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NASICON-type NaTi2(PO4)3 (NTPO) is a promising anode for Na+ batteries owing to its excellent thermal stability, high Na+ conductivity, high theoretical capacity, low price, and good safety. However, the electronic conductivity of NTPO is not satisfactory for practical applications in rechargeable Na+ batteries. In this work, NTPO@C electrode anchored to B-doped graphene (BG) sheets is synthesized via a combination of facile sol-gel procedure and solid-state reaction at high temperature. As envisioned in the design step, the BG coupled with the carbon layer forms a network that improves the electronic conductivity of BG/NTPO@C anode, resulting in excellent Na+ storage properties. It provides a high specific capacity of 127.9 mAh g-1 at 0.1C in the potential range of 1.5–3.0 V. Furthermore, it displays a high reversible capacity of 103.4 mAh g-1 at 10C over 500 cycles while retaining 93.7% of the initial capacity. These electrochemical experiments demonstrate that the developed BG/NTPO@C composite is a promising novel anode for high-performance Na+ batteries.

Over the past decade, metal-loaded hollow carbon nanostructures have been hailed as man-made nanoreactors (MHC nanoreactors) for extensive applications in dealing with energy and environmental issues due to their tailorable structure and electronic properties. Unlike conventional reports of hollow nanostructures with regard to synthetic methodologies or structural properties, a distinctive viewpoint on the microenvironment effects of MHC nanoreactors, i.e., metal–support interaction effect, reactant enrichment effect, molecular sieving effect, spatial compartmentation effect, and metal stabilization effect, is highlighted herein from this perspective. Furthermore, to emphasize the great potential of MHC nanoreactors in constructing a sustainable energy system to achieve a greener modern lifestyle, a review of the applications of MHC nanoreactors in the hydrogenation of typical biomass-derived molecules is presented. Additionally, prospects for broader biomass valorization applications of MHC nanoreactors, i.e., in situ hydrogen source-assisted hydrogenation, hydrogenation-involved cascade-type reactions, hydrogenation product distribution modulation, stability prolongation and recyclability enhancement, are forecasted. Toward the end of this paper, some feasible suggestions are further proposed for the enhancement of the catalytic reactivity, selectivity, stability, and sustainability of MHC nanoreactors in biomass hydrogenation, with a sincere expectation to contribute to the development of a highly efficient biomass refining system.

The hydrogenation of furfural (FUR), a typical bio-based furan derivative, is a critical reaction within the roadmap for upgrading lignocellulosic biomass into high value-added chemicals and liquid fuels, the performance of which is strongly correlated with the catalysts' intrinsic peculiarities. Metal catalysts with tailorable sizes, uniform dispersions and robust sintering resistance are generally recognized as a prerequisite for obtaining better hydrogenation activity, selectivity and stability, which has prompted intensive research into metal particle size effects and their regulation strategies. The roles of metal particle sizes and corresponding dispersions of metal catalysts used for FUR hydrogenation have been clearly recognized to be crucial over the past decade. In this regard, this systematic Minireview aims to provide profound insights into particle size effects in the metal-catalyzed hydrogenation of FUR, as well as conditional and structural approaches to regulating these effects. In addition, from the aspect of catalyst stability, the impacts and improvements of the metal particle sintering issue are analyzed. Moreover, several suggestions are proposed in response to the challenges in regulating particle size effects. Furthermore, the viewpoints presented herein would potentially contribute to the rational development of metal hydrogenation catalysts and further help to boost a more sustainable biomass refining system.

As a result of low porosity and low permeability in tight reservoirs, spontaneous imbibition plays an important role in oil recovery. While wettability has a crucial impact on the imbibition, the m...

Hierarchically porous activated carbons with high specific surface areas are synthesized by chemical activation of the leaves of Schefflera octophylla. The specific surface areas of the materials are over 2300 m2 g−1 and the specific pore volume is as high as 1.92 cm3 g−1. The optimized material achieves a high specific capacitance of 336 F g−1 in 6 M KOH aqueous electrolyte at a current density of 0.5 A g−1, and it also shows excellent cycling stability with 97.5% capacitance retention after 10,000 cycles at a current density of 10 A g−1. The simple synthesis route of hierarchically porous activated carbon from renewable bio-wastes enables a promising strategy in both reducing wastes and producing useful energy storage materials.

Cactus structure MnO2/N-rich carbon nanofiber composites were synthesized via an in situ redox reaction to be utilized as the interlayer in lithium–sulfur batteries. The exposed MnO2 nanosheets vertically aligned on carbon nanofibers provide a large amount of active sites for polysulfide adsorption and conversion. Unlike physical barriers or simple surface interactions, the MnO2 nanosheets generate an anchor and transfer mediator for polysulfides to dissolve into the electrolyte, and then control the deposition of Li2S2 or Li2S on the designed interlayer. This structure induces an arranged relocation of sulfur species during cycling, resulting in a shortened electron passage and an improved utilization of the active material. With a sulfur loading of 1.65 mg cm−2 and a sulfur content of 60% at the whole electrode level, the cell with the MnO2/carbon nanofiber interlayer delivered an initial discharge capacity of 1102 mA h g−1, 965 mA h g−1, and 712 mA h g−1 at 0.1C, 1C and 5C, respectively. It could maintain a reversible capacity of 646 mA h g−1 after 100 cycles at 1C and a specific capacity of 414 mA h g−1 after 1000 cycles at 5C with a fade rate of 0.04% per cycle.

