Density Functional Theory Simulations Research Articles

Structural, optoelectronic, and magnetic properties of Q‑carbon studied by hybrid density functional theory ab initio calculations and experiment

This work presents a theoretical study of the structural, optoelectronic, and magnetic properties of Q‑carbon, utilizing hybrid functionals within density functional theory (DFT) ab initio calculations. Moreover, experiments were conducted to measure structural parameters, dielectric functions, and magnetic properties, using various techniques. From the DFT simulations, structural, electronic, and optical properties have been simulated. The band gap energy was calculated using a hybrid approach, which combine HSE functional with different values of exact Hartree-Fock (HF) exchange (α). We propose a theoretical investigation of cubic and quasi-cubic forms of Q‑carbon. Our findings indicate that a non-cubic Q‑carbon cell is energetically more stable and possesses higher cell mass density and bulk modulus compared to a cubic cell. Calculations indicated that Q‑carbon exhibits semiconductor behavior; an indirect band gap of 3.10 eV and a direct band gap of about 3.4 eV was obtained for α = 0.44, in good agreement with experimental values. The density of states analysis allowed us to identify the p orbital of sp2 hybridized atoms as being prevalent on the top of the valence band and in the lowest energy conduction band states. Magnetic moment values of 0.37 μB and 0.41μB was found in two sp2 bonded C atoms, in accordance with the experimental observation. Several optical properties were calculated. The theoretical findings are compatible with the experimental results shown here and available in the literature, with excellent agreement found between the calculated optical band gap and that obtained from absorption measurements.

Unveiling the high-pressure behavior of thymol+carvone NADES: A combined experimental-computational approach

this study considers the high-pressure behavior of thymol + carvone Natural Deep Eutectic Solvent using a combined experimental and computational approach. Experimentally, PVT (pressure – volume/density - temperature) measurements were conducted to characterize the fluid volumetric behavior as well as compressibility and internal pressure, which are directly related with hydrogen bonding and nanoscopic structuring. Likewise, these measurements provide crucial insights into the thermodynamic properties of the considered fluid under high pressure, which is pivotal for scaling up and process design for high pressure operations. Computationally, the PC-SAFT equation of state was employed to predict phase equilibria and PVT behavior, Machine Learning for density predictions, while Density Functional Theory and Classical Molecular Dynamics simulations were considered for the structural and dynamic characterization. These simulations provides insights into the electronic structure, intermolecular interactions (hydrogen bonding), liquid structuring and they unveil the pressure's impact on microscopic interactions, structural organization, and transport properties. This comprehensive investigation aims to shed light on the behavior under high pressure, facilitating their optimization for applications in chemical processing, energy storage, and materials science.

Mild polarization electric field in ultra-thin BN-Fe-graphene sandwich structure for efficient nitrogen reduction

The electrocatalytic N2 reduction reaction (NRR) is expected to supersede the traditional Haber-Bosch technology for NH3 production under ambient conditions. The activity and selectivity of electrochemical NRR are restricted to a strong polarized electric field induced by the catalyst, correct electron transfer direction, and electron tunneling distance between bare electrode and active sites. By coupling the chemical vapor deposition method with the poly(methyl methacylate)-transfer method, an ultrathin sandwich catalyst, i.e., Fe atoms (polarized electric field layer) sandwiched between ultrathin (within electron tunneling distance) BN (catalyst layer) and graphene film (conducting layer), is fabricated for electrocatalytic NRR. The sandwich catalyst not only controls the transfer of electrons to the BN surface in the correct direction under applied voltage but also suppresses hydrogen evolution reaction by constructing a neutral polarization electric field without metal exposure. The sandwich electrocatalyst NRR system achieve NH3 yield of 8.9 μg h−1 cm−2 and Faradaic Efficiency of 21.7%. The N2 adsorption, activation, and polarization electric field changes of three sandwich catalysts (BN-Fe-G, BN-Fe-BN, and G-Fe-G) during the electrocatalytic NRR are investigated by experiments and density functional theory simulations. Driven by applied voltage, the neutral polarized electric field induced by BN-Fe-G leads to the high activity of electrocatalytic NRR.

