Atomic Electron Research Articles

Advancing mechanical durability and radiation shielding properties in Silicon dioxide (SiO2) glasses through various incorporations: A comparative analysis

Silicon dioxide (SiO2) glasses, known for their high thermal stability, excellent optical transparency, and substantial mechanical strength, are crucial in numerous technological applications, including radiation shielding. This research explores the impact of compositional variations in SiO2-based glasses on their mechanical and radiation shielding properties, particularly focusing on the inclusion of heavy metal oxides (HMO) and rare earth elements (REE) like neodymium (Nd). Through the systematic investigation of fifteen distinct glass samples with varying concentrations of specific oxides and elements, we investigate the compositional changes and their influence on physical properties and their effectiveness in attenuating radiation. Our findings demonstrate that the incorporation of Nd significantly enhances the glass's radiation shielding capabilities. Glasses doped with Nd exhibited higher effective atomic numbers and electron densities, which translate to superior attenuation characteristics at lower photon energies. This is highlighted by the exceptional performance of the 20Nd sample, showing the lowest exposure build-up factors (EBF) at 10 mean free paths (mfp), indicating its potential as a premier candidate for shielding applications against various energy levels of radiation. Moreover, the variation in the Elastic Modulus of the glass samples underscores the significant impact of the glass matrix composition on its mechanical properties, suggesting a delicate balance between network formers and modifiers in determining the glass properties. It can be concluded that the neodymium-doped SiO2-based glasses may be considered as targeted compositions in fine-tuning material properties to meet specific application requirements. As the demand for efficient radiation shielding materials grows across medical, industrial, and space exploration sectors, our findings provide a solid foundation for the development of new glass formulations tailored for enhanced mechanical properties and superior radiation protection levels.

Nanotubes from Lanthanide-Based Misfit-Layered Compounds: Understanding the Growth, Thermodynamic, and Kinetic Stability Limits.

Gaining insights into the kinetics and the thermodynamic limits of nanostructures in high-temperature reactions is crucial for controlling their unique morphology, phase, and structure. Nanotubes from lanthanide-based misfit-layered compounds (MLCs) have been known for more than a decade and were successfully produced mostly via a chemical vapor transport protocol. The MLC nanotubes show diverse structural arrangements and lattice disorders, which could have a salient impact on their properties. Though their structure and charge transfer properties are reasonably well understood, a lack of information on their thermodynamic and kinetic stability limits their scalable synthesis and their applicability in modern technologies. In this study, the growth, thermodynamic stability, and decomposition kinetics of lanthanide-based misfit nanotubes of two model compounds, i.e., (LaS)1.14TaS2 and (SmS)1.19TaS2 are elucidated in detail. The nanotubes were carefully analyzed via atomic resolution electron microscopy imaging and synchrotron-based X-ray and electron diffraction techniques, and the information on their morphology, phase, and structures was deduced. The key insights gained would help to establish the parameters to explore their physio-chemical properties further. Furthermore, this study sheds light on the complex issue of the high-temperature stability of nanotubes and nanostructures in general.

Inhibitory Effect of the Biosynthesized ZnO Nanoparticles by Musa acuminata Fruits Peels against Pathogenic Bacteria Isolated from Diabetic Foot Ulcer

