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International audience; The influences of the electrode/ionic liquids interfaces on the charge transfer kinetics are addressed with the example of the oxidation of chromocene at a single crystal Ag(111) electrode. We considered three different imidazolium-based room temperature ionic liquids (RTILs) with alkyl chains of different lengths but with a common anion. The standard charge transfer rate constants k° are extracted from cyclic voltammograms (CVs) by analyzing the peak potential variations with the scan rate and/or performing semi-integral electroanalysis with a careful treatment of the ohmic drop. Linear variations between the logarithms of k° and the longitudinal relaxation times τL or the dynamic viscosity η of the ionic liquids are obtained. However, the amplitude of the decrease is much larger than it could be expected from the sole bulk properties of the ionic liquid indicating a strong effect of the interface on the kinetics. These observations agree with a well-organized electrode/RTIL interface that behaves as a sort of self-assembled monolayer that controls the charge transfer kinetics with an exponential tunneling coefficient β of 5.51 nm−1.

Gel electrolytes show certain advantages over conventional liquid and solid electrolytes, but their mechanical strength and surface adhesion to the electrode remain to be improved. To address the challenges, we design and fabricate herein the core-shell nanofiber mats in situ on the LiFePO4 electrode as matrices for gel electrolytes, in which the core is poly(m-phenylene isophthalamide) (PMIA) nanofiber and the shell are composite of Al2O3 nanoparticles and poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP). The mechanical property of the core-shell polymeric nanofiber mats and their surface interaction with LiFePO4 electrode are characterized complementarily using dynamic thermomechanical analysis and scanning electron microscopy. The electrochemical properties of the gel electrolytes based on the as-prepared matrices after being loaded with lithium salt solution are studied systematically on half coin cells. It is found that the ultimate strength of the core-shell PMIA@PVdF-HFP/Al2O3 mat can reach 6.70 MPa, 2 times higher than that of the PVdF-HFP/Al2O3 nanofiber mat. Meanwhile, the shell PVdF-HFP/Al2O3 can ensure manifest surface affinity to the LiFePO4 electrode and enhance lithium-ion conductance. Thus, the as-assembled LiFePO4 half coin cells using PMIA@PVdF-HFP/Al2O3 gel electrolyte show good electrochemical performances, especially the long cycle stability with the capacity retention of 96.6% after 600 cycles under 1C.

Rapid and homogeneous precipitation of nano-sized Si particles with high density was achieved in Al–1%Si alloy by electric pulses treatment (EPT) in a liquid nitrogen bath (∼77 K). In contrast, when processed by EPT in air or by high-temperature (527–720 K) salt bath treatment, the precipitate density decreases dramatically. The homogeneous precipitation of Si could be facilitated by both the low-temperature environment and the non-thermal effects of EPT. The low-temperature environment provides a high driving force for nucleation, and retains the quenched-in vacancies serving as potential nucleation sites. The non-thermal effects of EPT can significantly promote local migration of solutes and vacancies at such low temperatures.

Achieving high-efficiency photoelectrochemical water splitting requires a better understanding of ion kinetics, e.g., diffusion, adsorption and reactions, near the photoelectrode’s surface. However, with macroscopic three-dimensional electrodes, it is often difficult to disentangle the contributions of surface effects to the total photocurrent from that of various factors in the bulk. Here, we report a photoanode made from a InSe crystal monolayer that is encapsulated with monolayer graphene to ensure high stability. We choose InSe among other photoresponsive two-dimensional (2D) materials because of its unique properties of high mobility and strongly suppressing electron–hole pair recombination. Using the atomically thin electrodes, we obtained a photocurrent with a density >10 mA cm−2 at 1.23 V versus reversible hydrogen electrode, which is several orders of magnitude greater than other 2D photoelectrodes. In addition to the outstanding characteristics of InSe, we attribute the enhanced photocurrent to the strong coupling between the hydroxide ions and photo-generated holes near the anode surface. As a result, a persistent current even after illumination ceased was also observed due to the presence of ions trapped holes with suppressed electron-hole recombination. Our results provide atomically thin materials as a platform for investigating ion kinetics at the electrode surface and shed light on developing next-generation photoelectrodes with high efficiency., Achieving efficient photoelectrochemical cells requires insights into the ion kinetics at the surface of photoelectrode. Here, the authors show a new platform for investigating strong coupling between hydroxide ions and surface charge carriers by using monolayer InSe as the anode with high photocurrent density.

In addition to tuning the composition, precipitate, and grain microstructure of an alloy, manipulating dislocation structure provides an additional strategy of designing novel alloys. One promising dislocation structure, in the form of periodic dislocation arrays, conventionally forms in cubic alloys under cyclic loading. In this paper, we demonstrate new possibility of synthesizing periodic dislocation arrays in pure Mg under static loading, a simple processing route. This finding provides insight in advancing dislocation substructures, which promote the performance of engineering alloys.

Summary The morphology and mechanical property of SEIs for lithium anodes crucially affect the electrochemical cycling performance of Li-metal batteries such as Li-S and Li-O2 batteries. Herein, we establish the standards for rapidly assessing SEIs for Li and Li-free type of anodes by AFM nanoindentation features toward prediction of corresponding electrochemical performances. A series of single-layered and multi-layered SEIs with known composition and structures are purposely constructed. A set of unique nanoindentation features representative of mechanical properties of the basic SEIs are formed, serving as the standards for rapidly assessing the mechanical properties and electrochemical performances of unknown SEIs together with their Young’s modulus, smoothness, and thickness. To validate the applicability of the method, SEIs formed by electrochemical aging and formed on Cu substrates are further evaluated. Our work not only contributes to understanding the influence of SEIs on cycling performances but also provides a rapid way for screening SEIs.

