Designing N-doped graphene/ReSe_(2)/Ti_(3)C_(2) MXene heterostructure frameworks as promising anodes for high-rate potassium-ion batteries

Developing high-performance anodes for potassium ion batteries(KIBs) is of paramount significance but remains challenging.In the normal sense,electrode materials are prepared by ubiquitous wet chemical routes,which otherwise might not be versatile enough to create desired heterostructures and/or form clean interfacial areas for fast transport of K-ions and electrons.Along this line,rate capability/cycling stability of resulting KIBs are greatly handicapped.Herein we present an all-chemical vapor deposition approach to harness the direct synthesis of nitrogen-doped graphene(NG)/rhenium diselenide(ReSe_2)hybrids over three-dimensional MXene supports as superior heterostructure anode material for KIBs.In such an innovative design,1 T'-ReSe2 nanoparticles are sandwiched in between the NG coatings and MXene frameworks via strong interfacial interactions,thereby affording facile K~+ diffusion,enhancing overall conductivity,boosting high-power performance and reinforcing structural stability of electrodes.Thus-constructed anode delivers an excellent rate performance of 138 mAh g^(-1) at 10.0 A g^(-1) and a high reversible capacity of 90 mAh g^(-1) at 5 A g^(-1) after 300 cycles.Furthermore,the potassium storage mechanism has been systematically probed by advanced in situlex situ characterization techniques in combination with first principles computations.

Insight into the promotional mechanism of Cu modification towards wide-temperature NH3-SCR performance of NbCe catalyst

A simple strategy of Cu modification was proposed to broaden the operation temperature window for NbCe catalyst.The best catalyst Cu0.010/Nb1Ce3 presented over 90%NO conversion in a wide temperature range of 200-400℃and exhibited an excellent H_(2)O or/and SO_(2) resistance at 275℃.To understand the promotional mechanism of Cu modification,the correlation among the"activity-structure-property"were tried to establish systematically.Cu species highly dispersed on NbCe catalyst to serve as the active component.The strong interaction among Cu,Nb and Ce promoted the emergence of NbO4 and induced more Bronsted acid sites.And Cu modification obviously enhanced the redox behavior of the NbCe catalyst.Besides,EPR probed the Cu species exited in the form of monomeric and dimeric Cu^(2+),the isolated Cu^(2+)acted as catalytic active sites to promote the reaction:Cu^(2+)-NO_(3)^(-)+NO(g)→Cu^(2+)-NO_(2)^(-)+NO_(2)(g).Then the generated NO_(2) would accelerate the fast-SCR reaction process and thus facilitated the lowtemperature deNO_(x) efficiency.Moreover,surface nitrates became unstable and easy to decompose after Cu modification,thus providing additional adsorption and activation sites for NH3,and ensuring the improvement of catalytic activity at high temperature.Since the NH3-SCR reaction followed by E-R reaction pathway efficaciously over Cu_(0.010)/Nb_(1)Ce_(3) catalyst,the excellent H_(2)O and SO_(2) resistance was as expected.

Moir patterns and step edges on few-layer graphene grown on nickel films

Few-layer graphene grown on Ni thin films has been studied by scanning tunneling microscopy. In most areas on the surfaces, moir′e patterns resulted from rotational stacking faults were observed. At a bias lower than 200 mV, only one sublattice shows up in regions without moir′e patterns while both sublattices are seen in regions with moir′e pattens. This phenomenon can be used to identify AB stacked regions. The scattering characteristics at various types of step edges are different from those of monolayer graphene edges, either armchair or zigzag.

Coulomb-dominated oscillations in a graphene quantum Hall Fabry–Pérot interferometer

The electronic Fabry–Pérot interferometer operating in the quantum Hall regime may be a promising tool for probing edge state interferences and studying the non-Abelian statistics of fractionally charged quasiparticles. Here we report on realizing a quantum Hall Fabry–Pérot interferometer based on monolayer graphene. We observe resistance oscillations as a function of perpendicular magnetic field and gate voltage both on the electron and hole sides. Their Coulomb-dominated origin is revealed by the positive(negative) slope of the constant phase lines in the plane of magnetic field and gate voltage on the electron(hole) side. Our work demonstrates that the graphene interferometer is feasible and paves the way for the studies of edge state interferences since high-Landau-level and even denominator fractional quantum Hall states have been found in graphene.

