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In the present study, we have prepared glutathione capped gold and platinum alloy nanoclusters (Au-PtNCs) in a controlled way by employing the hydrothermal method and optimized through adjusting the ratio of raw materials, reaction temperature, and time. Compared with the corresponding monometallic gold and platinum nanoclusters, the alloy nanoclusters' catalytic activity is improved dramatically in the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2. And the maximum velocity is calculated to be 106 × 10−8 M∙s−1 for TMB as substrate, being much better than that of other reported metallic nanoclusters and nanoparticles. Further study shows that the high catalytic activity mainly attributes to the synergistic effect of gold and platinum. Besides, they have been applied to determine H2O2 in the presence of TMB, which shows high sensitivity with a limit of detection (LOD) at 100 nM. The proposed method has been used to determine H2O2 in milk and contact lens solutions, which shows very good recovery and exhibits high practical application potential. Therefore, the present study provides a new type of alloy nanoclusters with high peroxidase-like activity, which will inspire more research interests on doping and alloying with Pt to improve the catalytic activity of metal nanoclusters.

Ultrasonic fatigue tests are performed on a magnesium alloy with and without ultrasonic peening treatment (UPT). Surface enhancement layer leads to the complete change of crack initiation sites. However, crack initiation mechanism keeps the same and results in a single-faceted morphology at crack initiation site. Microcracks initiate as Mode II crack within the original grain, but deflect to Mode I crack outside of the original cracked grain. A threshold SIF value is proposed to evaluate the retarding effect of grain boundary on microcrack propagation. Outside of the original cracked grain, Mode I crack propagation below the threshold ΔKσ-th is responsible for the formation of fine granular area (FGA, a nanograin layer). Based on the Numerous Cyclic Pressing (NCP) model, it is proposed that crack type should be another necessary condition for the formation of FGA.

High density and uniform distribution of the gold nanoparticles functionalized single-stranded DNA modified reduced graphene oxide nanocomposites were obtained by non-covalent interaction. The positive gold nanoparticles prepared by phase inversion method exhibited good dimensional homogeneity and dispersibility, which could readily combine with single-stranded DNA modified reduced graphene oxide nanocomposites by electrostatic interactions. The modification of single-stranded DNA endowed the reduced graphene oxide with favorable biocompatibility and provided the preferable surface with negative charge for further assembling of gold nanoparticles to obtain gold nanoparticles/single-stranded DNA modified reduced graphene oxide nanocomposites with better conductivity, larger specific surface area, biocompatibility and electrocatalytic characteristics. The as-prepared nanocomposites were applied as substrates for the construction of cholesterol oxidase modified electrode and well realized the direct electron transfer between the enzyme and electrode. The modified gold nanoparticles could further catalyze the products of cholesterol oxidation catalyzed by cholesterol oxidase, which was beneficial to the enzyme-catalyzed reaction. The as-fabricated bioelectrode exhibited excellent electrocatalytic performance for the cholesterol with a linear range of 7.5–280.5 µmol·L−1, a low detection limit of 2.1 µmol·L−1, good stability and reproducibility. Moreover, the electrochemical biosensor showed good selectivity and acceptable accuracy for the detection of cholesterol in human serum samples.

Atomistic exploration of Li+ diffusion behaviors in electrodes of lithium-ion batteries (LIBs) has been documented to be an effective strategy to uncover Li+ storage mechanisms and to guide the design of promising electrode materials. In this work, we prepared two different types of SnO2 nanorods-graphene hybrids with anchored (A-SnG) and sandwiched (S-SnG) structures, investigated their electrochemical performances and unveiled the Li+ diffusion behaviors at atomic level. The Li+ diffusion behaviors of two SnO2-G hybrids during lithification were analyzed by in situ transmission electron microscopy. It is noted that Li+ orientation-dependently intercalated into crystal planes of SnO2 and induce anisotropic volume expansion upon the lithiation process. We assume that dislocations inside SnO2 nanorods provide effective channels for Li+ diffusion. In addition, graphene matrix accelerates the electron transfer, which can promote the electrochemical reaction kinetics. These merits in the SnO2 nanorods-graphene hybrids during lithiation process give clues to thoroughly regulate the Li+ diffusion behaviors and thus to get clear insight into advanced electrode material design.

The gate and drain bias dependence of hot electron-induced degradation in GaN-based metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) was investigated in this work. Devices exhibit an abnormal increase in peak transconductance ( ${G}_{m}$ ,max) during hot carrier stress (HCS) and a partially quick recovery of that after removing the electrical stress. A physical model is proposed to explain the abnormal electrical characteristics caused by HCS. By using density functional theory (DFT), we calculated the energy for electrons to dehydrogenate preexisting [NGaH3]−1 complexes in GaN layer during stress. The dehydrogenation of defects affects the Gm,max of devices. Meanwhile, the neutralization of donor traps in AlGaN barrier layer also plays a significant role in the increase of Gm,max and the detrapping effect of electrons from these traps after removing the electrical stress accounts for the partially quick recovery of ${G}_{m, \text{max}}$ .