A self-standing nitrogen/oxygen dual-doped carbon nanofiber matrix is prepared on the basis of polymer chain design and electrospinning followed by a one-step carbonization. The interlayer can subs...

A novel concept of acoustic fiber Bragg grating (AFBG) was conceived and experimentally validated as an effective technique for high-temperature sensing. Similar to the well-known optical fiber Bragg grating, the AFBG employs interactions between waves and periodic structures on an elongated waveguide. Acoustic waves reflected from periodic structures interfere with each other and result in the emergence of resonance frequency when acoustic wavelength matches with pitch length of the periodic structures. When the single-mode operation condition is satisfied, the resonance frequency location can be accurately resolved and thus be used as an effective indicator for temperature sensing. To demonstrate this concept, an AFBG sample was fabricated on a telecommunication optical fiber (125- $\mu \text{m}$ diameter) with femtosecond laser micromachining setup, and it demonstrated sensing capability up to 700 °C, which was limited by the fiber material (fused silica) and could be over 1400 °C if other material, such as sapphire, was used as the waveguide. With the features of various applicable material, low system cost, and potential multiplexing capability, this AFBG technology is a promising candidate for high-temperature sensing, even in a distributed manner.

The commercial LiFePO4 cathode has attracted great attention for large-scale energy storage because of its high safety, low cost, low toxicity and excellent thermal stability. Unfortunately, the poor electronic conductivity of LiFePO4 leads to bad lithium storage property. In this work, the nitrogen-doped graphene-decorated LiFePO4 was prepared via a facile hydrothermal method followed by a conventional solid-state route. Benefiting from the advantages of nitrogen-doped graphene, the conductivity of LiFePO4 is greatly improved. Therefore, the obtained composite shows excellent electrochemical performances, including high reversible capacity (163.1 mAh g−1 at 0.1 C), good rate capability (113.7 mAh g−1 at 10 C) and stable cycle-life (111.6 mAh g−1 after 150 cycles at 10 C). These results reveal that the designed nitrogen-doped graphene-decorated LiFePO4 composite is a promising cathode material for rechargeable lithium-ion batteries.

Spinel Li4Ti5O12 material has been regarded as the next-generation anode for lithium-ion batteries owing to its excellent safety and good structural stability. Nevertheless, the low electrical conductivity and bad Li+-ion diffusion efficiency of pristine Li4Ti5O12 greatly limit its wide applications in electrochemical energy storage. Herein, the nanosized Li4Ti5O12 crystals are prepared via a simple sol-gel method to shorten the diffusion pathway of Li+-ion. Meanwhile, the conductive PEDOT layer is adopted to modify the electrical conductivity of Li4Ti5O12. The PEDOT-coated Li4Ti5O12 composite is successfully prepared by using the in-situ polymerization method. Benefit from the advantages of nanosized Li4Ti5O12 particles and conductive PEDOT coating, the obtained electrode exhibits enhanced electrochemical performances. It can deliver the initial discharge capacities of 169.6 and 125.2 mAh g−1 at 0.1 and 20 C. These results demonstrate that the designed composite is a potential electrode for high-rate electrochemical lithium storage.

Sodium-ion batteries have been regarded as the most attractive alternative to lithium-ion batteries because of their low cost, abundance of sodium resources and promising applications for energy storage systems. In this work, boron-doped graphene decorated Na3V2(PO4)3@C (BG-Na3V2(PO4)3@C) composite is successfully synthesized for the first time by using a simple sol-gel assisted solid-state method. In this composite, the ultrafine Na3V2(PO4)3@C particles are uniformly distributed on the boron-doped graphene sheets. The carbon layer and boron-doped graphene greatly increase the electron/ion transport kinetics of Na3V2(PO4)3 and assure the material structure integrity, leading to excellent electrochemical performances in terms of high-rate capability and long cycle-life. It delivers a high reversible capacity of 94.7 mAh g−1 at 10C and keeps 96.4% of the capacity after 100 cycles. These preliminary results reveal that the as-fabricated BG-Na3V2(PO4)3@C composite is a new promising cathode material for sodium energy storage.

