Synthesis and Broadband Photodetection of a P-Type 1D Van der Waals Semiconductor HfSnS3.

1D van der Waals (vdW) materials have attracted significant interest in recent years due to their giant anisotropic and weak interlayer-coupled characters. More 1D vdW materials are urgently to be exploited for satisfying the practice requirement. Herein, the study of 1D vdW ternary HfSnS3 high-quality single crystals grown via the chemical vapor transport technique is reported. The Raman vibration modes and band structure of HfSnS3 are analyzed via DFT calculations. Its strong in-plane anisotropic is verified by the polarized Raman spectroscopy. The field-effect transistors (FETs) based on the HfSnS3 nanowires demonstrate p-type semiconducting behavior as well as outstanding photoresponse in a broadband range from UV to near-infrared (NIR) with short response times of ≈0.355 ms, high responsivity of ≈11.5 A W-1 , detectivity of ≈8.2 × 1011 , external quantum efficiency of 2739%, excellent environmental stability, and repeatability. Furthermore, a typical photoconductivity effect of the photodetector is illustrated. These comprehensive characteristics can promote the application of the p-type 1D vdW material HfSnS3 in optoelectronics.

Ternary GePdS3: 1D van der Waals Nanowires for Integration of High-Performance Flexible Photodetectors.

One-dimensional (1D) van der Waals (vdW) materials are anticipated to leverage for high-performance, giant polarized, and hybrid-dimension photodetection owing to their dangling-bond free surface, intrinsic crystal structure, and weak vdW interaction. However, only a few related explorations have been conducted, especially in the field of flexible and integrated applications. Here, high-quality 1D vdW GePdS3 nanowires were synthesized and proven to be an n-type semiconductor. The Raman vibration and band gap (1.37-1.68 eV, varying from bulk to single chain) of GePdS3 were systemically studied by experimental and theoretical methods. The photodetector based on a single GePdS3 nanowire possesses fast photoresponse at a broadband spectrum of 254-1550 nm. The highest responsivity and detectivity reach up to ∼219 A/W and ∼2.7 × 1010 Jones (under 254 nm light illumination), respectively. Furthermore, an image sensor with 6 × 6 pixels based on GePdS3 nanowires is integrated on a flexible polyethylene terephthalate (PET) substrate and exhibits sensitive and homogeneous detection at 808 nm light. These results indicate that the ternary noble metal chalcogenides show great potential in flexible and broadband optoelectronics applications.

Tailoring the epitaxial growth of oriented Te nanoribbon arrays.

As an elemental semiconductor, tellurium (Te) has been famous for its high hole-mobility, excellent ambient stability and topological states. Here, we realize the controllable synthesis of horizontal Te nanoribbon arrays (TRAs) with an angular interval of 60°on mica substrates by physical vapor deposition strategy. The growth of Te nanoribbons (TRs) is driven by two factors, where the intrinsic quasi-one-dimensional spiral chain structure promotes the elongation of their length; the epitaxy relationship between [110] direction of Te and [110] direction of mica facilitates the oriented growth and the expansion of their width. The bending of TRs which have not been reported is induced by grain boundary. Field-effect transistors based on TRs demonstrate high mobility and on/off ratio corresponding to 397 cm2 V-1 s-1 and 1.5×105, respectively. These phenomena supply an opportunity to deep insight into the vapor-transport synthesis of low-dimensional Te and explore its underlying application in monolithic integration.

Degradation and residues of mandipropamid in soil and ginseng and dietary risk assessment in Chinese culture.

Mandipropamid, a new fungicide for oomycete disease, has a strong effect on the blight of many crops and has been registered for the treatment of ginseng blight in China. However, no maximum residue limit (MRL) of mandipropamid has been identified for ginseng, and there have been few related studies. We established and verified the analysis method of mandipropamid in ginseng using high-performance liquid chromatography-tandem mass spectrometry. The method has good linearity and accuracy in the range of 0.002-0.5 mg/kg. The average recovery of mandipropamid was 87.4-101.6%, and the standard deviation was 1.1-4.0. Mandipropamid in ginseng plants and soil rapidly degraded following first-order kinetics models. The degradation dynamics showed that the half-life of mandipropamid in ginseng plant and soil was 13.8-28.0 and 9.8-27.4 d, respectively. After the recommended dose of mandipropamid was applied once, the residual content of mandipropamid in fresh ginseng, dried ginseng, red ginseng, ginseng plant, and ginseng soil was < 0.01-0.185, < 0.01-0.265, 0.085-1.544, 0.075-4.800, and < 0.01-0.014 mg/kg, respectively. The dietary risk assessment of mandipropamid on ginseng showed that the risk quotient value was far less than 100%, indicating that the recommended dose of mandipropamid does not cause unacceptable risks to humans. After the recommended dose of mandipropamid was applied once, it did not cause unacceptable risks to humans. This study not only provides a reasonable spray dosage of mandipropamid to ginseng but also offers a reference for the establishment of MRLs in China.

