and flexible adjustment ability,which is superior to other relative graded distribution structures and satisfied with the requirements of lightweight equipment.In addition,this work elucidates the intrinsic microwave regulation mechanism of the multiscale hybrid electromagnetic wave absorber.The excellent impedance matching and moderate dielectric parameters are exhibited to be the dominative factors for the promotion of microwave absorption performance of the optimized materials.This strategy to prepare gradient-distributed microwave absorbing materials initiates a new way for designing and fabricating wave absorber with excellent impedance matching property in practical applications.

FeCo alloy catalysts promoting polysulfide conversion for advanced lithium-sulfur batteries

Lithium sulfur batteries(LSBs)draw extensive interest because of the ultra-high capacity and low material cost.However,the sluggish lithium polysulfides(LIPSs)conversion processes are detrimental to cycle stability and rate capability,inhibiting the commercial application of LSBs.Here we present the well-designed Fe Co alloy catalysts anchored on porous carbon(FeCo-C)as sulfur host to improve the electrochemical performance by accelerating the conversion reactions.The FeCo alloy demonstrates high catalytic effect and strong adsorption capability of LIPSs,in which potential polarization can be greatly decreased and"shuttle effects"can be largely avoided.As a result,the obtained S/Fe Co-C composites show an initial specific capacity of 791.9 m Ah g^-1 at a large current density of 2 C and maintain 502.5 mAh g^-1 even after 500 cycles.Moreover,720 m Ah g^-1(corresponding to 70%retention)can be achieved after 100 cycles at 0.2 C with a high sulfur content of 80 wt%,enabling high sulfur utilization.This work not only provides a new insight to investigate the conversion kinetics of Li PSs,but also opens up a new avenue for advanced lithium sulfur batteries.

Recent advances in interlayer and separator engineering for lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries have great potential in next-generation energy storage due to its high theoretical specific capacity and energy density.However,there are several challenges to the practical application of Li-S batteries including the growth of lithium dendrites and the shuttle effect of polysulfide.Introducing interlayeres(freestanding or coated on the separator)is an effective approach to reduce these obstacles and improve the electrochemical performance of Li-S batteries.In this review,we briefly summarize the interlayer materials and structures modified on both cathodic and anodic sides including(ⅰ)carbon-based materials,(ⅱ)polymers,(ⅲ)inorganic metal compounds,(iv)metal-organic frameworks,as well as(v)the novel separators in recent years.We also systematically address the fabrication processes,assembling methods,and functions of interlayers for enhancing the performance of Li-S batteries.Furthermore,the prospects and outlooks of the future development of advanced interlayers and separators are also presented.

High-loading Co-doped NiO nanosheets on carbon-welded carbon nanotube framework enabling rapid charge kinetic for enhanced supercapacitor performance

Developing high power and energy supercapacitors(SCs)is a long-pursued goal for the application in transportation and energy storage station.Herein,a rationally-designed Co-doped nickel oxide nanosheets@carbon-welded carbon nanotube foam(Co-doped NiO@WCNTF)as freestanding electrode is successfully prepared for high power and energy SCs.The WCNTF framework with high specific surface area provides three dimensional highly conductive network for fast charge transport and ensures high loading of active materials(9.2 mg/cm2).Moreover,porous Co-doped NiO nanosheets uniformly anchored on the WCNTF framework enable rapid charge kinetics due to the high intrinsic conductivity of Co-doped Ni O nanosheets and their good contact with conductive WCNTF substrate.As a result,the unique integrated electrode with 3D architecture exhibits an ultrahigh specific capacitance of 11.45 F/cm2 at 5 mA/cm2,outstanding rate capability(11.45 F/cm2 at 5 mA/cm2 and a capacitance retention of 86.2%at 30 mA/cm2)and good cycling stability,suggesting great potential for high performance supercapacitor.

