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.

Enhancing the cycling stability of Na-ion batteries by bonding MoS2 on assembled carbon-based materials

Room temperature Na-ion batteries(SIBs) show great potential for use as renewable energy storage systems.However, the large-scale application of SIBs has been hindered by the lack of an ideal SIBs anode material. We synthesized MoS2 on carbonized graphene-chitosan(G-C) using the hydrothermal method. The strong interaction between the MoS2 and the G-C greatly improved the electron transport rate and maintained the structural stability of the electrode, which lead to both an excellent rate capability and long cycle stability. The G-C monolith was proven to enhance the electrical conductivity of the composites and served as a matrix for uniformly dispersing active MoS2 nanosheets(NSs), as well as being a buffer material to adapt to changes in volume during the cycle.Serving as an anode material for SIBs, the MoS2-G-C electrode showed good cycling stability(527.3mAh g-1 at100 m A g-1 after 200 cycles), excellent rate capability, and a long cycle life(439.1 m Ah g-1 at 1 A g-1 after 200 cycles).

Salt-assisted vapor-liquid-solid growth of high-quality ultrathin nickel oxide flakes for artificial synapses in image recognition applications

Transition metal oxides have attracted intense interest owing to their abundant physical and chemical properties.The controlled preparation of large-area,high-quality two-dimensional crystals is essential for revealing their inherent properties and realizing high-performance devices.However,fabricating two-dimensional(2D)transition metal oxides using a general approach still presents substantial challenges.Herein,we successfully achieve highly crystalline nickel oxide(NiO)flakes with a thickness as thin as 3.3 nm through the salt-assisted vapor-liquid-solid(VLS)growth method,which demonstrated exceptional stability under ambient conditions.To explore the great potential of the NiO crystal in this work,an artificial synapse based on the NiO-flake resistive switching(RS)layer is investigated.Short-term and long-term synaptic behaviors are obtained with external stimuli.The artificial synaptic performance provides the foundation of the neuromorphic application,including handwriting number recognition based on artificial neuron network(ANN)and the virtually unsupervised learning capability based on generative adversarial network(GAN).This pioneering work not only paves new paths for the synthesis of 2D oxides in the future but also demonstrates the substantial potential of oxides in the field of neuromorphic computing.

无定型NiCoS_(x)纳米片在多孔碳基纳米纤维表面的原位可控形成及其超级电容性能研究

近年来,导电碳基质与过渡金属硫化物(TMS)的巧妙结合在超级电容器中取得了一系列的研究进展.然而,在长期的充/放电过程中,这些复合物在异质界面处较弱的兼容性和结合力通常导致TMS的剥离和电极容量的衰减.基于此,本文设计了一种简单且可扩展的原位硫化方法,用于构建稳定的超级电容器电极,其中多孔NiCo/C纳米纤维作为核芯,无定形NiCoS_(x)纳米片作为壳层,形成NiCo/C@NiCoS_(x)(CNCS)分级核壳结构.外部NiCoS_(x)纳米片的质量负载和尺寸在很大程度上取决于内部NiCo/C纳米纤维的碳化温度.优化后的CNCS电极表现出优异的比容量和良好的倍率性能.组装的非对称超级电容器具有突出的能量密度和较高的循环稳定性.这种调节异质界面的原位策略有望用于开发稳定的基于TMS的复合电极.

A bifunctional wood membrane modified by MoS_(2)/covalent organic framework heterojunctions for effective solar-driven water evaporation and contaminant degradation

Interfacial solar evaporation technology is considered one of the most promising strategies for alleviating the scarcity of freshwater resources.However,solar-driven evaporation technology cannot eliminate the pollutants in the residual wastewater.To solve this problem,we have prepared a two-in-one solar-driven evaporation/photocatalysis system by decorating MoS_(2)/covalent organic framework(COF)heterojunctions on wood(MoS_(2)/COF-wood).Thanks to the unique porous structure of wood,it provides a strong guarantee for water transport and vapor release during the evaporation process.The introduction of MoS_(2)and COFs can promote the breaking of hydrogen bonds between water molecules,which leads to a significant decrease in the enthalpy of evaporation,achieving a water evaporation rate as high as 2.17 kg m^(-2)h^(-1)under 1 sun irradiation.Meanwhile,the resulting MoS_(2)/COF-wood exhibits good salt resistance and reusability.In addition,the heterojunctions formed between COFs and MoS_(2)can effectively inhibit charge carrier complexation and improve the photocatalytic degradation ability of pollutants(over 99%).This study highlights the construction strategy of bifunctional wood-based materials for freshwater production and wastewater remediation.

