Average Electrostatic Potential Research Articles

Theoretical analysis of naproxen reaction with sulfate and hydroxyl radicals in the aqueous phase: Investigating reactive sites and reaction kinetics

In this study, we have utilized theoretical calculations to predict the reaction active sites of naproxen when reacting with radicals and to further study the thermodynamics and kinetics of the reactions with ·OH and SO4−·. The evidence, derived from the average local ionization energy and electrostatic potential, points to the naphthalene ring as the preferred site of attack, especially for the C2, C6, C9, and C10 sites. The changes in Gibbs free energy and enthalpy of the reactions initiated by ·OH and SO4−· ranged between −19.6 kcal/mol - 26.3 kcal/mol and −22.3 kcal/mol −18.5 kcal/mol, respectively. More in-depth investigation revealed that RA2 pathway for ·OH exhibited the lowest free energy of activation, suggesting this reaction is more inclined to proceed. The second-order rate constant results indicate the ·OH attacking reaction is faster than reactions initiated by SO4·-, yet controlled by diffusion. The consistency between theoretical findings and experimental data underscores the validity of this computational method for our study.

WITHDRAWN: Vacancies and antisites investigation at InAlAs/InGaAs hetero-interface: A first-principles study

The vacancies and antisites at InAlAs/InGaAs hetero-interface have been investigated by first-principles calculation based on hybrid density functional (HSE06). We propose an approach to obtain the chemical potentials based on the growth process of hetero-junction. The valence-band maximum of hetero-interface supercell is aligned with the reference of the average electrostatic potential of bulk material. The VIn, VGa, and VAl defects are deep acceptors, while VAs-1, VAs-2, and VAs-3 defects would behave as donor defects. The antisites are amphoteric defects, whereas they will only behave as donor defects due to the Fermi-level should be below the conduction-band minimum of InGaAs side. For InAlAs/InGaAs devices, the impact of the cation vacancies (acceptors) and antisites (donors) is associated to the bias conditions, while it is bias-independent for As vacancies (donors).

Evaluating the impact of structural and rotational isomerization, as well as halogenation, on Y18 and Y18-ID small molecule acceptors: A DFT and TD-DFT study

In the present work, using a systematic approach with DFT and TD-DFT techniques, we investigate the isomerization impact on Y18 and Y18-ID, two electron acceptors belonging to the Y family. Furthermore, the effect of the halogen atom was assessed by changing the original fluorine atoms with chlorine, bromine, and iodine. Two structural isomers were proposed for each acceptor, and a configurational (rotamer) for each structural isomer. A benchmarking was performed for relative energies, molecular planarity, light-harvesting features, frontier molecular orbitals alignment, electron-accepting indexes, reorganization energies, and average electrostatic potential. Mainly, structural isomerization yields the most significant modification to the studied properties and, to a lower extent, rotamerization. Nonetheless, the impact of rotamers might not be ignored, mainly in electron-accepting character and intermolecular electric field. Indeed, the modification that rotamers induce in some properties is comparable to that induced by the modification of halogen atoms.

Over 19 % Efficiency Organic Solar Cells Enabled by Manipulating the Intermolecular Interactions through Side Chain Fluorine Functionalization.

Fluorine side chain functionalization of non-fullerene acceptors (NFAs) represents an effective strategy for enhancing the performance of organic solar cells (OSCs). However, a knowledge gap persists regarding the relationship between structural changes induced by fluorine functionalization and the resultant impact on device performance. In this work, varying amounts of fluorine atoms were introduced into the outer side chains of Y-series NFAs to construct two acceptors named BTP-F0 and BTP-F5. Theoretical and experimental investigations reveal that side-chain fluorination significantly increase the overall average electrostatic potential (ESP) and charge balance factor, thereby effectively improving the ESP-induced intermolecular electrostatic interaction, and thus precisely tuning the molecular packing and bulk-heterojunction morphology. Therefore, the BTP-F5-based OSC exhibited enhanced crystallinity, domain purity, reduced domain spacing, and optimized phase distribution in the vertical direction. This facilitates exciton diffusion, suppresses charge recombination, and improves charge extraction. Consequently, the promising power conversion efficiency (PCE) of 17.3 % and 19.2 % were achieved in BTP-F5-based binary and ternary devices, respectively, surpassing the PCE of 16.1 % for BTP-F0-based OSCs. This work establishes a structure-performance relationship and demonstrates that fluorine functionalization of the outer side chains of Y-series NFAs is a compelling strategy for achieving ideal phase separation for highly efficient OSCs.