Tunable and highly sensitive temperature sensor based on graphene photonic crystal fiber

Optical fiber temperature sensors have been widely employed in enormous areas ranging from electric power industry,medical treatment,ocean dynamics to aerospace.Recently,graphene optical fiber temperature sensors attract tremendous attention for their merits of simple structure and direct power detecting ability.However,these sensors based on transfer techniques still have limitations in the relatively low sensitivity or distortion of the transmission characteristics,due to the unsuitable Fermi level of graphene and the destruction of fiber structure,respectively.Here,we propose a tunable and highly sensitive temperature sensor based on graphene photonic crystal fiber(Gr-PCF)with the non-destructive integration of graphene into the holes of PCF.This hybrid structure promises the intact fiber structure and transmission mode,which efficiently enhances the temperature detection ability of graphene.From our simulation,we find that the temperature sensitivity can be electrically tuned over four orders of magnitude and achieve up to~3.34×10^(-3) dB/(cm·℃)when the graphene Fermi level is~35 meV higher than half the incident photon energy.Additionally,this sensitivity can be further improved by~10 times through optimizing the PCF structure(such as the fiber hole diameter)to enhance the light–matter interaction.Our results provide a new way for the design of the highly sensitive temperature sensors and broaden applications in all-fiber optoelectronic devices.

Direct insight into sulfiphilicity-lithiophilicity design of bifunctional heteroatom-doped graphene mediator toward durable Li-S batteries

The practical applications of lithium-sulfur(Li-S)battery have been greatly hindered by the severe polysulfide shuttle at the cathode and rampant lithium dendrite growth at the anode.One of the effective solutions deals with concurrent management of both electrodes.Nevertheless,this direction remains in a nascent stage due to a lack of material selection and mechanism exploration.Herein,we devise a temperature-mediated direct chemical vapor deposition strategy to realize the controllable synthesis of three-dimensional boron/nitrogen dual-doped graphene(BNG)particulated architectures,which is employed as a light-weighted and multi-functional mediator for both electrodes in Li-S batteries.Benefiting from the“sulfiphilic”and“lithiophilic”features,the BNG modified separator not only enables boosted kinetics of polysulfide transformation to mitigate the shuttle effect but also endows uniform lithium deposition to suppress the dendritic growth.Theoretical calculations in combination with electro-kinetic tests and operando Raman analysis further elucidate the favorable sulfur and lithium electrochemistry of BNG at a molecular level.This work offers direct insight into the mediator design via controllable synthesis of graphene materials to tackle the fundamental challenges of Li-S batteries.

Intercalation of van der Waals layered materials: A route towards engineering of electron correlation

Being parent materials of two-dimensional (2D) crystals, van der Waals layered materials have received revived interest. In most 2D materials, the interaction between electrons is negligible. Introducing the interaction can give rise to a variety of exotic properties. Here, via intercalating a van der Waals layered compound VS2, we find evidence for electron correlation by extensive magnetic, thermal, electrical, and thermoelectric characterizations. The low temperature Sommerfeld coefficient is 64 mJ·K-2·mol-1 and the Kadowaki-Woods ratio rKW^0.20a0. Both supports an enhancement of the electron correlation. The temperature dependences of the resistivity and thermopower indicate an important role played by the Kondo effect. The Kondo temperature TK is estimated to be around 8 K. Our results suggest intercalation as a potential means to engineer the electron correlation in van der Waals materials, as well as 2D materials.