Large-area growth of ultra-high-density single-walled carbon nanotube arrays on sapphire surface

获得高密度的、大区域的围单人赛的碳 nanotube (SWNT ) 的可伸缩的途径穿的 A 为在实际电子设备认识到 SWNT 的完整的潜力是必要的；这仍然是大挑战。这里，我们由联合特洛伊催化剂在蓝宝石表面上为 ultra-high-density SWNT 数组的大区域的生长报导一个改进合成方法(免除了底层，保证超离频密度) 与瞬间 nanoparticles (在表面上装载了，稳定释放特洛伊催化剂) 作为合作催化剂。稠密、非常排列的 SWNT 盖住全部底层，本地密度象 160 tubes/m 一样高。在如此的数组上造的地效果晶体管(联邦货物税) 在排水管来源电压给了 488 A/m 的产量电流密度(V ds )= 门来源电压(V gs )=2 V，相应于在传导力上每 244 S/m 的宽度。这些结果在 SWNT 的控制结构的生长证实特洛伊瞬间催化剂的潜在的应用的宽范围。

Advanced low-dimensional carbon materials for flexible devices

We live in a digitized era,where we are completely surrounded by a plethora of automated electronic systems,be it a smart home energy controller or a selfoperated diagnostic kiosk in a clinic.With the recent advent of onedimensional(1D)and two-dimensional(2D)nanomaterials like carbon nanotube(CNT)and graphene,the world of electronics has revolutionized with state-of-the-art product paradigms.These nanomaterials possess desirable features of large surface area,excellent electrical conductivity,and high mechanical strength.Electronic devices made out of these materials have the added advantages of being flexible,light-weight,and durable.Thus,presentday devices that utilize these substances as channel or electrode materials have been able to undergo a positive transformation as compared with conventional structures.Flexibility and bendability are some of the coveted aesthetics of modern-day electronics and the use of these 1D and 2D nanomaterials imparts such features to the devices,without having to compromise on key output characteristics like sensitivity and efficiency.In this short review,we discuss about various new configurations that are based on graphene,CNT,and other materials like transition metal dichalcogenides,and how these materials have been able to metamorphose the attributes of conventional devices.

Integration of filter membrane and Ca_(2)Nb_(3)O_(10) nanosheets for high performance flexible UV photodetectors

We report that the integration of filter membrane and Ca_(2)Nb_(3)O_(10)nanosheets(FM@CNO) UV photodetector(UV PD) shows high performance and excellent flexibility. The Ca_(2)Nb_(3)O_(10)nanosheets were prepared by a facile solid-state reaction and liquid exfoliation process. The Ca_(2)Nb_(3)O_(10)nanosheets can be integrated into the pores of a filter membrane via a simple vacuum filtration method. The FM@CNO UV PD shows high performance under 300 nm light illumination at 5 V bias, including high responsivity(0.08 AW^(-1)), high detectivity(1.1 × 10^(12)Jones), high UV/visible rejection ratio(3.86 × 10^(3)) and fast speed(0.12/1.24 ms). Furthermore, the FM@CNO device exhibits excellent flexibility after many bending cycles.In addition, the FM@CNO array device was used as a pixel array detector for UV imaging. This work provides a novel approach to achieve high performance flexible PDs based on filter membrane and two dimensional materials.

Phase-pure two-dimensional Fe_(X)GeTe_(2) magnets with near-room-temperature Tc

Two-dimensional(2D)ferromagnets with out-of-plane(OOP)magnetic anisotropy are potential candidates for realizing the next-generation memory devices with ultra-low power consumption and high storage density.However,a scalable approach to synthesize 2D magnets with OOP anisotropy directly on the complimentary metal-oxide semiconductor(CMOS)compatible substrates has not yet been mainly explored,which hinders the practical application of 2D magnets.This work demonstrates a cascaded space confined chemical vapor deposition(CS-CVD)technique to synthesize 2D FexGeTe_(2) ferromagnets.The weight fraction of iron(Fe)in the precursor controls the phase purity of the as-grown FexGeTe2.As a result,high-quality Fe_(3)GeTe_(2) and Fe_(5)GeTe_(2) flakes have been grown selectively using the CS-CVD technique.Curie temperature(Tc)of the as-grown FexGeTe2 can be up to-280 K,nearly room temperature.The thickness and temperature-dependent magnetic studies on the Fe_(5)GeTe_(2) reveal a 2D Ising to 3D XY behavior.Also,Terahertz spectroscopy experiments on Fe_(5)GeTe_(2) display the highest conductivity among other FexGeTe_(2) 2D magnets.The results of this work indicate a scalable pathway for the direct growth and integration of 2D ternary magnets on CMOS-based substrates to develop spintronic memory devices.