Zinc Oxide nanoparticles was synthesized by green method with zinc nitrate as precursor and alcoholic extract of Musa acuminata fruits peels as a reducing agent, color changing from white to yellowish -white, which was an indication of the formation of ZnO NPs. Characterization were made by UV-Visible light spectroscopy (Uv-Vis), X-Ray Diffraction (XRD), Atomic force microscopy (AFM) and Field Emission Scan Electron Microscope (FE-SEM), the results showed the sharp UV peaks were at 374 nm , XRD analysis estimated the crystallites sizes in 25.9 nm, AFM was used to determine the average size and forme of the nanoparticles which was 40, 45, and 50 nm, FE- SEM analysis displayed average particles size were 75.6 nm. Clinical of 125 samples were collected from diabetic foot ulcer from patients admitted to Baquba Teaching Hospital during beginning of November 2021 to the end of January 2022, included isolation and diagnosis of 76 isolates of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis. Antibacterial activity test was done of ZnO NPs. which was tested toward these isolates. Different concentrations of ZnO NPs. (12.5, 25, 50, 100, 200) mg/ml were examined against pathogenic bacteria , the results showed the highest diameter of inhibition zone against E.coli, K.pneumoniae, P.aeruginosa, S.aureus and S.epidermidis were (28, 27, 31, 29. 26) mm respectively at concentration 200 mg/ ml and the lowest zone at concentration 12.5 mg/ml to the same isolates were (22, 23, 24, 24, 21) mm respectively.

Low-resistance TiAl3/Au ohmic contact and enhanced performance on AlGaN/GaN HEMT

The advent of an era characterized by intelligent, interconnected systems of AlGaN/GaN High Electron Mobility Transistors (HEMTs) electronic devices is underway. Within this context, the performance of ohmic contacts in HEMTs bears substantive influence on the electrical characteristics of power devices, notably impacting parameters such as on-resistance and output current. Therefore, the improvement of ohmic contacts attributes in AlGaN/GaN HEMT devices has perennially constituted a focal point of considerable industry. Based on the AlGaN/GaN heterostructure, a novel TiAl3/Au ohmic contact has been successfully developed for HEMTs. A low contact resistance of 0.23 Ω·mm (2.33 × 10-6 Ω·cm2) is obtained, which proposes a new interface contact for AlGaN/GaN heterojunction. Transmission electron microscope (TEM) illustrates that the contact mechanism for low resistance is direct contact with two-dimensional electron gas (2DEG) through the substitution of the TiN compound with a smaller area Au dominated penetration. Concurrently, in contrast to TiN, Au exhibits a diminished capacity for Ga dissolution, thereby substantiating its efficacy in preserving the structural integrity of the crystal lattice. In addition, the reduction of Al can impede the diffusion notably, further showing the smooth surface morphology of the electrode with atomic force microscope (AFM) and scanning electron microscopy (SEM) measurements. The ohmic contacts of HEMTs are individually fabricated with Ti/Al/Ni/Au and TiAl3/Au configurations. The HEMTs with TiAl3/Au ohmic contacts demonstrate superior DC characteristics.

Standardization and quantification of backscattered electron imaging in scanning electron microscopy

Backscattered electron (BSE) imaging based on scanning electron microscopy (SEM) has been widely used in scientific and industrial disciplines. However, achieving consistent standards and precise quantification in BSE images has proven to be a long-standing challenge. Previous methods incorporating dedicated calibration processes and Monte Carlo simulations have still posed practical limitations for widespread adoption. Here we introduce a bolometer platform that directly measures the absorbed thermal energy of the sample and demonstrates that it can help to analyze the atomic number (Z) of the investigated samples. The technique, named Atomic Number Electron Microscopy (ZEM), employs the conservation of energy as the foundation of standardization and can serve as a nearly ideal BSE detector. Our approach combines the strengths of both BSE and ZEM detectors, simplifying quantitative analysis for samples of various shapes and sizes. The complementary relation between the ZEM and BSE signals also makes the detection of light elements or compounds more accessible than existing microanalysis techniques.

Secluded scalar dark matter and the muon anomalous magnetic moment

Abstract We consider a dark matter model with a singlet scalar, $\chi$, as our dark matter (DM) candidate which is secluded from the Standard Model (SM) and annihilates to the singlet scalar, $\phi$, via a contact interaction. 
The singlet scalar, $\phi$, has a leptophilic interaction with the SM leptons 
and may decay leptonically at tree level, and decays into a pair of photons at loop level. 
The focus in this work is to consider DM masses below 10 GeV. 
It is found a viable secluded region in the parameter space after imposing the observed 
relic density. There is a one-loop interaction between scalar dark matter and the atomic electron in this model. We then apply the available direct detection bounds from Xenon10, Xenon1T, and DarkSide on the DM-electron elastic scattering cross section. While the model can explain the muon anomalous magnetic moment, we put bounds from current and future lepton collider experiments.