Surface rotation rolling (SRR) treatment has been applied to cold-rolled and fully-annealed commercial-purity aluminums to refine the microstructure at the surface region. The treatments result in a strengthening in the as-annealed aluminum but a softening in the cold-rolled one. Although the grain size and dislocation density are different in the initial states, they evolve to the same saturation level after SRR treatment. Comparisons of microstructures produced by SRR, ARB (Accumulative roll-bonding) and SMAT (Surface mechanical attrition treatment) reveal that the saturations of grain size and dislocation density are controlled by strain rate and strain path of the plastic deformation process.

The surface areas of porous ceramics can be enhanced by increasing their porosity but this improvement is at the expense of strength. To improve performance, it is necessary to fabricate porous ceramics with large surface areas and high strength. In this study, porous ceramics with spherical shell structures known as spherical-shell ceramics (SCs), characterised by a hollow ceramic sphere in each pore, were fabricated to address the abovementioned problem. They were fabricated using soaked millet coated with slurries as the pore-forming agents. The compositions and particle sizes of the slurries as well as the sintering temperature were tuned to tailor the integrity, wall thicknesses and surface structures of the SCs. In addition, the formation mechanism of the SCs was proposed. Overall, the porous ceramics with SCs demonstrated large surface areas and high flexural strength. This study paves the way for the fabrication of high-performance porous ceramics.

To investigate the functions of eIF3b in chronic myelogenous leukemia (CML). The expression of eIF3b was inhibited by transfecting aspecifically designed shRNA into the CML cell lines of TK-6 and K562. The CCK8 assay was conducted to determine cell viability, and flow cytometry was used to examine the change in the cell cycle and cell apoptosis. RNAsequencing was applied to screen the candidate targets of eIF3b to identify the underlying mechanisms of eIF3b.An in vivo tumour xenograft mouse model was established by injecting shRNA transfected cells into the NCG mice. The tumour size and body weight of mice were monitored every other day. The mice were sacrificed 2 weeks after the tumour cell injection. The expression of eIF3b and target genes in the tumour tissues were determined by immunohistochemical staining and Western blotting. The group with inhibited expression of eIF3b led to about 50% lower cell viability compared with that of the control group (P

International audience; Establishing electronic hinder/ionic transfer pathway in SEI film is key issue for high-performance Li-metal anodes (LMA), which requires the SEI with high ionic conductivity to enable fast Li+ diffusion and regulated Li deposition behavior, and poor electronic conductivity to block the electrolyte consumption. Herein, we propose a strategy to construct heterogeneous SEI via selective reduction of electrolytes components to improve Li stability and suppress dendrite growth. The inner N-rich sub-layer of SEI film enables fast Li+ transportation for nodule-like Li deposition while the outer C-rich sub-layer of SEI film exhibits an electronic insulation property to block electrolyte decomposition. This hybrid SEI endows the LMA with high Coulombic efficiency (99.0%), long lifespan, and dendrite suppression. Theoretical calculations, XPS and AFM were employed to examine the heterogeneous SEI structure and clarify its formation mechanism. A high-capacity retention of 91.6% after 160 cycles at 0.5 C in LiCoO2/Li pouch cells with ultra-thin Li anodes (25 μm) and low N/P ratio (1.67), and an excellent performance with 85.7% capacity retention after 300 cycles at higher charge potential (4.5 V) was also obtained. The insight in heterogeneous SEI formation provides new opportunities for rational electronic/ionic transfer pathway construction for achieving high-performance Li-metal batteries.

Novel microencapsulation of Syringa essential oil (EO) was successfully prepared via the inclusion method, with encapsulation efficiency of 39.52% and loading capacity of 11.54%. Eugenol, caryophyllene and humulene were demonstrated to be the principal constituents in vitro released from Syringa EO microencapsulation (SEOM) independent of the environmental temperature. Furthermore, the potential delivery encapsulated by Syringa EO and 1-methylcyclopropene (1-MCP) synergistically maintained quality attributes and storage behavior of postharvest Prunus persia fruit. The SEOM and/or 1-MCP treatments retained fruit firmness and acidity, as well as inhibited fruit decay and ethylene release. And SEOM promoted ester and terpenoid biosynthesis as well as inhibited aldehyde production in Prunus persia fruit during storage.

Rapid dissolution of sub-boundaries into dense dislocation arrays in electric-pulse-treated aluminum was observed using ex-situ transmission electron microscopy. This unusual increase of interior dislocations, which has rarely been observed in materials treated by conventional thermal treatments, suggests the rapid and possibly simultaneous operations of three mechanisms for sub-boundary dissolution, i.e., emission, extraction and collective migration of boundary dislocations. This phenomenon could be attributed to the enhanced dislocation mobility and the reduced obstacle to dislocation extraction by electric pulsing. This finding provides a new pathway to tailor the microstructure of metallic materials by concurrently coarsening subgrains and increasing dislocation density.

The layered LiNi1/3Co1/3Mn1/3−x Mg x O2 (x = 0, 0.01, 0.02, 0.03) were synthesised by a stepwise co-precipitation method. The effects of Mg substitution on the crystal structure of the synthesised powder have been characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) mapping. Their electrochemical properties were evaluated by charge/discharge and electrical impedance spectroscopy tests. The results of XRD, SEM and EDS mapping characterisation indicated that all the modified cathode materials with their Ni, Co and Mn components doped by magnesium without destroying the crystal structure. Electrochemical characterisation confirms that the materials have optimal cycling performance and the least capacity loss under the 2% Mg-doping. The specific capacity of the LiNi1/3Co1/3Mn1/3−0.02Mg0.02O2 was 180 mAh g−1 at 0.1 C and 138 mAh g−1 at 8 C, which compares favourably to 175 mAh g−1 at 0.1 C and 121 mAh g−1 at 8 C for the LiNi1/3Co1/3Mn1/3O2. The LiNi1/3Co1/3Mn1/3−0.02Mg0.02O2 also exhibited the best electrochemical performance with capacity retention of 89.4% after 50 cycles at 0.2 C between 2.5 and 4.3 V.