Dissipation and Dietary Risk Assessment of Pydiflumetofen Residues in Soybean.

In this study, the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method, combined with high-performance liquid chromatography−tandem mass spectrometry, was chosen for detecting pydiflumetofen residues in soybean plants, soybeans and soil, and assessing the risk of short- and long-term dietary intake. Pydiflumetofen concentrations ranging from 0.001−0.5 mg/L exhibited good linearity (r > 0.997). At varying doses, the average pydiflumetofen recovery rates and relative standard deviations among soybean plants, soybeans, and soil ranged from 83.9 ± 1.1% to 99.5 ± 3.3% and from 0.77 to 7.77%, respectively. The sensitivity, accuracy, and precision of the chosen methodology met the requirements of pesticide residue analysis. The results of the degradation dynamics test showed that the half-life of pydiflumetofen (t1/2) in soybean plants and in soil were 3.6 to 5.7 and from 7.9 to 25.7 d, respectively. Assessment of the concentration of pydiflumetofen residues in soybeans revealed acute and chronic dietary exposure risks of 0.06 and 7.54%, respectively. As these values are very low, pydiflumetofen residues in soybeans present an acceptable risk to public health. The results of this study will help to guide the practical application of pydiflumetofen and minimize the environmental risks associated with its use.

Complete surface reconstruction of nanoporous gold during CH4 pyrolysis.

The catalytic activity and selectivity of metallic nanocatalysts can be controlled using physical and chemical methods to tune the exposed crystal facets. Nanoporous metals (NPMs) have unique bicontinuous structures, large specific surface areas, and high catalytic activities, and are widely used in the field of heterogeneous catalysis. However, owing to the complex surface topography of NPMs, it is difficult to regulate their exposed crystal facets over a large area. In this study, nanoporous gold (NPG) is successfully prepared with a complete regular surface that exposes the Au {111} and {100} facets through a methane pyrolysis reaction. The results of high-spatial and -temporal resolution in situ experiments and theoretical calculations indicate that C species significantly weaken the interaction between surface Au atoms with low coordination numbers and their surrounding atoms, which results in the migration and recombination of surface atoms. This research fundamentally clarifies the reconstruction mechanism of porous materials during methane pyrolysis and provides a theoretical basis for the targeted regulation of exposed NPM surfaces.

A Novel Analysis Method for Simultaneous Determination of 31 Pesticides by High-Performance Liquid Chromatography-Tandem Mass Spectrometry in Ginseng.

Ginseng is a perennial herb with a long growth cycle and is known to easily accumulate pesticides during its growth process, seriously threatening people's health. Therefore, to ensure safe consumption, it is necessary to detect and monitor pesticide residues in ginseng. In this study, a novel analysis method was established for simultaneous determination of 31 pesticides in ginseng by high-performance liquid chromatography-mass spectrometry. Ginseng samples were extracted using acetonitrile, cleaned up by primary secondary amine (PSA) solid-phase extraction column eluted with acetonitrile-toluene, and then detected in multiple reaction mode (MRM). The calibration curves of target compounds were linear in the range of 0.005-1.0 mg/L, with correlation coefficients greater than 0.9921. The limits of detection of all the pesticides in ginseng were between 4.4×10-5 and 1.6 × 10-2 mg/kg. For fresh ginseng, the average recoveries ranged from 72.1 to 111.6%, and the relative standard deviations were 1.3-12.2%. For dry ginseng, the average recoveries were 74.3-108.3%, and the relative standard deviations were 0.9-14.9%. The residual concentrations of some pesticides in real samples were greater than the maximum residue limit (MRL) for European Union (EU). The method established here is rapid and simple with high sensitivity and good reproducibility, which is sensitive in the residue analysis of many pesticides in ginseng.

Long-Life Dendrite-Free Lithium Metal Electrode Achieved by Constructing a Single Metal Atom Anchored in a Diffusion Modulator Layer.