2D/2D atomic double-layer WS_(2)/Nb_(2)O_(5)shell/core nanosheets with ultrafast interfacial charge transfer for boosting photocatalytic H_(2)evolution

Low-efficiency charge transfer is a critical factor to limit the photocatalytic H_(2)evolution activity of semiconductor photocatalysts.The interface design is a promising approach to achieve high chargetransfer efficiency for photocatalysts.Herein,a new 2 D/2 D atomic double-layer WS_(2)/Nb_(2)O_(5)shell/core photocatalyst(DLWS/Nb_(2)O_(5))is designed.The atom-resolved HAADF-STEM results unravel the presence of an unusual 2 D/2 D shell/core interface in DLWS/Nb_(2)O_(5).Taking advantage of the advanced femtosecond-resolved ultrafast TAS spectra,the average lifetime of charge carriers for DLWS/Nb_(2)O_(5)(180.97 ps)is considerably shortened as compared to that of Nb_(2)O_(5)(230.50 ps),strongly indicating that the 2 D/2 D shell/core interface enables DLWS/Nb_(2)O_(5)to achieve ultrafast charge transfer from Nb_(2)O_(5)to atomic double-layer WS_(2),thus yielding a high photocatalytic H_(2)evolution rate of 237.6 mmol/h,up to10.8 times higher than that of pure Nb_(2)O_(5)nanosheet.This study will open a new window for the development of high-efficient photocatalytic systems through the interface design.

Controlled growth of ultrathin ferromagneticβ-MnSe semiconductor

Two-dimensional(2D)magnetic crystals with intrinsic ferromagnetism are highly desirable for novel spin-electronic devices.However,the controllable synthesis of 2D magnets,especially the direct growth of 2D magnets on substrate surfaces,is still a challenge.Here,we demonstrate the synthesis of ultrathin zinc-blende phase manganese selenide(β-MnSe)nanosheets using the chemical vapor deposition(CVD)technique.The 2Dβ-MnSe crystals exhibit distinct ferromagnetic properties with a Curie temperature of 42.3 K.Density functional theory(DFT)calculations suggest that the ferromagnetic order inβ-MnSe originates from the exchange coupling between the unsaturated Se and Mn atoms.This study presents significant progress in the CVD growth of ultrathin 2D magnetic materials by thinning bulk magnets,and it will pave the way for the building of energy-efficient spintronic devices in the future.

Space-confined microwave synthesis of ternary-layered BiOCl crystals with high-performance ultraviolet photodetection

In recent years,two-dimensional(2D)ternary materials have attracted wide attention due to their novel properties which can be achieved by regulating their chemical composition with a very great degree of freedom and adjustable space.However,as for the precise synthesis of 2D ternary materials,great challenges still lie ahead that hinder their further development.In this work,we demonstrated a simple and reliable approach to synthesize 2D ternary-layered BiOCl crystals through a microwave-assisted space-confined process in a short time(<3 minutes).Their ultraviolet(UV)detection performance was analyzed systematically.The photodetectors based on the as-obtained BiOCl platelets demonstrate high sensitivity to 266-nm laser illumination.The responsivity is calculated to be8 A/W and the response time is up to be18 ps.On the other hand,the device is quite stable after being exposed in the ambient air within 3 weeks and the response is almost unchanged during the measurement.The facile and fast synthesis of single crystalline BiOCl platelets and its high sensitivity to UV light irradiation indicate the potential optoelectronic applications of 2D BiOCl photodetectors.

Two-dimensional perovskite Pb_(2)Nb_(3)O_(10) photodetectors

For the first time,we report high-performance two-dimensional(2D)perovskite Pb_(2)Nb_(3)O_(10) photodetectors(PNO PDs).The few-layer PNO nanosheets are obtained successfully through a simple calcination and liquid exfoliation method.The individual PNO nanosheet devices with various structures(Au-PNO-Au,Au-PNO-Ti,Ti-PNO-Ti)are fabricated and investigated.The Au-PNO-Ti device exhibits a high rectification factor(∼102)owing to a large Schottky barrier difference between the PNO nanosheet and two asymmetric electrodes.Notably,the Au-PNO-Ti device shows excellent self-powered performance,including high responsivity(2.8 A/W),high detectivity(1.1×10^(12) Jones),and fast speed(0.2/1.2 ms)at 350 nm light illumination.This work not only suggests the performance of the PNO nanosheet PDs but also sheds light on the development of high-stability and high-performance devices based on 2D perovskite niobate in the future.

Understanding and unveiling the electro-chemo-mechanical behavior in solid-state batteries

Solid-state batteries(SSBs)are attracting growing interest as long-lasting,thermally resilient,and high-safe energy storage systems.As an emerging area of battery chemistry,there are many issues with SSBs,including strongly reductive lithium anodes,oxidized cathodes(state of charge),the thermodynamic stability limits of solid-state electrolytes(SSEs),and the ubiquitous and critical interfaces.In this Review,we provided an overview of the main obstacles in the development of SSBs,such as the lithium anode|SSEs interface,the cathode|SSEs interface,lithium-ion transport in the SSEs,and the root origin of lithium intrusions,as well as the safety issues caused by the dendrites.Understanding and overcoming these obstacles are crucial but also extremely challenging as the localized and buried nature of the intimate contact between electrode and SSEs makes direct detection difficult.We reviewed advanced characterization techniques and discussed the complex ion/electron-transport mechanism that have been plaguing electrochemists.Finally,we focused on studying and revealing the coupled electro-chemo-mechanical behavior occurring in the lithium anode,cathode,SSEs,and beyond.