Over 19 % Efficiency Organic Solar Cells Enabled by Manipulating the Intermolecular Interactions through Side Chain Fluorine Functionalization

AbstractFluorine side chain functionalization of non‐fullerene acceptors (NFAs) represents an effective strategy for enhancing the performance of organic solar cells (OSCs). However, a knowledge gap persists regarding the relationship between structural changes induced by fluorine functionalization and the resultant impact on device performance. In this work, varying amounts of fluorine atoms were introduced into the outer side chains of Y‐series NFAs to construct two acceptors named BTP‐F0 and BTP‐F5. Theoretical and experimental investigations reveal that side‐chain fluorination significantly increase the overall average electrostatic potential (ESP) and charge balance factor, thereby effectively improving the ESP‐induced intermolecular electrostatic interaction, and thus precisely tuning the molecular packing and bulk‐heterojunction morphology. Therefore, the BTP‐F5‐based OSC exhibited enhanced crystallinity, domain purity, reduced domain spacing, and optimized phase distribution in the vertical direction. This facilitates exciton diffusion, suppresses charge recombination, and improves charge extraction. Consequently, the promising power conversion efficiency (PCE) of 17.3 % and 19.2 % were achieved in BTP‐F5‐based binary and ternary devices, respectively, surpassing the PCE of 16.1 % for BTP‐F0‐based OSCs. This work establishes a structure‐performance relationship and demonstrates that fluorine functionalization of the outer side chains of Y‐series NFAs is a compelling strategy for achieving ideal phase separation for highly efficient OSCs.

Comprehensive solubility study and inter-molecular interactions on fenbendazole dissolved in some aqueous aprotic and protic co-solvent solutions

The isothermal shake-flask saturation method was used to experimentally determine the mole-fraction solubility of fenbendazole in three aqueous co-solvent blends of 1,4-dioxane/acetone/NMP encompassing the range of 283.15 to 328.15 K. The solubility of fenbendazole in various blended solvents ranks NMP + water (4.852 × 10−2) > 1,4-dioxane + water (14.81 × 10−4) > acetone + water (2.285 × 10−4) with composition of 1,4-dioxane (acetone or NMP) of 1 at 298.15 K. The solubility data rises monotonically with 1,4-dioxane/acetone/NMP concentration at the same temperature. X-ray power diffraction images show that no solvate production or crystal transition appeared throughout the studies. The solubility to solvent composition and temperature was satisfactorily associated by the modified van't Hoff-Jouyban-Acree, quantitative structure–property relationship, and Jouyban-Acree models with relative average deviations of no higher than 7.05 % and root-mean-square deviation of no higher than 1.225 × 10−3. In addition, the 1,4-dioxane/acetone/NMP + water blends studied in this paper and the methanol/ethanol/EG/DMF + water blends previously reported both used the extended Hildebrand solubility approach to quantitatively describe the solubility behavior at 298.15 K. The average relative deviations were kept under 4.06 % on both cases. As stated by the examination of the linear solvation energy relationship, the solubility parameter and dipolarity-polarizability of solutions have a significant influence on the solubility variation. The effective method of inverse Kirkwood-Buff integrals was used to investigate the preferred solvation of fenbendazole at 298.15 K. In blends with intermediate and rich ethanol/DMF/1,4-dioxane/acetone/NMP composition areas, the preferred solvation parameters of ethanol/DMF/1,4-dioxane/acetone/NMP displayed positive values, indicating the preferential solvation of fenbendazole by the co-solvents. Thermodynamic examination of the entropy-enthalpy compensation and dissolution parameters for fenbendazole dissolving in blends led to the identification of an enthalpy and/or entropy-driven mechanism as well as an endothermic process. Moreover, the average local ionization energy and electrostatic potential of molecular surface were utilized as effective instruments to demonstrate the microscopic electrostatic properties of acidity and basicity, respectively. The fenbendazole molecule's groups of –N in the five-membered ring and –NH in the straight chain serve as the main targets for electrophilic and nucleophilic assault. The weak interactions between fenbendazole and several solvents were shown using an independent gradient model based on Hirshfeld partition analysis.

