Variation Of Binding Energy Research Articles

Potential-dependent kinetics of oxygen chemisorption as the crucial step of oxygen reduction reaction: GCDFT study

Nitrogen-doped carbon materials (NCMs) are widely regarded as promising alternatives to expensive platinum-based electrocatalysts for the oxygen reduction reaction (ORR). While NCMs exhibit considerable electrochemical activity in alkaline media, their performance in acidic environments remains a significant challenge. However, acidic conditions are commercially desirable for ORR’s catalysis in proton-exchange membrane fuel cells (PEMFCs). The dramatic pH dependence of NCM effectiveness has sparked ongoing debate, with several factors under consideration, including surface protonation, variations in hydrogen binding energy, differences in proton donors, and interface structure. In this work, we present a grand canonical density functional theory (GCDFT) study of the chemisorption step on pristine and nitrogen-doped graphene. Through nudged elastic band (NEB) calculations at various electrode potentials, we propose a potential-dependent (and thus pH-dependent) mechanism of oxygen chemisorption at graphitic nitrogen (Ngr) defects, offering new insights into the pH dependency of the onset potential in NCM catalysts.

SO3NH3 crystal growth in (CH3)3SBr solution

SO3NH3 (Sulfamic acid, or SA) is known for its excellent piezoelectric and optical properties, making it valuable for various optical applications. However, it usually takes weeks to months to grow the SA single crystals with centimeter-scale size by traditional growth method from solution. In this study, we use (CH3)3SBr (Me3SBr) as an additive to enhance the growth rate of SA single crystals, and the growth time was reduced to just 48 h. The mechanism of accelerated crystallization process is attributed to the variations of electrostatic potential and binding energy on SA crystal modified by the additive. In addition, structural analysis and basic characterization on the newly grown SA are performed, and first-principles calculations provide insights into the energy band structure and phonon spectrum.

Highly Stretchable, Self-Healing, and Sensitive E-Skins at -78 °C for Polar Exploration.

Ultralow temperature-tolerant electronic skins (e-skins) can endow polar robots with tactile feedback for exploring in extremely cold polar environments. However, it remains a challenge to develop e-skins that enable sensitive touch sensation and self-healing at ultralow temperatures. Herein, we describe the development of a sensitive robotic hand e-skin that can stretch, self-heal, and sense at temperatures as low as -78 °C. The elastomeric substrate of this e-skin is based on poly(dimethylsiloxane) supramolecular polymers and multistrength dynamic H-bonds, in particular with quadruple H-bonding motifs (UPy). The structure-performance relationship of the elastomer at ultralow temperatures is investigated. The results show that elastomers with side-chain UPy units exhibit higher stretchability (∼3257%) and self-healing efficiency compared to those with main-chain UPy units. This is attributed to the lower binding energy variation and lower potential well. Based on the elastomer with side-chain UPy and man-made electric ink, a sensitive robotic hand e-skin for usage at -78 °C is constructed to precisely sense the shape of objects and specific symbols, and its sensation can completely self-recover after being damaged. The findings of this study contribute to the concept of using robotic hands with e-skins in polar environments that make human involvement limited, dangerous, or impossible.

Modeling the Zigzag Curves of Transition Metal Ions' Charge Transition Levels in Crystals.

Predicting the defect levels of transition metal (TM) dopants in the band gap of crystals is critical in determining the charge states of TM dopants and explaining their electronic and optical properties. By analyzing the calculated charge transition levels and the crystal-field strengths of all the 3d-TM ions in several insulators, we demonstrate that the variation trend of the 3d-TM dopants in a crystal is a scaling of the variation of 3d-electron binding energies (ionization potential) of the free TM ions corrected by adding the contribution of the 3d-orbital's crystal-field splitting. We therefore develop a model to predict the relative location of TM ions' defect levels in the band gap from the defect level and crystal-field splitting of a reference TM ion in the host of concern. The model is applied to predict the defect levels of the series of TM ions in β-Ga2O3 and ZnO, which have moderate to small band gaps, making some of the levels fall into the conduction or valence bands. These results show that the model may serve as a quick reference for related material design and optimization.