CO_(2)-promoted transfer-free growth of conformal graphene

Gaseous promotors have readily been adopted during the direct synthesis of graphene over insulators to enhance the growth quality and/or boost the growth rate.The understanding of the real functions of carbon-containing promotors has still remained elusive.In this study,we identify the critical roles of a representative CO_(2)promotor played in the direct growth of graphene.The comparative experimental trials validate CO_(2)as an effective modulator to decrease graphene nucleation density,improve growth kinetics,mitigate adlayer formation.The first-principles calculations illustrate that the generation of gas-phase OH species in CO_(2)-assisted system helps decrease the energy barriers of CH4 decomposition and carbon attachment to the growth front,which might be the key factor to allow high-quality direct growth.Such a CO_(2)-promoted strategy enables the conformal coating of graphene film over curved insulators,where the sheet resistance of grown graphene on quartz reaches as low as 1.26 kΩ·sq^(−1)at an optical transmittance of~95.8%.The fabricated endoscope lens based on our conformal graphene harvests an apoptosis of 82.8%for noninvasive thermal therapy.The work presented here is expected to motivate further investigations in the controllable growth of high-quality graphene on insulating substrates.

Optically modulated dual-mode memristor arrays based on core-shell CsPbBr_(3)@graphdiyne nanocrystals for fully memristive neuromorphic computing hardware

Artificial synapses and neurons are crucial milestones for neuromorphic computing hardware,and memristors with resistive and threshold switching characteristics are regarded as the most promising candidates for the construction of hardware neural networks.However,most of the memristors can only operate in one mode,that is,resistive switching or threshold switching,and distinct memristors are required to construct fully memristive neuromorphic computing hardware,making it more complex for the fabrication and integration of the hardware.Herein,we propose a flexible dual-mode memristor array based on core–shell CsPbBr3@graphdiyne nanocrystals,which features a 100%transition yield,small cycle-to-cycle and device-to-device variability,excellent flexibility,and environmental stability.Based on this dual-mode memristor,homo-material-based fully memristive neuromorphic computing hardware—a power-free artificial nociceptive signal processing system and a spiking neural network—are constructed for the first time.Our dual-mode memristors greatly simplify the fabrication and integration of fully memristive neuromorphic systems.

Theoretical investigations on the growth of graphene by oxygenassisted chemical vapor deposition

Recently,graphene has drawn considerable attention in the field of electronics,owing to its favorable conductivity and high carrier mobility.Crucial to the industrialization of graphene is its high-quality microfabrication via chemical vapor deposition.However,many problems remain in its preparation,such as the not fully understood cracking mechanism of the carbon source,the mechanism of its substrate oxidation,and insufficient defect repair theory.To help close this capability gap,this study leverages density functional theory to explore the role of O in graphene growth.The effects of Cu substrate oxidation on carbon source cracking,nucleation barriers,crystal nucleus growth,and defect repairs are discussed.OCu was found to reduce energy change during dehydrogenation,rendering the process easier.Moreover,the adsorbed O in graphene or its Cu substrate can promote defect repair and edge growth.

Highly selective growth of(6,5)single-walled carbon nanotubes from sigma phase alloy catalyst

The chirality structure of a single-walled carbon nanotube(SWNT)strongly depends on the composition of catalyst used in the chemical vapor deposition process.In this study,we develop a porous magnesia supported manganese-rhenium(MnRe/MgO)catalyst for chirality-selective synthesis of SWNTs.Detailed characterizations reveal that(6,5)tubes with a selectivity higher than 70%are grown from the Re-rich MnRe/MgO catalyst.By comparing the SWNT growth results with those of monometallic Mn or Re,the formation of sigma phase,an intermetallic compound occurring in transition-metal alloy systems,is revealed to be crucial for the dominant synthesis of(6,5)SWNTs.This work not only extends the application of sigma phase alloy for catalytic synthesis of SWNTs,but also sheds lights on the growth of SWNTs with a high chirality selectivity.