Ferroelectric polarization tailored spin polarized electronic structure and magnetic anisotropy in two-dimensional ScSi2N4/CuInP2S6 multiferroic heterostructures

Two-dimensional (2D) van der Waals (vdW) multiferroic heterostructures which consist of vdW intrinsic magnets and ferroelectrics (FEs) plays an extremely important role in novel 2D spintronic devices. In this paper, the electronic structure and magnetic anisotropy of 2D vdW ScSi2N4/CuInP2S6 heterostructure are systematically investigated using first-principles calculation. CuInP2S6 is a 2D FE material with out-of-plane polarization, and ScSi2N4 is a half-metal with ferromagnetic (FM) properties. After the ab initio molecular dynamics simulations, the structures of upward polarization (P↑) and downward polarization (P↓) states are stable. Both the P↑ and P↓ states of ScSi2N4/CuInP2S6 heterostructure are FM half-metals. Biaxial strains modulate the electronic structure and magnetic properties of the ScSi2N4/CuInP2S6 heterostructure. With the application of compressive strains in P↓ state, the spin-up band crosses Fermi level and the P↓ state changes from half-metal to metal. The transition from half-metal to metal in P↑ state is realized at ϵ = −4% and ϵ = −6%. The magnetic anisotropy energy of the P↓ state can be enhanced by compressive strains of −2% and −4%. The P↓ state shows the largest average planar electrostatic potential of 0.819 eV at ϵ = −6%, which keeps the maximum electrostatic field between ScSi2N4 and CuInP2S6 monolayers. As the strain increases from −2% to −6%, the potential difference of P↑ state increases gradually. At +6% tensile strain, the band structure inversion occurred in both P↑ and P↓ states. These results demonstrate the potential of 2D vdW multiferroic heterostructures and can enrich the field of spintronic devices.

A candidate exchange-biased vdW heterostructure based on Cr2NO2 and Cr2CF2 MXenes

We investigated the van der Waals heterostructure Cr2NO2/Cr2CF2 by spin-polarized first-principles calculations. The aim is to create two-dimensional ferromagnetic/antiferromagnetic heterostructures where the exchange bias effect can occur. Cr2NO2 MXene is a half-metal ferromagnetic material, while Cr2CF2 MXene is an antiferromagnetic semiconductor. The lattice mismatch of both MXenes is ∼4%, good enough to construct the heterostructure. Three different stackings were considered in the heterostructure: H3, T4, and Top. Also, three different cell parameters are considered: larger lattice constant a(Cr2CF2), shorter lattice constant a(Cr2NO2), and both relaxed. In all cases, T4 staking is the most favorable interaction configuration. Non-covalent interactions show that van der Waals forces dominate in the heterostructure. Also, the average electrostatic potential along the z-axis explains the stability in the T4 stacking. Antiferromagnetic coupling is the most stable when fixing a(Cr2CF2) as the heterostructure lattice parameter, while for the short lattice constant, a(Cr2NO2), the magnetic coupling becomes Ferromagnetic. Band diagrams evidence that both MXenes preserve their electronic properties after the interaction, so the antiferromagnetic alignment is intrinsic in the heterostructure for the larger lattice constant. Our theoretical findings open the door to consider the versatile MXenes as promising candidates for the new generation of information storage nanodevices.