One-step solution processing of printable Sb2S3 nano-rods for high-performance photoconductors

Abstract Achieving large-scale, affordable, and highly dependable production of antimony sulfide is crucial for unlocking its potential in various applications, including photoconductors, solid-state batteries, thermoelectrics, and solar cells. In our study, we introduce a straightforward, economical, and catalyst-free single-step solution process for fabricating one-dimensional Sb2S3 nanostructures on flexible polyimide substrates, and we explore their use as photoconductors in the ultraviolet (UV) and visible light spectrum. The precursor solution for creating the Sb2S3 films is prepared by dissolving specified quantities of elemental Sb and S in a solution mixture of ethylenediamine and 2-mercaptoethanol. This solution is then spin-coated onto a polyimide substrate and subsequently annealed at 300 °C for several minutes. Utilizing field emission scanning electron microscopy, grazing incidence x-ray diffraction, Raman spectroscopy, and transmission electron microscopy, we demonstrate that the Sb2S3 films possess high crystallinity, uniform morphology, and a composition that is nearly stoichiometric. Additionally, through Tauc plot analysis, we determine that the films exhibit a direct bandgap of approximately 1.67 eV, which is in close agreement with the bandgap predicted by Heyd–Scuseria–Ernzerhof (HSE06) density-functional theory simulations. The metal-semiconductor–metal photoconductors fabricated with these films display a significant photoresponse to both UV and visible light. These devices achieve a UV on/off ratio of up to 160 at a light intensity of 30 mW cm−2, with brief rise and fall times of 44 ms and 28 ms, respectively.

Acidity and stability of Nb(V) active sites doped in SBA-15 and ZrSBA-15: A DFT study

Mesoporous silicas are of great interest in heterogeneous catalysis due to the structural characteristics of their pores and the adjustable catalytic properties that arise from incorporating heteroatoms. The substitution of Zr and Nb into SBA-15 introduces active sites into the material, rendering it a potential catalyst for acid catalysis reactions. However, discussions regarding the acid properties and metal-support interactions in amorphous silicas functionalized with metals are limited in computational chemistry. This study aims to determine the acid strength and charge transfer effects between Zr(IV) and Nb(V) species in mesoporous silica by proposing a representative SBA-15 cluster of type 5–6. Density Functional Theory (DFT) simulations were conducted using the B3LYP/6-31G(d,p)/def2TZVP levels. The model successfully replicated trends from larger clusters, demonstrating that the more grafted onto the silica structure (i.e. have more Si-O-M bonds), the greater the acid strength of the active site. Additionally, it was found that ZrSBA-15 structures are more stable than NbSBA-15 and possess higher acid strength, a trend supported by experimental observations. The results also suggest that Nb(V) species are more effectively stabilized in ZrSBA-15 than SBA-15, likely due to the presence of Zr(IV) centers in ZrSBA-15. This research contribute to a better understanding of how the support affects the stabilization of active phases, paving the way for the rational design of silica-based heterogeneous catalysts.

Synthesis, Characterization, Bioactivity Evaluation, and POM/DFT/Docking Analysis of Novel Thiazolidine Derivatives as Potent Anticancer and Antifungal Agents

