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Vanadium dioxide ( VO 2) as a typically strongly correlated material has an attractive near-room-temperature metal–insulator transition (MIT). This transition shifted between metallic rutile and insulating monoclinic phases can be reversed by external thermal stimulation, accompanied by alterations in the lattice structure and electronic energy band structure, which bring about drastic changes in optical, electrical, thermal, and mechanical properties. Based on these unique characteristics, the VO 2 -integrated element can be utilized in the versatile transduction that converts indirect measurable factors into detectable physical quantities, representing a leap forward in sensing technology and facilitating the development of advanced systems toward an unprecedented level of sensitivity and responsiveness. In this perspective, we review the multifunctional advantages of VO 2 , driven by its thermally induced MIT, which transforms its crystal and electronic structures, leading to changes in optical, electrical, thermal, and mechanical properties. Our paper highlights that VO 2 can serve as a high-performance transduction element, leveraging its attractive properties to facilitate the conversion of various variations into measurable signals, thereby enabling diverse advanced applications. To maximize the advantages of VO 2 , we identify the key challenges and opportunities related to this material, offering guidance and recommendations for future research directions. [ABSTRACT FROM AUTHOR]

The outstanding catalytic property of cerium oxide (CeO2) strongly depends on the polaron formation due to the oxygen vacancy ( V ̈ O ) defect and Ce4+ to Ce3+ transformation. Temperature plays an important role in the case of polaron generation in CeO2 and highly influences its electrical transport properties. Therefore, a much needed attention is required for detailed understanding of the effect of temperature on polaron formation and oxygen vacancy migration to get an idea about the improvement in the redox property of ceria. In this work, we have probed the generation of polarons in CeO2 thin-film deposited on a silicon (Si) substrate using the resonance photoemission spectroscopy (RPES) study. The RPES data show an increase in polaron density at the substrate–film interface of the thermally annealed film, indicating the formation of an interfacial Ce2O3 layer, which is, indeed, a phase change from the cubic to hexagonal structure. This leads to a modified electronic band structure, which has an impact on the capacitance–voltage (C–V) characteristics. This result nicely correlates the microscopic property of polarons and the macroscopic transport property of ceria. [ABSTRACT FROM AUTHOR]

The present study focuses on the oxygen (O)-ion implantation-induced structural and electronic modifications in the single crystals of strontium-titanate (s-STO) using synchrotron-based x-ray diffraction (XRD), x-ray photoemission spectroscopy (XPS), and resonant x-ray photoemission spectroscopy. The crystallinity of the epitaxially aligned phases of s-STO is confirmed through XRD. This direct evidence of heavy ion implantation is supported by the Monte Carlo-based simulation of stopping and range of ions in matter/transport of ions in matter. XPS at different core levels is performed to detect the exact oxidation state of Ti ions in s-STO. The dominance of Ti3+ over Ti4+ upon oxygen implantation suggests the disorder in the perovskite material, primarily in the form of oxygen vacancies (VO). The confirmation of VO is explicitly shown by the enhancement in the spectral area of the assigned peak in the O 1s XPS. Resonant photoemission spectroscopy measurements were performed by varying photon energy from 32 to 46 eV to understand the nature of the valence band electronic structure of s-STO. The resonance in the different hybridized states of s-STO is confirmed by the spectral features of constant initial state plots. There is a correlation between the defective state of Ti and the oxygen-deficient state. The transformation from SrTiO3 to SrTiO2.5, partially or completely, is essentially required to underline any modification in the electronic properties of s-STO. s-STO is in a mixed state of an ionic conductor and an electronic conductor. This study outlines the creation of VO due to O-ion implantation and investigates the changes in the electronic structures of s-STO. [ABSTRACT FROM AUTHOR]

In this work, spin transport in ferroelectric tunnel junctions with composite barriers and magnetic electrodes is investigated theoretically using spin-dependent screening theory. The shape of the insulator barrier and the electronic structure of the ferromagnetic electrode inevitably affect the spin transport properties. Interestingly, we find that when the Fermi level approaches the bottom of the minority-spin band of the electrode, an approximately ±100% bidirectional spin-filtering effect can be realized due to the included exchange potential with an appropriate electronic band structure of electrodes. Additionally, electrically induced magnetic reconstruction would occur on the electrode surface due to spin-dependent band bending. Our study significantly deepens the current understanding of spin-dependent screening on metal surfaces and at metal/ferroelectric interfaces and provides a feasible method for achieving the interface magnetoelectric effect. [ABSTRACT FROM AUTHOR]