A monolithic bidirectional switch based on anti-paralleled two reverse blocking p-GaN HEMTs has been proposed and demonstrated in this work. The recessed Schottky drain technique is utilized to effectively reduce the on-state voltage and thus lowering the power loss of bidirectional switches. A significant reduction in parasitic elements and switch area is obtained by monolithic integration. The fabricated bidirectional switch exhibits a threshold voltage of ~1.85 V, on-state voltage of ~0.63 V, and the forward and reverse off-state breakdown voltages of ~650 V at ${I}_{{\text {S1}-\text {S2}}} = 1\,\,\mu \text{A}$ /mm. In addition, the function of proposed bidirectional switch as an AC power chopper has been successfully verified.

Copper interconnect electroplating is one of the core technologies for the manufacture of high-end electronic devices including but not limited to chips. To promote the development of advanced copper interconnect process, it is necessary to clarify the mechanisms of copper electroplating additives. Herein, we provide a brief overview of the research progress on the interfacial structures and mechanisms of the three types of additives (accelerator, suppressor and leveler) in copper sulfate plating baths from a methodological perspective. Besides, the advantages and limitations of different research methods are discussed and the scientific issues related to the Damascene copper electroplating are summarized, to afford a hint for the further research and development of the additives in advanced chip fabrication.

Direct optical probing of the antiferromagnetic order parameter in atomically thin samples is challenging, for example, via magneto-optical spectroscopy, due to the lack of net magnetization. Here, we report zigzag-antiferromagnetism (AFM) induced optical linear dichroism (LD) in layered transition-metal thiophosphate FePS3 down to the monolayer limit. The observed LD is giant despite having the optical wave vector parallel to the Neel vector. The LD is at least one order of magnitude larger than those reported in other antiferromagnetic systems, where the optical wave vector is orthogonal to the Neel vector. The large LD enables the probe of 60° orientated zigzag-AFM domains. The optical anisotropy in FePS3 originates from an electronic anisotropy associated with the zigzag direction of the AFM order and is independent of the spin-pointing direction. Our findings point to a new optical approach for the investigation and control of zigzag or stripe magnetic order in strongly correlated systems.

Purpose The purpose of this paper is to establish an accurate model to quantify the effect of conductor roughness on insertion loss (IL) and provide improved measurements and suggestions for manufacturing good conductive copper lines of printed circuit board. Design/methodology/approach To practically investigates the modified model of conductor roughness, three different kinds of alternate oxidation treatments were used to provide transmission lines with different roughness. The IL results were measured by a vector net analyzer for comparisons with the modified model results. Findings An accurate model, with only a 1.8% deviation on average from the measured values, is established. Compared with other models, the modified model is more reliable in industrial manufacturing. Originality/value This paper introduces the influence of tiny roughness structures on IL. Besides, this paper discusses the effect of current distribution on IL.

Wire based plasma transferred arc (PTA)-laser hybrid additive manufacture has the potential to build large-scale metal components with high deposition rate and near-net shape. In this process, a single bead is the fundamental building block of each deposited component, and thus the bead shape control is essential for the deposition of different geometries. However, how to control the bead shape by manipulating various process parameters is still not understood. In this study, the effect of different process parameters, including laser power, energy distribution between the PTA and laser, wire feed speed, travel speed, and laser beam size on the deposition process and bead shape was investigated systematically. The results show that the optimum operating regime for the hybrid process is with the wire being fully melted by the PTA and the melt pool being controlled by the laser, which gives a good bead shape as well as a stable deposition process. The bead shape is significantly affected by the laser power and travel speed due to the large variation in energy input. The effect of wire feed speed is more complex with the bead width initially increasing to a maximum and then decreasing as the wire feed speed increases. The laser beam size has a minor effect on the bead shape, but a small beam size will result in an irregular bead appearance due to the unstable process caused by the high power density. In addition, a procedure for controlling the bead shape in the hybrid process was proposed, which provided a reference for selection of different process parameters to achieve required bead shapes. The feasibility of this proposed procedure was demonstrated by the two deposited multi-layer single-pass walls.

Frontal ring-opening metathesis polymerization was used to in situ prepare polydicyclopentadiene (PDCPD)/carbon nanotubes (CNTs) and PDCPD/CNT-NH2 composites with high glass transition temperature. Compared with PDCPD/CNT composites, PDCPD/CNT-NH2 composites have similar dielectric constants, but their loss tangent significantly reduces. The uniform dispersion of CNT-NH2 leads to the formation of dielectric interfacial polarization. The results of dynamic mechanical analysis (DMA) showed that the glass transition temperature (Tg) of the composites increased with the increase of filler. With the increase of the filler, the elongation at break of the PDCPD/CNT composites decreased, while the elongation at break of PDCPD/CNT-NH2 composites increased, reaching up to 17% because of the stronger interfacial affinity. The PDCPD/CNT-NH2 composites exhibited high dielectric permittivity (47.5 at a frequency of 100 Hz) that originates from the interfacial polarization between PDCPD and CNT-NH2, and the nonconducting –NH2 groups can prevent the conductive path of CNTs and support a low loss tangent (0.096). High Tg PDCPD/CNT-NH2 composite with enhanced dielectric properties was prepared by a simple and quick one-step reaction method of FROMP. Keywords: Polydicyclopentadiene; Composites; Carbon nanotubes; Dielectric properties, Interfacial polarization