Study on the interaction between fluoroelastomer and silica: Characterizations

AbstractDue to their excellent chemical stability, fluoroelastomers have been widely used in various severe circumstances since birth. At present, carbon blacks and inorganic fillers are the two most prominent reinforcing agents in fluoroelastomers. However, despite the rise of silica in the rubber industry, it is still difficult to apply this non‐carbon filler alone as a reinforcing agent in fluoroelastomer. Research on the interaction between silica and fluoroelastomer is even less and not systematical. Based on the above, we analyzed the interaction between silica and fluoroelastomer under different conditions through x‐ray photoelectron spectroscopy (XPS), Fourier‐transform infrared spectroscopy, bound rubber (BR) content analysis and rheological properties, and so forth. The interaction between fluoroelastomer and silica can be characterized by the binding energy variation at different temperatures (especially 260°C the new peak at about 685 eV) and wavenumber shift of Si–OH and Si–O–Si in XPS and infrared (IR) analysis, respectively. The BR content varied with loading, temperature, and atmosphere, reflecting the strength of the interaction from a macro perspective. The evolution of the rheological curves of different recipes and test conditions correlate closely with the results of XPS, IR, and BR content analysis, which also shows the sensitive response of polymer‐filler interaction to temperature and load. The observation results of transmission electron microscopy (TEM) directly demonstrate the differences in the dispersion of fillers at different temperatures. The proposed mechanism of fluoroelastomer–silica interaction mode will provide us with novel approaches to the applications of silica in the fluorine industry.Highlights X‐ray photoelectron spectroscopy analysis indicates new fluorine species on the interfaces. Infrared and bound rubber tests verify the fluoroelastomer–silica interactions. Rheological curves reflect the interaction strength.

Surface-Induced Electronic and Vibrational Level Shifting of [Fe(py)2bpym(NCS)2] on Al(100).

It is essential that one understands how the surface degrees of freedom influence molecular spin switching to successfully integrate spin crossover (SCO) molecules into devices. This study uses density functional theory calculations to investigate how spin state energetics and molecular vibrations change in a Fe(II) SCO compound named [Fe(py)2bpym(NCS)2] when deposited on an Al(100) surface. The calculations consider an environment-dependent U to assess the local Coulomb correlation of 3d electrons. The results show that the adsorption configurations heavily affect the spin state splitting, which increases by 10-40 kJmol-1 on the surface, and this is detrimental to spin conversion. This effect is due to the surface binding energy variation across the spin transition. The preference for the low-spin state originates partly from the strong correlation effect. Furthermore, the surface environment constrains the vibrational entropy difference, which decreases by 8-17 Jmol-1K-1 (at 300 K) and leads to higher critical temperatures. These results suggest that the electronic energy splitting and vibrational level shifting are suitable features for characterizing the spin transition process on surfaces, and they can provide access to high-throughput screening of spin crossover devices.

Simultaneous effects of hydrostatic pressure and temperature on the electronic spectrum in the presence of a single off-center donor atom in a hemi-quantum ring

This study numerically investigates the electronic and donor atom properties of an electron and off-center donor atom confined in a hemi-quantum-ring (HQR) using the effective mass approximation and an infinite confinement potential. The Schrödinger equation is solved using finite element and difference methods to obtain the system’s eigenenergies and eigenfunctions. The study examines the influence of the electronic spectrum under the simultaneous effects of HQR sizes, temperature, and hydrostatic pressure applied to three directions Rg, Rc, and φ0. Additionally, the influence of donor displacement on binding and donor energies is evaluated. The numerical results show that the electronic and binding energies are highly sensitive to the size of the HQR nanostructure. Furthermore, the study found that the donor atom displacement can control the variation of binding energy and donor energy for different values of hydrostatic pressure and temperature, such as the pressure (temperature) contribution increases (decreases) the binding energy. Also, the hydrostatic pressure (temperature) applied leads to a decrease (increase) of the first four confined state energies and donor energy. The simultaneous influence of geometrical parameters, hydrostatic pressure, and temperature can help improve the efficiency of electronic devices.