This Tutorial provides a comprehensive overview of various k ⋅ p models used to describe the electronic band structures of semiconductors with cubic diamond and zinc blende symmetries. Our primary focus is on III–V semiconductors, with a particular emphasis on highly mismatched alloys. We begin our exploration with the six-band k ⋅ p model, which effectively captures interactions within the highest valence bands. Following that, we delve into the intricacies of the eight-band k ⋅ p model, which takes into account strain effects and modifications to energy dispersion. The Tutorial also introduces the band anticrossing model and its corresponding ten-band k ⋅ p models, specifically tailored for dilute nitride semiconductors. Furthermore, we extend our discussion to the valence band anticrossing model and its application to the 14-band k ⋅ p model in the context of dilute bismide materials. Additionally, we emphasize the significance of more comprehensive models, exemplified by the 30-band k ⋅ p model, for faithfully representing the entire Brillouin zone. [ABSTRACT FROM AUTHOR]

Harnessing the boundless solar energy, photovoltaic cells emerge as pivotal players in the world's sustainable energy landscape. The efficiency of solar cells is intimately tied to the carrier properties influenced by defects and impurities within the sunlight-absorbing semiconductors. In this Perspective, we offer a brief overview of recent advances in exploring doping properties with a focus on three vital thin-film photovoltaic semiconductors: CdTe, CIGS, and halide perovskites. Our discourse encompasses their electronic band structure, intrinsic and extrinsic doping behaviors, defect-assisted nonradiative recombination losses, as well as promising strategies poised to enhance solar cell efficiency. Additionally, we discuss several lingering challenges associated with defects in the advancement of photovoltaic technologies. [ABSTRACT FROM AUTHOR]

The effects of tensile strain and contact transmissivity on the performance limits of monolayer molybdenum disulfide ( MoS 2) nanoscale n-channel MOSFETs are studied using a semi-classical Monte Carlo method. Density functional theory calculations were performed to parametrize the electronic band structure of MoS 2 subject to tensile and shear strain. Tensile strain decreases the bandgap, increases the inter-valley band-edge energy separation between the light-mass K-valleys and heavier-mass Q-valleys, and decreases the K-valley effective mass in a way that depends on the direction and the amount of the applied strain. Biaxial tensile strain and uniaxial tensile strain along the x- or y-directions are found to have the largest effect. In bulk materials, low-field phonon-limited electron mobility is enhanced, peak and saturation drift velocities are increased, and high-field negative differential resistance becomes more pronounced. Both 200 and 15 nm gate length MoS 2 MOSFETs with end-contacts with ideal (unity) and more realistic (significantly sub-unity) contact interface transmissivity were simulated. These MoS 2 devices exhibited substantial sensitivity to strain with ideal contact transmissivity, and more so for the 15 nm quasi-ballistic device scale than 200 nm long-channel devices. However, the results showed much less strain sensitivity for devices with more realistic contact transmissivities, which may be good or bad depending on whether strain-insensitive or strain-sensitive performance is desired for a particular application and may be possible to modify with improved contact geometries. [ABSTRACT FROM AUTHOR]

Lateral compressions of (n, n) and (n, 0) single-walled carbon nanotube (SWCNT) bundles are simulated by density functional theory. Feasible transition pathways are verified by the body-centered tetragonal C4 (bct-C4) phase from the (4, 4) bundle and the carbon-centered orthorhombic C8 (Cco-C8) phase from (6, 6) and (8, 8) bundles. Three new phases, the sp3-hybridized phases Cco-C16 from the (4, 0) bundle and Cco-C32 from the (8, 0) bundle, the hexagonal phase Hex-C24 composed of sp2- and sp3-hybridized carbons from the (6, 0) bundle, under non-proportional triaxial loading are predicted. Measured hardness values for Cco-C16/C32 exceed 40 GPa, indicating super-hardness. Electronic band structures of Cco-C16/C32 exhibit a 3.64 eV bandgap, while Hex-C24 exhibits metallic carbon properties. Our results provide the potential phase transition pathways of SWCNT bundles under non-proportional compression. [ABSTRACT FROM AUTHOR]