Embedded resistors in printed circuit boards (PCBs) are fabricated to provide high integration, improved electrical performance, and reduced parasitic capacitance and inductance in the high-frequency and high-speed environment. At present, the embedded resistance errors caused by etching metal film accuracy are generally more than 20%. In this work, real-time monitoring technology is developed to precisely control the resistance of electroless-plated embedded resistors. During the deposition process, the resistances of embedded resistors are monitored until reaching the targeted resistance, realizing the very ideal resistance error lower than 10%. Arbitrary shapes including serpentine and zigzag structures of embedded resistors are attempted to validate the practical capability of this approach. Reliability Characterization experiments such as high-temperature and high-pressure lamination, thermal shock and thermal cycles confirm the thermal and mechanical stability. It is demonstrated that the embedded resistors through real-time monitored electroless plating have tremendous potential in the manufacture of high-frequency and high-speed PCBs.

Heterobilayers of transition metal dichalcogenides (TMDCs) can form a moiré superlattice with flat minibands, which enables strong electron interaction and leads to various fascinating correlated states. These heterobilayers also host interlayer excitons in a type-II band alignment, in which optically excited electrons and holes reside on different layers but remain bound by the Coulomb interaction. Here we explore the unique setting of interlayer excitons interacting with strongly correlated electrons, and we show that the photoluminescence (PL) of interlayer excitons sensitively signals the onset of various correlated insulating states as the band filling is varied. When the system is in one of such states, the PL of interlayer excitons is relatively amplified at increased optical excitation power due to reduced mobility, and the valley polarization of interlayer excitons is enhanced. The moiré superlattice of the TMDC heterobilayer presents an exciting platform to engineer interlayer excitons through the periodic correlated electron states., Heterobilayers of transition metal dichalcogenides host moiré superlattices that give rise to strong electron interactions. Here, the authors study the photoluminescence from interlayer excitons in a WS2/WSe2 heterobilayer to reveal the onset of various correlated insulating states.

In this paper, quaternary oxide semiconductor was applied as sensing material for the fabrication of gas sensors. One-step solvothermal method was utilized to synthesize the sensing material. Various characterization methods including XRD, XPS, SEM, HRTEM were employed to analyze the composition and structure of the sensing material. Composite composed of CuInW2O8 and CuWO4 was successfully prepared at last characterized by XRD result. The SEM result revealed the structure of the sensing material: nanoparticles assembled spindle-like nanostructure with ~200 nm long axis and ~60 nm short axis. Sensor based on the spindle-like nanostructures was systemically tested to acquire the information about the sensing properties. The sensor exhibited responses to acetone at the operating temperatures from 190 to 275 °C. The results showed that the sensor was more sensitive to acetone compared with other gases at the optimal operating temperature of 210 °C. The response of the sensor was also tested under the relative humidity from 25 RH% to 95 RH% at the operating temperature of 210 °C. The response variation was only 13.9%, demonstrating that the sensor possessed strong anti-humidity ability. It was worth noting that the sensor showed acceptable long-term stability compared with other acetone sensors. The gas sensing mechanism was also discussed here. This work might provide ideas for the development of novel sensitive materials for the application of gas sensors.

Conductive polymer direct electroplating technology is one of the research hotspots in printed circuit board manufacturing. In this work, we designed a simple, efficient and environmental friendly chemical polymerization method to form a conductive polymer-based metal-mixed composite film where the polymer was polythiophene and the metals included copper and silver (PT-based Cu/Ag composite film). The work function of the PT-based Cu/Ag composite film decreased from 4.822 eV of pure PT to 4.638 eV, which serves as a seed layer to prepare conductive circuits by the additive process. The method without the metal etching and photolithography steps solves the problems of conventional subtractive processes for forming conductive patterns. Besides, the PT-based Cu/Ag composite film is able to increase the roughness of the substrate to improve the bonding force between the electroplated copper layer and the substrate. Moreover, due to the particularity of oxidation solution for preparing the PT-based Cu/Ag composite film, conductive lines and patterns can be selectively formed on insulating substrate with arbitrary shapes by the additive process.

In this article, the AlGaN barrier fully removed recessed-gate normally off AlGaN/GaN high electron mobility transistors (HEMTs) with N2O plasma treatment are fabricated. The low speed and low damage etching is used in recessed-gate etching, the etching depth is about 26 nm with 0.4 nm remaining, and then, the remaining barrier layer is oxidized by N2O plasma treatment. In the terms of devices’ characteristics, the threshold voltage of the recessed-gate HEMT is +1.5 V, and the channel current of recessed-gate HEMTs at $V_{\mathrm {GS}} - V_{\mathrm {TH}} = 1.5$ V is about 110 mA/mm. Moreover, 14 mV/V of drain-induced barrier lowering (DIBL) and 70 mV/decade of subthreshold slope (SS) are achieved. More importantly, the fully recessed-gate HEMT shows the average breakdown electric field at $V_{G}= 0$ V of about 0.64 MV/cm, which is a very high value in the fully normally off recessed-gate HEMTs without metal insulator semiconductor (MIS) structure, which will be beneficial to the application of this device in the low power supply topology circuit.