Pt atomic catalyst on MXene (Ti3C2O2) sheet: A superior candidate for enhanced adsorption and gas sensing of NH3, H2S and CO2

In intelligent agriculture, the development of gas sensing technology has practical significance. In a bid to achieve fast, accurate and effective detection of noxious gases NH3, H2S and CO2 from breeding farms, Ti3C2O2, an excellent gas sensing material in the MXene family, was investigated by means of density functional theory (DFT) calculations. The optimal configuration of Pt atomic catalyst doped Ti3C2O2 sheet was obtained via the analysis of binding energy (−1.796 eV) and charge transfer (0.373 e). The adsorption energy, charge transfer, deformation charge density (DCD), density of states (DOS), average electrostatic potential, and work function of NH3, H2S and CO2 adsorbed on Ti3C2O2 and Pt-Ti3C2O2 sheet were further scrutinized. From comparative analysis against Ti3C2O2, Pt-Ti3C2O2 possesses excellent adsorption capacity, electron density rearrangement and electrostatic binding ability for the adsorption of NH3, H2S and CO2, among which the adsorption energy for NH3 is the largest (−2.593 eV). The results verify that Pt-Ti3C2O2 is a potential material for gas sensors, providing guidance for expanding the gas sensing application of MXene materials.

Band alignment and crystal stability of Y3Al5−xGaxO12 garnets using density functional theory with hybrid functional

In this study, the dependence of band gap, band alignment, and structural stability of Y3Al5−xGaxO12 garnet (YAGG) solid solutions on Ga content (x) have been investigated using density functional theory (DFT) with PBE0 hybrid functional. The most stable model of YAGG for each x is identified using evolutionary algorithm-based USPEX method. The band alignment was determined by connecting valence band maximum (VBM) and conduction band minimum (CBM) to vacuum level via macroscopic average electrostatic potential of the slab model. Solid solution formation energy as a function of x indicates that YAGG with x = 3.0 (Y3Al2Ga3O12) exhibits remarkable structural stability. At x = 3.0, the analysis of the formation energy contribution shows a dominant contribution from electronic charge redistribution energy while there is no contribution from distortion energy. Bader charge, electron localization function, as well as the projected density of state analysis reveal a strong covalent character of Ga under oxygen tetragonal environment. The calculated PBE0 band gap as a function of x agrees well with the experimental results. Ga admixing significantly lowers the CBM, which exhibits a potential to envelop the shallow electron traps from the forbidden gap. The YAGG band alignment calculated using the proposed vacuum-connecting method is consistent with VRBE results from experiment. The proposed methods used to model site-preferred solid solution and calculate the vacuum-connected band alignment are viable in predicting structural stability and band edge modification via compositional engineering of garnet solid solutions. We expect that this work provides a promising strategy for material design through compositional engineering in obtaining high stability and enhanced performance in garnet compounds.

Structural, optoelectronic and photocatalytic properties of MX (M=Ga, In; X=S, Se, Te) contact with novel janus GaInS3 monolayers

Using DFT calculations, we have fabricated the MX-GaInS3 (M = Ga, In; X = S, Se, Te) van dar Waals Heterostructures (vdWHs) and systematically calculated the structural, electronic, optical and photocatalytic properties. The calculated binding energies and AIMD simulations confirm the robust evidence for the stability of MX-GaInS3 vdWHs. Despite of the indirect bandgap nature of MX (M = Ga, In; X = S, Se, Te) monolayer, interestingally MX-GaInS3 vdWHs are direct bandgap semiconductors with type-II band alignments. Charge density difference, bader charges and the average electrostatic potential are calculated to investigate the transfer of charges amoung the layers at the interface of MX-GaInS3 vdWHs. Using dispersion along high symmetry path by fitting the band edges, we have also calculated the effective mass of carriers in MX-GaInS3 vdWHs. Smaller effective mass with higher mobility of carrier, suggest MX-GaInS3 vdWHs best candidate for optoelectronic devices. Absorption spectra in term of ε2(ω) of MX-GaInS3 (M = Ga, In; X = S, Se, Te) vdWHs are also calculated and investigated in detail. Both the conduction and valence band edges in GaS-GaInS3 vdWHs straddle the standard redox band edge potentials, hence have the ability to perform both reduction and oxidation, confirming the potentiality for full water splitting at pH = 0.