A Robust Wood-inspired Catalytic System for Highly Efficient Reduction of 4-Nitrophenol

Porous solid scaffolds play key roles in preventing nanocatalysts from agglomeration,greatly maintaining the catalytic efficiency and stability of nanocatalysts.However,facile preparation of robust scaffolds with high mass transfer efficiency for loading nanocatalysts remains a major challenge.Here,we fabricate a wood-inspired shape-memory chitosan scaffold for loading Au nanoparticles to reduce 4-nitrophenol via a simple“freeze-casting and dip-adsorption”approach.The obtained catalytic scaffold highly resembles the unidirectional microchannel structure of natural wood,resulting in robust mechanical properties and outstanding water absorption capacity.Additionally,Au nanoparticles can be firmly and uniformly anchored on the inner surface of these microchannels via electrostatic interaction,forming numerous microreactors.This catalytic system exhibits a high 4-nitrophenol conversion rate of 99%in 5 s and impressive catalytic stability even after continuously treating with more than 3 L of highly concentrated 4-nitrophenol solution(1 mmol/L).Therefore,the wood-like catalytic system presented here demonstrates the potential to be applied in the field of water treatment and environmental protection.

Porous Y_2O_3 microcubes:synthesis and characterization

In this work, a facile route using a simple solvothermal reaction and sequential heat treatment process to prepare porous Y2O3 microcubes is presented. The as-synthesized products were characterized by X-ray powder diffraction （XRD）, scanning electronic microscope （SEM）, energy dispersive spectrometer （EDS）, thermogravimetric analysis （TG）, and differential thermal analysis （DTA）. The thermal decomposition process of the Y203 precursor was investigated. SEM results demonstrated that the as-prepared porous Y203 microcubes were with an average width of about 20 μm and thickness of about 8μm. It was found that the morphology of the Y2O3 precursor could be readily tuned by varying the molar ratio of S2O2- to y3＋. Y203：Eu3＋ （6.6%） microcubes were also prepared and their photoluminescence properties were investigated.

CoNi nanoparticles anchored inside carbon nanotube networks by transient heating:Low loading and high activity for oxygen reduction and evolution

Transitional metal alloy and compounds have been developed as the low cost and efficient bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).However,a high mass loading of these catalysts is commonly needed to achieve acceptable catalytic performance,which could cause such problems as battery weight gain,mass transport blocking,and catalyst loss.We report herein the preparation of fine CoNi nanoparticles(5-6 nm)anchored inside a nitrogendoped defective carbon nanotube network(CoNi@N-DCNT)by a transient Joule heating method.When utilized as an electrocatalyst for oxygen reduction and evolution in alkaline media,the CoNi@N-DCNT film catalyst with a very low mass loading of 0.06 mg cm^(-2) showed excellent bifunctional catalytic performance.For ORR,the onset potential(Eonset)and the half-wave potential(E_(1/2))were 0.92 V versus reversible hydrogen electrode(vs.RHE)and 0.83 V(vs.RHE),respectively.For OER,the potential at the current density(J)of 10 mA cm^(-2)(E_(10))was 1.53 V,resulting in an overpotential of 300 mV much lower than that of the commercial RuO_(2) catalyst(320 mV).The potential gap between E_(1/2) and E_(10) was as small as 0.7 V.Considering the low mass loading,the mass activity at E_(10) reached at 123.2 A g^(-1),much larger than that of the RuO_(2) catalyst and literature results of transitional metal-based bifunctional catalysts.Moreover,the CoNi@N-DCNT film catalyst showed very good long-term stability during the ORR and OER test.The excellent bifunctional catalytic performance could be attributed to the synergistic effect of the bimetal alloy.

All Binder-Free Electrodes for High-Performance Wearable Aqueous Rechargeable Sodium-Ion Batteries

Extensive efforts have recently been devoted to the construction of aqueous rechargeable sodium-ion batteries(ARSIBs)for large-scale energy-storage applications due to their desired properties of abundant sodium resources and inherently safer aqueous electrolytes.However,it is still a significant challenge to develop highly flexible ARSIBs ascribing to the lack of flexible electrode materials.In this work,nanocube-like KNiFe(CN)6(KNHCF)and rugby balllike NaTi2(PO4)3(NTP)are grown on carbon nanotube fibers via simple and mild methods as the flexible binder-free cathode(KNHCF@CNTF)and anode(NTP@CNTF),respectively.Taking advantage of their high conductivity,fast charge transport paths,and large accessible surface area,the as-fabricated binder-free electrodes display admirable electrochemical performance.Inspired by the remarkable flexibility of the binder-free electrodes and the synergy of KNHCF@CNTF and NTP@CNTF,a high-performance quasi-solid-state fiber-shaped ARSIB(FARSIB)is successfully assembled for the first time.Significantly,the as-assembled FARSIB possesses a high capacity of 34.21 mAh cm?3 and impressive energy density of 39.32 mWh cm?3.More encouragingly,our FARSIB delivers superior mechanical flexibility with only 5.7%of initial capacity loss after bending at 90°for over 3000 cycles.Thus,this work opens up an avenue to design ultraflexible ARSIBs based on all binder-free electrodes for powering wearable and portable electronics.