Elucidating the dynamic couplings of hydrogen bonds remains an important and challenging goal for spectroscopic studies of bulk systems, because their vibrational signatures are masked by the collective effects of the fluctuation of many hydrogen bonds. Here we utilize size-selected infrared spectroscopy based on a tunable vacuum ultraviolet free electron laser to unmask the vibrational signatures for the dynamic couplings in neutral trimethylamine-water and trimethylamine-methanol complexes, as microscopic models with only one single hydrogen bond holding two molecules. Surprisingly broad progression of OH stretching peaks with distinct intensity modulation over ∼700 cm-1 is observed for trimethylamine-water, while the dramatic reduction of this progression in the trimethylamine-methanol spectrum offers direct experimental evidence for the dynamic couplings. State-of-the-art quantum mechanical calculations reveal that such dynamic couplings are originated from strong Fermi resonance between the stretches of hydrogen-bonded OH and several motions of the solvent water/methanol, such as translation, rocking, and bending, which are significant in various solvated complexes commonly found in atmospheric and biological systems.

Cutouts are widely used in ships and offshore structures. Cutouts of big size are used mainly for inspection, passing pipes, and weight reduction. Some cutouts of small size may be used for various purposes, such as water hole in the web of stiffeners. The stiffeners with perforated web are the most commonly adopted structure members in the shipbuilding industry, and they are mainly fabricated by cutting and bending the frame to meet the requirements of desired design configuration. In ship production, the manufacture of the curved stiffener with holes is desirable to perforate first and then to bend the frame. This fabrication procedure is adopted for efficient production because of the layout of the production line. However, structural distortion and damage may occur during cold bending of the frames with perforated web, such as necking, wrinkling, and even crack initiation. This problem should be solved in ship production. In this study, cold bending experiments and finite element simulations were performed to analyze the deformation characteristics of curved frames with cutouts. A fabrication method is proposed to control the deformation in the cutouts during the bending process. In this method, the block cut out during the first step is filled in the hole and afterward the frame is bent. The results show that this method can control well the deformation localized around the hole during the bending process. It offers an important guidance for cold bending steel frames in ship production.

Spectroscopic characterization of clusters is crucial to understanding the structures and reaction mechanisms at the microscopic level, but it has been proven to be a grand challenge for neutral clusters because the absence of a charge makes it difficult for the size selection and detection. Infrared (IR) spectroscopy based on threshold photoionization using a tunable vacuum ultraviolet free electron laser (VUV-FEL) has recently been developed in the lab. The IR-VUV depletion and IR+VUV enhancement spectroscopic techniques open new avenues for size-selected IR spectroscopies of a large variety of neutral clusters without confinement (i.e., an ultraviolet chromophore, a messenger tag, or a host matrix). The spectroscopic principles have been demonstrated by investigations of some neutral water clusters and some metal carbonyls. Here, the spectroscopic principles and their applications for neutral clusters are reviewed.

The effect of gamma ( $\gamma $ )-irradiation on AlGaN-based light-emitting diodes (LEDs) in the short-wavelength ultraviolet (UVC, 210–280 nm) spectral range under electrical stress is characterized by electroluminescence and current–voltage measurement. Different from previous reports that $\gamma $ -irradiation can hardly damage nitride devices, we observe that the optical power decreases and leakage current increases obviously after electrical stress under $\gamma $ -irradiation. To delve into the nature of degradation, variation of defects is studied using temperature-dependent low-frequency noise measurement. After stress, the ~0.78-eV defects attributed to N antisite are generated and lead to device degradation, which is accompanied by a reduction of the intrinsic Ga vacancy with an energy level of ~0.38 eV. The variation of defects after stress in $\gamma $ -irradiated environment is more evident than that in nonirradiated environment, which is well corresponding to the performance degradation behavior. In conclusion, $\gamma $ -irradiation is found to accelerate degradation induced by electrical stress, and the study can help improve irradiation resistance in AlGaN-based UVC LEDs.

Neutral titanium-metal carbonyl complexes with the chemical formula Ti(CO)n (n = 4-7) are produced in the gas phase by the reactions of titanium atoms with carbon monoxide in a pulsed laser vaporization-supersonic expansion source. Their infrared absorption spectra in the carbonyl stretching frequency region are measured by infrared plus vacuum ultraviolet (IR+VUV) two-color ionization spectroscopy based on a tunable VUV free electron laser. Infrared spectroscopy in conjunction with quantum chemical calculations confirm that all of these complexes have unexpected titanium ketenylidene OTiCCO(CO)n-2 structures. Bonding analysis indicates that the OTiCCO core structure can be described by the bonding interactions between a TiO+ cation in the doublet ground state and a doublet ground state of CCO-. The results reveal that the C-O bond breaking and C-C bond formation proceed efficiently in the reactions between laser-vaporized titanium atoms and carbon monoxide.