The development of organic thin-film transistors (OTFTs) with low power consumption and high gain will advance many flexible electronics. Here, by combining solution-processed monolayer organic crystal, ferroelectric HfZrOx gating and van der Waals fabrication, we realize flexible OTFTs that simultaneously deliver high transconductance and sub-60 mV/dec switching, under one-volt operating voltage. The overall optimization of transconductance, subthreshold swing and output resistance leads to transistor intrinsic gain and amplifier voltage gain over 5.3 × 104 and 1.1 × 104, respectively, which outperform existing technologies using organics, oxides and low-dimensional nanomaterials. We further demonstrate battery-powered, integrated wearable electrocardiogram (ECG) and pulse sensors that can amplify human physiological signal by 900 times with high fidelity. The sensors are capable of detecting weak ECG waves (undetectable even by clinical equipment) and diagnosing arrhythmia and atrial fibrillation. Our sub-thermionic OTFT is promising for battery/wireless powered yet performance demanding applications such as electronic skins and radio-frequency identification tags, among many others., Exploiting negative capacitance effects in organic thin-film transistors (OTFTs) is advantageous for enhancing device performance. Here, the authors report solution-processed sub-thermionic OTFTs and circuits with ferroelectric hafnium oxides that show ultra-low power and ultra-high gain.

As one of the most promising biomass-based platform molecules, γ-valerolactone (GVL) can be synthesized from a variety of lignocellulosic feedstocks through different hydrogen supply pathways. Among these transformation routes, the hydrogenation of levulinic acid (LA) to GVL by using formic acid (FA) as the internal hydrogen source is regarded as a critical path for the sustainable development of renewable energy systems. Although a large number of studies on the synthesis of GVL have been reported, the FA/LA catalytic system has not been interpreted as thoroughly as it should be. In this Minireview, core concerns are focused on key issues and their effects in this FA/LA catalytic system. The catalytic mechanism, together with competitive adsorption behavior between FA and LA on heterogeneous catalysts, is presented. The effects of active metal species and catalyst supports on the overall catalytic performance are summarized, and the influences of key condition parameters, including the time, temperature, FA/LA molar ratios, and aqueous solvent, are discussed. In particular, impacts and improvements of coke deposition and metal leaching, which could greatly affect the catalyst stability, are analyzed in detail. Additionally, several feasible suggestions for the enhancement of the catalytic efficiency and stability are also proposed.

Lithium metal anodes (LMAs) have exceptional promises for rechargeable Li-metal batteries. However, their practical applications have long been hindered by the safety concerns related to excessive Li dendrite growth and huge volume expansion during cycling, especially in high-capacity cycles. In this work, we developed a new strategy to suppress the dendrite growth via a 3D reinforced lithium metal composite anode with a nanostick structured copper oxide @copper mesh. Such nanostick structured copper oxide would not only reduce the lithium nucleation overpotential to 11 mV, but also would uniformly accommodate lithium ions to suppress the dendrite effect. Moreover, the 3D structure of copper mesh could effectively alleviate the aggressive volume changes of the lithium metal electrode after hundreds of cycles. Based on CuO@copper mesh, highly reversible lithium stripping/plating are achieved for LMAs at current density of 1 mA cm–2 with a limited volume fluctuation of 13.6% after 1000 h. With ultrahigh capacity densities of 5 mAh cm−2, the CuO@Cu mesh/Li cell exhibits low overpotential of 12 mV and ultralong cycle life over 600 h, which is 2–3 times of the reported average cycling lifespan. The proposed preparation process is simple and easy to scale-up, demonstrating a promising prospect as a commercial Li metal anode with large capacity.

This paper reports fabrication technique and demodulation algorithm developments to use multiplexable intrinsic Fabry-Perot interferometer (IFPI) fiber sensor array for distributed vibration measurements at high temperatures. Using femtosecond laser direct writing scheme, IFPI array were fabricated through laser-induced Type II scattering points in single mode fiber cores. Reflection spectra of IFPI array were demodulated in real-time using modified Bunemen frequency analysis. The demodulation algorithm, which was implemented using a photodetector-array spectrometer, achieves 64-ne dynamic strain resolution at 1-kHz spectral acquisition rate and 2-kHz maximum vibration bandwidth. Performance and stabilities of IFPI sensor array were characterized from room temperatures to 800 °C. The static strain resolution was 0.6 μe and the minimum detectable dynamic strain amplitude was 23 ne/√Hz at 800 °C. The multiplex performance was also tested by measuring dynamic strain in time domain through six IFPI sensor array fabricated in one fiber. This paper presents an integrated and low-cost sensing solution to perform distributed vibration measurements in harsh environments.

