Binding Energy Of Atom Research Articles

Enhanced water molecule sensitivity on defective WS2 monolayers through (ZnO)12 spherical nanocages decoration: A theoretical study

The adsorption of water molecules on sulfur vacancies (VS and V2S2) and gold atoms embedded in the sulfur vacancies (AuS) of tungsten disulfide (WS2) monolayers (ML) decorated with zinc-oxide (ZnO)12 nanocages were studied using dispersion-corrected density functional theory. Since the WS2 monolayer is predominantly inert, the introduction of defect states into the mid-bandgap region is significant due to its chemical and physical implications. The possibility of turning from an electron acceptor (p-type) to an electron donor (n-type) semiconductor character, when the sulfur vacancy density is varied or if the sulfur vacancies are filled with gold atoms, was demonstrated. The binding energy of the Au atom forming the AuS defect and the diffusion energy barrier from the VS defect to an adjacent site for Au were determined as 2.99 and 2.16 eV, respectively. Consequently, the substitutional defect AuS remains attached to the ML. The adsorption energy showed that the water molecule is chemisorbed on AuS defect on WS2 (n-type). Also, the density of states suggests a clear response as the chemiresistive sensor. Besides, how zinc-oxide spherical nanocages behave as sensors for different relative humidity levels was discussed. The response to water molecules was significantly enhanced by the chemisorption of the (ZnO)12 spherical nanocage on WS2-AuS. These composed systems formed WS2-ZnO heterojunctions with differences in the electronic structure. The study provides a comprehensive outlook on analyte interactions with WS2 (n-type) and WS2-ZnO surfaces, which have been utilized in the design of semiconductor gas sensors.

Interfacial coordination bonds accelerate charge separation for unprecedented hydrogen evolution over S-scheme heterojunction

Inspired by natural photosynthesis, fabricating high-performance S-scheme heterojunction is regarded as a successful tactic to address energy and environmental issues. Herein, NH2-MIL-125(Ti)/Zn0.5Cd0.5S/NiS (NMT/ZCS/NiS) S-scheme heterojunction with interfacial coordination bonds is successfully synthesized through in-situ solvothermal strategy. Notably, the optimal NMT/ZCS/NiS S-scheme heterojunction exhibits comparable photocatalytic H2 evolution (PHE) rate of about 14876.7 μmol h−1 g−1 with apparent quantum yield of 24.2% at 420 nm, which is significantly higher than that of recently reported MOFs-based photocatalysts. The interfacial coordination bonds (Zn–N, Cd–N, and Ni–N bonds) accelerate the separation and transfer of photogenerated charges, and the NiS as cocatalyst can provide more catalytically active sites, which synergistically improve the photocatalytic performance. Moreover, theoretical calculation results display that the construction of NMT/ZCS/NiS S-scheme heterojunction also optimize the binding energy of active site-adsorbed hydrogen atoms to enable fast adsorption and desorption. Photoassisted Kelvin probe force microscopy, in-situ irradiation X-ray photoelectron spectroscopy, femtosecond transient absorption spectroscopy, and theoretical calculations provide sufficient evidence of the S-scheme charge migration mechanism. This work offers unique viewpoints for simultaneously accelerating the charge dynamics and optimizing the binding strength between the active sites and hydrogen adsorbates over S-scheme heterojunction.

Oriented Crystal Polarization Tuning Bulk Charge and Single-Site Chemical State for Exceptional Hydrogen Photo-Production.

Rapid bulk charge recombination and mediocre surface catalytic sites harshly restrict the photocatalytic activities. Herein, the aforementioned concerns are well addressed by coupling macroscopic spontaneous polarization and atomic-site engineering of CdS single-crystal nanorods for superb H2 photo-production. The oriented growth of CdS nanorods along the polar axis, vectorially superimposing substantial polar units with orderly arrangement, renders a strong polarization electric field (20.1 times enhancement), which boosts bulk charge separation with an efficiency up to 72.4% (80.4-fold). Remarkably, polarization electric field alters the chemical state of Pt single sites by orderly reducing the binding energy of Pt atom with stepwise polarization enhancement of CdS substrate, which increases the onsite electron density of Pt from 10.232 to 10.261e- and *H key intermediates, providing preponderant Volmer-Tafel/Volmer-Heyrovsky reaction pathways with significantly decreased energy barriers for H2 production. Thus, highly polarized CdS nanorods with atomically dispersed Pt sites perform an outstanding H2 space-time yield of 118.5mmol g-1 h-1 and apparent quantum efficiency of 57.7% at λ = 420nm, and a record-high H2 turnover frequency of 57798.4 h-1, being one of the best catalysts for photocatalytic H2 evolution. This work highlights the function of polarization in manipulating charge separation and catalytic reaction.