Photocatalytic reduction of CO2 into value-added chemical fuels is an appealing approach to address energy crisis and global warming. CsPbBr3 quantum dots (QDs) are good candidates for CO2 reduction because of their excellent photoelectric properties, including high molar extinction coefficient, low exciton binding energy, and defect tolerance. However, the pristine CsPbBr3 QDs generally have low photocatalytic performance mainly due to dominant charge recombination and lack of efficient catalytic sites for CO2 adsorption/activation. Herein, we report a new photocatalytic system, in which CsPbBr3 QDs are coupled with covalent triazine frameworks (CTFs) for visible-light-driven CO2 reduction. In this hybrid photocatalytic system, the robust triazine rings and periodical pore structures of CTFs promote the charge separation in CsPbBr3 and endow them with strong CO2 adsorption/activation capacity. The resulting photocatalytic system exhibits excellent photocatalytic activity towards CO2 reduction. This work presents a new photocatalytic system based on CTFs and perovskite QDs for visible-light-driven CO2 reduction, which highlights the potential of perovskite-based photocatalysts for solar fuel applications.

Hollow spherical and hierarchical structures of ammonium tungsten bronze ((NH4)xWO3) were prepared via a two-step hydrothermal method. It was found that the (NH4)xWO3 hollow spherical structure without adding citric acid, while the (NH4)xWO3 hierarchical structure formed when adding citric acid at the second hydrothermal step. Both structures consist of nanorods and nanoparticles with connected frames. The possible formation mechanism of these two (NH4)xWO3 structures was proposed and discussed. The current approach is simple, and can also be applied for the synthesis of other tungsten bronze materials with novel structures.

Developing high-performance electrode materials for energy-storage devices with high energy-power densities, such as sodium ion hybrid capacitors (SIHCs), is of vital importance for applications in electric vehicles and portable electronics. Porous hard carbon is one of the most fascinating anode materials for SIHCs due to the rapid Na+ diffusion. Doping with heteroatoms, such as pyridinic N and thiophene S, may boost both the rate performance and specific capacity. However, it is still very challenging to modulate the content and configuration of N and S dopants efficiently. Furthermore, the trade-off for several storage mechanisms, which is vital for carbon anodes with rapid storage and release of sodium ions, is still scarce. Herein, a simple and efficient method is proposed to regulate the configuration of nitrogen dopants, increase the content of thiophene S, create micropores and adjust the structure of curved graphitic domains of hard carbon. Besides, the evolution mechanism of the structure and component is explored through ex situ XRD and XPS analysis. As-prepared NS-pHC-1.348 (N and S co-doped porous hard carbon with 1.348 g MgCl2 precursor) delivers high reversible capacity (383.9 mA h g−1 at 0.05 A g−1), excellent rate ability (183.2 mA h g−1 at 20 A g−1) and fine cycle stability (287.2 mA h g−1 at 1 A g−1 after 1000 cycles). The ratio of pseudocapacitive behaviors in NS-pHC-1.348 reaches up to 70.19% at 0.2 mV s−1, which could balance the electrochemical kinetics of the cathode and anode in SIHCs. Therefore, SIHCs, assembled from the presodiated NS-pHC-1.348 anode and NPC (N-doped porous carbon) cathode, showed superb power characteristics (92.03 kW kg−1 at 5.98 W h kg−1). This work will contribute to the design of high-performance anodes with tunable multi-active sites and the construction of high-power SIHCs.

The effect of charge on the dihydrogen storage capacity of Sc2–C6H6 has been investigated at B3LYP-D3/6-311G(d,p) level. The neutral system Sc2–C6H6 can store 8H2 with gravimetric density of 8.76 wt %, and one H2 dissociates and bonds atomically on the scandium atom. The adsorption of 8H2 on Sc2–C6H6 is energetically favorable below 155 K. The atom-centered density matrix propagation (ADMP) molecular dynamics simulations show that Sc2–C6H6 can adsorb 3H2 within 1000 fs at 300K. Compared with Sc2–C6H6, the charged systems can adsorb more hydrogen molecules with higher gravimetric density, and all the H2 are adsorbed in the molecular form. The gravimetric densities of Sc2–C6H6+ and Sc2–C6H62+ are 9.75 and 10.71 wt%. Moreover, the maximum adsorption of charged systems are favorable in wider temperature range. Most importantly, the ADMP-MD simulations indicate that Sc2–C6H62+ can adsorb 6 hydrogen molecules within 1000 fs at 300K. It can be found that the gravimetric density (6.72 wt%) of Sc2–C6H62+ still exceeds the target of US Department of Energy (DOE) under ambient conditions.