Topographical and morphological changes of the single‐crystal (La0.3Sr0.7)(Al0.65Ta0.35)O3 (001) surface treated with high‐purity deionized water

The topological and morphological changes of the (001) surface of single‐crystal (La0.3Sr0.7)(Al0.65Ta0.35)O3 during treatment with high‐purity deionized water (DI) have been investigated by atomic force microscopy and scanning transmission electron microscopy (STEM). Etching by DI treatment at room temperature proceeded mainly in anisotropic etching mode, resulting in rectangular etch pits with {001} inner surfaces forming in the surface. The dominant etching mode changed from anisotropic to isotropic with increasing DI‐treatment temperature, and the lowest surface roughness occurred for DI treatment at 50°C for 60 min. Direct observation of the atomic structure of the surface by STEM showed that the etched surface was the B‐site‐terminated (001) surface after anisotropic etching at 50°C for 60 min, in which the B‐site‐terminated atomic layer was found to maintain the B‐site ordered structure existing in the crystal. This is because DI treatment, which does not require high‐temperature heat treatment of the substrate, suppresses element diffusion, sublimation, and formation of point defects on and in the vicinity of the surface.

Enhancing CFRP laminates with plasma jet arrays: A study of interlaminar mechanical properties

AbstractThis study delves into the efficacy of plasma jet array treatment in bolstering the interlaminar toughness of Carbon Fiber Reinforced Polymer (CFRP) prepregs, a crucial parameter for their deployment in high‐performance domains. Employing high‐frequency pulsed microsecond plasma jet arrays for surface modification, this research not only demonstrated a 19.49% upsurge in peak load capacity but also a remarkable 29.94% enhancement in Mode I interlaminar fracture toughness, as evident from Double Cantilever Beam (DCB) tests. Furthermore, the surface wettability improvements were underscored by a substantial decrease in water contact angle from 108.33° to 31.45° and a total surface energy augmentation from 12.20 to 64.16 mN/m, post a 1‐min plasma treatment. X‐ray Photoelectron Spectroscopy (XPS) results indicated an appreciable rise in oxygen functionalities, suggesting enhanced resin‐fiber bonding. Additionally, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) analyses revealed notable decreases in surface roughness and microscale defects, contributing to smoother surfaces conducive to better adhesive bonding and reduced manufacturing defects. These multifaceted improvements, stemming from alterations in surface chemistry and topography, underpin the significant potential of plasma treatment in advancing CFRP laminate applications requiring superior durability and mechanical resilience.Highlights A plasma jet arrays method to enhance CFRP's interlaminar properties was studied. The influence mechanism of plasma modification was revealed in detail. The interlayer toughening mechanism of CFRP after plasma modification is proposed.

Design and characterization of novel Zr-Al-Fe-Y metallic glasses with nanoscale phase separation

We present a new phase-separated Zr-based metallic glass (MG) composition, free of toxic elements (Ni and Cu) prepared in a glass-forming system by alloying addition. The substitution of Y in Zr70-xAl12.5Fe17.5Yx (x = 0–15 at.%) results in phase separation, giving rise to nano-amorphous domains in a glassy matrix. A homogeneous MG feature is observed for low concentrations of Y up to x = 5. Microstructure and thermal property analysis indicate that the glasses with x = 10 and 15 at.% Y exhibit a typical liquid phase separation-induced two-glassy phase (Zr-rich and Y-rich) with droplet-like microstructures (nano-amorphous domains). With increasing Y addition, the domain size increases. The microstructural evolution arising due to phase separation in these alloys is confirmed by a combination of transmission electron microscopy (TEM) and atom probe tomography (APT) analysis. The formation of nanometer-size Y-enriched clusters is confirmed by APT for x = 15.