To understand the influence of atmospheric turbulence on optical vortex pulse, the transmission equation of vortex pulse beam is derived. The multiple phase-screen method is used to calculate the intensity distribution of vortex beam that influenced by atmospheric turbulence. Some main parameters, such as pulse width, the topological charge, strength of turbulence and propagation distance, are discussed in detail to show the propagation characteristics of the vortex pulse in atmospheric turbulence. Results show that with the increasing of the strength of turbulence, the vortex pulse beam is distorted more seriously. For the parameters of the vortex pulse itself, with the increasing of pulse width, the ability of resisting distortion is decreasing.

This research studied the morphological characterization and quality attributes of ‘Kyoho’ and ‘Yongyou NO.1’ (Vitis vinifera L. × Vitis labrusca L.) grape berry and rachis in response to postharvest treatment with 1-methylcyclopropene (1-MCP) alone or in combination with elevated 80% O 2 (H-O 2 ) / 20% CO 2 (H-CO 2 ). Results indicated that the integrated application of exogenous 1-MCP alone and combined with H-O 2 /H-CO 2 significantly prevented the rachis browning and chlorophyll degradation, maintained the cellular microstructure integrity and promoted esters and terpenes synthesis. Additionally, the transcriptional expression of genes involved in ethylene biosynthesis was sharply downregulated by 1-MCP treatment in both cultivar rachis and berries. And genes expression related to softening was also downregulated by 1-MCP alone and plus elevated O 2 /CO 2 atmospheres treatment. Particularly, the combinatorial treatment of 1-MCP and H-O 2 effectively impeded berry abscission and alcohols accumulation; whereas 1-MCP with H-CO 2 treatment maintained the membrane permeability in berries. Nevertheless, 1-MCP alone or in combination with elevated atmospheres did not significantly affect total soluble solids and titratable acidity and did not harm sensory quality in both ‘Kyoho’ and ‘Yongyou NO.1’ cultivars after 32 days of storage.

Postharvest strawberries (Fragaria × ananassa Duch.) were coated either by the layer-by-layer (LBL) electrostatic deposition, based on chitosan and carboxymethyl cellulose (CMC), or coated by 1% chitosan. Results suggested that LBL edible coating was significantly effective at inhibiting the loss of fruit firmness and aroma volatiles of strawberry, with little effect on the total soluble solids and total acidity contents. Through an untargeted metabolomic analysis, we found that the LBL application significantly reduced the primary metabolite contents involved in carbohydrate, fatty acids and amino acids metabolism, as well as the secondary metabolite contents involved in terpenoid, carotenoid, phenylpropanoid and flavonoid metabolism after storage. Our results indicated that the LBL edible coating could be potential to maintain strawberry quality with lower metabolites contents after eight days of storage.

We report the synthesis of two-dimensional metal-organic frameworks (MOFs) on nickel foam (NF) by assembling nickel chloride hexahydrate and 1,1'-ferrocenedicarboxylic acid (NiFc-MOF/NF). The NiFc-MOF/NF exhibits superior oxygen evolution reaction (OER) performance with an overpotential of 195 mV and 241 mV at 10 and 100 mA cm-2 , respectively under alkaline conditions. Electrochemical results demonstrate that the superb OER performance originates from the ferrocene units that serve as efficient electron transfer intermediates. Density functional theory calculations reveal that the ferrocene units within the MOF crystalline structure enhance the overall electron transfer capacity, thereby leading to a theoretical overpotential of 0.52 eV, which is lower than that (0.81 eV) of the state-of-the-art NiFe double hydroxides.

Structural mapping of intermediate size and large molecules and biomolecules at ultra-high resolution using single-crystal electrodes and in situ scanning tunnelling microscopy continues to disclose surprising findings. In situ scanning tunnelling spectroscopy has also recently disclosed new electrochemical conductivity features at the level of the single molecule. We overview briefly elements of this development over the last few years, with focus on three recent discoveries: (1) a new packing mode of a core monolayer target thiol, the amino acid cysteine (Cys) on Au(100)-electrodes, quite different from Cys packing on Au(111)- and Au(110)-electrodes; (2) transition of a core ferrocene in situ scanning tunnelling spectroscopy probe from stochastic single-molecule to macroscopic behaviour, a concept at the heart of nanoscience; and (3) unexpected behaviour of the large molybdenum enzyme sulfite oxidase, when going from macroscopic to single-molecule electrochemistry. We compare these studies with other recent discoveries of single-molecule protein conductivity and molecular scale inorganic nanostructures.

In this study, amino hyperbranched polymers (HBP)-grafted polyacrylonitrile (PAN) fiber was prepared through an amidation reaction in an autoclave. The prepared PAN-G-HBP fiber can complex Ag+ through amino groups of amino HBP, and in a hot steaming condition, Ag+ can be converted to Ag0 through the reducibility of HBP. PAN-G-HBP and Ag nanoparticles (NPs)-coated fibers were then characterized through FTIR, UV–VIS DRS, FE-SEM, EDS, XPS and antibacterial measurement. FTIR results confirmed HBP was grafted on the surface of PAN fiber. FE-SEM showed that after grafting with HBP, the average diameter of PAN fibers was amplified. EDS, XPS, and UV–VIS DRS method indicated that under hot steaming condition and with the reducibility of HBP, Ag NPs uniform coating on the PAN-G-HBP. Ag NPs-coated fibers exhibits excellent antibacterial property against Escherichia coli and Staphylococcus aureus. Even under 20 times home washing conditions, the antibacterial reduction of Ag NPs-coated PAN fiber can achieved more than 98.94%.