Effects of Ir and B co-doping on H2 adsorption properties of armchair carbon nanotubes using Optical Spectra Analysis for energy storage

In this research, DFT+U approach was used to investigate the performance of Iridium (Ir) and Boron (B) co-doped armchair (8, 8) Single-walled Carbon Nanotube (SWCNT). Calculations of the structural electronic and optical spectra analysis of the system under study were carried out using the ab’initio quantum simulations implemented in Quantum ESPRESSO and thermo_pw codes within the popular density functional theory. In the doping process, carbon atoms have been replaced by Ir and B atoms in the SWCNT, the investigations were done on the basis of distance of H2 (d) from the co-doped SWCNT at intervals of 6.12 Å, 6.45 Å and 6.77Å, variations of temperature, variations of external electric field, band gaps, optical adsorptions and binding energy variations were all taken in to account. It is found that Ir/B co-doping in pristine SWCNT significantly enhanced the H2 adsorption capacity of the SWCNT. Furthermore, an increase in temperature decrease the performance ability of the co-doped SWCNT, negative adsorptions intensities were recorded by temperature increase by 650, 700 and 750 0C, this can be termed as exothermic adsorption. Therefore it can be demonstrated that H2 by co-doped SWCNT undergoes endothermic adsorption under ambient temperature and shows exothermic adsorption under higher temperatures.

Synthesis and experimental investigations of organic perovskite solar cell material; 2,5-bis(5-aminofuran-2-yl) thiophene 1,1-dioxide; photo-voltaic data validation using computational model and spectroscopic tools

The Doped crystal architectures based on the Perovskite structure are most promising for creating photovoltaic solar cells. In recent years, much research effort has been directed towards increasing the solar power conversion efficiency of organic crystal materials. The ultimate challenge is to improve the light-harvesting power gain in organic synthetic materials and it was proved from the attainment of the Birefringence (Δn) Kλ/t −1.98. In this context, we report herein fabrication of organic 2,5-bis(5-aminofuran-2-yl) thiophene 1,1-dioxide as a perovskite-like lattice in the form of molecular clusters. Its photo-conversion efficiency was calculated as 18%. Its short-circuit current density was determined as JSC = 0.91 mA/cm2, with open-circuit voltage VOC of 1.05 V. The charge transfer (CT) exciton binding energy variation of dielectric constant of the material medium has been calculated. The diffusion path length was defined as <10 Å and the direct band gap was measured as 2.15 eV. The Urbach energy of the prepared sample was estimated as 110–220 meV. The molecular mechanism of exciton productions in the photo-voltaic process has been probed through the use of computational software and experimental tools. The light harvesting ability has been assessed in terms of morphological, optical and electro-optical properties. To characterize weak interactions between the organic molecular sites, vibrational studies have been carried out on polar and nonpolar bonds. The production of Frenkel excitons at the HOMO-LUMO interface and the binding energy variation for electron-hole dissociation has been estimated from the Coulomb capture radius. The photo-energy conversion efficiency and fill factor (FF = 0.511) have been estimated to prove the efficiency of the cell.

Hydrogen adsorption on osmium and boron co-doped single walled carbon nanotubes for energy storage: A DFT study

The osmium and boron co-doped armchair single walled carbon nanotubes (SWCNTs) have been studied for hydrogen storage using ab-initio method. The calculations have been carried out using Gaussian software with Density functional theory. We have replaced a carbon atom by osmium atom in SWCNT & neighboring carbon atoms are replaced by boron atoms sequentially. In the present work, the hydrogen adsorption ability of osmium/boron co-doped CNTs has been investigated on the basis of bond distances, variation of binding energy, chemical hardness, band gaps, charge distribution and adsorption energies. It is found that osmium/boron co-doping in SWCNTs enhanced the hydrogen storage capacity but increase of boron atom concentration in osmium doped SWCNT reduces the storage ability. The maximum hydrogen adsorption energy was calculated in case of osmium atom decorated single boron atom doped SWCNT (Os-BCNT) i.e. E ads - 0.490 eV. And study reveal that osmium doped CNT (Os-CNT) and osmium/boron co-doped CNT (Os-BCNT) both can efficiently adsorb five hydrogen molecules at 298.15 Kelvin temperature/1 atm pressure. • Modified structural and electrical properties of osmium/boron co-doped SWCNT • Enhanced hydrogen storage capacity of osmium/boron co doped SWCNT. • Effect of boron concentration on hydrogen storage capacity on SWCNT