A series of inorganic acid post-treated carbon nitride was synthesized to regulate the electronic structure, surface properties and then improve the photocatalytic activity. Carbon nitride displayed a thinner and smaller nanosheet structure after acid post-treatment, which could provide more exposed active sites and improve the charge carrier separation. The electronic band gap structure revealed that the phosphoric acid-treated sample (HP-CN) had a more positive valence band edge, endowing it with a higher oxidation ability. Furthermore, electron spin resonance (EPR) and transient photoinduced voltage (TPV) analyses demonstrated that the acid-treated carbon nitride had a higher electron–hole pair separation and transfer efficiency, thus boosting the photocatalytic performance. HP-CN possessed an optimal removal efficiency of 87.7% towards Reactive Brilliant Red X-3B (RBR X-3B), which was 1.62 times that of g-C3N4. Moreover, HP-CN showed an outstanding stability and satisfactory ability to remove RhB (rhodamine B) and TC (tetracycline), proving its potential application in environmental remediation. The photocatalytic mechanism measurement indicated that photogenerated h+, ˙O2− and ˙OH played critical roles during photocatalytic RBR X-3B decomposition. [ABSTRACT FROM AUTHOR]

The structural, electronic, optical and thermodynamic properties of the halide perovskite material Cs2AgBiCl6 have been investigated using the density functional theory (DFT) method. As a first step, the structural properties of Cs2AgBiCl6 were examined to determine an optimized lattice constant, which was then used to calculate other physical properties. Analysis of the electronic band structure reveals that Cs2AgBiCl6 exhibits semiconductor characteristics. Optical properties, in particular the refractive index, have been investigated in the 1–3 eV energy range, corresponding to the bandgap region of the material. In addition, thermodynamic properties were analyzed using the quasi-harmonic Debye model over a temperature range of 0–600 K and a pressure range of 0–8 GPa. It was found that the Debye temperature decreases with increasing temperature but increases with increasing pressure. [ABSTRACT FROM AUTHOR]

Bulk photovoltaic effect, i.e. shift current, is a nonlinear second‐order optical response that can rectify an alternating current (AC) electric field into a direct current (DC). Depending on the wavelength of the incident light, shift current finds applications in various fields, including solar energy conversion and radiation detection. Its promising application in energy conversion and information processing has inspired investigations to uncover the relationship between shift current and electronic structures of materials. Despite numerous efforts dedicated to designing principles for strong bulk photovoltaic effect materials, the only widely accepted crucial parameter is the joint density of states (JDOS). In this study, employing effective model analysis and first‐principles calculations, an enhancement effect of bulk photovoltaic effect is found to arise from band hybridization that is typically along with anti‐crossing‐like electronic band structures, similar to the Berry curvature effects in intrinsic anomalous Hall conductivity. While this mechanism does not offer a comprehensive understanding of the relationship between electronic structure and the magnitude of bulk photovoltaic effect, it represents practical progress in the design of materials with strong bulk photovoltaic effect. [ABSTRACT FROM AUTHOR]