A superconducting linear accelerator operating in continuous-wave mode could produce X-ray free electron lasers (XFEL) at megahertz repetition rate, with the capability that delivering wide spectral range coherent radiation to multi end stations. In this Letter, the energy recovery Linac (ERL) mode is proposed to flexibly control the electron beam energy for a continuous-wave superconducting Linac. Theoretical investigations and multi-dimensional numerical simulations are applied to the Linac case of Shanghai high-repetition-rate XFEL and extreme light facility. The results show that, with ERL operation in the last 25 cryo-modules, the strict requirements on RF power system could be significantly relaxed. And if one exhaust the RF power, the maximum electron beam energy can be enhanced from 8.74 GeV to 11.41GeV in ERL mode. The optimization of the ERL operation, the multi-energy electron beam transport and the XFEL performance improvements are presented., 9 pages, 5 figures

Electrochemical electron transfer (ET) of transition metal complexes or redox metalloproteins can be catalyzed by more than an order of magnitude by molecular scale metallic nanoparticles (NPs), often rationalized by concentration enhancement of the redox molecules in the interfacial region, but collective electronic AuNP array effects have also been forwarded. Using DFT combined with molecular electrochemical ET theory we explore here whether a single molecular scale Au nanocluster (AuC) between a Au (111) surface and the molecular redox probe ferrocene/ferricinium (Fc/Fc+) can trigger an ET rate increase. Computational challenges limit us to Au n Cs (n up to 147), which are smaller than most electrocatalytic AuCs studied experimentally. AuC-coating thiols are addressed both as adsorption of two S atoms at the structural Au55 bridge sites and as superexchange of variable-size AuCs via a single six-carbon alkanethiyl bridge. Our results are guiding, but enable comparing many AuC surface details (apex, ridge, face, direct vs superexchange ET) with a planar Au(111) surface. The rate-determining electronic transmission coefficients for ET between Fc/Fc+ and AuC are highly sensitive to subtle AuC electronic features. The transmission coefficients mostly compete poorly with direct Fc/Fc+ ET at the Au(111) surface, but Fc/Fc+ 100 face-bound on Au79 and Au147 and ridge bound on Au19 leads to a 2- or 3-fold rate enhancement, in different distance ranges. Single AuCs can thus indeed cause rate enhancement of simple electrochemical ET, but additional, possibly collective AuNC effects, as well as larger clusters and more complete coating layers, also need to be considered.

Drought forecasting is helpful for understanding the inherent mechanism of hydrological extremes and taking corresponding measures to mitigate drought impacts. Northeast China, which is an important, major grain-producing area in China, has been challenged by substantial losses due to frequent drought. In this study, to predict the spatiotemporal variation in drought events over Northeast China, a model-based simulation framework is proposed based on precipitation data at 70 meteorological stations from 1960 to 2018. The core of the model framework is run theory, modified Copula model- based Bayesian-MCMC, Gibbs sampling, and a new definition of drought intensity center and drought intensity accumulation area. The results showed that a total of 6408 drought events occurred at the 70 meteorological stations in Northeast China over the past 59 years. The empirical distribution functions of longitude, latitude, and time can be used to fit the edge distribution of the original variable. In comparison to the traditional maximum likelihood method, the Bayesian-MCMC method is more accurate for parameter estimation of the Copula model. The Frank Copula is the optimum joint function of longitude and latitude, while the Gaussian Copula is the optimum joint function of location and time. Gibbs sampling can provide a relatively larger sample size for predicting future drought conditions. The spatiotemporal variation in drought in Northeast China changes similarly throughout the year. Drought is mainly concentrated in southwestern Liaoning from February to April. The drought intensity center moves to the northeast from May to September. Western Heilongjiang is the main drought-stricken area from October to November. The drought intensity center moves southwest from December to January of the following year. This study provides a method for effectively predicting drought events and is of great significance to the protection, development, and utilization of water resources.

Humid hydrophobic ionic liquids—widely used as electrolytes—have narrowed electrochemical windows due to the involvement of water, absorbed on the electrode surface, in electrolysis. In this work, we performed molecular dynamics simulations to explore effects of adding Li salt in humid ionic liquids on the water adsorbed on the electrode surface. Results reveal that most of the water molecules are pushed away from both cathode and anode, by adding salt. The water remaining on the electrode is almost bound with Li+, having significantly lowered activity. The Li+-bonding and re-arrangement of the surface-adsorbed water both facilitate the inhibition of water electrolysis, and thus prevent the reduction of electrochemical windows of humid hydrophobic ionic liquids. This finding is testified by cyclic voltammetry measurements where salt-in-humid ionic liquids exhibit enlarged electrochemical windows. Our work provides the underlying mechanism and a simple but practical approach for protection of humid ionic liquids from electrochemical performance degradation., Water adsorbed on the electrode surface of electrochemical energy storage devices narrows the electrochemical windows. Combining atomistic simulations and cyclic voltammetry experiments the authors demonstrate an approach to expand the voltage window of humid ionic liquids based on the addition of lithium salt.

The genesis of the Curie-Weiss magnetic response observed in most transition metals that are Fermi liquids at low temperatures has been an enigma for decades and has not yet been fully explained from microscopic principles. We show on the single-impurity Anderson model how the quantum dynamics of strong electron correlations leads to the Curie-Weiss magnetic susceptibility sufficiently above the Kondo temperature. Such behavior has not yet been demonstrated and can be observed only when the bare interaction is substantially screened (renormalized) and a balance between quantum and thermal fluctuations is kept. We set quantitative criteria for the existence of the Curie-Weiss law., Comment: 13 pages with 12 figures

The spectroscopic techniques for time-resolved fine analysis of matter require coherent x-ray radiation with femtosecond duration and high average brightness. Seeded free-electron lasers (FELs), which use the frequency up-conversion of an external seed laser to improve temporal coherence, are ideal for providing fully coherent soft x-ray pulses. However, it is difficult to operate seeded FELs at a high repetition rate due to the limitations of present state-of-the-art laser systems. Here, we report a novel self-modulation method for enhancing laser-induced energy modulation, thereby significantly reducing the requirement of an external laser system. Driven by this scheme, we experimentally realize high harmonic generation in a seeded FEL using an unprecedentedly small external laser-induced energy modulation. An electron beam with a laser-induced energy modulation as small as 1.8 times the slice energy spread is used for lasing at the seventh harmonic of a 266-nm seed laser in a single-stage high-gain harmonic generation (HGHG) setup and the 30th harmonic of the seed laser in a two-stage HGHG setup. The results mark a major step toward a high-repetition-rate, fully coherent x-ray FEL.