Lithium metal electrodes have shown great promise for high capacity and the lowest potential. However, wide application is restricted by uncontrollable plating/stripping lithium behaviors, an uneven solid electrolyte interphase, and a lithium dendrite. Herein, the highly active single metal atom anchored in vacant catalyst is synthesized on the hierarchical porous nanocarbon (SACo/ADFS@HPSC). Acting as an artificial protective modulation layer on the lithium surface, the numerous atomic sites show the superiority in modulating lithium ion behaviors and smoothing the lithium surface without dendrite growth. As a consequence, the SACo/ADFS@HPSC-modified Li electrode lowers nucleation barrier (15 mV), extends the smooth plating lifespan (1600 h), and improves Coulombic efficiency, significantly accelerating the horizonal deposition of plated lithium. Coupled with a sulfur cathode, the fabricated pouch cell with 5.4 mg cm-2 delivers a high capacity of 3.78 mA h cm-2 corresponding to 1505 Wh kg-1, showing the promising practical application.

Synergetic interaction between neighboring platinum and ruthenium monomers boosts CO oxidation.

Sub-nanometer noble metal catalysts, especially single atom (SA), are a new class of catalytic materials for boosting catalysis and possess unique catalytic properties and high atomic utilization efficiency. Exploring the interaction between two neighboring atom monomers has great potential to further improve the performance of SA catalysts and deepen the understanding on the catalytic mechanism of heterogeneous catalysis at the atomic level. Herein, we demonstrate that the synergetic effect between neighboring Pt and Ru monomers supported on N vacancy-rich g-C3N4 promotes the catalytic CO oxidation. The experimental observation and theoretical simulation reveal that the N vacancy in the g-C3N4 structure builds an optimized triangular sub-nanometer cavity for stabilizing the neighboring Pt-Ru monomers by forming Pt-C and Ru-N bonds. The mechanistic studies based on the in situ IR spectrum and theoretical simulation confirm that the neighboring Pt-Ru monomers possess a higher performance for optimizing O2 activation than Ru-Ru/Pt-Pt monomers or isolated Ru/Pt atoms by balancing the energy evolution of reaction steps in the catalytic CO oxidation. The discovery of the synergetic effect between neighboring monomers may create a new path for manipulating the catalytic properties of SA catalysts.

Atomic-scale selectivity of hydrogen for storage sites in Pd nanoparticles at atmospheric pressure.

Hydrogen-storage materials are important carriers for a viable hydrogen economy. Despite palladium being the most studied storage material, the hydrogen-storage mechanism of Pd remains ambiguous owing to the lack of atomic-scale evidence of the diffusion and storage of H atoms in its lattice. In the study reported here, this classical process was investigated on the atomic scale using an in situ transmission electron microscope equipped with an atmospheric-pressure sample holder. The expansion of the Pd interplanar spacings was found to comprise three distinct stages during the diffusion of H atoms. Moreover, the expansion in d-spacing of Pd{111} was markedly different from that of Pd{220}. First-principles calculations indicate that H atoms mainly occupy the centers of the tetrahedral cages in the Pd unit cells during the diffusion stage, and they eventually occupy the octahedral cage centers in the equilibrium state. Moreover, H atoms were detected in substantially high densities in defects such as stacking faults and twin boundaries. These observations on the preferred hydrogen-storage domains can help clarify the hydrogen-storage mechanism and offer guidelines on the future design of higher-capacity hydrogen-storage materials.

Effect of permanent magnetic field on scale inhibition property of circulating water.

Effect of a permanent magnet field on the scale inhibition property of circulating water was investigated. Orthogonal experiments of L16(45) were performed and analyzed using the range analysis method. The operating parameters included magnetic field intensity, initial concentration of Ca2+ and Mg2+, magnetic treatment time, temperature, and flow velocity. Scale inhibition rate, hardness, relative variation in the proportion of free water molecules, electrical conductivity, and relative variation of molecular energy were chosen as the objectives. In addition, the morphology and the composition of CaCO3 and MgCO3 scale were studied by X-ray diffraction analysis. The optimal conditions were initial concentration of 900 mg/L, magnetic field intensity of 0.5 T, temperature of 303 K, time of 54 h and flow velocity of 0.17 m/s. The nuclear magnetic resonance results demonstrated that the number of hydrogen bonds increased between water molecules and hydrated ions. The magnetic field can promote the increase in the number of hydrogen bonds, which can inhibit the formation of calcium and magnesium carbonate precipitation. Moreover, the ratio of calcite, aragonite and vaterite will be changed at different magnetic field intensities, and the aragonite ratio will reach the peak at the optimum conditions.