The use of pesticides together with nano-delivery systems can improve the utilization rate of pesticides due to the envelope and controlled release function of nano-carriers. This precisely matches the needs of different target crops. Herein, a dinotefuran supramolecularly bonded layered double hydroxide (D-LDH) nano-pesticide has been designed to improve the controlled release properties and insecticidal activity in cucumber and cotton plants. As confirmed by XRD patterns, FT-IR spectroscopy, SEM images and zeta potentials, dinotefuran molecules are supramolecularly bonded onto LDH nano-carriers, which can be effectively controlled by regulating the carrier ratio. The wettability performance and foliar surface adhesion of D-LDH are significantly improved due to hydrogen bonding interaction. The control effect of D-LDH on Aphis gossypii remains 90.1% after 60 days, which means only a one time application can achieve effective control during the whole growth cycle. The applications of foliar spraying on cucumber against Trialeurodes vaporariorum and Bemisia tabaci show that the control effect is still more than 80% after 14 days when the dose is ∼33% less than the recommended minimum dose. Overall, this novel D-LDH nano-pesticide shows the possibility in improving the utilization rate of pesticides and reducing application times.

It has been a consensus that the exciton binding energies in two-dimensional (2D) Ruddlesden–Popper perovskites is closely correlated with the number of layers. However, the detailed recombination dynamics of excitons and free carriers in these 2D perovskites are still highly controversial. Using transient spectroscopic techniques, carrier dynamics of 2D Ruddlesden–Popper perovskites are investigated at both room and low temperatures. We confirmed that 2D perovskites of (BA)2PbI4, with the number of [PbX6]4− layers n = 1, exhibit clearly exciton characteristic properties. Meanwhile, (BA)2(MA)Pb2I7 and (BA)2(MA)2Pb3I10, n = 2 and 3, exhibit free carrier behaviour, which is inconsistent with their binding energies of more than 100 meV. Such anomalous exciton and free carrier behaviours are attributed to the effective exciton in-plane transport and dissociation by the edge state. This investigation provides novel insights into exciton and charge carrier dynamics of 2D perovskites as well as the influence of edge states.

A reverse-blocking AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (RB-MISHEMT) is proposed and fabricated. Compared with the conventional MISHEMT with ohmic drain, the proposed device features a hybrid Schottky-ohmic drain with a low work function Tungsten (W), based on which the state-of-the-art ultralow turn-on voltage ( ${V} _{\mathrm{ on}}$ ) of 0.25 V could be realized without degradation in on-state characteristics. In addition, the fabricated RB-MISHEMT exhibits the excellent reverse blocking voltage of −1332 V (at ${V} _{\mathrm{ GS}}= 0$ V) and forward blocking voltage of 1315 V (at ${V} _{\mathrm{ GS}} = -15$ V) with a specific on-resistance ( ${R} _{\mathrm{ on,sp}}$ ) of 3.5 $\text{m}\Omega $ cm2, leading in the highest power figure-of-merit (FOM) of > 494 MW/cm2. The good thermal stability could also be observed in fabricated RB-MISHEMT. The corresponding operation mechanism of RB-MISHEMT are also revealed by Silvaco ATLAS simulations. These results demonstrate the great potential in power electronics applications.

Flame retardancy of epoxy resin (EP) plays a vital role in its applications. When inorganic nanomaterials form inorganic/organic nanocomposites, they exhibit special flame-retardant effects. In this study, EP nanocomposites were prepared by the incorporation of SiO2 nanoparticles and phenethyl-bridged 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative (DiDOPO), and the synergistic effects of SiO2 nanoparticles and DiDOPO on the flame-retardant performance of EP were discussed. Results indicated that the introduction of only 15 wt % SiO2 and 5 wt % DiDOPO in EP leads to the increase in the limiting oxygen index from 21.8 to 30.2%, and the nanocomposites achieve the UL-94 V-0 rating. Thermogravimetric analysis revealed that char yield increases with the increase in the SiO2 content of the nanocomposites and that an increased amount of thermally stable carbonaceous char is formed. SiO2 nanoparticles can improve the thermal stability and mechanical performance of EP; hence, the nanoparticles can serve as an efficient adjuvant for the DiDOPO/EP flame-retardant system.

Direct X-ray detectors are considered as competitive next-generation X-ray detectors because of their high spatial resolution, high sensitivity, and simple device configuration. However, their potential is largely limited by the imperfections of traditional materials, such as the low crystallization temperature of α-Se and the low atomic numbers of α-Si and α-Se. Here, we report the Sb(2)Se(3) X-ray thin-film detector with a p-n junction structure, which exhibited a sensitivity of 106.3 µC/(Gy(air)·cm(2)) and response time of < 2.5 ms. This decent performance and the various advantages of Sb(2)Se(3), such as the average atomic number of 40.8 and μτ product (μ is the mobility, and τ is the carrier lifetime) of 1.29 × 10(−5) cm(2)/V, indicate its potential for application in X-ray detection. [Image: see text]

The repeated wetting–drying (WD) cycles can cause the deterioration of rock and thus affect the service performance of the related rock engineering, e.g., the crushed-rock embankment and the reservoir. The study comprehensively investigated the deterioration mechanism of sandstone under the WD cycles based on a series of multi-scale experiments, including the microstructure, the meso–micro pore characteristics, and the macroscopic physical and mechanical properties. The results indicate that the content of dissolved minerals and the permeability are two key factors that determine the deterioration effect caused by the WD cycles. During the WD cycles, the pore size range of sandstone becomes wider due to the formation of new small pores and the connection of original pores. Thus, low-density area forms within the samples, which causes the increasing of density dispersion. The structure deterioration weakens the physical and mechanical properties of the samples. The ultrasonic test indicates that the decreasing rate of the P-wave velocity is larger than that of the S-wave velocity, especially in the first 5 cycles. Besides, the exponential equations of uniaxial compressive strength and elastic modulus with the number of WD cycles are established to describe the deterioration of mechanical characteristics.