Protein-derived carbon dots as green corrosion inhibitors for carbon steel in sulfuric acid solution

At present, the development of eco-friendly corrosion inhibitors (CIs) is considered an important and attractive method for controlling the corrosion of metals in acidic media. In this study, protein-derived carbon dots (P-CDs) were prepared via hydrothermal reaction using protein as the raw material, and the corrosion inhibition performances of P-CDs for carbon steel (CS) were investigated systematically. The electrochemical test results showed that the corrosion inhibition efficiency of 500 mg/L P-CDs on CS reached 95.1 % in 0.5 M H2SO4, and the corrosion inhibition efficiency was enhanced to 98.1 % after 8 h of immersion time. The composition and characterization of P-CDs was analysed using Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet Spectroscopy (UV), X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) characterization showed that the surface of CS with P-CDs was smoother than that without P-CDs, and that P-CDs was able to adsorb on the surface of CS to form a protective layer, thereby inhibiting corrosion. Adsorption studies indicate that P-CDs form a protective layer on the surface of CS through both physisorption and chemisorption. Overall, these findings demonstrate that P-CDs exhibit superior protective effects against the corrosion of CS in 0.5 M H2SO4.

Anomalous magnetization induced by local chemistry fluctuations in Mn-containing α’-martensite

An anomalous increase in magnetization was investigated in a cold-rolled high-Mn TRIP steel (16.8 wt% Mn) annealed at 350°C for times varying from 5 to 120 min, before the start of austenite reversion (α’ → γ). Besides in-situ and ex-situ magnetic measurements, the full characterization of this phenomenon was also performed with the aid of X-ray diffraction (XRD), Mössbauer spectroscopy, and microstructural characterization using electron backscatter diffraction (EBSD) and atom probe tomography (APT). Based on XRD measurements, the volume fraction of austenite and α’-martensite was estimated as a function of annealing time, as well as their lattice strain. Phase quantification confirmed the absence of newly-fresh α’-martensite in the material during annealing at 350°C. Short annealing up to 15 min promoted the increase of Ms (saturation magnetization) due to stress relief in α’-martensite (Villari effect). Further annealing to 30 min promotes the decrease in Ms driven by short-range solute reorganization within the lattice. After 60 min annealing, the creation of long-range solute-depleted zones (i.e. confined zones highly enriched in Fe) causes a new increase in Ms. In comparison, for 120 min of annealing time, Ms tends to remain unaltered. These findings revealed that short- and long-range chemical fluctuations strongly affect the saturation magnetization of the steel and brought new insights on the use of magnetic probing as a tool for phase quantification in Mn-bearing steels.

Facile and Bioinspired Approach from Gallic Acid for the Synthesis of Biobased Flame Retardant Coatings of Basalt Fibers.

A sustainable, bioinspired approach to functionalize basalt fibers with an innovative gallic acid (GA)-iron phenyl phosphonate complex (BF-GA-FeP), for the purpose of improving the flame retardancy in composite materials, is developed. BFs were at first pretreated with O3, obtaining surface free hydroxyl groups that allowed the subsequent covalent immobilization of biosourced GA units on the fiber through ester linkages. Phenolic -OH groups of the GA units were then exploited for the complexation of iron phenyl phosphonate, resulting in the target-complex-coated BF fiber (BF-GA-FeP). Microwave plasma atomic emission spectroscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analyses of BF-GA-FeP highlighted an increase in iron content, modification of fiber morphology, and occurrence of phosphorus, respectively. BFs, modified with a low amount of the developed complex, were used to reinforce a poly(lactic acid) (PLA) matrix in the production of a biocomposite (PLA/BF-FeP). PLA/BF-FeP showed a higher thermal stability than neat PLA and PLA reinforced with untreated BFs (PLA/BF), as confirmed by thermogravimetric analysis. The cone calorimeter test highlighted several advantages for PLA/BF-FeP, including a prolonged time to ignition, a reduced time to flame out, an 8% decrease in the peak heat release rate, and a 15% reduced fire propagating index compared to PLA/BF.