AbstractA series of 2,2′‐(1,4‐phenylene)bis(N‐substituted phenylthiazolidine‐4‐amide) derivatives, denoted as (A3–9), were synthesized, and characterized for their potential applications against prostate cancer cells (PC3), and Candida albicans fungi. These compounds incorporate various substituents on the phenyl ring such as 4‐NO2, 3‐NO2, 4‐COCH3, 4‐H, 4‐OCH3, 4‐OCH2CH3, and 4‐Cl. The chemical structures of these derivatives were confirmed by NMR, FTIR, and mass spectroscopy. Biological assays, utilizing the MTT assay for prostate cancer cells (PC3) and the disk diffusion assay for Candida albicans fungi, were conducted to evaluate the bioactivity of these compounds. The results revealed promising cytotoxic and antifungal activities. Specifically, compounds A3 (IC50=69.74±0.96), A4 (IC50=63.64±0.950), and A9 (IC50=57.14±0.88 μg/mL) exhibited notable potency against PC3 cells, while A7 and A8 exhibited considerable antifungal efficacy against Candida albicans with MIC of 312 μg/mL. Moreover, density functional theory (DFT) simulations were used to study electronic properties and reactivity descriptors such as energy gap (Eg), ionization potential (IP), electron affinity (EA), chemical potential (μ), chemical hardness (η), global softness (σ), electronegativity (χ), and electrophilicity (ω) to gain a better understanding of the Structure‐Activity Relationship (SAR). Molecular docking analysis against DNA Gyrase and EGFR tyrosine kinase enzymes revealed strong binding interactions of the investigated molecules within their active sites, making them valuable candidates for further development as therapeutic agents against prostate cancer and fungal infections. POM analysis indicates the presence of two antifungal pharmacophore sites (O1δ−, O2δ−) and (O3δ−, O4δ−), as well as two antitumor pharmacophore sites (O1δ−, NH1δ+) and (O4δ−, NH2δ+).

Two P, Ten P, White P, Red P: Mechanistic Exploration of the Oligomerization of Red Phosphorus from Diphosphorus with the Ab Initio Nanoreactor.

Phosphorus is critical to humans on many fronts, yet we do not have a mechanistic understanding of some of its most basic transformations and reactions─namely the oligomerization of white phosphorus to red. With heat or under ultraviolet (UV) exposure, it has been experimentally demonstrated that white phosphorus dissociates into diphosphorus units which readily form red phosphorus. However, the mechanism of this process is unknown. The ab initio nanoreactor approach was used to explore the potential energy surface of phosphorus clusters. Density functional theory and metadynamics simulations were used to characterize potential reaction pathways. A mechanism for oligomerization is proposed to take place via diphosphorus additions at π-bonds and weak σ-bonds through three membered ring intermediates. Downhill paths through P6 and P8 clusters eventually result in P10 clusters that can oligomerize into red phosphorus chains. The initial, rate limiting step for this process has an energy barrier of 24.2 kcal/mol.

Unveiling novel drug delivery mechanism: Cisplatin’s bonding behaviour with BC4N Nanostructure

Recent advancements in nanotechnology have opened avenues to address the selectivity challenges in targeted drug delivery systems, minimizing adverse effects. While carbon nanotubes (CNTs) have gained traction as drug carriers, their B, N-containing counterpart, pristine boron carbonite (p-BC4N), remains underexplored. This study investigates the possibility of pristine boron carbonite (p-BC4N) nanotubes as a drug carrier for the anticancer medication cisplatin (CPT). Using first-principles Density Functional Theory (DFT) simulations, we examined the interaction between CPT and p-BC4N nanotubes, revealing favourable adsorption energies (−0.523 eV) due to orbital interactions and charge transfer between the C 2p orbitals of BC4N and the 1 s orbitals in H of CPT. Ab initio molecular dynamics (AIMD) simulations confirmed the stability of the system at room temperature. Furthermore, pH and temperature-dependent desorption measurements demonstrated the effectiveness of p-BC4N nanotubes as a promising candidate for CPT drug delivery, highlighting their potential in targeted cancer therapy. This work opens up new avenues for the development of nanotechnology-based drug delivery systems.

Speed of sound for understanding metals in extreme environments

Knowing material behavior is crucial for successful design, especially given the growing number of next-generation energy, defense, and manufacturing systems operating in extreme environments. Specific applications for materials in extreme environments include fusion energy, semiconductor manufacturing, metal additive manufacturing, and aerospace. With increased applications, awareness of foundational science for materials in extreme environments is imperative. The speed of sound provides insights into phase boundaries, like shock-induced melting. Thermodynamic integration of the speed of sound enables the deduction of other desirable properties that are difficult to measure accurately, like density, heat capacity, and expansivity. Metrology advancements enable the speed of sound to be measured at extreme conditions up to 15 000 K and 600 GPa. This comprehensive review presents state-of-the-art sound speed metrology while contextualizing it through a historical lens. Detailed discussions on new standards and metrology best practices, including uncertainty reporting, are included. Data availability for condensed matter speed of sound is presented, highlighting significant gaps in the literature. A theoretical section covers empirically based theoretical models like equations of state and CALPHAD models, the growing practice of using molecular dynamics and density functional theory simulations to fill gaps in measured data, and the use of artificial intelligence and machine learning prediction tools. Concluding, we review how a lack of measurement methods leads to gaps in data availability, which leads to data-driven theoretical models having higher uncertainty, thus limiting confidence in optimizing designs via numerical simulation for critical emerging technologies in extreme environments.