Sulfate and carbonate can cause serious degradation of cement-based materials at low temperature; degradation products generally include ettringite, gypsum and thaumasite. The degradation process is very slow in a natural environment and no useful test method exists to accelerate the degradation process. This study used a voltage of 30 V and an electrical field duration of 20 s to study the acceleration effect of an electrical field on the degradation. Visual observations and compressive strength were used to reflect the degree of degradation. X-ray diffraction, Fourier transform infrared spectroscopy and ion concentration distribution were applied to study the degradation mechanism. The test results indicated that an electrical field can accelerate the degradation within 180 d and that the degradation rate was faster than that associated with full immersion. Moreover, the degree of degradation of a solution with sodium sulfate (Na2SO4) as the cathode and magnesium sulfate (MgSO4) as the anode was higher than that of a solution with magnesium sulfate as both cathode and anode; also the degradation degree of a magnesium sulfate solution under full immersion was higher than that of a sodium sulfate solution under full immersion.

A density functional study of dihydrogen adsorption and storage capacity of reported stable clusters MLi4+ (M = C, Si, Ge) has been performed at different levels. The cationic systems MLi4+ (M = C, Si, Ge) can adsorb up to 12, 12, and 14 hydrogen molecules respectively with respective H2 gravimetric uptake capacity of 37.82, 30.22, and 21.94 wt%. The interactions of MLi4+ (M = C, Si, Ge) with H2 molecules are analyzed by means of the bond critical points (bcp) in the quantum theory of atoms in molecules (QTAIM). The Gibbs free energy corrected adsorption energies indicate that the maximum adsorption of MLi4+ (M = C, Si, Ge) are energetically favorable at low temperature or high pressure. Atom-centered density matrix propagation (ADMP) molecular dynamics simulations are performed at different temperatures. It can be found that MLi4+ (M = C, Si, Ge) can bind 3, 6, and 4 hydrogen molecules with respective gravimetric densities of 13.20, 17.80, and 7.43 wt% at 200 K and 1atm. At room temperature, MLi4+ (M = C, Si, Ge) can adsorb 3, 5, and 3 hydrogen molecules with gravimetric densities of 13.20, 15.29, and 5.68 wt%.

The hydrogen adsorption and storage of Cu3Bx (X = 1–4) compounds have been computationally investigated at B3LYP-D3/6-311G (3df, 3pd) level. The most stable compounds of Cu3Bx (X = 1–4) can adsorb 16, 11, 15, and 9 hydrogen molecules with H2 gravimetric densities of 13.80, 9.46, 11.94, 7.20 wt%, respective. Their average adsorption energies are in the range of 0.26–0.43 eV/H2. The Gibbs free energy corrected adsorption energies indicate that the maximum adsorption of Cu3Bx (X = 1–4) are energetically favorable under ambient conditions. Atom-centered density matrix propagation (ADMP) molecular dynamics simulations are used to analyzed the real time dynamics of H2 and Cu3Bx (X = 1–4). We can find that Cu3Bx (X = 1–4) can bind with 4–5 H2 within 1000 fs at 200 K.

CoS2 with a three-dimensional porous structure has attracted great interest because of its excellent electrical, magnetic, and optical properties. However, the nonlinear optical properties of CoS2 ...

Polyvinylpyrrolidone (PVP) is studied in this paper as an inhibitor of cobalt electrodeposition. The suppression effect of PVP was analyzed through electrochemical methods, including cyclic voltammetry (CV) and galvanostatic measurements (GM) tests. It is indicated that PVP effectively suppresses the electrodeposition of cobalt and chloride ion accelerates this suppression. Further experiments verify that PVP inhibits the deposition of cobalt through the adsorption on the electrode surface. Quantum chemical calculations were employed to calculate the molecular orbitals of PVP and the electrostatic potential (ESP) energy of the involved molecules. The simulation results imply that the amide group acts as the main electrophilic attack region and facilitates nucleophilic reactions to bond with cobalt. High aspect ratio trench filling on silicon wafer was achieved with the addition of PVP, which confirms that PVP is an applicable inhibitor for the practical electrodeposition of cobalt filling. The mechanism of cobalt trench filling was proposed to explain the role of PVP in the electroplating filling. Besides, crystalline and morphological characterizations reveal that PVP is able to inhibit the specific crystal growth of cobalt, especially the growth of 220 crystal plane, affect the crystal morphology of cobalt and improve surface compactness.