On the Binding Energy of Atoms in Crystals of Noble Gases and Metals and the Speed of Sound

The speed of sound depends on the structure and material properties of the crystal, such as density and Young’s modulus. On the other hand, from atomistic arguments it is possible to associate Young’s modulus with other material properties. These observations lead to a relationship between binding energy of atoms in a crystal (which is one of the parameters appearing in Mie-Lennard-Jones potential), speed of sound in the longitudinal direction and mass of one atom in the lattice. This subject was addressed by several authors, providing different implementations of this relation. A literature review on this topic is made and the mathematical derivation of the relation is carried out. Applications of this relationship to rare gases, some metals and some rare earths are presented and the results compared to others taken from literature.

Hexa-Penta nanobelt: a novel stable structure with potential optical application

ABSTRACT We report a theoretical investigation of a new carbon nanobelt called Hexa-Penta-belt with molecular formula C 42 H 18 . Hexa-Penta-belt is a variation of the synthesised Methylene-bridged[6]cycloparaphenylene (M-b[6]CPP) with molecular formula C 42 H 24 . Hexa-Penta-belt consists of carbon pentagon and hexagon rings and was inspired by the Penta-belt (theoretically derived from the penta-graphene sheet), the [12]cyclophenacene, and the M-b[6]CPP synthesised by Itami and Segawa [1]. Using Density Functional Theory (DFT), we calculated Hexa-Penta-belt electronic, optical, and thermodynamic properties and their vibrational frequencies. Hexa-Penta-belt is a structurally and thermally stable molecule, as Quantum Molecular Dynamics (QMD) showed. The results exhibited that the Hexa-Penta-belt has excellent electronic stability comparable to C 60 , and it behaves as a semiconductor with a gap estimated at 0.89 eV. It absorbs in the ultraviolet and the visible region (corresponding to the violet, green, and red colours) presenting an absorption more consistent in the visible region than M-b[6]CPP, which could indicate application, for example, as an optical nanosensor. We verified through the carbon atom binding energy that Hexa-Penta-belt is an intermediate molecule between Penta-belt and [12]cyclophenacene.

Factors influencing the stability of Pt-based ORR electrocatalysts in HT-PEMFCs: A theoretical investigation

Electrocatalyst stability is a key parameter for commercializing high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). Here, we used density functional theory (DFT) to investigate the stability of Pt-based electrocatalysts by calculating the binding energy (ΔEb) of surface Pt atoms under working conditions. Our results show that Pt(111) is more stable than Pt(100) and Pt(110) under vacuum conditions. Stress hurts the stability of Pt(111), regardless of compressive or tensile stress. Most of the transition metals alloyed with Pt improve the stability of Pt(111), especially PtV, PtY, and PtTa, which increase the ΔEb by 0.60–0.70 eV (ΔΔEb). However, the stability of Pt is significantly destroyed under the working conditions of oxygen reduction reaction (ORR). The specific adsorption of ORR intermediates and electrolyte ions decreases the ΔEb of Pt(111) by 0.35–0.95 eV, and the effect of PO43-* is more significant. Furthermore, when the electric field of the electrochemical double layer is coupled with PO43-* specific adsorption, ΔΔEb further increases to 1.12 eV. Our results highlight the importance of the intrinsic ΔEb and the working conditions for the stability of Pt-based electrocatalysts. This work provides important guidelines for the design of stable ORR electrocatalysts for HT-PEMFCs.

Influence of He injection amount on the microstructure of ion irradiated Cr0.8FeMnNi medium entropy alloy compared with 316L stainless steel

In recent years, medium and/or high-entropy alloys (M/HEAs) have attracted attention due to their excellent mechanical properties, positioning them as potential candidates for structural materials in advanced nuclear reactors. This study investigated the effect of He injection amount on the microstructural evolution in Cr0.8FeMnNi MEA and 316L stainless steel. Helium atoms were injected, followed by Fe2+ irradiation. Transmission electron microscopy was used to characterize the irradiation-induced defects. The primary irradiation-induced defects observed across all He injection amounts were black dots; no voids were seen under any irradiation conditions. In He-injected Cr0.8FeMnNi, the number density of black dots was significantly lower than in non-He-injected Cr0.8FeMnNi, while the average size of black dots increased with higher He injection rates. As the He injection amount increased, the binding energy of the self-interstitial atom (SIA) to the He-V complex decreased. This reduction facilitated the nucleation and growth of numerous SIA clusters within the matrix, consequently increasing the number density of black dots. The change in the number density of black dots in Cr0.8FeMnNi was much smaller than that observed in 316L. This could be ascribed to the enhanced self-healing process caused by the diversity of point defects and higher lattice distortion in Cr0.8FeMnNi.