Direct low-temperature synthesis of graphene on various glasses by plasma-enhanced chemical vapor deposition for versatile, cost-effective electrodes

在低温度的各种各样的玻璃底层上的 graphene 的没有催化剂、可伸缩的合成具有到象便宜透明电子学和最先进的显示器那样的众多的应用程序的首要的意义。然而，在这个有希望的研究领域以内的系统的学习远这样仍然保持少见。此处，我们用一个低温度的提高血浆的化学蒸汽免职方法在各种各样的眼镜上报导 graphene 的直接生长。如此的一条灵巧、可伸缩的途径在 400600 的一个生长温度范围在各种各样的玻璃底层上保证一致、没有转移的 graphene

Confining MOF-derived SnSe nanoplatelets in nitrogen-doped graphene cages via direct CVD for durable sodium ion storage

Tin-based compounds are deemed as suitable anode candidates affording promising sodium-ion storages for rechargeable batteries andhybrid capacitors.However,synergistically tailoring the electrical conductivity and structural stability of tin-based anodes to attain durablesodium-ion storages remains challenging to date for its practical applications.Herein,metal-organic framework(MOF)derived SnSe/C wrappedwithin nitrogen-doped graphene(NG@SnSe/C)is designed targeting durable sodium-ion storage.NG@SnSe/C possesses favorable electricalconductivity and structure stability due to the"inner"carbon framework from the MOF thermal treatment and"outer"graphitic cage from thedirect chemical vapor deposition synthesis.Consequently,NG@SnSe/C electrode can obtain a high reversible capacity of 650 mAh·g^-1 at 0.05 A·g^1,a favorable rate performance of 287.8 mAh·g^1 at 5 A·g^1 and a superior cycle stability with a negligible capacity decay of 0.016%percycle over 3,200 cycles at 0.4 A·g^1.Theoretical calculations reveal that the nitrogen-doping in graphene can stabilize the NG@SnSe/Cstructure and improve the electrical conductivity.The reversible Na-ion storage mechanism of SnSe is further investigated by in-situ X-raydiffraction/ex-s/tu transmission electron microscopy.Furthermore,assembled sodium-ion hybrid capacitor full-cells comprising our NG@SnSe/Canode and an active carbon cathode harvest a high energy/power density of 115.5 Wh·kg^-1/5,742 W·kg^-1,holding promise for next-generationen ergy storages.

Natural Biopolymers for Flexible Sensing and Energy Devices

Natural biopolymers feature natural abundance,diverse chemical compositions,tunable properties,easy processability,excellent biocompatibility and biodegradability,as well as nontoxicity,providing new opportunities for the development of flexible sensing and energy devices.Generally,biopolymers are utilized as the passive and active building blocks to endow the flexible devices with mechanical robustness and good biocompatibility.This review aims to provide a comprehensive review on natural biopolymer-based sensing and energy devices.The diverse structures and fabrication processes of three typical biopolymers,including silk,cellulose,and chitin/chitosan,are presented.We review their utilities as the supporting substrates/matrix,active middle layers,separators,electrolytes,and active components of flexible sensing devices(sensors,actuators,transistors)and energy devices(batteries,supercapacitors,triboelectric nanogenerators).Finally,the remaining challenges and future research opportunities are discussed.

A transparent, conducting tape for flexible electronics

透明电极是为象显示和薄电影的太阳能电池那样的 optoelectronic 设备的必要部件。传统地，透明的进行的层的免职并且封上设备是分开的步。这里，我们在一盘高度透明、传导性、灵活的磁带上报导，它能被把银 nanowire 网络转移到常规透明磁带获得。我们利用了磁带的粘质减少在银 nanowires 之间的连接抵抗并且进一步保护 nanowires 免受腐蚀，氧化和机械损坏的伤害。由这个简单方法，我们与高透明性获得了一盘灵活磁带(~90% 在 550 nm 波长) 并且低表抵抗(接近 22 ? 潣灭獯瑩獥吗？？

Large-area chemical vapor deposition-grown monolayer graphene-wrapped silver nanowires for broad-spectrum and robust antimicrobial coating