A fluorescent probe NFP-G, with β- d -galactose as the targeted unit and hydrazine as the recognition group for formaldehyde (FA), was designed and synthesized for specifically detecting endogenous FA in HepG-2 cells via asialoglycoprotein receptor-mediated endocytosis. The experimental results show that probes NFP-G/NFP-A exhibited highly fluorescent responses toward FA, which could be ascribed to the restriction of the photoinduced electron transfer (PET) process by the formation of hydrazone. Good selectivity and competition of NFP-G toward FA over potentially interfering species ensure it an appropriate candidate for FA detection. The sensing mechanism of the probes toward FA was studied by theoretical calculation, high performance liquid chromatography and mass spectrum. The confocal bioimaging results reveal that NFP-G could selectively visualize the endogenous FA in asialoglycoprotein receptor overexpressed HepG-2 cells over other cells. Pretreated with β-galactosidase made both asialoglycoprotein receptor positive and negative cells display strong green fluorescence, revealing β- d -galactose is essential in targeting HepG-2 cells.

Silicon (Si) is a promising anode material for lithium-ion batteries (LIBs) owing to its very high lithium storage capacity; however, fragmentation of Si caused by drastic volume change during lithium insertion and extraction leads to serious capacity decay during cycling. In this work, we report a novel method to synthesize an in situ nanocomposite containing Si nanoparticles evenly embedded in an electrically conductive SiOx@C network (Si/SiOx@C) from one single polysiloxane precursor. In our process, Si nanocrystals were reduced from the polysiloxane precursor using a low temperature molten salt reduction method, and carbon segregated out in the SiOx@C phase which evolved during the subsequent pyrolysis. As an anode material for LIBs, the Si/SiOx@C nanocomposite showed a specific capacity up to 1292 mA h g−1 at a current density of 0.4 A g−1 and 81.84% capacity retention after 200 cycles. The high capacity and stable performance of Si/SiOx@C as an anode material can be attributed to the continuous SiOx@C matrix which provides reliable mechanical support, electronic and ionic conductivity, and a stable solid–electrolyte interphase (SEI). This work demonstrated the viability of deriving a homogenous nanocomposite from a single polymeric precursor, which creates a promising anode material for next-generation LIBs.

The development of advanced Li 4 Ti 5 O 12 anode with high capacity and long cycle-life is a central issue for rechargeable Li-ion batteries. In this study, we report that a novel composite, nanosized Li 4 Ti 5 O 12 particles supported by N-doped graphene sheets, has been successfully prepared by a facile and rapid strategy. Compared to the pure Li 4 Ti 5 O 12 anode, improved electronic conductivity, higher flexibility and enhanced mechanical strength are demonstrated in N-doped graphene modified Li 4 Ti 5 O 12 . When used as anode materials for Li-ion batteries, the specific discharge capacities of the pure and N-doped graphene modified Li 4 Ti 5 O 12 electrodes for the first cycle at a current density of 0.5 C between 1.0 and 2.5 V (vs. Li + /Li) are 163.6 and 171.2 mA h g −1 , respectively, and their capacity retentions over 100 cycles are 96.1% and 99.3%, respectively. Moreover, the high-rate capacities of N-doped graphene decorated anode are also much better than that of the pure Li 4 Ti 5 O 12 at various current densities. Even at 40 C, it can still achieve a high reversible capacity of 136.9 mA h g −1 and tolerate a long-term cycling with 1000 cycles. This design strategy provides a promising pathway for developing high-performance Li 4 Ti 5 O 12 anode for Li-ion batteries.

Valerate esters (VAEs) commonly derived from levulinic acid (LA), which is deemed as one of the most promising biomass platform molecules, have been hailed as "valeric biofuels" in recent years. The cascade transformation of LA to VAEs consists of a series of acid- and metal-catalyzed processes alternately, in which heterogeneous bifunctional catalysts are required for better catalytic performance. The transformation pathway from LA to VAEs is presented, and bifunctional catalytic systems for the cascade transformation of LA into valeric acid (VA) and its esters, as well as one-pot conversion processes, are reviewed. Additionally, effects of metal and acid sites on the catalytic performance are discussed in detail. Impacts of and improvements to coke deposition, which is determined to be the primary reason for the reduction in catalytic activity, are also analyzed. Finally, feasible suggestions are proposed for enhanced catalytic performance and a reduction in overall costs.

2D semiconductors are promising candidates for future electronic device applications due to their immunity to short-channel effects (SCE), but many issues regarding mobility, contact, interface and power consumption still remain (Fig. 1). We develop a low-field model to calculate the mobility of monolayer MoS 2 FETs. Guided by the model, high carrier mobility of 150 cm2/Vs and saturation current over $450 \mu \mathrm{A}/\mu \mathrm{m}$ are realized in long-channel monolayer MoS 2 FETs, through a series of interface optimization by high- $\boldsymbol{\kappa}$ dielectric and thiol chemical treatment. For low-power applications, we demonstrate hysteresis-free MoS 2 negative capacitance FETs (NCFETs) using ferroelectric HtZrO x (HZO) as gate dielectric, achieving sub-60m V/dec subthreshold slope (SS) over 6 orders of I D , minimum SS of 24 mV/dec and 107 on/off ratio under $V_{dd}=0.5\mathrm{V}$ . We further study the high frequency performance and show that sub-60mV/dec is maintained at least to 10 kHz without signs of degradation. Finally, by performing different gate sweeps we conclude that the steep slope is indeed due to NC effects rather than ferroelectric switching of HZO.