Hydrogen is a promising candidate for green energy sources for future endeavors because of its abundance on Earth. Although its storage is a major challenge for the researchers of this era because of its unsafe and highly explosive nature. The structural, optoelectronic, thermoelectric, vibrational, thermodynamic properties and hydrogen storage capacity of XMgH3 (X = Sr , Ba) are carried out by using the full potential linearized augmented plane wave (FP-LAPW) method in the DFT framework. The theoretical study about these magnesium-based metal hydride perovskites, i.e., SrMgH3 and BaMgH3, declares them structurally stable compounds in space group Pm-3m. The optimization graph for SrMgH3 and BaMgH3 reflects the lowest ground state energy, i.e., −6759 Ry and −16683 Ry, respectively. Comparatively, BaMgH3 seems to be more stable. The electronic band structures and density of states declare them pure metallic due to zero band gap and overlapping of electronic states of the valence and the conduction bands. The electrical conductivity of BaMgH3 increases up to 4. 5 × 1 0 2 0 (Ω ⋅ m ⋅ s) − 1 and thermal conductivity 1. 2 5 × 1 0 1 6 (Ω ⋅ m ⋅ s) − 1 in the temperature range 100 K to 1000 K revealing the good metallic character of BaMgH3. The optical analysis portrays the absorption of compounds in the visible range along with valance shell electrons to the weak bond of hydrogen and dissociates hydrogen molecules at a certain intensity of light. BaMgH3 compound shows minimum scattering and maximum absorption of light in the visible region up to 3 eV. The reflectivity peaks in the visible region 3.0 eV show that 40% of light energy is absorbed due to the opaque nature of BaMgH3. Both these compounds are declared thermodynamically stable due to negative free energy such as −1.20 eV for SrMgH3 and −1.50 eV energy for BaMgH3 at 1000 K, respectively. Moreover, the three acoustic modes showing zero imaginary phonon frequencies at Γ symmetry points predict these compounds' structural and thermodynamical stability. The gravimetric hydrogen storage concentration of SrMgH3 and BaMgH3 is determined as 2.637% and 1.836%, respectively. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive investigation of the electronic, mechanical, and thermodynamic properties of Zintl phase hydrides XGaSiH (X = Sr, Ca, Ba) using Density Functional Theory (DFT) and the FP-LAPW method within the WIEN2k package. Our analysis covers the structural stability, electronic properties, and hydrogen interaction mechanisms in these compounds. The hydrides exhibit narrow band gaps, with values ranging from 0.1 to 0.5 eV using GGA and LDA functionals, and 0.6–1.0 eV with mBJ-GGA and mBJ-LDA. The hydrogen storage capacities are determined to be 0.34 wt %, 0.47 wt %, and 0.40 wt % for SrGaSiH, CaGaSiH, and BaGaSiH, respectively, highlighting their potential for energy storage applications. Thermodynamic properties, evaluated through the quasi-harmonic Debye model, provide insights into the Grüneisen parameter, heat capacity, and thermal expansion coefficient over a range of pressures (0–50 GPa) and temperatures (up to 1000 K). Elastic constants reveal that these compounds are mechanically stable, with a notable anisotropy in the {100} plane and varying degrees of compressibility among the different hydrides. Our study further highlights the slightly ordered hexagonal Ga and Si layers, which contribute to the enhanced hydrogen storage capabilities of these materials. The compounds demonstrate high structural stability, facilitating effective hydrogen retention and release at practical temperatures, making them promising candidates for hydrogen storage applications. Additionally, the analysis of electronic band structures and density of states suggests significant conductivity potential, with band gaps ranging from 0.1 to 1.0 eV, depending on the computational method used. The unique combination of structural, electronic, thermodynamic, and mechanical properties in XGaSiH compounds positions them as valuable materials for renewable energy applications. These findings lay the groundwork for future research focused on optimizing these materials through structural modifications or doping to enhance performance metrics such as hydrogen storage capacity and electrical conductivity. [Display omitted] • Hydrogen storage properties of Zintl Phase Hydrides XGaSiH (X = Sr, Ca, Ba) have been investigated using DFT. • The mechanical stability test performed on the computed elastic constants Cij demonstrate that investigated compounds are mechanically stable. • The hydrogen storage capacity is 0.34%, 0.47%, and 0.40% for SrGaSiH, CaGaSiH, and BaGaSiH, respectively. • These materials could be useful for storage of hydrogen application. [ABSTRACT FROM AUTHOR]