Efficient and tunable emission of Na5Lu(WO4)4:Tb3+,Eu3+ phosphors for warm white LEDs with high color rendering index

Phosphors with high luminescence efficiency, tunable emission and high color rendering index (CRI) are vital importance for the quality of white light emitting diodes (w-LEDs) in real application. In this work, a new single phase color-tunable Na5Lu(WO4)4:Tb3+,Eu3+ phosphor with outstanding luminescent properties was designed and synthesized. Its crystal structure, electronic structure, and luminescence features were studied in detail. The band gap of the host was calculated to be at about 4.68 eV. The differential charge distribution after Tb, Eu doping through density functional theory simulation theoretically proved the electron redistribution in the W-O bond upon substitution of Tb3+/Eu3+. The energy transfer of Tb3+→Eu3+ enabled tunable emission of luminescent colors from green to orange-red due to the quadrupole-quadrupole interaction. The optimal Na5Lu(WO4)4:60%Tb3+,20%Eu3+ phosphor exhibited excellent photoluminescence quantum yield of 84.19% and good luminescent thermal stability (I423K/298K = 75.90%) with an activation energy of 0.1976 eV. Finally, a white LED device with color coordinates of (0.3371, 0.3636), color rendering index of 89.4 and correlated color temperature of 5334 K was fabricated. These findings demonstrated that Na5Lu(WO4)4:60%Tb3+,20%Eu3+ phosphor could be a potential orange-red-emitting color converter for white LEDs. This work not only assisted in the understanding of experimental observations but also provided a theoretical basis for the rational design of phosphors.

Nanoscale Synergy: Unveiling Gas Sensing Paradigms Through First Principles Exploration of Vertical Hexagonal Boron Nitride/Graphene Heterostructures

Modern civilization relies on rapid and accurate gas molecule identification at low concentrations for environmental surveillance, civilian security, healthcare evaluation, and inside atmospheric control. Density functional theory simulations are used to study the adsorption of CH4, CO2, PH3, N2O, NH3, O3, and SO2 gas molecules on a vertical hexagonal boron nitride/graphene heterostructure using the CASTEP code. Negative adsorption energy is only detected for NH3, O3, and SO2 gases. Our adsorption energy measurements show that the heterostructure is sensitive to NH3, O3, and SO2 gas molecules but insensitive to other gas molecules, as shown by the positive results. Further electrical and optical properties are only performed on gas‐adsorbed structures. It is found that the pure heterostructure acts like a semiconductor and has a band gap of 1.742 eV, which changes when gas is absorbed. Each of the structures has high absorption coefficients in the UV region, making them promising candidates for optoelectronic devices. The determination of the adsorbed gas type can be achieved by measuring the peak intensity and peak position of reflection or absorption. Heterostructures exhibit superior sensing capabilities for NH3 compared to other gases because of their enhanced adsorption energy, distinctive electrical band gap, and notable optical characteristics.