Investigation on the Role of antimony in CdTe QDs sensitized solar cells

In this work, the effect of Sb doping on the structural, optical and photovoltaic properties of the CdTe quantum dots (QDs) were reported. Sb doped CdTe (SDC) QDs were synthesized with different dopant concentration in aqueous phase. Prepared QDs were analytically characterized for their structural, optical and compositional informations. Prepared SDC QDs possessed cubic zinc blende crystalline structure, which was revealed through XRD studies. XRD patterns also elucidate that the crystalline nature was not altered by the dopant ion incorporation. The optical response of SDC QDs revealed the size and dopant dependent optical properties. Presence of different functional groups and it's composition confirmed the formation of SDC QDs and it also confirmed the superior capping effect of thiol capping agent. Formation of SDC QDs was further confirmed by XPS analysis through binding energy variation of individual elements. Sandwich type QDs senstized solar cell was fabricated to study the photovoltaic response of the prepared QDs. At the standard illumination condition, Sb doped CdTe QDs sensitized TiO2 photoanodes showed superior photovoltaic response than pure CdTe QDs.

Charmonium Suppression in an Anisotropic Hot Qcd Medium Using Quasi-Particle Model

We have studied the properties of charmonium states through the in- medium modifications to both perturbative and non-perturbative term using the Cornell potential. The flavor dependence of the binding energies of the heavy quarkonia states in isotropic as well as anisotropic case have been obtained by employing the quasi-particle Debye mass with baryonic chemical potential at fixed value of μb =300MeV, which is computed by employing the quasi-particle picture. There is significant comparision has been made for the variation of binding energy using different Debye masses, such as quasi-particle Debye mass, leading order Debye mass, and quasi-particle Debye mass with baryonic chemical potential in isotropic and as well as anisotropic case. Further, we observe that the dissociation temperatures of anisotropic medium are higher than the isotropic medium using quasi-particle picture in full QCD case. By using these dissociation temperatures as an input, we explore the sensitivity of prompt and sequential suppression at LHC (1).

Self‐Polarization of Hydrogenic Impurity in Quantum Wells Made of Different Materials

The effect of the external electric field on the ground state binding energy and self‐polarization of a hydrogenic donor impurity in quantum wells (QWs) made of different materials is calculated within the effective mass approximation using a variational scheme. The variations of binding energy and self‐polarization depending on well width, electric field, and impurity position have been studied in detail. For each QW made of different materials, it has been observed that the binding energy decreases with the increase of the electric field, whereas the self‐polarization increases. Also, it has been observed that InP/In1−x Ga x P has higher binding energy values among the structures discussed. It is seen that material selection has a noticeable effect on self‐polarization and binding energy in QW‐based structures.

Computational studies on the structural variations of MAO-A and MAO-B inhibitors - An in silico docking approach

The neurological disorder is a concerning problem in the present social scenario. The malfunction of the monoamine oxidase (MAO) enzyme is the responsible factor behind this disorder because this enzyme regulates the metabolism of monoamine neurotransmitters. This work aimed to design and propose the best MAO inhibitors through extensive computational analysis so that the favourable drug-like molecules could be identified for future synthesis. The drugs selected in this study were three MAO-A inhibitors namely Moclobemide, Tolxatone and Brofaromine and two MAO-B inhibitors namely Selegiline and Rasagiline. By substituting hydrophilic and hydrophobic groups at the specified positions, structural variations were designed for each drug. The designed variations and their parent drugs were optimized (basis set is B3LYP/6-311G(d, p)) and the optimized structures were docked to the target using PyRx software. The binding energy of each variation was compared to that of parent drug. The drug-likeness, physicochemical properties (solubility, polarity, flexibility, gastrointestinal absorption, saturation etc.) and toxicity of the lower binding energy variations were analysed using the swissADME, Osiris property explorer and ProTox-II servers. The interacting residues of the enzymes were obtained from the LigPlot+ program. The safe and low binding energy variations with favourable drug properties are suggested for further drug research