Reversible hydrogen storage with Na-modified Irida-Graphene: A density functional theory study

Two-Dimensional carbon-based materials as a potential hydrogen storage medium have attracted great attention. In this study, various key aspects such as structure, electronic properties, stability, and hydrogen storage performance of Na-modified Irida-Graphene (IG) were thoroughly investigated using density functional theory (DFT) calculation methods. The calculation results show that the binding energy of Na atoms with the substrate is 1.51 eV, far exceeding the cohesive energy. The AIMD results reflect the good thermal stability of the model. One Na atom can adsorb up to 5H2 molecules. The IG loaded with eight Na atoms on both sides can adsorb 32H2 molecules, achieving a hydrogen storage capacity of 7.82 wt%, far exceeding the US DOE target of 5.5 wt%. The calculated Van ’t Hoff equation indicates a desorption temperature of 248 K for the model. Moreover, reversible hydrogen storage can be achieved at medium to low pressures, with desorption temperatures ranging from 285 K to 417 K. These results suggest that Na-Modified IG models are candidate materials for reversible hydrogen storage under near-ambient conditions.

Electron Binding Energies of Open-Shell Species from Diagonal Electron-Propagator Self-Energies with Unrestricted Hartree-Fock Spin-Orbitals.

For closed-shell molecules, valence electron binding energies may be calculated accurately and efficiently with ab initio electron-propagator methods that have surpassed their predecessors. Advantageous combinations of accuracy and efficiency range from cubically scaling methods with mean errors of 0.2 eV to quintically scaling methods with mean errors of 0.1 eV or less. The diagonal self-energy approximation in the canonical Hartree-Fock basis is responsible for the enhanced efficiency of several methods. This work examines the predictive capabilities of diagonal self-energy approximations when they are generalized to the canonical spin-orbital basis of unrestricted Hartree-Fock (UHF) theory. Experimental data on atomic electron binding energies and high-level, correlated calculations in a fixed basis for a set of open-shell molecules constitute standards of comparison. A review of the underlying theory and analysis of numerical errors lead to several recommendations for the calculation of electron binding energies: (1) In calculations that employ the diagonal self-energy approximation, Koopmans's identity for UHF must be qualitatively correct. (2) Closed-shell reference states are preferable to open-shell reference states in calculations of molecular ionization energies and electron affinities. (3) For molecular electron binding energies between doublets and triplets, calculations of electron detachment energies are more accurate and efficient than calculations of electron attachment energies. When these recommendations are followed, mean absolute errors increase by approximately 0.05 eV with respect to their counterparts obtained with closed-shell reference orbitals.

RESISTANCE OF FERRITE-PERLITE STEEL TUBING BRANCH PIPE METAL TO DESTRUCTION IN HYDROGEN SULFIDE MEDIUM

This paper discusses the problems of resistance of the metal of the tubing branch pipe (tubing) to the process of its destruction in a medium containing hydrogen sulfide and when exposed to external forces. A 73х73 tubing nozzle made of 38G2SFA steel was selected as the material for research. The tubing fragment was destroyed during production well operation. To establish the reasons for the failure of the tubing nozzle, a visual inspection was carried out, tests were performed to assess the hardness and mechanical properties, the microstructure and microtexture of the metal were analyzed using scanning electron microscopy (SEM) methods. To analyze the nature of the distribution of introduced defects, the mutual orientation of structural components and crystallographic texture, studies were carried out by the method electron backscatter diffraction (EBSD). Studies of the suspended branch pipe, which does not have chemical protection, showed that the cause of its destruction was hydrogen sulfide stress corrosion cracking (SSCC) as a result of hydrogen embrittlement and the action of external tensile forces exceeding the yield strength of the metal. It was established that as a result of the interaction of hydrogen sulfide of the distilled product with the metal of the branch pipe, hydrogen embrittlement of the material of the branch pipe occurred. The process of hydrogen embrittlement of the fragment was proved by detecting hydrogen blisters in the metal microstructure and establishing the process of coalescence of neighboring inclusions. In addition, the results of the test to measure the hardness of the metal along the wall thickness further supported the hypothesis of hydrogen embrittlement of the tubing. EBSD analysis showed that the threaded part of the branch pipe is characterized by a small size of structural elements and an increased density of introduced defects (geometrically necessary dislocations), which are a promising site for the deposition of molecular hydrogen. It is concluded that reaching the limit concentration of molecular hydrogen reduces the binding energy of metal atoms and this process initiates the formation of pores. It has been established that the development of cracks along large-angle grain boundaries is facilitated, and small-angle and coincidence site lattice (Σ3, Σ5, Σ11 and Σ13b) grain boundaries are active barriers to crack propagation. It has been shown that by optimizing the elemental composition of steel, controlling the microstructure, crystallographic texture, as well as the type and state of grain boundaries, new pipeline steels can be produced that are more resistant to SSCC.