Study of the reaction mechanism based on the formation of the first carbocyclic ring from propargyl and diacetylene

The formation of the first carbon ring is a crucial rate-controlling step in developing polycyclic aromatic hydrocarbons (PAHs). It is vital to investigate the mechanism of the creation of the first carbon ring to inhibit the formation of PAHs. To explore the growth process of the first carbocyclic ring, this work used the average localized ionization energy (ALIE) and electrostatic potential (ESP) to predict the reaction sites. Moreover, the reaction paths and chemical kinetic parameters for the generation of the first carbocyclic ring from propargyl (C3H3) + diacetylene (C4H2) are calculated based on the density functional theory (DFT) method and transition state theory (TST). The results showed that the addition reaction of C3H3 +C4H2 can form five-, six- and seven-membered ring molecules, in which the five-membered ring formation is fastest and the six-membered ring formation is slowest. During the formation of the first carbon ring, the activation energy required for the H transfer and cyclization reactions is large, and the reaction rate is slow, which determines the formation rate of the first carbon ring. The rate of H-transfer reaction on each carbon ring depends on the number of C atoms of the carbon ring, with the five-membered ring being the fastest and the six-membered ring the slowest. This paper improves the reaction kinetics and thermodynamic data of the first carbon ring formation during the combustion of hydrocarbon fuels, which offers a powerful theoretical basis for predicting the generation of PAHs.

Unlocking the electronic, optical and transport properties of semiconductor coupled quantum dots using first principles methods

Semiconductor coupled quantum dots provide a unique opportunity for tuning band gaps by tailoring band offsets, making them ideal for photovoltaic and other applications. Here, we have studied stability, trends in the band gap, band offsets, and optical properties for a series of coupled quantum dots comprised of II–VI semiconductors using a hybrid functional method. We have shown how the quantum confinement and interfacial strain considerably affect the band gap and band offsets for these heterostructures at the nanoscale. We show that the trend in band offsets obtained from our first-principles electronic structure calculations agrees with that obtained from the method of average electrostatic potential. It is found that a common anion rule for band offset is followed for these heterostructures at the nanoscale. Further, the calculated optical absorption spectra for these coupled quantum dots reveal that absorption peaks lie in the ultra-violet (UV) region, whereas absorption edges are in the visible region. In addition to electronic and optical properties, we have also explored transport properties for two representative coupled quantum dots, either having common cations or common anions, which revealed asymmetric nature in current–voltage characteristics. Therefore, these semiconductor coupled quantum dots may be useful for photovoltaic, light-emitting diode, and optoelectronic devices.

Modulating the organic photovoltaic properties of non-fullerene acceptors by molecular modification based on Y6: a theoretical study.

Developing non-fullerene acceptors (NFAs) by modifying the backbone, side chains and end groups is the most important strategy to improve the power conversion efficiency of organic solar cells (OSCs). Among numerous developed NFAs, Y6 and its derivatives are famous NFAs in the OSC field due to their good performance. Herein, in order to understand the mechanism of tuning the photovoltaic performance by modifying the Y6's center backbone, π-spacer and side-chains, we selected the PM6:Y6 OSC as a reference and systematically studied PM6:AQx-2, PM6:Y6-T, PM6:Y6-2T, PM6:Y6-O, PM6:Y6-1O and PM6:Y6-2O OSC systems based on extensive quantum chemistry calculations. The results indicate that introducing quinoxaline to substitute thiadiazole in the backbone induces a blue-shift of absorption spectra, reduces the charge transfer (CT) distance (Δd) and average electrostatic potential (ESP), and increases the singlet-triplet energy gap (ΔEST), CT excitation energy and the number of CT states in low-lying excitations. Inserting thienyl and dithiophenyl as π spacers generates a red-shift of absorption spectra, enlarges Δd and average ESP, and reduces ΔEST and the number of CT states. Introducing furo[3,2-b]furan for substituting one thieno[3,2-b]thiophene unit in the Y6's backbone causes a red-shift of absorption spectra and increases ΔEST, Δd and average ESP as well as CT excitation energy. Introducing alkoxyl as a side chain results in a blue-shift of absorption spectra, and increases ΔEST, Δd, average ESP, CT excitation energy and the number of CT states. The rate constants calculated using Marcus theory suggest that all the molecular modifications of Y6 reduce the exciton dissociation and charge recombination rates at the heterojunction interface, while introducing furo[3,2-b]furan and alkoxyl enlarges CT rates.