Single-atomic-layered materials are important for future electronics. They allow optoelectronic devices to be fabricated at the single-atomic layer level. A single-atomic-layered two-dimensional (2D) transition metal dichalcogenide (TMD) film is usually composed of randomly orientated single-crystalline domains, and the size distribution of the domains on a large-area film has a significant impact on the applications of the film, but the impact is difficult to characterize. We report an approach to evaluate the size of the single-crystalline domains by measuring the second-harmonic generation divergence caused by the domains of different orientations. Using this method, domain size mapping on an 8 × 8 m m 2 region of a continuous M o S 2 film is achieved. This method provides a fast and efficient way of domain size characterization across a large area in a non-destructive and transfer-free manner for single-atomic-layered TMD films.

Fast hole hopping in Ti17cat4, a 1 nm diameter molecular polyoxotitanate cluster bearing four catechol ligands (Ti17(μ4-O)4(μ3-O)16(μ2-O)4(cat)4(OPri)16), was investigated by ultrafast spectroscopy and quantum dynamics simulations. The catechol moieties coupled to the TiO2 core of the cluster give rise to a charge-transfer band, the excitation of which promotes an electron from the highest occupied molecular orbital of the ligand to the inorganic core, resulting in the formation of {cat+•,Ti3+}, a vibrationally hot polaronic exciton. Dynamic depolarization measurements indicate that within less than 100 fs the Franck–Condon polaronic state formed at the interface evolves into a fully charge-separated state and the injected electron delocalizes over the quasi conduction band of the cluster. The positive charge (hole) resulting from the injection does not remain static either. The initial hole hopping between the catechol sites occurs with the rate of ∼5 × 1011 s–1 or more and competes with the intramolecul...

In this study, nitrogen-doped carbon is coated on LiVPO 4 F electrode for the first time via a simple chemical refluxing process, using ethylenediamine (EDA) as the carbon and nitrogen source. The structure, morphology and microstructure of the as-prepared electrode are characterized by XRD, XPS, Raman spectra, SEM and TEM. The uniform coating of nitrogen-doped carbon improves the electronic conductivity of LiVPO 4 F. As cathode material for lithium-ion batteries, the nitrogen-doped carbon coated LiVPO 4 F composite exhibits superior rate capability and excellent cycle performance over the carbon coated LiVPO 4 F. The electrode delivers an initial discharge capacity of 109.6 mAh g − 1 at high rate of 10 C and 103.1 mAh g − 1 of capacity is retained after 100 cycles. Thus, this novel modification method of nitrogen-doped carbon coating is highly effective and could be widely used to optimize the electronic conductivity of other electrode materials for lithium-ion batteries.

In this paper, we report a novel high-speed white light interferometry (WLI) demodulation algorithm for multiplexed low-finesse Fabry–Perot interferometers (FPIs). The dependence of the demodulation speed on the number of multiplexed sensors was characterized through simulations. An experimental demonstration of 70-kHz real-time WLI demodulation of two extrinsic FPIs was conducted. Sub-nanometer spatial resolution was well achieved for both channels. The crosstalk between the two channels was characterized with respect to the cavity modulation frequency.

The reasonable and effective use of lignocellulosic biomass is an important way to solve the current energy crisis. Cellulose is abundant in nature and can be hydrolyzed to a variety of important energy substances and platform compounds—for instance, glucose, 5-hydroxymethylfurfural (HMF), levulinic acid (LA), etc. As a chemical linker between biomass and petroleum processing, LA has become an ideal feedstock for the formation of liquid fuels. At present, some problems such as low yield, high equipment requirements, difficult separation, and serious environmental pollution in the production of LA from cellulose have still not been solved. Thus, a more efficient and green catalytic system of this process for industrial production is highly desired. Herein, we focus on the reaction mechanism, pretreatment, and catalytic systems of LA from cellulose and cellulosic biomass, and a series of existing technologies for producing LA are reviewed. On the other hand, the industrial production of LA is discussed in depth to improve the yield of LA and make the process economical and energy efficient. Additionally, practical suggestions for the enhancement of the stability and efficiency of the catalysts are also proposed. The use of cellulose to produce LA is consistent with the concept of sustainable development, and the dependence on fossil resources will be greatly reduced through the realization of this process route.

Hierarchical micro/nanostructure surface structures with different spatial characteristics are achieved after irradiation of crystalline silicon via femtosecond (fs) laser pulses (800 nm, 120 fs, 1 kHz) with the sample submerged in ethanol. According to laser pulse energy and fabrication parameters (such as scanning speed and superimposed writing), a characteristic morphology evolution of ovoid-like smooth modified area, ripple-like, wave-like, and coral-like micro/nanostructures is demonstrated, and the underline principle is discussed. The amorphization of fs laser-modified area is verified and investigated by Raman spectroscope. These modified structures have potential applications in sensors, silicon photovoltaic cells, and sterilization.