Bimetallic ions pre-intercalated hydrated vanadium oxides for high-performance aqueous zinc-ion batteries

A new generation of rechargeable batteries known as Aqueous Zinc-Ion Batteries (AZIB) offers benefits including affordability, eco-friendliness, dependability, and safety. Hydrated vanadium oxides (V2O5·nH2O) show potential as cathodes for AZIB due to their layered structure and multivalent properties. However, the zinc storage performance is limited by the structural instability and slow zinc ion mobility. In this work, TiK-VOH (the bimetallic ions system of Ti4+ and K+ co-pre-intercalated in V2O5·nH2O) with lamellar fish scale-like structure is synthesized using a simple sol-gel method. The high positive charge density of the tetravalent Ti4+ is more beneficial to attract the electrons in the V-O layer and regulate the layer spacing (12.1 Å), which not only improves the diffusion kinetics of zinc ions, but also acts as a pillar to stabilize the layer structure. K+ mainly plays the role of improving electrical conductivity, and then accelerates the charge transfer in the electrode reaction process. Auxiliary density functional theory simulation further confirms that the diffusion energy barrier and Fermi level are optimized by pre-intercalating bimetallic ions. Based on the synergistic effect of Ti4+ and K+, the TiK-VOH material shows excellent zinc storage performance, the highest specific capacity of TiK-VOH reaches 393.4 mAh g−1 at a current density of 0.2 A g−1, even at 10 A g−1 (increased by 20 times), it still maintains a discharge specific capacity of 202 mAh g−1 with a capacity retention rate of 94 % after 2000 cycles, the overall performance is much better than the Ti-VOH and K-VOH. This work offers an alternative perspective for the modification of vanadium-based cathode of AZIBs.

Bioinspired Homonuclear Diatomic Iron Active Site Regulation for Efficient Antifouling Osmotic Energy Conversion.

Membrane-based reverse electrodialysis is globally recognized as a promising technology for harnessing osmotic energy. However, its practical application is greatly restricted by the poor anti-fouling ability of existing membrane materials. Inspired by the structural and functional models of natural cytochrome c oxidases (CcO), the first use of atomically precise homonuclear diatomic iron composites as high-performance osmotic energy conversion membranes with excellent anti-fouling ability is demonstrated. Through rational tuning of the atomic configuration of the diatomic iron sites, the oxidase-like activity can be precisely tailored, leading to the augmentation of ion throughput and anti-fouling capacity. Composite membranes featuring direct Fe-Fe motif configurations embedded within cellulose nanofibers (CNF/Fe-DACs-P) surpass state-of-the-art CNF-based membranes with power densities of ca. 6.7Wm-2 and a 44.5-fold enhancement in antimicrobial performance. Combined, experimental characterization and density functional theory simulations reveal that homonuclear diatomic iron sites with metal-metal interactions can achieve ideally balanced adsorption and desorption of intermediates, thus realizing superior oxidase-like activity, enhanced ionic flux, and excellent antibacterial activity.

Insights into the Structural Modification of Selenium-Doped Derivatives with Narrowband Emissions: A Theory Study.

The research on boron/nitrogen (B/N)-based multiresonance thermally activated delayed fluorescence (MR-TADF) emitters has been a prominent topic due to their narrowband emission and high luminous efficiency. However, devices derived from the common types of narrowband TADF materials often experience an efficiency roll-off, which could be ascribed to their relatively slow triplet-singlet exciton interconversion. Since inserting the heavy Se atom into the B/N scheme has been a proven strategy to address the abovementioned issues, herein, extensive density functional theory (DFT) and time-dependent DFT (TD-DFT) simulations have been employed to explore the effects of the structural modification on a series of structurally modified selenium-doped derivatives. Furthermore, the two-layered ONIOM (QM/MM) model has been employed to study the pressure effects on the crystal structure and photophysical properties of the pristine CzBSe. The theoretical results found that the introduced tert-butyl units in Cz-BSeN could result in a shorter charge transfer distance and smaller reorganization energy than the parent CzBSe. In contrast to directly incorporating the o-carborane (Cb) unit to CzBSe, incorporating the bridged phenyl units is important in order to achieve narrowband emissions and high luminous efficiency. The lowest three triplet excited states of CzBSe, Cz-BSeN and PhCb-BSeN all contribute to their triplet-singlet exciton conversions, resulting in a high utilization of triplet excitons. The pressure has an evident influence on the photophysical properties of the aggregated CzBSe and is favored for obtaining narrowband emissions. Our work is promised to provide a feasible strategy for designing selenium-doped derivatives with narrowband emissions and rapid triplet-singlet exciton interconversions.