The electrostatic potential inside and around α-lactalbumin: Fluctuations and mean-field models.

The electrostatic potential (EP) generated by the protein α-lactoalbumin in the presence of added salt is computed as a thermal average at a given point in space. With this aim, constant pH Monte Carlo (MC) simulations are performed within the primitive model, namely, the solvent is treated as a continuum dielectric. The study of the thermal and spatial fluctuations of the EP reveals that they are remarkably high inside the protein. The calculations indicate that fluctuations inside the protein are mainly due to the asymmetric distribution of the charge groups, while the charge fluctuations of the titratable groups play a minor role. The computed EP matches very well with the one obtained from the Poisson equation for the average charge density in spherical symmetry. The Tanford-Kirkwood multipole expansion reproduces the simulated angular-averaged potential rather accurately. Surprisingly, two of the simplest mean-field models, the linear Poisson-Boltzmann (PB) equation and Donnan potential, provide good estimations of the average EP in the effective protein surface (surface EP). The linear PB equation predicts a linear relationship between charge and surface EP, which is numerically reproduced only if the small ions within the protein are taken into account. On the other hand, the partition coefficients of the small ions inside and outside the protein predicted by Donnan theory reproduce reasonably well the simulation results.

Tools for Understanding and Predicting the Affinity of Per- and Polyfluoroalkyl Substances for Anion-Exchange Sorbents.

Anion-exchange (AE) sorbents are gaining in popularity for the remediation of anionic per- and polyfluoroalkyl substances (PFAS) in water. However, it is unclear how hydrophobic and electrostatic interactions contribute to anionic PFAS retention. The goal of this study was to understand the effects of PFAS chain length and head group on electrostatic interactions between PFAS and an aminopropyl AE phase. Liquid chromatography-mass spectrometry (LC-MS) was used with an aminopropyl AE guard column to find relative retention times. The average electrostatic potential (EPavg) of each PFAS was calculated, which correlated positively with the PFAS chromatographic retention time, demonstrating the value of EPavg as a proxy for predicting electrostatic interactions between PFAS and the aminopropyl AE phase. The order of greatest to lowest PFAS AE affinity for an aminopropyl column based on chromatographic retention times and electrostatic interactions was n:3 fluorotelomer carboxylic acids (n:3 FtAs) > n:2 fluorotelomer carboxylic acids (n:2 FtAs) > perfluoroalkyl carboxylates (PFCAs) > perfluoroalkyl sulfonamides (FASAs) ∼ n:2 fluorotelomer sulfonates (n:2 FtSs) > perfluoroalkyl sulfonates (PFSAs). This study introduces a methodology for qualitatively characterizing electrostatic interactions between PFAS and AE phases and highlights that electrostatic interactions alone cannot explain the affinity of PFAS for AE resins in water treatment/remediation scenarios.

A Medium-Bandgap Nonfullerene Acceptor Enabling Organic Photovoltaic Cells with 30% Efficiency under Indoor Artificial Light.

The correlation between molecular structure and photovoltaic performance is lagging for constructing high-performance indoor organic photovoltaic (OPV) cells. Herein, this relationship is investigated in depth by employing two medium-bandgap nonfullerene acceptors (NFAs). The newly synthesized NFA of FTCCBr exhibits a similar bandgap and molecular energy level, but a much stronger dipole moment and larger average electrostatic potential (ESP) compared with ITCC. After blending with the polymer donor PB2, the PB2:ITCC and PB2:FTCCBr blends exhibit favorable bulk-heterojunction morphologies and the same driving force, but the PB2:FTCCBr blend exhibits a large ESP difference. In OPV cells, the PB2:ITCC-based device produces a power conversion efficiency (PCE) of 11.0%, whereas the PB2:FTCCBr-based device gives an excellent PCE of 14.8% with an open-circuit voltage (VOC ) of 1.05V, which is the highest value among OPV cells with VOC values above 1.0V. When both acceptor-based devices work under a 1000 lux of 3000 K light-emitting diode, the PB2:ITCC-based 1 cm2 device yields a good PCE of 25.4%; in contrast, the PB2:FTCCBr-based 1 cm2 device outputs a record PCE of 30.2%. These results suggest that a large ESP offset in photovoltaic materials is important for achieving high-performance OPV cells.