A robust solid electrolyte interphase film formed on the anode is of importance for the electrochemical performances of a lithium-ion battery. In this work, the formation and decomposition of the s...

Based on the generalized Huygens Fresnel principle, the propagation equation of fundamental Gaussian vortex beam with phase distortion is derived. To quantitatively analyze the influence of random phase distortion on the quality of vortex beam, the variance of light intensity relative deviation is proposed as the evaluation parameter. The influences of some key factors on the quality of a vortex beam are emphatically discussed. The results show that with the increasing of distortion strength the beam quality becomes worse. On the contrary, with the increasing of the topological charge, the beam quality improves gradually.

Using surface rotation rolling (SRR) treatment with various vertical loads (120 to 280 N) while maintaining other processing parameters (rotation speed and horizontal velocity), the SRR-treated AZ31 Mg alloy sheets exhibit through-thickness gradients of both grain size and basal texture, as revealed by cross-sectional hardness tests and microstructure analysis. An optimal strength–ductility combination is achieved as the vertical load is around 200 N. The corresponding microstructure exhibits two characters: (1) The affected depth reaches the very center of the sheet and (2) the gradients approach the allowable maximum. Texture gradient is found to be the major contributor to the significant ductility enhancement.

The plasmoelectric potential effect, based on all-metal nanostructures, is a newly discovered plasmon-induced photoelectric converting mechanism. In this work, we have experimentally demonstrated that gold and silver nanoparticles exhibit opposite plasmoelectric potentials under the same excitation source, depending on their distinct surface plasmon resonance (SPR) frequencies. Three-dimensional mapping of plasmoelectric potentials on gold and silver nanoparticles depicts height-related surface potential information as well as the charge density evolution process down to the single nanoparticle level with Kelvin Probe Force Microscopy (KPFM). Upon employing a statistical method, the quantitative plasmoelectric potential is obtained. Under the power intensity of 5.4 mW/cm2, the maximum value of the plasmoelectric potential reaches −79 mV on the gold nanoparticle and 54 mV on silver nanoparticles. Finally, our work may provide guidance to the understanding of plasmoelectric potential on the single nanoparti...

Ionic liquids (ILs) are novel type of electrolytes and have found various applications in electrochemistry. Understanding their electrochemical stability has been one of fundamental and important subject of researches, which would promote further application of ionic liquids in electrochemistry. Electrochemical surface enhanced Raman spectroscopy (EC-SERS) can provide abundant finger print information of surface-bound species for elucidating reaction mechanism, while normal Raman (NR) spectroscopy of thin layer region near electrode surface can provide more information about products without interference of signals from surface adsorption. Here we report combined EC-SERS and NR studies with DFT calculations on the cathodic process of 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (EMITFSI) on Ag electrodes, aiming to identify reaction products and to reveal reaction mechanisms. It has been found that during the reduction of EMI cation, N-heterocyclic carbenes (NHCs) as an intermediate product were formed first and then underwent dimerization to form double-bond dimer. Single-bond dimer were also generated through single-electron radicals whose lifetime was too short to be detected directly though. In addition, dealkylation may happen, leading to formation of methylimidazole and ethylimidazole. This work not only deepens our insight into the cathodic process of EMI + , but also provides a guideline for electrochemical Raman study to be employed for tracing and understanding the process of electrode reaction.

Sodium metal is a very promising anode for energy storage and conversion in the post lithium ion battery era because of its high capacity (1166 mA h g−1), earth-abundance and low cost. However, the sodium metal anode suffers from unstable plating and stripping cycling and thus low Coulombic efficiency. One of the important reasons for the situation is the high overpotential for sodium nucleation and thus non-uniform deposition and even dendrites growth. Herein we report a facile method by introducing a “sodiophilic” layer of Au-Na alloy onto the Cu substrate that acts as the current collector to significantly reduce the nucleation overpotential. Thus, the sodium metal can be plated on and stripped from the modified current collector with good reversibility. The average Coulombic efficiency maintains 99.8% at the current of 2.0 mA cm−2 for 300 cycles. As a proof of concept, an anode-free full cell consisting of Cu@Au and presodiated FeS2 was assembled. Our work demonstrates the great importance of sodiophilic modification of substrate to the deposition process for sodium metal battery.

Organic molecules featuring weak spin-orbit and hyperfine interactions show promise in the construction of effective spintronic devices. However, the impact of molecular structures on anisotropic magnetoresistance at the single-molecule level remains to be explored. In this work, we report systematic investigations on the construction and magnetoresistance of spintronic single molecule junctions of aliphatic dicarboxylic acids HOOC−(CH2)n−COOH (n=1−4) and conjugated benzenedicarboxylic acids HOOC-(C6H4)n-COOH (n=1-3) binding to Fe electrodes by employing electrochemically assisted jump-to-contact STM break junction technique (JTC-STM-BJ) under a constant of external magnetic field. Results show that single-molecule tunneling anisotropic magnetoresistance (AMR) of alkanedicarboxylic acids is independent of the molecular length and can reach as large as 44% (average), which is about twice that of benzenedicarboxylic acids. The almost same constant βN value but different contact conductance Gc with the applied magnetic field indicate that AMR arise from interface effect and spin injection. Besides Br substituent on the benzene ring can almost double the AMR by changing the spatial distribution of molecular charge density and frontier orbital characteristics. The present work shows that molecular structures play important roles in electron transport through single-molecule spintronic junctions.