Ni/V-MgnHm nanoclusters: Recent advances toward improving the dehydrogenation thermodynamics for efficient hydrogen storage

Understanding the properties of solid-state materials at the nanoscale is a crucial scientific endeavor in the pursuit of a sustainable energy future. Since magnesium hydride is the most practical material for hydrogen storage, research is still ongoing to reduce the enthalpy for dehydrogenation. In this computational theory, we systematically investigated the enthalpy of dehydrogenation of MgnHm nanoclusters of different sizes (0.5–2.8 nm) through density functional theory (DFT) and ab-initio molecular dynamic (AIMD) simulations. Our results revealed that increasing the MgnHm nanocluster size can remarkably improve the formation energy compared to the MgH2-bulk stabilization; the formation energy shifted from −65.12 kJ/mol for (0.5 nm)-MgnHm nanocluster to −51.37 kJ/mol for (2.8 nm)-MgnHm nanocluster. As compared to bulk phase, the lower stability of the nanoclusters indicates that it is much easier to desorb hydrogen from the surface. According to the effects of compressive/tensile strains, (2.8 nm)-MgnHm nanocluster does not improve the dehydrogenation temperature in the desired direction. Unlike metal doping, 9.10%@Ni and 10.14%@V-doped (2.8 nm)-MgnHm nanocluster exhibit formation energies of −47.27 and −46.34 kJ/mol with calculated desorption temperatures of 362.89 and 355.75 K, respectively, which ensures the room temperature applicability of this hydrogen storage material.

Removal of trace Na and K metal ions by resin-grafted crown ether for electronic-grade N-methyl pyrrolidone purification

The semiconductor industry’s rapid evolution necessitates ultra-high-purity N-methyl pyrrolidone (NMP) as an essential electronic-grade solvent. The development of an efficient coordination material to reduce trace metal ions, particularly Na and K metal ions, to below 1 ppb in NMP solution is a significant challenge. To address this, a novel coordination material, St-DVB-g-ACE, has been developed for the removal of Na and K metal ions from NMP. The material was synthesized by grafting 4′-aminobenzo-15-crown-5-ether onto a strong acid gel resin. The resulting St-DVB-g-ACE-3 exhibited excellent coordination performance for Na and K metal ions, with maximum Langmuir adsorption capacities reaching 20,000 μg/g and 33,333 μg/g, respectively. Of particular interest was the ability of St-DVB-g-ACE-3 to reduce all trace metal ions in industrial-grade NMP to below 1 ppb within a fixed bed column, achieving the stringent requirements for electronic-grade NMP at the G3 level. Additionally, the absorbent enhances the purity of NMP from 99.82 % to 99.84 %, indicating that the material is not dissolved and can exist stably in NMP. Its excellent recyclability and reproducibility make it highly practical for industrial use. Density functional theory (DFT) simulation, complemented by spectral analyses, revealed the interaction force and thermodynamic properties between Na and K metal ions and crown ether ring, and illustrated the interaction between anionic sulfonic group (−SO3−) and metal ions. The prepared resin-grafted crown ether adsorbents are highly effective in the thorough removal of trace metal ions from NMP solution, offering a novel and effective method for the production of electronic-grade NMP.

Room Temperature Sensing of Volatile Organic Compounds Using Hybrid Layered SnO Mesoflowers and Laser-Induced Graphitic Carbon Devices.

In this work, we demonstrate chemiresistive volatile organic compound (VOC) sensors prepared by drop-cast assembly of layered tin monoxide mesoflowers (SnO-MFs) on additively produced laser-induced graphene-like carbon (LIG). The SnO-MFs were synthesized below 100 °C at ambient pressure and offer a low fabrication energy alternative route to typical furnace-prepared metal-oxide materials. The additive dropcast assembly of room-temperature operating metal oxide active material allows the substitution of LIG for metal current collectors and glass for alumina, reducing the environmental footprint of the sensor. The sensors can detect methanol (150-4000 ppm) at room temperature and humidity (∼18 °C, ∼55% RH), with response and recovery times (150 ppm methanol) of t 90,resp ≈ 50 ± 10 s and t 90,rec ≈ 5 ± 0.5 s, respectively. The sensors demonstrated a limit of detection (170 ± 40 ppm) below 8 h worker safety exposure levels (200 ppm) and stable DC resistance responses ΔR/R = 9 ± 2% to 710 ppm of methanol for over 21 days in ambient laboratory conditions, n = 4. First-principles density functional theory simulations were used to elucidate the interactions of VOC species on the SnO surfaces. LIG-SnO hybrid sensors thus present a resource-efficient route to develop chemiresistive sensors for low-power applications, although with cross-selectivity to other alcohol species.