Hydrogen Atom Binding Energy of Structurally Well-Defined Cerium Oxide Nodes at the Metal–Organic Framework–Liquid Interfaces

Hydrogen Atom Binding Energy of Structurally Well-Defined Cerium Oxide Nodes at the Metal–Organic Framework–Liquid Interfaces

Non-Metal Doping as a First-Principles Study for Promoting the Hydrogen Evolution of Two-Dimensional Electride Y2C Electrocatalysts

The two-dimensional electrochemical Y2C’s low work function and strong charge transfer qualities limit its applicability in catalysis due to its poor catalytic activity. In this paper, based on density functional theory calculations, we use two techniques to increase the HER catalytic activity of the Y2C monolayer: substitution doping (XC) and adsorption doping (XT) of non-metal (X = N, P, O, S, and F). The results showed that the absolute values of hydrogen free energies (ΔGH*) of the substitutional dopants of PC, SC and adsorptive dopants of NT, OT, ST, and PT had increased catalytic activity compared with those of the pristine Y2C monolayer (−0.673 eV). It was highlighted that the adsorption doping of PT can further reduce the adsorption free energy of the pristine Y2C monolayer to −0.19 eV, which is close to the optimal zero value, and the binding energy of the hydrogen atoms on the Y2C surface significantly increased from −0.913 to −0.438 eV, which is more favorable for the desorption of hydrogen atoms. These results demonstrate that the doping of non-metals activates the adsorption of hydrogen atoms on monolayer Y2C and provides a feasible method for hydrogen generation.

New-Generation Electron-Propagator Methods for Molecular Electron-Binding Energies.

A new generation of electron-propagator methods for the calculation of electron binding energies has surpassed its antecedents with respect to accuracy, efficiency, and interpretability. No adjustable parameters are introduced in these fully ab initio procedures. Numerical tests versus several databases of valence, vertical electron binding energies of closed-shell molecules and atoms have been performed. Easily interpreted self-energy approximations with cubic arithmetic scaling produce mean absolute errors (MAEs) of 0.2 and 0.3 eV for electron detachments and attachments, respectively. The most accurate explicitly renormalized methods with fifth-power arithmetic scaling yield MAEs below 0.1 eV for detachments and attachments. Approximate renormalization leads to more efficient fifth-power alternatives for electron detachments that achieve similar accuracy with fewer bottleneck operations. Composite protocols generate excellent predictions versus highly accurate basis-extrapolated standards and experiments. The validity of the diagonal self-energy approximation and the accuracy of the approximate renormalizations are confirmed. The success of these perturbative methods based on canonical Hartree-Fock orbitals rests on a Hermitized, intermediately normalized superoperator metric. The results of all of the new-generation calculations may be analyzed in terms of final-state orbital relaxation and differential correlation effects.

In Silico Analysis of Selected Glycyrrhiza glabra (Licorice) Constituents: Exploring Their Modulatory Effects on Human Superoxide Dismutase, Human Phosphodiesterase-9 and Human Dipeptidyl Peptidase-4.

Background Glycyrrhiza glabra (Licorice) has been known for its various biological activities. In the current investigation, we aimed to evaluate 11 (10 natural and one synthetic) selected constituents of G. glabra as potent modulatory agents of human superoxide dismutase (hSOD), human phosphodiesterase-9 (hPDE 9) and human dipeptidyl peptidase-4 (hDPP 4) using in silico method. Methodology The 11 selected constituents of G. glabra (Licorice) were investigated on the docking behaviour of hSOD, hPDE 9 and hDPP 4 by using the PatchDock method. In addition to docking, toxicity analysis was also carried out using the pkCSM free online server (University of Melbourne,Melbourne,AUS). Results Toxicity analysis has shown that four ligands (36%) of G. glabra (Licorice) are predicted to have human ether-a-go-go-related gene-2 (hERG 2) inhibition activity. The docking analysis showed that glabridin (-224.13 kcal/mol) has shown the highest atomic contact binding energy with the hSOD enzyme, whereas carbenoxolone has shown the maximum atomic contact binding energy with both the hPDE 9 and hDPP 4 enzymes(-239.57 and -173.50 kcal/mol) respectively. Conclusion Thus the present finding provides new information about 11 selected ligands of G. glabra (Licorice) as potent modulatory agents of hSOD, hPDE 9and hDPP 4.