Properties of optical bipolaron in symmetric quantum dot

Optical bipolaron properties in the symmetric quantum dot were investigated using the Lee-Low-Pines-Huybrechts method and the Tokuda linear combination operator method. Algebraic expressions are derived for the energies of the fundamental and first excited states, the effective mass, mobility, binding energy and oscillation period of the optical bipolaron. Results prove that the energies of fundamental and first excited states increase with the coupling constant. Another point is that the strong coupling method dominates the weak coupling and the intermediate one when the electron-phonon coupling enhances. We also observe that the binding energy becomes always positive when confinement strength is above 5. In other points, the binding energy of optical bipolaron is well studied in all coupling, especially in weak coupling. It is also noticed that energies are increasing the function of the dielectric ratio and the oscillation period is reducing with the dielectric ratio. This proves that the electron-electron interaction is strengthened in a quantum dot. The stronger the coupling, the higher mobility in the case of low temperature. • The ground and first excited energies, binding energy, Oscillation Period, Effective mass and mobility of bipolaron. • We have plotted Ground state energy and excited state energy of bipolaron versus the electron-phonon coupling constant in different couplings. • Ground state energy, excited state energy and oscillation period of bipolaron versus confinement strength at various values of the dielectric ratio are plotted. • We plotted Variation of binding energy of bipolaron versus confinement strength in all coupling. (a) Ω ≺ 4 ; (b) Ω ≻ 4 • We have plotted Variation of mobility versus confinement strength at different values of dielectric ratio. • We have plotted Variation of ground state effective mass (a) and excited effective mass (b) versus electron-phonon coupling constant.

Ultrafast electronic linewidth broadening in the C 1s core level of graphene

Core level binding energies and absorption edges are at the heart of many experimental techniques concerned with element-specific structure, electronic structure, chemical reactivity, elementary excitations and magnetism. X-ray photoemission spectroscopy (XPS) in particular, can provide information about the electronic and vibrational many-body interactions in a solid as these are reflected in the detailed energy distribution of the photoelectrons. Ultrafast pump-probe techniques add a new dimension to such studies, introducing the ability to probe a transient state of the many-body system. Here we use a free electron laser to investigate the effect of a transiently excited electron gas on the core level spectrum of graphene, showing that it leads to a large broadening of the C 1s peak. Confirming a decade-old prediction, the broadening is found to be caused by an exchange of energy and momentum between the photoemitted core electron and the hot electron system, rather than by vibrational excitations. This interpretation is supported by a line shape analysis that accounts for the presence of the excited electrons. Fitting the spectra to this model directly yields the electronic temperature of the system, in agreement with electronic temperature values obtained from valence band data. Furthermore, making use of time- and momentum-resolved C 1s spectra, we illustrate how the momentum change of the outgoing core electrons leads to a small but detectable change in the time-resolved photoelectron diffraction pattern and to a nearly complete elimination of the core level binding energy variation associated with the narrow $\sigma$-band in the C 1s state. The results demonstrate that the XPS line shape can be used as an element-specific and local probe of the excited electron system and that X-ray photoelectron diffraction investigations remain feasible at very high electronic temperatures.

Trion Binding Energy Variation on Photoluminescence Excitation Energy and Power during Direct to Indirect Bandgap Crossover in Monolayer and Few-Layer MoS2

The behavior of the trion and exciton photoluminescence (PL) under various laser excitation conditions, that is, energy and power, is studied in monolayer and few-layer (FL) chemical vapor deposition (CVD)-MoS2 flakes grown on SiO2/Si. The room-temperature μ-PL spectroscopy of the flakes shows that the A exciton at 1.86 eV is overlapped by the trion component. First, the thickness-dependent characterization of the flakes has been carried out. The trion spectral weight and dissociation energy are observed to increase with the number of layers, which is correlated with an increase in nonequilibrium electron density. We propose the presence of many-body effects explaining this unusual dependence in CVD-MoS2 on n-type SiO2/Si. In the power-dependent μ-PL measurements, the deconvolution of spectra for the exciton and trion bands shows a faster intensification of the trion component compared to the A exciton with increasing laser power. The trion binding (dissociation) energy varied from 28 to 33 meV in the monolayer and from 32 to 46 meV in FL MoS2, when increasing the power of excitation light. The phenomenon is found to be more prominent when increasing the energy of excitation from 2.33 to 3.06 eV. The enhancement of the trion binding energy leads to a strong intensification of the trion component. Thereby, the intense A exciton/trion PL band redshifts and becomes more asymmetric when increasing the power of excitation at both energies of 2.33 or 3.06 eV. Simultaneously, the B exciton contribution to the spectrum also increases. Such an enhanced formation of the trions and B excitons is explained by a rate of photogenerated electron–hole pairs, leading to a higher population of nonequilibrium electrons. In the measurements under a higher excitation energy of 3.06 eV, the PL redshift is more prominent because the trion component is more intense compared to the A band. This is explained by considering a higher absorption of MoS2 at higher energies.