Doping effects on electronic structures and current-voltage characteristics of GR/InSe/GR selectors

The graphene(GR)/InSe/GR selector was designed based on the rectifying effect of the Schottky barrier at the GR/InSe heterostructure interface. The selector performance was improved by doping groups I–VII A elements, and the effects were studied by first-principles calculations. The band structure results showed that InSe retained p-type semiconductor characteristics only when Se atoms were substitutionally doped by groups IV A (C, Si, Ge) and VI A (O, S) elements. The band gap of the GR/InSe heterostructure doped with group IV A (C, Si, Ge) elements became narrower, and the conductivity became stronger. The band structures of the GR/InSe heterostructures doped with group VI A (O, S) elements were hardly changed. From the plane average electrostatic potential and the charge density difference, it is observed that doping of group IV A (C, Si, Ge) elements reduced the height and width of the Schottky barrier at the interface and enhanced the built-in electric field strength of the heterostructures. Finally, the current-voltage (I-V) curves show that compared with the undoped GR/InSe/GR selector, the on-state current (Ion) and nonlinearity (NL) coefficient of selectors doped with group IVA (C, Si, Ge) elements increased, and the threshold voltage (Vth) and off-state current (Ioff) decreased. It can better suppress the influence of the leakage current on the RRAM, which is important for the development of high-performance and low-power selectors.

Structure and Electronic Properties of 2D GaN/AlxGa1−xN 2D/3D Heterostructure Controlled by Al Components and Interlayer Distance

Herein, the structure and electronic properties of 2D GaN/AlxGa1−xN 2D/3D heterostructure with different Al components and interlayer distance using first‐principle calculations are studied. The results show that the ordered arrangement of Al components in AlxGa1−xN materials is more conducive to form heterostructures. By comparing binding energy under different Al components, it can be found that graphene‐like GaN(g‐GaN)/Al0.5Ga0.5N is the most stable. Expect g‐GaN/AlN heterostructure, there is effect of chemical bonds in other g‐GaN/AlxGa1−xN models from charge density distribution. The bandgap of the heterostructure enlarges with the increase in Al components. The g‐GaN/AlN has an indirect bandgap, while the other heterostructure models have characteristics with direct bandgap. There are impurity levels appearing near the Fermi level in band structure of heterostructure, which are mainly induced by the surface dangling bonds between g‐GaN layer and AlxGa1−xN layer. Through the analysis of binding energy, average electrostatic potential, and band structure of different interlayer distance, the optimal interlayer distance range of g‐GaN/AlxGa1−xN heterostructure is 2.5–3 Å.

Three-Dimensional Quantitative Structure and Activity Relationship of Flavones on Their Hypochlorite Scavenging Capacity.

Flavonoids, a class of polyphenolic substances widely present in the plant realm, are considered as ideal hypochlorite scavengers. However, to our knowledge, little study has focused on the structure-activity relationship between flavonoids and hypochlorite scavenging capacity. Herein, we report for the first time the three-dimensional quantitative structure and activity relationship (3D-QSAR) combined with comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). Four models derived from CoMFA and CoMSIA with different combinations of descriptors were built and compared; the CoMFA model, which included both steric and electrostatic fields, showed great potential (R2 = 0.989; Q2 = 0.818) in predictive quality according to both internal and external validation criteria. Additionally, the average local ionization energy (ALIE), electrostatic potential (ESP), and orbital weighted dual descriptor (OWDD) were determined to identify the key structural moiety for scavenging capacity of flavonoids against hypochlorite. The computational results indicated that hypochlorous acid (HClO) serves as an electrophile undergoing electrophilic addition to the C6 carbon, which has the highest negative charge density, which are influenced by the functional groups on the flavones. The DFT calculated mechanism revealed the catalytic role of water of mono- and di-chlorination reactions, characterized by low activation barriers, and the involvement of neutral, instead of high-energy carbocation, intermediates.