Zinc oxide (ZnO) nanorods were grown on the surface of a polypropylene (PP) nonwoven fabric (NWF) using the low-temperature hydrothermal method. The finishing process was investigated, and the prepared PP NWF was characterized. Results of the scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, anti-ultraviolet (UV) properties, and energy dispersive spectrometry indicate that the ZnO nanorods can be synthesized and uniformly coated on the surface of the PP NWF. The UV-degradation behavior and antibacterial activity of 0.025 M zinc nitrate hexahydrate-treated PP NWFs was good, with an ultraviolet protection factor value exceeding 100. Furthermore, the ZnO nanorods can inhibit the photodegradation of PP NWF. No obvious cracks were found on the fiber surface under 72 h of UV-light irradiation. The longitudinal and cross-breaking strength reduction properties were enhanced substantially. The ZnO nanorod-coated PP NWF achieved 99.5% bacterial reduction of Staphylococcus aureus and 99.9% bacterial reduction of Escherichia coli.

Summary Electrochemical interfaces in ionic liquids (ILs) are structurally anisotropic with multi-scaled and multi-natured interactions between electrode and IL as well as among ions of IL. Combined short-ranged and long-ranged surface techniques with high spatial, time and energy resolutions need to be employed to precisely characterize the lateral structure and vertical arrangement of IL at the interface. We briefly review recent advancements on the understanding of the molecular structure of electric double layer (EDL) at electrode–IL interfaces, with emphasis laid on the necessity of detailed and systematic potential-dependent measurements across and at close to the potential of zero charge (PZC). Future directions of fundamental investigations on EDL are briefly discussed.

A considerable amount of superfine Si precipitates with the sizes ranging from 5 to 15 nm were found uniformly dispersed in the Al matrix of an Al-1Si (wt.%) alloy after electropulsing treatment. Through high resolution transmission electron microscopy (HRTEM), an unusual 9R (ABCBCACAB…) ordered stacking faults were identified within the Si precipitates with a truncated tetrahedral morphology that hold a (1 1 1)Si//(1 1 1)Al & [ 1 0 1 ‾ ] Si // [ 1 1 ‾ 0 ] Al orientation relationship with the Al matrix. An atomistic model was established to preform image simulations and explain that the existence of these nanosized Si precipitates is attributable to increment of coincidence lattice sites between Si and Al.

To enrich the properties of chitosan (CS) and improve its applicability, we prepared carboxymethyl-chitosan (CMCS) by carboxymethylation and developed a layer-by-layer assembly (LBL) by the ultrasonic nebulization-assisted technique. The degree of carboxymethylation was 42.20% and the structure of CMCS was characterized using Fourier transform infrared, nuclear magnetic resonance spectroscopy. The ultrasonic nebulization-assisted LBL (UNLBL) edible coating was developed based on an inner negatively CMCS charged layer and an external positively charged CS layer. As compared to conventional LBL (CLBL) assembly, the greater thickness, stronger mechanical properties and lower water vapor permeability were detected in UNLBL assembly. Through an untargeted metabolomic analysis and real-time quantitative PCR, it was evident that ultrasonic nebulization-assisted LBL assembly is a promising alternative for promoting phenylpropanoid metabolism in strawberries.

Nonequilibrium stochastic reaction networks are commonly found in both biological and nonbiological systems, but have remained hard to analyze because small differences in rate functions or topology can change the dynamics drastically. Here, we conjecture exact quantitative inequalities that relate the extent of fluctuations in connected components, for various network topologies. Specifically, we find that regardless of how two components affect each other's production rates, it is impossible to suppress fluctuations below the uncontrolled equivalents for both components: one must increase its fluctuations for the other to be suppressed. For systems in which components control each other in ringlike structures, it appears that fluctuations can only be suppressed in one component if all other components instead increase fluctuations, compared to the case without control. Even the general $N$-component system---with arbitrary connections and parameters---must have at least one component with increased fluctuations to reduce fluctuations in others. In connected reaction networks it thus appears impossible to reduce the statistical uncertainty in all components, regardless of the control mechanisms or energy dissipation.

The exact muffin tin orbital (EMTO) method features high efficiency and accuracy for first-principles simulations with density functional theory. In this paper we report our implementation of the EMTO method for electronic-structure and quantum transport simulation of device materials. We consider a device-material structure with a central device region in contact with different semi-infinite electrodes. Based on the Green's function method, the infinite device, nonperiodic in transport direction, is transformed into a calculable finite material system by treating the semi-infinite electrodes with electrode self-energies, and the Green's function of the device region is calculated with an efficient recursive technique. In the present implementation we adopt the spherical cell approximation to treat the electrostatics, and we solve the electrostatic potential of the finite device region by enforcing the boundary conditions to the known potential of electrode materials. The coherent potential approximation is incorporated for treating the atomic disorders inevitable in realistic materials, and the effects of multiple disorder scattering on electron transport are accounted for by vertex correction for simulating disordered electronic devices. To demonstrate the capability of the present implementation, we calculate the monolayer two-dimensional material MoS2 and black phosphorus, and study the spin-dependent tunneling in the Fe/MgO/Fe magnetic tunneling junction. We find the EMTO electronic structures of the calculated systems agree well with the results of the projector augmented wave method. The EMTO transport simulation produces the important spin-filtering effect of the Fe/MgO/Fe junction and the important influence of the interfacial disorders on the spin-dependent tunneling, agreeing well with previous theoretical and experimental studies. The implementation of the EMTO based device simulator provides an effective simulation tool for simulating both ordered and disordered device materials, extending the capability for theoretical design of electronic devices from first principles.