An ab initio and monte carlo study of MS2/VS2 (M=Mo, W) ferromagnetic bilayer with negative magnetoresistance in MoS2/VS2 heterostructure

Herein, the electronic and magnetic properties of ferromagnetic van der Waals MS2/VS2 (M=Mo, W) heterostructures, investigated using density functional theory (DFT) and Monte Carlo (MC) simulations are reported. Stability was confirmed via interlayer binding energy, and electronic band structure analysis revealed an indirect band gap with staggered (type II) heterojunctions. The systems exhibit potential for opto-spintronics devices due to large band offsets in both spin channels. Ferromagnetic ground states were identified with Curie temperatures of 299 K and 301 K for MoS2/VS2 and WS2/VS2, respectively. Biaxial strain studies indicated that while WS2/VS2 transitions to half-metallic behavior under tensile strain beyond 1%, the Curie temperatures decrease under both compressive and tensile strains, demonstrating tunable magnetic properties. Additionally, MoS2/VS2 heterostructures fabricated via drop casting exhibited negative magnetoresistance, suggesting potential in spintronics applications.

Insight into electronic and magnetic properties of Ba2NiOsO6 double perovskite: A Monte Carlo study and a comparative investigation between TB-mBJ and GGA+U

The structural, electronic, and magnetic properties of the Ba2NiOsO6 double perovskite were comprehensively studied using density functional theory (DFT) and Monte Carlo simulations. Based on DFT calculations, we found that the double perovskite is stable in the ferromagnetic phase. The compound exhibited thermodynamic stability, confirmed by its negative formation energy and phonon spectrum. The electronic and magnetic properties were analyzed using various approximations, including the Generalized Gradient Approximation (GGA), modified Becke–Johnson approximation (mBJ), and Hubbard correction (GGA+U). The electronic profile indicated a metallic nature with GGA and a half-metallic nature with GGA+U and mBJ. The total magnetic moment was approximately 4 μB across all approximations. The Monte Carlo simulations revealed intriguing phenomena, such as a tri-critical point, second-order and first-order phase transitions, a reentrant phenomenon, and both simple and double hysteresis loops.

Coupling defect-inherent built-in electric fields to promote directional charge migration for rapid photocatalytic degradation of levofloxacin

By enhancing the intrinsic built-in electric field (IEF) of the catalyst through defect engineering, and coupling the IEF of the catalyst via an S-type heterojunction structure, a 3-in-1 IEF is formed, which drives the directional migration of electrons and holes, and can effectively improve photocatalytic performance. In this paper, an oxygen vacancy-type Bi2WO6 (Ov-BWO) composite with twin-type Zn0.5Cd0.5S (ZCS) was synthesized to construct an S-scheme heterojunction. The twin structure results in an IEF in ZCS that points from the twin plane Zn to the twin boundary S. The oxygen vacancies, on the other hand, create an internal electric field from Bi and W to O by altering the local charge density. By coupling the IEF of the catalyst through the S-type heterojunction, an enhanced IEF is formed, pointing from the twin plane Zn to the O in Ov-BWO, enabling rapid directional migration of photogenerated charge carriers. Furthermore, potential Levofloxacin (LVFX) intermediates and degradation pathways were found by combining Liquid chromatography-mass spectrometry (LC-MS) data with Density Functional Theory (DFT) simulations. This study systematically elucidates the photocatalytic degradation system, from catalyst design to the degradation process of pollutants, through the analysis of theoretical calculations and experimental results.