Spectroscopic Characterization of Highly Excited Neutral Chromium Tricarbonyl.

Spectroscopic characterization of highly excited neutral transition-metal complexes is important for understanding the multifaceted reaction mechanisms between metals and ligands. In this work, the reactions of neutral chromium atoms with carbon monoxide were probed by size-specific infrared spectroscopy. Interestingly, Cr(CO)3 was found to have an unprecedented 7A2″ septet excited state rather than the singlet ground state. A combination of experiment and theory shows that the gas-phase formation of this highly excited Cr(CO)3 is facile both thermodynamically and kinetically. Electronic structure and bonding analyses indicate that the valence electrons of Cr atoms in the septet Cr(CO)3 are in a relatively stable configuration, which facilitate the highly excited structure and the planar geometric shape (D3h symmetry). The observed septet Cr(CO)3 affords a paradigm for exploring the structure, properties, and formation mechanism of a large variety of excited neutral compounds.

Unraveling the role of Cu2+ induced Jahn-Teller distortion and electron occupation alternation in modulating electronic and optical properties of CuxFe1-xFe2O4

In recent years, attractive Fe3O4 and transition metal-doped Fe3O4 magnetic ferrites have received increasing attention due to their wide range of applications in catalyst carriers. The doping of Cu in Fe3O4 can tune optical and electrical properties. Due to the arrangement of the valence electrons of the Cu atoms, the distortion of Jahn-Teller (J-T) is very easy to occur. It needs to be studied that the physical mechanism of J-T distortion and energy band gap variation with Cu concentration. In this study, the electronic structure and optical properties of the CuxFe1-xFe2O4 (x = 0–1) defect system have been calculated based on the density-functional theory using the hybrid functional method. Two distinct types of J-T distortion, compression distortion and elongation distortion, have been present in our calculations. Furthermore, projected density of states (PDOS) has verified that the electron arrangement of compressed Cu2+ is (t2g)6 (dx2−y2)2 (dz2)1, then the electron arrangement of elongated Cu2+ is (t2g)6 (dz2)2 (dx2−y2)1. The doped Cu lowers the position of conduction band minimum (CBM), so the energy gap decreases with increasing of Cu concentration (0 < x < 1). When x = 1, the FeOct2+ is completely replaced by CuOct2+ and the valence band maximum (VBM) levels are provided by the doped Cu atom, then the energy gap is maximum. The elongated Cu2+ results in the CBM localized around the doped Cu, and increase the absorption intensity of visible light. It shows that the doped Cu atom system in the visible region of the absorption intensity increases and the absorption of light range is more extensive. Our findings demonstrate that distinct J-T distortions induced by Cu can efficiently modulate the electronic and optical properties of CuxFe1-xFe2O4. Cu doping changes the light absorption and extinction coefficients of Fe3O4. This provides a theoretical basis for the application of CuxFe1-xFe2O4 in wave absorption. At x = 0.5, the absorption coefficient of Cu-doped Fe3O4 is increased by 1.8 times. Because of its magnetic properties, it is easy to separate the catalyst. The application in catalyst support engineering has far-reaching research significance. This study is groundbreaking as it provides a detailed explanation at the electronic level for the physical mechanism of Jahn-Teller distortion in Cu2+. It is useful to investigate defect-induced light absorption and energy band engineering at the microscopic level.

Self-Assembly of Hierarchical High-χ Fluorinated Block Copolymers with an Orthogonal Smectic-within-Lamellae 3 nm Sublattice and Vertical Surface Orientation.