Combined effects of the hydrostatic pressure and temperature on the self-polarization in a finite quantum well under laser field

In this study, the self-polarization and binding energy of the donor impurity atom in the laser field applied G a 1 − x A l x A s / G a A s quantum well are investigated under the combined influence of hydrostatic pressure and temperature. Variation of self-polarization and binding energy depending on temperature, hydrostatic pressure, impurity position, well width and laser field parameters are shown. Using the effective mass approximation, subband energy has been found by finite difference method and impurity energy has been found by variation method. Our results showed that hydrostatic pressure and temperature have a noticeable effect on the calculated self-polarization and binding energy in a quantum well under the effect of the laser field. We think that the results obtained will be useful in determining the physical properties of the quantum well under the influence of laser field, hydrostatic pressure and temperature. • The square quantum well is considered. • The effects of hydrostatic pressure and temperature on self-polarization have been calculated under laser field. • The variational and finite differences calculations have been performed. • Laser field parameter, hydrostatic pressure and temperature are important factor.

Structural and Electronic Properties of Zigzag Single Wall (8,0), (9,0), and (10,0) Silicon Carbide Nanotubes Sandwiched between Different Elements

Using first principles density functional theory calculations, the electronic and geometric structures of three different types of zigzag single wall silicon carbide nanotubes (ZSSiCNt), (8,0), (9,0), and (10,0), have been studied by sandwiching nanotubes between different semiconductors, group three elements, and some transition metal elements. When the (9,0) zSSiCNt is sandwiched between different semiconductors, the binding energy (B E ) varies from 2.05 to 5.68 eV/atom. When the (10,0) zSSiCNt is sandwiched between group III elements, the B E varies from 4.35 to 6.89 eV/atom. When the (10,0) zSSiCNt is sandwiched between some transition elements, the B E varies from 1.63 to 5.97 eV/atom. The binding energy variation of SWSiCNT by substituting different elements at the site of carbon and silicon at the end of the zigzag silicon carbide nanotubes is shown. Substitution of Fe and Ga at the site of Si increases the binding energy to 4.04 eV/atom & 6.32 eV/atom, respectively. The cohesive energy appears to saturate between 6.00 to 6.90 eV, and the stability of different (8,0) SWNt is compared.

Structural and Electronic Properties of Zigzag Single Wall (8,0), (9,0), and (10,0) Silicon Carbide Nanotubes Sandwiched Between Different Semiconductor and Transition Metal Elements

Using first principles density functional theory calculations, the electronic and geometric structures of three different types of zigzag single wall silicon carbide nano-tubes (ZSSiCNt), (8,0), (9,0), and (10,0), have been studied by sandwiching nano-tubes between different semiconductors, group three elements, and some transition metal elements. When the (9,0) zSSiCNt is sandwiched between different semiconductors, the binding energy (B E ) varies from 2.05 to 5.68 eV/atom. When the (10,0) zSSiCNt is sandwiched between group III elements, the B E varies from 4.35 to 6.89 eV/atom. When the (10,0) zSSiCNt is sandwiched between some transition elements, the B E varies from 1.63 to 5.97 eV/atom. The binding energy variation of SWSiCNT by substituting different elements at the site of carbon and silicon at the end of the zigzag silicon carbide nano-tubes is shown. Substitution of Fe and Ga at the site of Si increases the binding energy to 4.04 eV/atom & 6.32 eV/atom, respectively. The cohesive energy appears to saturate between 6.00 to 6.90 eV, and the stability of different (8,0) SWNt is compared.