Waveguide external cavity narrow linewidth semiconductor lasers

Narrow linewidth light source is a prerequisite for high-performance coherent optical communication and sensing.Waveguide-based external cavity narrow linewidth semiconductor lasers(WEC-NLSLs)have become a competitive and attractive candidate for many coherent applications due to their small size,volume,low energy consumption,low cost and the ability to integrate with other optical components.In this paper,we present an overview of WEC-NLSLs from their required technologies to the state-of-the-art progress.Moreover,we highlight the common problems occurring to current WEC-NLSLs and show the possible approaches to resolving the issues.Finally,we present the possible development directions for the next phase and hope this review will be beneficial to the advancements of WEC-NLSLs.

Dyeing bacterial cellulose pellicles for energetic heteroatom doped carbon nanofiber aerogels

精力危机和环境污染是那个人文学科将面对为的严肃的挑战长期。尽管有巨大的努力，环境地友好的方法的发展仍然正在质问制作新精力材料。第一次，这里，我们报导新策略制作各种各样的做的碳 nanofiber (CNF ) 由细菌的纤维素(BC ) 的热分解的 aerogels 与不同有毒的器官的染料吸附了或被染的薄皮。建议策略使把有毒的染料从废水移开然后综合可能把染的 BC 薄皮用作先锋的做的 CNF aerogels。与为准备的另外的报导过程相比， heteroatom 做了碳(HDC ) nanomaterials，现在的合成方法有一些重要优点例如是绿的，一般、便宜、容易可伸缩。而且，象为氧减小反应(ORR ) 的 electrocatalysts 并且作为为 supercapacitors 的电极材料潜在的同样准备的做的 CNF aerogels 展览伟人。

Microwave-assisted synthesis of photoluminescent glutathione-capped Au/Ag nanoclusters： A unique sensor-on-a-nanoparticle for metal ions, anions, and small molecules

Even though great advances have been achieved in the synthesis of luminescent metal nanoclusters, it is still challenging to develop metal nanoclusters with high quantum efficiency as well as multiple sensing functionalities. Here, we demonstrate the rapid preparation of glutathione-capped Au/Ag nanoclusters （GS-Au/Ag NCs） using microwave irradiation and their unique sensing capacities. Compared to bare GS-Au NCs, the doped Au/Ag NCs possess an enhanced quantum yield （7.8% compared to 2.2% for GS-Au NCs）. Several characterization techniques were used to elucidate the atomic composition, particulate character, and electronic structure of the fabricated NCs. According to the X-ray photoelectron spectroscopy （XPS） and X-ray absorption near-edge structure （XANES） spectra, a significant amount of Au exists in the oxidized state as Au（I）, and the Ag atoms are positively charged. In contrast to those nanoclusters that detect only one analyte, the GS-Au/Ag NCs can be used as a versatile sensor for metal ions, anions, and small molecules. In this manner, the NCs can be regarded as a unique sensor-on-a-nanoparticle.

Binary synergistic enhancement of dielectric and microwave absorption properties： A composite of arm symmetrical PbS dendrites and polyvinylidene fluoride

Arm symmetrical PbS dendrite （ASD-PbS） nanostructures can be prepared on a large scale by a solvothermal process. The ASD-PbSs exhibit a three-dimensional symmetrical structure, and each dendrite grows multiple branches on the main trunk. Such unique ASD-PbSs can be combined with polyvinylidene fluoride （PVDF） to prepare a composite material with enhanced dielectric and microwave-absorption properties. A detailed investigation of the dependence of the dielectric properties on the frequency and temperature shows that the ASD-PbS/PVDF composite has an ultrahigh dielectric constant and a low percolation threshold. The dielectric permittivity is as high as 1,548 when the concentration of the ASD-PbS filler reaches 13.79 vol.% at 102 Hz, which is 150 times larger than that of pure PVDF, while the composite is as flexible as pure PVDF. Furthermore, the maximum reflection loss can reach -36.69 dB at 16.16 GHz with a filler content of only 2 wt.%, which indicates excellent microwave absorption. The loss mechanism is also elucidated. The present work demonstrates that the addition of metal sulfide microcrystals to polymer matrix composites provides a useful method for improving the dielectric and microwave-absorption properties.