Hierarchical structure-within-structure assemblies offer a route toward increasingly complex and multifunctional materials while pushing the limits of block copolymer self-assembly. We present a detailed study of the self-assembly of a series of fluorinated high-χ block copolymers (BCPs) prepared via postmodification of a single poly(styrene)-block-poly(glycidyl methacrylate) (S-b-G) parent polymer with the fluorinated alkylthiol pendent groups containing 1, 6, or 8 fluorinated carbons (termed trifluoro-ethanethiol (TFET), perfluoro-octylthiol (PFOT), and perfluoro-decylthiol (PFDT), respectively). Bulk X-ray scattering of thermally annealed samples demonstrates hierarchical molecular assembly with phase separation between the two blocks and within the fluorinated block. The degree of ordering within the fluorinated block is highly sensitive to synthetic variation; a lamellar sublattice was formed for S-b-GPFOT and S-b-GPFDT. Thermal analyses of S-b-GPFOT reveal that the fluorinated block exhibits liquid crystal-like ordering. The complex thin-film self-assembly behavior of an S-b-GPFOT polymer was investigated using real-space (atomic force microscopy and scanning electron microscopy) and reciprocal-space (resonant soft X-ray scattering (RSoXS), grazing incidence small- and wide-angle scattering) measurements. After thermal annealing in nitrogen or vacuum, films thicker than 1.5 times the primary lattice spacing exhibit a 90-degree grain boundary, exposing a thin layer of vertical lamellae at the free interface, while exhibiting horizontal lamellae on the preferential (polystyrene brush) substrate. RSoXS measurements reveal the near-perfect orthogonality between the primary and sublattice orientations, demonstrating hierarchical patterning at the nanoscale.

Enhancing biocompatibility and osseointegration of medical implants using ti based nanocomposite coatings

The surface of the replacement medical implant can be coated, which is one of the most basic and effective ways to develop and strengthen bones and increase their compatibility for the human body to solve problems with bone defects, such as the problem of releasing ions from some elements of the body Medical alloy implants are one of the major drawbacks in bone fracture surgery, and biocompatible implants are new ways to ensure that these implants work well. These implants play a major role in accelerating osseointegration processes, but at the same time they suffer from the problem of releasing niobium and zirconium ions, which may cause serious diseases to human health. To stop these toxic ions from releasing, a bioceramic nanolayer coating was put on the alloy's surface. This made it more biocompatible and stopped the toxic ions from escaping. Among several types of coatings, the best nanocomposite coating was selected. Three criteria and levels were used: voltage, time, and cocentartion. A Takeuchi statistical program was used to collect data on all the tests (thickness, adhesion, contact angle, and roughness) in order to find the best coated sample. The study then used atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM) methods.

Microstructure characterization and phase evolution of equiatomic AlCoMoFeNi high entropy alloy synthesized by mechanical alloying

The present study deals with the fabrication of a novel AlCoMoFeNi high-entropy (HEA) alloy using mechanical alloying techniques. The developed HEA was characterized by X-ray diffraction, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) equipped with energy dispersive x-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The crystallite size of the high-entropy alloy solid solution was determined to be 20 ± 1 nm, with a lattice strain of 0.467 ± 0.03 % and a lattice parameter of 3.98 ± 0.08 Å. A number of characteristics, including melting point, mixing enthalpy change, mixing entropy change, atomic size difference, electronegativity difference, and valence electron concentration, were computed in order to ascertain the conditions regulating the formation of high-entropy alloys. A HEA with BCC and FCC solid solution was obtained after mechanical alloying, which was confirmed by experimental findings as well as thermodynamic calculations.