Calculations of the Binding-Energy Differences for Highly-Charged Ho and Dy Ions

The binding-energy differences for163Hoq+and163Dyq+ions with ionization degreesq=38, 39, and 40 are calculated. The calculations are performed using the large-scale relativistic configuration-interaction and relativistic coupled-clusters methods. The contributions from quantum-electrodynamics, nuclear-recoil, and frequency-dependent Breit-interaction effects are taken into account. The final uncertainty does not exceed 1 eV. Combining the obtained results with the binding-energy difference for neutral atoms calculated in [I.M.Savelyev, M.Y. Kaygorodov, Y.S. Kozhedub, I.I. Tupitsyn, and V.M. Shabaev, Phys. Rev. A105, 012806 (2022)], we get the secondary differences of the ion–atom binding energies. These values can be used to evaluate the amount of energy released in the electron capture process in163Hoatom (theQvalue), provided mass differences of highly charged ions163Hoq+and163Dyq+is known from experiment. TheQvalue is required by experiments on the determination of the absolute scale of the electron neutrino mass by studying the beta-decay process.

Prediction of the binding energy of self interstitial atoms in alpha iron by a graph neural network

The estimation of neutron irradiation embrittlement is crucial for the long-term operation of nuclear power plants. The jump of self-interstitial atoms is an essential process for understanding embrittlement, and their binding energy is critical to estimating the activation energy for jumping. This study presents a fast estimation method for the binding energy of self-interstitial atoms in iron using a graph neural network. The network assigns a self-interstitial atom to a node and the relationship between self-interstitial atoms to an edge. The graph neural network was trained using a large dataset of binding energies between self-interstitial atoms (∼0.5 % density) calculated using an embedded atom method interatomic potential. The network was also trained using smaller datasets of binding energies between self-interstitial atoms (∼2.0 % density) calculated using first principles calculations. The graph neural network accurately predicts binding energy with a mean absolute error of 0.05–0.06 eV and coefficient of determination (R2) of 0.9 without overfitting, using the large interatomic potential dataset. When trained on smaller first principles datasets, the network predicted binding energies with a mean absolute error of 0.15–0.16 eV and coefficient of determination (R2) of 0.6 with some degree of overfitting. The developed graph neural network provides a fast and accurate estimation method for the binding energy of self-interstitial atoms in iron.

Bandgap design of fabricated BN/ZnO/Al2O3/TiO2 doped graphene using XPS approach

This study investigates the use of BN/ZnO/Al2O3/TiO2 nanoparticles as dopants for Graphene nanoparticles. The sintering process was employed to manufacture semiconductor materials. The bandgap serves as the central feature of an atomic heterojunction, playing a crucial role in determining the characteristics or overall quality of the semiconductor materials involved. X-ray photoelectron spectroscopy (XPS) was employed to ascertain the bandgap values of Boron (B), Nitrogen (N), and Carbon (C) at the interfaces of BN/Graphene, BN/ZnO/Graphene, BN/Al2O3/Graphene, and BN/TiO2/Graphene. The survey spectra were examined to provide evidence of atoms' presence and their respective atomic proportions. The analysis of the narrow spectra of XPS was employed to determine the binding energy of atoms within various materials. The conduction band offset (CBO) and valence band offset (VBO) of the aforementioned heterojunctions were computed. The estimation of the ratio between the conduction band offset (CBO) and the valence band offset (VBO), is denoted as ΔEc/ΔEv,. The significant change in the energy gap in the valance band concerning the change in conduction band energy demonstrates that this material possesses the characteristics of an exemplary semiconductor. The present investigation reveals that the BN/TiO2/Graphene heterojunction exhibits the highest values of ΔEv/ΔEc, namely 13.07 for nitrogen (N) and 15.07 for boron (B). The results suggest that the combination of BN/TiO2/Graphene semiconductors holds promising potential for applications in nanoelectronics.