Herein, the amino-capped TiO2 nanoparticles were synthesized using tetrabutyl titanate and amino polymers by a two-step sol-gel and hydrothermal method technique for the fabrication of functional cotton fabric. The prepared TiO2 nanoparticles and the treated cotton fabric were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), field emission scanning electron microcopy (FE-SEM) photocatalytic and antibacterial measurement. The results indicate the typical characteristic anatase form of the amino-capped TiO2 NPs with an average crystallite size of 14.9 nm. The treated cotton fabrics exhibit excellent antibacterial property and good photocatalytic degradation of methylene blue.

X-ray free-electron lasers (XFELs) are cutting-edge scientific instruments for a wide range of disciplines. Conventionally, the narrow bandwidth is pursued in an XFEL. However, in recent years, the large-bandwidth XFEL operation schemes are proposed for x-ray spectroscopy and x-ray crystallography, in which overcompression is a promising scheme to produce broad-bandwidth XFEL pulses through increasing the electron beam energy chirp. In this paper, combining with the beam yaw correction to overcome the transverse slice misalignment caused by the coherent synchrotron radiation, finding out the overcompression working point of the linac is treated as a many-objective (having four or more objectives) optimization problem, thus the nondominated sorting genetic algorithm III (NSGA-III) is applied to the beam dynamic optimization for the first time. Start-to-end simulations demonstrate a full bandwidth of 4.79% for Shanghai soft x-ray free-electron laser user facility. Furthermore, the NSGA-III is found to be very efficient by providing a set of reference points with preferences. This paves the way for applying this algorithm to online optimization of a real machine.

Perovskite solar cells are strong competitors for silicon-based ones, but suffer from poor long-term stability, for which the intrinsic stability of perovskite materials is of primary concern. Herein, we prepared a series of well-defined cesium-containing mixed cation and mixed halide perovskite single-crystal alloys, which enabled systematic investigations on their structural stabilities against light, heat, water, and oxygen. Two potential phase separation processes are evidenced for the alloys as the cesium content increases to 10% and/or bromide to 15%. Eventually, a highly stable new composition, (FAPbI3)0.9(MAPbBr3)0.05(CsPbBr3)0.05, emerges with a carrier lifetime of 16 μs. It remains stable during at least 10 000 h water–oxygen and 1000 h light stability tests, which is very promising for long-term stable devices with high efficiency. The mechanism for the enhanced stability is elucidated through detailed single-crystal structure analysis. Our work provides a single-crystal-based paradigm for stab...

Voltammetric responses, adsorption behaviors and layered structures of 1-ethyl-2, 3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide (EMMITFSI) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) at Au (111) have been investigated by cyclic voltammetry, in-situ STM and in-situ AFM force curve measurements, respectively. Cyclic voltammetry measurements pointed out that two pairs of sharp redox peaks are located at around 0.1 and 0.7 V in EMMITFSI, but not in EMITFSI. In-situ STM studies revealed no etching of the Au (111) surface in the investigated potential region in EMMITFSI, but an etched Au (111) surface was observed in EMITFSI in the same potential region, indicating that the interaction between EMITFSI and the Au (111) surface is much stronger than that between EMMITFSI and the Au (111) surface. In-situ AFM force curve measurements showed three layered structures at Au (111)/EMITFSI interface, but no force curves with saw-toothed feature can be obtained when the potential is higher than +0.5 V, which implies the disappearance of layered structures. In EMMITFSI, force curves with saw-toothed feature can be obtained even at +1.2 V. The fact that layered structures can form in a broader potential region indicates that a stronger interaction exists between the EMMI cation and the TFSI anion. It is inferred that the methylation of the hydrogen position provides a configuration for EMMI cations with an increased hydrophobic interaction, which maintains the layered structure in wider potential region. As a consequence, the electrode potential may induce structural transition of the layered structures, which is responsible for the origin of the voltammetric features. This work is supported by Natural Science Foundation of China (Nos. 21673193, 21533006, 21727807 and 21621091) and the Natural Science Foundation of Fujian Province of China (Grant 2016J01075). MICINN (Spain) support from project CTQ2016-76221-P is greatly acknowledged. ELECTRONANOMAT (Grant Agreement Number: PIRSES-GA-2012-318990) under European Framework Programme-Marie Curie Actions is also acknowledged.

Cysteine (Cys) is an essential amino acid with a carboxylic acid, an amine and a thiol group. We have studied the surface structure and adsorption dynamics of L-cysteine adlayers on Au(100) from aqueous solution using electrochemistry, high-resolution electrochemical scanning tunnelling microscopy (in situ STM), and molecular modelling. Cys adsorption on this low-index Au-surface has been much less studied than Cys adsorption on Au(111)- and Au(110)-electrode surfaces. Chronopotentiometry was employed to monitor the adsorption dynamics at sub-second resolution and showed that adsorption is completed in 30 minutes at Cys concentrations above 100 μM. Two consecutive steps could be fitted to these data. Two separate reductive desorption peaks of Cys adlayers on Au(100) with a total coverage of 2.52 (±0.15) × 10-10 mol/cm2 were observed. In situ STM showed that adsorbed Cys is organized in stripes with “fork-like” features which co-exist in (11×2)-2Cys and (7×2)-2Cys lattices, quite differently from Cys adsorption on Au(111)-electrode surfaces. Stripe structures with bright STM contrast in the center suggest that a second Cys adlayer on top of a first adlayer is formed, supporting the dual-peak reductive desorption of Cys adlayers. In addition, monolayers of both pure L-Cys, pure D-Cys and a 1:1 racemic mixture of L- and D-Cys on Au(100) were studied. Virtually identical macroscopic electrochemical features were found, but in situ STM discloses many more defects for the racemic mixture than for the pure enantiomers due to structural mismatch of L- and D-Cys. Density functional theory (DFT) calculations combined with a cluster model for the Au(100) surface were carried out to investigate the adsorption energy and geometry of adsorbed monomer and dimer Cys species in different orientations, with detailed attention to the chirality effects. Optimized DFT geometries were used to construct model STM images, and kinetic Monte Carlo simulations undertaken to illuminate the growth of adsorbate rows and the mechanism of the adlayer formation as well as the Cys adsorption patterns specific to the Au(100)-electrode surface.