Reduced graphene oxide/gold nanoparticles based ultrasensitive resistive sensor for PCA3

Early prostate cancer detection can be improved by detecting more specific markers like PCA3 RNA. This study reports a novel and simple method for detecting PCA3 RNA using a sensor based on reduced graphene oxide (RGO), gold nanoparticles (AuNP), and a single-stranded DNA (ssDNA). The device was characterized at each fabrication step using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The RGO/AuNP/ssDNA sensor exhibited a significant change in resistance (6.51–15.01%) when exposed to varying concentrations of PCA3 (0.1–100 ng/mL). The developed device showed selective response towards PCA3 (14.5% for 50 ng/mL) when compared with negative controls like phosphate buffer saline solution (0.28%), PCA3-negative control sample (1.03%), RNA extracted from lung cancer (0.88%), and breast cancer (1.17%) cell lines. The RGO/AuNP/ssDNA sensor could also be employed to quantify the PCA3 RNA present in the RNA mixture extracted from a prostate cancer cell line and the observed findings were in excellent agreement with semi-quantitative real-time polymerase chain reaction (RT-PCR) results.

Catalytic dechlorination of carbon tetrachloride to combustible hydrocarbons by Pd-Fe hydroxides through atomic hydrogen attack and direct electron transfer

Carbon tetrachloride (CT), a common persistent pollutant in groundwater, has attracted widespread attention from environmental researchers. The dechlorination from CT to combustible hydrocarbons not only represents the removal of contaminants, but also offers the possibility of recovering carbon resources from water. In this work, we used the coprecipitation of Fe(II) and Pd(II) to synthesize Pd-Fe hydroxides for the dechlorination of CT. When Pd and Fe dosages were 0.4 and 5 mM respectively, CT with 26 µM concentration can be fast removed within 5 min, and 43.3 % of CH4 and 11.6 % of C2H6 (mol%) were generated after 110 min. The alkaline condition was more conducive to the complete dechlorination of CT comparing with acidic and neutral conditions. During the olation process, Fe(II) as electron donor transferred electrons to Pd(II) to form Pd(0) clusters. Pd(0) active sites act on the binding of CT and transfer electron to H+/H2O to form adsorbed atomic hydrogen (Hads•). The adsorbed CT molecules on the surface of Pd-Fe hydroxides undergo continuous dechlorination to form CH4 and C2H6 through the attack of Hads• and direct electron transfer. In real groundwater applications, CT was rapidly removed, with CH4 and C2H6 yields reaching 24.5 % and 4.6 % (mol%), respectively. Encouragingly, incomplete dechlorinated products, including chloroform and dichloromethane, did not show signs of subsequent rebound even after 60 min. Furthermore, Pd-Fe hydroxides also exhibit resistance to the oxidation effects of dissolved oxygen, which demonstrates the promising application prospects.

2D WS2/WSe2(Er) Heterojunction for High Performance Photodetectors

Abstract2D transition metal dichalcogenides and their heterojunctions have demonstrated great potentialities for applications in optoelectronics, and rare‐earth doping has proven an effective way for achieving high performance. Here, 2D WS2 and Er3+ in situ doped WSe2 are prepared by the chemical vapor deposition method. Thicknesses and atomic structures of the prepared WS2 and WSe2 are characterized by atomic force microscopy and transmission electron microscope, while qualities of the membranes are characterized by photoluminescence spectroscopy and Raman spectroscopy, respectively. The 13.7 and 15.8 at% of Er3+ doping concentration in WSe2 are examined by energy dispersive spectroscopy and X‐ray photoelectron spectroscopy, respectively. Performances of photodetectors based on the WSe2 and Er3+ doped WSe2 membranes are characterized individually. A microregion fixed‐point transfer technique is used to transfer the monolayer WS2 onto the Er‐doped monolayer WSe2 to form vertical van der Waals heterojunctions. Excellent performances are measured from the monolayer WS2/WSe2(Er3+) heterojunction photodetector with a photoresponsivity (Rλ) of up to 40.5 A W−1 and external quantum efficiency (EQE) of 8793%. The results prove the effectiveness of Er3+ in situ doping in WS2/WSe2(Er) heterojunctions for high‐performance photodetectors.