A novel additive system comprising bis-(sodium sulfopropyl)-disulfide, polyethylene glycol and hydroquinone (HQ) was developed and investigated to achieve high rate copper electrodeposition at high temperature. HQ, as the key additive compound in this system, refines the Cu grain, makes the coating surface bright and smooth at high current density. The underlying mechanism of the additive-assisted electroplating was investigated through electrochemical, morphological characterizations and molecular dynamics simulation. Nanocubical copper particles were found through chronoamperometry tests, which explains the fine crystalline Cu grains and the bright coating surface. Additionally, the formation of the nanocubical copper particles is caused by the different adsorption energies of HQ on (311), (111) and (220) crystal faces and further leads to a strong suppression on the (220) orient crystal faces. Moreover, the electroplating results of through-holes illustrate the feasibility of this additive system in practical applications.

Photocatalytic CO2 reduction is an appealing approach to convert solar energy into high value-added chemicals. All-inorganic CsPbBr3 quantum dots (QDs) have emerged as a promising photocatalyst for reducing CO2. However, pristine CsPbBr3 has a low catalytic performance, mainly due to severe charge recombination. Herein, a 0D/2D heterojunction of CsPbBr3 QDs/Bi2WO6 nanosheet (CPB/BWO) photocatalysts is fabricated for photocatalytic CO2 reduction. The CPB/BWO photocatalyst achieves excellent photocatalytic performance: the total yield of CH4/CO is 503 μmol g-1, nearly 9.5 times higher than the pristine CsPbBr3. The CPB/BWO heterojunction also exhibits much-improved stability during photocatalytic reactions. On the basis of various characterization techniques, our investigations verified a direct Z-scheme charge migration mechanism between CsPbBr3 QDs and Bi2WO6 nanosheets. The improved photocatalytic performance is originated from the high spatial separation of photoexcited charge carriers in CPB/BWO, which can also preserve strong individual redox abilities of two components. This work reports an efficient direct Z-scheme heterojunction photocatalytic system based on metal halide perovskites. The novel strategy we proposed may bring up new opportunities for the development of metal halide perovskite photocatalysts with greatly enhanced activities.

Surface modification plays a vital role in improving the rate performance and cycling stability of layered Ni-rich LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode materials for Li-ion batteries. In this study, Li2MgTi3O8 (LMTO)-coated NCM622 was successfully synthesized by wet coating combined with sintering process. The results of morphological analysis showed a uniform LMTO layer coated on the surface of NCM622 materials. The dual ions of Ti4+ and Mg2+ on surface structure of NCM622 were identified by X-ray diffraction and X-ray photoelectron spectroscopy. The surface coating layer prevented the direct contact between the active cathode material and the electrolyte which significantly reduced the side reactions, and the doping of Ti4+ and Mg2+ improved the structural stability of the NCM622 materials. The electrochemical performance indicates that NCM622 cathode with a coating layer of 0.5 wt% LMTO exhibited excellent cycle stability and maintained a capacity retention up to 76% after 200 cycles at 25 °C at 1 C-rate, which was higher than the value of 52% for the NCM622.

The advanced rechargeable batteries have been upgraded by the production of free-standing electrodes through electrospinning technology. This study aimed to introduce a novel hybrid composition to design a free-standing carbon nanofiber (CNF) based anode by the addition of iron acetylacetonate Fe(AcAc)3 as active material and TEOS(tetraethoxysilane)/APTES(aminopropyl triethoxysilane) as an additive for Li-ion batteries. Polyacrylonitrile(PAN) was used as the polymer matrix in the spin dope, and the inclusion of Fe(AcAc)3 and TEOS/APTES resulted in compositional change, producing iron oxide and silica nanoparticles throughout the matrix. Different oxidation states and the presence of embedded iron oxide nanoparticles in CNF were identified by XPS and EDX elemental mapping analysis. PAN-TEOS-APTES-Fe(AcAc)3 based anode material was capable of enhancing the reversible specific capacity as much as 732 mAhg−1 at 500 mAg−1 lasting for 300 cycles, along with the rate capability as high as 815 mAhg−1 at 200 mAg−1. Furthermore, EIS analysis and EX-situ FESEM showed decreased impedance after cycling with the stable morphology of PAN-TEOS-APTES-Fe(AcAc)3 CNF-film. Conclusively, non-woven, binder-free, current collector free, free-standing CNF anode film doped with iron-oxide and silica nanoparticles was indeed a novel approach for Li-ion batteries and can be considered for other batteries particularly for Li-S batteries.

Zeolites that prefer alkynes Alkenes such as ethylene and propene must be separated from alkynes before they can be converted in polymers. Drawbacks in current methods, such as hydrogenation of alkynes producing unwanted alkanes, has spurred interest in sorption separation methods. Zeolites have generally been inefficient, given the similar sizes and volatilities of the molecules. Chai et al. incorporated atomically dispersed divalent transition metal cations into faujasite zeolite and found that the nickel-containing analog efficiently removed alkynes from olefins through chemoselective binding at open nickel(II) sites. At ambient conditions in the presence of water and carbon dioxide, the zeolites retained separation selectivities of 100 and 92, respectively, for acetylene over ethylene and propyne over propylene for 10 adsorption-desorption cycles. Science , this issue p. 1002

The observation of low-energy edge photoluminescence and its beneficial effect on the solar cell efficiency of Ruddlesden–Popper perovskites has unleashed an intensive research effort to reveal its...