Understanding the stability and reactivity of ultrathin tellurium nanowires in solution： An emerging platform for chemical transformation and material design

nanomaterials 的稳定性和反应具有为他们的申请的关键重要性，但是稳定性的长期的效果和在实际条件下面的 nanomaterials 的反应仍然不是理解的井。在这研究，我们首先建立了全面策略通过一个加速的氧化过程在水的答案作为模型材料与 ultrathin 碲 nanowires TeNWs 从反应动力学的观点调查高度反应的 nanomaterial 的稳定性。这允许我们用在不同条件下面在动态氧化过程期间捕获的中间的 nanostructures 由一个化学转变过程为另外的唯一的一个维的 nanostructures 的设计和合成建议一条新途径。实质上， ultrathin TeNWs 的氧化是包含液体，气体和稳固的阶段的煤气固体的反应。在水的答案的 ultrathin TeNWs 的氧化进程能被划分成三个阶段，这被表明了，也就是，限制的氧， ultrathin TeNWs 限制和质量转移限制阶段的抵抗。为 ultrathin TeNWs 的明显的氧化动力学是近似与第一顺序反应动力学一致当模特儿并且有象 13.53 kJ 一样低的一个明显的激活精力 ? 敤 ? 楤? 敗捩?楥慬? 瑳敨楳? 畡 ? 瑥慷 ?┰瘠牥 k 吗？？

Mass-production of flexible and transparent Te-Au nylon SERS substrate with excellent mechanical stability

In the past two decades,the field of surface-enhanced Raman scattering (SERS) has flourished and many rational strategies have been reported for the successful construction of SERS substrates.However,it still lacks the mass-production and programmability for practical applications with arbitrary configurations,and it is highly desirable to develop SERS substrates with strong signal enhancement,large-scale surface area,easy fabrication and low cost.Herein,we demonstrate a large-area fabrication (1.5 m × 5 m) of low-cost (18.8 dollars per square meter),highly sensitive,flexible and transparent SERS substrate by a simple solution process.The high sensitivity of SERS substrate using 3,3'-diethylthiatricarbocyanine iodide (DTTCI) as probe molecules is strongly dependent on the density and diameter of gold nanoparticles (NPs) on the surface of nylon mesh with the best enhancement factor (EF) of 9.17 × 10^10 and the SERS detection limit of DTTCI molecules is as low as 10-14 M which shows no obvious degradation even after 10,000 cycles of fatigue test,high temperature (above than 160 ℃) and acid-alkali treatment,indicating their excellent stability for the performance in all climates.

Stability and protection of nanowire devices in air

Nanowire devices have attracted considerable attention because of their unique structure and novel properties, and have opened up significant development opportunities. However, not many studies have focused on their stability and durability under practical conditions, which limits the rapid development of real applications. Herein, we systematically investigate three different treatments, polymer coating, inert atmosphere protection, and thickness-induced self-protection, to protect the tellurium nanowire devices from oxidation when exposed to open air. The degree of oxidation was monitored by examining changes in the valence states of tellurium element and in the morphology of the nanowires~ After the protective treatments, the tellurium nanowire devices showed improved stability and remained stable even after 800 days of storage. This work highlights the importance of investigating the stability of nanowire devices, especially for their practical applications.

Critical importance of current collector property to the performance of flexible electrochemical power sources

Flexible electrochemical power sources are attracting increasing attentions for their unique advantages like flexibility, shape diversity, light weight and excellent mechanical properties. In this research, we discover that the current collector can dramatically affect the performance of flexible electrochemical power sources with large size. For flexible air-breathing proton exchange membrane fuel cell (PEMFC), the performance could have more than 8 times increase by only adjusting the directions of current collectors. The different performances of different current collection types are mainly attributed to the diverse lengths of the electron transfer pathways. In addition, the conductivity of current collector can dramatically affect the capability of flexible PEMFCs with large-size. The flexible PEMFCs with thicker carbon nanotube membrane as current collector (low electric resistance) show higher ability. A mathematic model is successfully built in this work to further understand the performance. Moreover, the model and simulation are also applicable to other flexible power sources, such as flexible Li-ion battery and supercapacitor.