In supercapacitors based on ionic liquid electrolytes, small amounts of absorbed water could potentially reduce the electrochemical window of electrolytes and cause performance degradation. The same would take place if ionic liquids are used as solvents for electrocatalysis involving the dissolved molecular species. In this work, we carry out molecular dynamics simulations, with gold and carbon electrodes in typical ionic liquids, hydrophobic and hydrophilic, to study electrosorption of water. We investigate the effects of hydrophobicity/hydrophilicity of ionic liquids and electrodes on interfacial distribution of ions and electrosorbed water. Results reveal that using hydrophilic ionic liquids would help to keep water molecules away from the negatively charged electrodes, even at large electrode polarizations. This conclusion is supported by electrochemical cyclic voltammetry measurements on gold and carbon electrodes in contact with humid ionic liquids. Thereby, our findings suggest potential mechanisms for protection of electrodes from water electrosorption., Ionic liquid electrolytes can impart increased operational voltage and energy density in supercapacitors, but water may diminish performance. Here the authors show that the hydrophilicity/hydrophobicity of ionic liquids can influence electrosorption of water and ultimately the supercapacitor performance.

Lithium metal anodes involve solid-electrolyte interphase (SEI) and various SEI-coupled interfaces, where Li deposition/dissolution and related processes take place. Important tasks of fundamental researches are to rationally designing and creating stable SEI and related interfaces based on in-depth understanding of the formation processes and the resultant interfacial/interphase structures. These issues fall into the category of and can be studied by taking the advantages of surface electrochemistry. In this review, we summarize recent advances in constructing SEI and lithiophilic interfaces via surface electrochemistry approaches as well as atomic force microscopic characterizations of morphology and nanomechanics for achieving long-term stability of Li anodes. Further fundamental research directions on Li metal anodes are also briefly discussed.

Surface roughness is a vital issue when evaluating the coating performance. In this work, Ti/TiN multilayer coatings were deposited on U Nb substrates with varied roughness of Ra 0.8/1.6/3.2/6.3 μm, and then the effect of substrate roughness on the service performance of Ti/TiN multilayer coating was studied. The interface structure, adhesion and corrosion behavior have been investigated by scanning electron microscopy (SEM), scratch tests and electrochemical measurements, respectively. The results showed that coating adhesion increased with a decrease of substrate roughness, along with the improvement of its corrosion rate. Both adhesion and corrosion properties degraded dramatically as Ra exceeding 3.2 μm, which may be explained by the residual stress and interfacial defects. And the coating failure occurred by spallation and cracking, typically along the peaks of the coating profile. This study offered guidance to optimize the substrate roughness for the deposition of hard protective coatings, especially for nuclear industries.

We study the low-temperature critical behavior of the one-dimensional Hubbard model near half filling caused by enhanced antiferromagnetic fluctuations. We use a mean-field-type approximation with a two-particle self-consistency renormalizing the bare interaction. It allows us to control a transition from high to low temperatures as well as from weak to strong-coupling. We show that there is a crossover temperature $T_{0}= t\exp\{-1/U��(0)\}$ for arbitrary interaction $U>0$ and the bare density of states at the Fermi energy $��(0)>0$. The solution at lower temperatures goes over to strong coupling and approaches a quantum critical point with the diverging staggered susceptibility and a gap in the excitation spectrum at zero temperature., 6 pages, 2 figures, Contributed talk at MMM 2020, to appear in AIP Advances

Adsorption of dye molecules on semiconductor surfaces dictates the interaction at and thus the electron transfer across the interface, which is a crucial issue in dye-sensitized solar cells (DSSCs). However, despite that surface enhanced Raman spectroscopy (SERS) has been employed to study the interface, information obtained so far is gathered from surfaces of irregularly arranged nanoparticles, which places complexities for precise attribution of adsorption configuration of dye molecules. Herein, we employ single crystalline rutile TiO2(110) for Raman spectroscopic investigation of TiO2–dye interfaces under electrochemical control by utilizing the enhancement of Au@SiO2 core–shell nanoparticles. FD-TD simulation is performed to evaluate the localized electromagnetic field (EM) created by the core–shell nanoparticles while Mott–Schottky measurements are used to determine the band structure of the semiconductor electrode. Comparative investigations are carried out on nanoporous P25 TiO2 electrodes. The pot...

The individual electrochemical anodic responses of dopamine (DA), epinephrine (EP), and pyrocatechol (CT) were investigated at arrays of recessed gold disk-microelectrodes arrays (MEAs) covered by a gold plane electrode and compared to those of their binary mixture (CT and EP) when the top-plane electrode was operated as a bipolar electrode or as a collector. The interferent species (EP) displays a chemically irreversible wave over the same potential range as the chemically reversible ones of DA or CT. As expected, in the generator-collector (GC) mode, EP did not contribute to the redox cycling amplification that occurred only for DA or CT. Conversely, in the bipolar mode, the presence of EP drastically increased the bipolar redox cycling efficiency of DA and CT. This evidenced that the chemically irreversible oxidation of EP at the anodic poles of the top plane floating electrode provided additional electron fluxes that were used to more efficiently reduce the oxidized DA or CT species at the cathodic poles. This suggests an easy experimental strategy for enhancing the bipolar efficiency of MEAs up to reach a performance identical to that achieved when the same MEAs are operated in a GC mode.