抗菌剂系统的新类型着急地由于获得抵抗到通常在日常生活和医疗保健使用的抗菌素的病原的微生物引起的种类的出现被需要。在这研究，我们第一次开发了用途广泛、柔韧的抗菌剂薄电影涂层基于大区域的化学蒸汽免职(CVD ) 种包 graphene 的银 nanowires (AgNWs ) 。抗菌剂 graphene/AgNW 混血儿涂层能在塑料由一个完整的 roll-to-roll 过程拍摄的商业灵活透明乙烯乙烯基 acetate/ 聚乙烯 terephthalate (EVA/PET ) 上被使用。graphene/AgNW 混血儿涂层显示出用途广泛的抗菌剂活动对克否定(Escherichia coli ) 并且克积极的细菌(葡萄球菌 aureus ) ，和真菌(Candida albicans ) 。这效果被归因于一个更弱的微生物引起的附件到极端光滑的 graphene 电影和 Ag+ 的消毒能力，它 sustainably 被免除 AgNWs 并且大概由 AgNWs 的电气化学的腐蚀提高了。而且， graphene/AgNW 涂层的柔韧的抗菌剂活动被 graphene 被 AgNW 封装增强。而且，抗菌剂效率能走水路百分之百被提高到 ~ 由把传导性的 graphene/AgNW 涂层用作阴极的电解。我们开发了用 graphene/AgNW/EVA/PET 和由 graphene/ AgNW 涂的一颗抗菌剂假牙做的一个透明、灵活的抗菌剂封面，到表演抗菌剂材料的潜在的应用程序。

All VN-graphene architecture derived self-powered wearable sensors for ultrasensitive health monitoring

The booming of wearable electronics has nourished the progress on developing multifunctional energy storage systems with versatile flexibility, which enable the continuous and steady power supply even under various deformed states. In this sense, the synergy of flexible energy and electronic devices to construct integrative wearable microsystems is meaningful but remains quite challenging by far. Herein, we devise an innovative supercapacitor/sensor integrative wearable device that is based upon our designed vanadium nitride-graphene (VN-G) architectures. Flexible quasi-solid-state VN-G supercapacitor with ultralight and binder-free features deliver a specific capacitance of^53 F·g^-1 with good cycle stability. On the other hand, VN-G derived pressure sensors fabricated throughout a spray-printing process also manifest favorably high sensitivity (40 kPa^-1 at the range of 2-10 kPa), fast response time (~130 ms), perfect skin conformability, and outstanding stability under static and dynamic pressure conditions. In tum, their complementary unity into a self-powered wearable sensor enables the precise detecti on of physiological motions ranging from pulse rate to phonetic recognition, holding promise for in-practical health monitoring applications.

Fast and uniform growth of graphene glass using confined-flow chemical vapor deposition and its unique applications

常规玻璃上的高质量的 graphene 的快、一致的生长为 graphene 玻璃的实际应用程序是很重要的。我们此处为 graphene 玻璃的高效率的制造报导一条范围流动化学药品蒸汽免职(CVD ) 途径。我们的途径的特色是 2-4 m 的制造在玻璃底层上面的宽差距，与很多的跌倒块；这差距被发现显著地增加在对方之间并且与玻璃表面的碳先锋和反应碎片的碰撞概率。作为结果， graphene 玻璃的生长率显著地增加了，和在象与那些相比的生长质量和在常规煤气的流动 CVD 技术的一致性的改进。这些高质量的 graphene 眼镜与以前报导的那些相比以许多更高的 defogging 速度和更高的稳定性展出了优秀 defogging 表演。graphene 蓝宝石玻璃被发现是为种制服和极端光滑的铝氮化物的理想的底层没有缓冲区层的乏味的免职前的薄电影。介绍范围流动 CVD 途径为 graphene 玻璃的大量生产提供一条简单、便宜的线路，它被相信支持各种各样的 graphene 眼镜的实际应用。