The viable Li metal anodes (LMAs) are still hampered by the safety concerns resulting from fast Li dendrite growth and huge volume expansion during cycling. Herein, carbon nanofiber matrix anchored with MgZnO nanoparticles (MgZnO/CNF) is developed as a flexible triple-gradient host for long cycling LMAs. The superlithiophilic MgZnO nanoparticles significantly increase the wettability of CNF for fast and homogeneous infusion with molten Li. The in-built potential and lithiophilic gradients constructed after an in situ lithiation of MgZnO and CNF enable nearly zero Li nucleation overpotential and homogeneous deposition of lithium at different scales. As such, the LMAs based on MgZnO/CNF achieve long cycling life and small overpotential even at a record-high current density of 50 mA cm-2 and a high areal capacity of 10 mAh cm-2 . A full cell paring with this designed LMA and LiFePO4 exhibits a capacity retention up to 82% after 600 cycles at a high rate of 5 C. A Li-ion capacitor also shows an impressive capacity retention of 84% at 5 A g-1 after 10 000 cycles. Such a Li@MgZnO/CNF anode is a promising candidate for Li-metal energy storage systems, especially working under ultrahigh current density.

Parallel-connected lithium-ion cells are extensively applied in electric vehicles to satisfy the capacity and power capability. However, unavoidable cell-to-cell parameter variations lead to inhomogeneous current and state-of-charge distributions, causing early degradation of the cells. Therefore, knowledge of correlations of the parameter variations on current and state-of-charge distributions is crucial for improving these inhomogeneities. In order to clearly analyze the correlations, this paper provides a simplified analytical circuit model consisting of a resistance and a capacitance in series, and the capacitance is a function of capacity and open circuit voltage slope. Using the two parallel-connected cells analytical model, the current and state-of-charge distributions are theoretically investigated by varying cell parameters. For a large number of parallel-connected cells with Gaussian distributed parameters, a Laplace transform-based approximate analytical model is proposed based on the simplified analytical circuit model and validated by the simulation. Then the model is utilized to deduce mathematical correlations of the standard deviation and mean value of the cell parameters on maximum differences of current rate and state-of-charge. Results verify that decreasing the deviation of the product of cell resistance and capacity can effectively reduce the inhomogeneities, which is helpful for optimal screening approach for parallel-connected new and retired batteries.

To realize steep-slope MoS2 n-type FET, we fabricate negative capacitance FET (NCFET) structure using ferroelectric HfZrOx (HZO)/AlOx as dielectric layer. The MoS2 NCFET devices exhibit ultra-low subthreshold swing (SS) of 23 mV/dec, sub-60mV/dec over 6 orders of Id, nearly hysteresis-free up to V ds = 1V, small |V th | on /I off ratio >109, and small DIBL of 25 mV/V. Importantly, we can modulate 5 orders of Id using a gate drive of 232 mV, clearly demonstrating the potential of MoS2 NCFET for low-power electronics applications. Furthermore, compared to normal MoS 2 FET with 11.2 nm equivalent oxide thickness (EOT), the NCFET achieve 60% improvement in Id (250 μA/μm) and 4 times improvement in transconductance.

Transition-metal dichalcogenides (TMDCs) are important class of two-dimensional (2D) layered materials for electronic and optoelectronic applications, due to their ultimate body thickness, sizable and tunable bandgap, and decent theoretical room-temperature mobility of hundreds to thousands cm2/Vs. So far, however, all TMDCs show much lower mobility experimentally because of the collective effects by foreign impurities, which has become one of the most important limitations for their device applications. Here, taking MoS2 as an example, we review the key factors that bring down the mobility in TMDC transistors, including phonons, charged impurities, defects, and charge traps. We introduce a theoretical model that quantitatively captures the scaling of mobility with temperature, carrier density and thickness. By fitting the available mobility data from literature over the past few years, we are able to obtain the density of impurities and traps for a wide range of transistor structures. We show that interface engineering such as oxide surface passivation, high-k dielectrics and BN encapsulation could effectively reduce the impurities, leading to improved device performances. For few-layer TMDCs, we analytically model the lopsided carrier distribution to elucidate the experimental increase of mobility with the number of layers. From our analysis, it is clear that the charge transport in TMDC samples is a very complex problem that must be handled carefully. We hope that this Review can provide new insights and serve as a starting point for further improving the performance of TMDC transistors., Comment: 61 pages, 9 figures, Advanced Functional Materials, in press

Terahertz (THz) detection technology is a new security technology, it is play a significant role for social public security in the current situation. In this paper, we propose a new fast recognition algorithm for detection of suspicious objects according to the characteristics of human THz images. The algorithm consists of the following steps: (1), Smoothing and using gray stretch algorithm to enhance the terahertz images, (2), Distinguish the suspicious object connected and not connected to the background images. Here, THz images are classified by using our morphological classification algorithm, (3), Extracting a full human body contour by using our Bilateral Contour Tracking Comparison algorithm(BCTC). Finally, the computer can automatically identify and mark the hidden suspicious objects in Terahertz Image. Through a large number of experiments show that the new detection algorithm accuracy is reaching 92%. Our test results show that the new algorithm is quite effective for segmentation and extraction with human body contour and less time-cost.