Tungsten nanostructure growth by sputtering and redeposition in BCA-MD-KMC hybrid simulation

The formation mechanism of fibrous tungsten nanostructures, fuzz, induced by helium plasma irradiation on tungsten materials has been investigated. We have developed a BCA-MD-KMC hybrid simulation, which solves the injection process of helium atoms by the Binary Collision Approximation (BCA) method, the diffusion process of helium atoms in tungsten materials by the Kinetic Monte-Carlo (KMC) method, and the deformation of tungsten materials due to helium bubbles by the Molecular Dynamics (MD) method. In addition, the model used to calculate the recoiling of tungsten atoms in BCA was improved to account for the reduced binding energy of tungsten atoms on rough surfaces. Using the hybrid simulation, the height of the nanostructures reached about 50 nm. The main mechanism of nanostructure growth was that sputtering and redeposition caused transport of tungsten atoms perpendicular to the surface. The present simulation was able to represent not only the dependence that the nanostructure height increases in proportion to the square root of the helium fluence, but also the existence of incubation fluence before the growth starts.

In silico analysis of selected nutrition rich fruit of Bunch berry (Lantana camara) constituents as human acetylcholinesterase (hAchE), carbonic anhydrase II (hCA-II) and carboxylesterase 1 (hCES-1) inhibitory agents

BackgroundBunch berry (Lantana camara) is primarily composed of flavonoids and vitamin C; therefore, it has been shown to possess various medical characteristics, including the ability to relieve fever, inflammation, and urinary tract infections. ObjectiveIn this study, we intended to assess twenty chosen constituents of Bunch berry as potent inhibitory agents of human acetylcholinesterase (hAchE), carbonic anhydrase II (hCA-II) and carboxylesterase 1 (hCES-1) employing in silico techniques. MethodsThe twenty chosen Bunch berry components were examined about docking behaviour of hAchE, hCA-II and hCES-I by using the Swissdock method. Apart from to docking, Molecular physico-chemical, drug-likeness, ADME (ingesting, dispersing, metabolising, and excreting), and toxicity assessments were also performed utilising the Molinspiration, Swiss ADME, pkCSM, and STITCH web sites, correspondingly. ResultsEight ligands (40 %) have exhibited strict adherence to Lipinski's rule of five (Ro5), according to molecular physico-chemical study. Drug-likeness property analysis has shown that five ligands (25 %) of Bunch berry predicted to exhibit moderate bioactivity score against all the descriptors. ADME analysis has shown that five ligands (25 %) of Bunch berry are predicted to possess high gastrointestinal absorption property Toxicity analysis has shown that six ligands (30 %) of Bunch berry are predicted to have hERG II (Human ether-a-go-go-related gene) inhibition activity. According to the docking analysis, lantic acid has the lowest atomic binding energy for all three target enzymes, hAchE (-6.23 kcal/mol), hCA-II (-4.46 kcal/mol), and hCES-I (-5.99 kcal/mol), respectively. ConclusionsThus the current find provides an advanced understanding the twenty selected ligands of Bunch berry as potent inhibitory agents of human acetylcholinesterase (hAchE), carbonic anhydrase II (hCA-II) and carboxylesterase 1 (hCES-1).

Judicious Selection of Precursors with Suitable Chemical Valence State for Controlled Growth of Transition Metal Chalcogenides

AbstractTransition metal chalcogenides (TMCs) have attracted wide attentions as a class of promising material for both fundamental investigations and electronic applications due to their atomic thin thickness, dangling bond‐free surface, and excellent electronic properties. Specifically, TMCs show outstanding properties such as good thermal conductivity, robust mechanical properties, and extraordinary electronical characteristics, bestowing them utility in both fundamental research and applications. Recently, the development of post‐Moore electronics based on TMCs calls for their large‐size and single‐crystal growth. However, researchers about synthesis usually focus on controlling several growth parameters (such as growth temperature, flow rate, and time). Herein, it is reported that the chemical valence states of transition metal precursors play an important role in controlling the lateral size and crystal quality for TMCs. The study discusses the valence states‐dependent growth mechanism for WS2 and MoS2 from four factors: evaporation temperature, skipping of reaction steps, atomic binding energy of the precursors, and formation energy. In addition, the as‐grown WS2 and MoS2 nanoflakes exhibit good photoelectric response properties. For EuS, the growth results are obviously different by using EuBr3 and EuBr2 as precursors. The studies provide a unique perspective and also new knowledge to controllably grow large‐size and good crystal quality TMCs.