Highly monodisperse, dendritic, and functionalized mesoporous silica nanospheres (MSNs) with sub-200 nm size were synthesized in a one-pot sol-gel reaction, by a dual-templating micelle system consisting of a partially fluorinated short-chain anionic fluorocarbon surfactant and cetyltrimethylammonium bromide. This kind of anionic fluorocarbon surfactant works simultaneously as a swelling agent to enlarge the pore of the MSNs, an ion-pair agent to the structure-directing silane in the preparation of amine-functionalized MSNs, and a surface tension reducing agent to make the system thermodynamically more stable for producing more uniform MSNs. The particle size and the morphology of the resultant MSNs can be fine-tuned by changing the amount of the fluorocarbon surfactant added and the ratio of the functional group containing organosilane to tetraethoxysilane. Subsequently, the as-prepared MSNs were used as base materials for the preparation of drug delivery nanomaterials through the surface grafting of a pH-sensitive drug-conjugated polymer and fluorescent nanomaterials through the embedding of europium(III) complex or the immobilization of large molecule fluorescein isothiocyanate-bovine serum albumin.

The growing demand for high-performance logic transistors has driven the exponential rise in chip integration, while the transistors have been rapidly scaling down to sub-10 nm. The increasing leakage current and subthreshold slope (SS) induced by short channel effect (SCE) result in extra heat dissipation during device operation. The performance of electronic devices based on two-dimensional (2D) semiconductors such as the transition metal dichalcogenides (TMDC) can significantly reduce power consumption, benefiting from atomically thin thickness. Here, we discuss the progress of dielectric integration of 2D metal–oxide–semiconductor field effect transistors (MOSFETs) and 2D negative capacitance field effect transistors (NCFETs), outlining their potential in low-power applications as a technological option beyond scaled logic switches. Above all, we show our perspective at 2D low-power logic transistors, including the ultra-thin equivalent oxide thickness (EOT), reducing density of interface trap, reliability, operation speed etc. of 2D MOSFETs and NCFETs.

A window-based battery parameter identification method can directly apply the historical battery operating data to observe the battery parameters and running states. However, the design principles of a parameter identification window remain unclear. In this study, two factors that affect the performance of a battery parameter identification algorithm are considered: characteristics of the parameter identification window and action mechanism of the historical data. Our aim is to understand the effects of the historical data application methods on the algorithm performance, including three perspectives: (1) the effect of a slow dynamic fluctuation in the parameter identification window on the battery identification results, (2) the effect of the parameter identification window length on the identification results, and (3) the difference in demand for the fractional- and integer-order equivalent circuit model for the parameter identification window. The battery parameters and states are simultaneously identified based on the coevolutionary particle-swarm optimization algorithm. A comparison of the results shows that the combination of a fractional-order equivalent circuit model and a linear approximation method can achieve more stable and consistent identification results. In addition, a linear approximation method has an advantage in terms of ensuring stationarity of the identification results.

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) have attracted enormous interests as the novel channel materials for atomically thin transistors. Despite considerable progress in recent years, the transistor performance is largely limited by the excessive contact resistance at the source/drain interface. In this review, a summary of recent progress on improving electrical contact to TMDC transistors is presented. Several important strategies including topology of contacts, choice of metals and interface engineering are discussed.

Just as biological synapses provide basic functions for the nervous system, artificial synaptic devices serve as the fundamental building blocks of neuromorphic networks; thus, developing novel artificial synapses is essential for neuromorphic computing. By exploiting the band alignment between 2D inorganic and organic semiconductors, the first multi-functional synaptic transistor based on a molybdenum disulfide (MoS2 )/perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) hybrid heterojunction, with remarkable short-term plasticity (STP) and long-term plasticity (LTP), is reported. Owing to the elaborate design of the energy band structure, both robust electrical and optical modulation are achieved through carriers transfer at the interface of the heterostructure, which is still a challenging task to this day. In electrical modulation, synaptic inhibition and excitation can be achieved simultaneously in the same device by gate voltage tuning. Notably, a minimum inhibition of 3% and maximum facilitation of 500% can be obtained by increasing the electrical number, and the response to different frequency signals indicates a dynamic filtering characteristic. It exhibits flexible tunability of both STP and LTP and synaptic weight changes of up to 60, far superior to previous work in optical modulation. The fully 2D MoS2 /PTCDA hybrid heterojunction artificial synapse opens up a whole new path for the urgent need for neuromorphic computation devices.

We present, for the first time to our knowledge, a sapphire-fiber-based distributed high-temperature sensing system based on a Raman distributed sensing technique. High peak power laser pulses at 532 nm were coupled into the sapphire fiber to generate the Raman signal. The returned Raman Stokes and anti-Stokes signals were measured in the time domain to determine the temperature distribution along the fiber. The sensor was demonstrated from room temperature up to 1200°C in which the average standard deviation is about 3.7°C and a spatial resolution of about 14 cm was achieved.

Two-dimensional transition-metal dichalcogenides (TMDs) represent a promising class of materials for electronic and photonic devices, benefiting from their sizable bandgap of 1–2eV and ultrathin body. However, one of the major issues is that the experimental mobility is much lower than the theoretical phonon limit. We carry out systematic investigations on the electron transport and field-effect transistors of monolayer TMDs, including MoS 2 and WS 2 . We find that the major extrinsic mobility limiting factors are charged impurities, traps and point defects. We develop a facile low-temperature thiol chemistry to repair the sulfur vacancies and improve the interface quality, resulting in significant reduction of the charged impurities and traps. In combination with high-k dielectrics, we are able to achieve room-temperature mobility of ∼150cm2/Vs and 83cm2/Vs for monolayer MoS 2 and WS 2 , respectively. We further develop a theoretical model to quantitatively correlate these extrinsic scattering sources to measured electrical data. Our study shows that interface engineering is critical for high-performance transistors based on 2D semiconductors.

We demonstrate a highly sensitive and stable fiber-optic Fabry–Perot cantilever microphone based on fast demodulated white-light interferometry. The cavity length of the low-finesse Fabry–Perot interferometry is absolutely measured by realizing a high-speed demodulation method utilizing a full spectrum, with the advantages of both high resolution and large dynamic range. An acoustic test demonstrates high sensitivities and linear responsivities at frequencies below 2 kHz. The pressure responsivity and the noise-limited minimum detectable acoustic pressure level are measured to be 211.2 nm/Pa and 5 μPa/Hz1/2, respectively, at the frequency of 1 kHz. Comparative experimental results show that the signal-to-noise ratio is over 10 times higher than a reference condenser microphone.

Phase transitions of electron-hole pairs on semiconductor/conductor interfaces determine fundamental properties of optoelectronics. To investigate interfacial dynamical transitions of charged quasiparticles, however, remains a grand challenge. By employing ultrafast mid-infrared microspectroscopic probes to detect excitonic internal quantum transitions and two-dimensional atomic device fabrications, we are able to directly monitor the interplay between free carriers and insulating interlayer excitons between two atomic layers. Our observations reveal unexpected ultrafast formation of tightly bound interlayer excitons between conducting graphene and semiconducting MoSe

By combining a high-κ dielectric substrate and a high density of charge carriers, Coulomb impurities in MoS2 can be effectively screened, leading to an unprecedented room-temperature mobility of ≈150 cm(2) V(-1) s(-1) and room-temperature phonon-limited transport in a monolayer MoS2 transistor for the first time.

There have been many intensive studies in the field of carbon capture and storage (CCS), and a large number of studies have delved into developing energy efficient approaches for heat duty reductions of post-combustion CO2 capture processes under pilot plant scale. This research implemented practical applications of amine regeneration to conduct an energy efficient method based on theoretical reaction energy estimation. The reaction energy calculations was completed on a conventional monoethanolamine (MEA)-based amine scrubbing process, in order to verify that there was a huge deviation of the reaction energy (18.69 kJ/mol CO2/425 kJ/kg CO2) comparing to the overall energy cost (1,300 kJ/kg CO2) including the heat duty and work of CO2 compressing and transportation. Then, two common terms were explained in detail here: 'energy distribution' and 'energy efficiency'. Catalytic amine regeneration was as another practical, beneficial and energy efficient methodology. [Received: October 7, 2015; Accepted: Mach 11, 2016]

The electrical and optical measurements, in combination with density functional theory calculations, show distinct layer-dependent semiconductor-to-semimetal evolution of 2D layered PtSe2 . The high room-temperature electron mobility and near-infrared photo-response, together with much better air-stability, make PtSe2 a versatile electronic 2D layered material.

In this letter, spin valve transistors are fabricated based on BiSbTeSe2 topological insulator (TI) with enhanced surface mobility ( $\sim 4039$ cm $^{2}\text{V}^{-1}\text{s}^{-1})$ . The output in our spin valve transistors exhibits a dominant steplike behavior when sweeping the magnetic field to change the magnetization orientation of the Ni21Fe79 electrode. Most importantly, the ON (low resistance)–OFF (high resistance) state can be even switched when reversing the direction of the dc current. The TI-based spin valve transistors enable the current-direction-dependent switching of ON–OFF state, allowing for the applicability in magnetic sensors and spin-logic circuits, and show the potential use of TIs as innovative current-driven spin generators.