The transition metal dichalcogenides (TMDs) are considered as promising candidates for their striking performance in optoelectronic properties. We have designed the novel heterostructures XSe 2 /SnS using XSe 2 (X = Pt, Zr, Hf) TMDs. The stabilities of structural, mechanical, dynamical, and thermal are calculated by formation energies, elastic constants, phonon dispersions and AIMD simulations respectively. The hybrid functional (HSE06) is used to calculate the electronic band structures and optical absorption. The DFT scheme (BGC based) indicates that XSe 2 /SnS vdWHs are viable photocatalyst for overall water splitting over a broad spectrum of light. The absorption spectra exhibit that these photocatalysts have absorption started from visible to the UV region of light in the order of 105. XSe 2 /SnS heterostructures display high carrier mobilities of order 104. The Gibbs free energies exhibit that PtSe 2 /SnS heterostructure has spontaneous, whereas other heterostructures need some external energies for overall water splitting. Finally, the corrected STH efficiency of PtSe 2 /SnS, ZrSe 2 /SnS and HfSe 2 /SnS vdW heterostructures are 12.54%, 28.15%, 21.03% respectively. This study depicts that XSe 2 /SnS (X = Pt, Zr, Hf) heterostructures are feasible candidates for overall water splitting over a broad range of light spectrum. [Display omitted] • XSe 2 /SnS (X = Pt, Zr, Hf) vdWHs possess bandgaps in range of 1.3–2.2 eV. • Above mentioned vdWHs show absorption in visible and UV region in range 105 cm−1. • XSe 2 /SnS (X = Pt, Zr, Hf) vdWHs display excellent carrier mobilities (104 cm2 v−1 s−1). • Gibbs free energies are computed to further explore photocatalytic activities. [ABSTRACT FROM AUTHOR]

Using first‐principle calculations, a new compound semiconductor based on titanium (Ti) is predicted. It has been observed that Ti when alloyed with germanium (Ge) can crystallize in the zincblende symmetry, and exhibits semiconducting nature with a narrow bandgap. To test the robustness of the semiconducting nature, the structural properties and electronic band structure have been modeled using three different exchange–correlation functionals, namely, local density approximation, generalized gradient approximation, and Perdew‐Burke‐Ernzerhof for solids. With a nominal composition of 1:1, TiGe exhibits a direct bandgap of 0.58 eV at the “X” point of the Brillouin zone. From lattice dynamics, the structural stability of the compound has been established. The new semiconductor is characterized in detail for its electronic band structure, carrier effective mass, charge density distribution, and linear optical properties. Zb‐TiGe exhibits large effective mass for conduction band holes and tentatively becomes a prototype system to study heavy holes resulting in carrier condensation at the bottom of the conduction band. The linear optical properties of the TiGe are found to be suitable for photosensitive devices in the infrared region. In addition, TiGe may find application in deep‐UV and far‐UV regions because of the surface plasmon resonance at 6.4 eV. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study of the intrinsic strain response of 3D heterostructures arising from lattice mismatch. Combining materials with different lattice constants induces strain, leading to the bending of these heterostructures. We propose a model for nonlinear elastic heterostructures such as bimetallic beams or nanowires that takes into account local prestrain within each distinct material region. The resulting system of partial differential equations (PDEs) in Lagrangian coordinates incorporates a nonlinear strain and a linear stress‐strain relationship governed by Hooke's law. To validate our model, we apply it to bimetallic beams and hexagonal hetero‐nanowires and perform numerical simulations using finite element methods (FEM). Our simulations examine how these structures undergo bending under varying material compositions and cross‐sectional geometries. In order to assess the fidelity of the model and the accuracy of simulations, we compare the calculated curvature with analytically derived formulations. We derive these analytical expressions through an energy‐based approach as well as a kinetic framework, adeptly accounting for the lattice constant mismatch present at each compound material of the heterostructures. The outcomes of our study yield valuable insights into the behavior of strained bent heterostructures. This is particularly significant as the strain has the potential to influence the electronic band structure, piezoelectricity, and the dynamics of charge carriers. [ABSTRACT FROM AUTHOR]

Given the diminishing reserves of fossil fuels, the development of renewable alternative energy sources is of global importance. Photocatalytic hydrogen (H 2) evolution stands out as a promising and cost-effective method to harness sunlight for producing carbon-free H 2 fuel. Recently, two-dimensional (2D) covalent organic frameworks (COFs) have garnered considerable research interest in photocatalysis on account of their exceptional surface area and predictable assembly of diverse molecules with adjustable electronic properties. Herein, six 2D COFs are constructed by topologically assembling phosphorus-alkynyl functional moieties and benzene-based building units, including benzene (COF-1), triazine (COF-2), heptazine (COF-3), triphenyl-benzene (COF-4), triphenyl-triazine (COF-5), and triphenyl-heptazine (COF-6), employing first-principles calculations. Our computational results illustrate that the variation of benzene-based building units significantly regulates the electronic structures of COFs, all of which possess semiconductor properties with tunable bandgaps spanning from 1.56 to 2.56 eV. Of particular importance, COF-1, COF-2, COF-4, COF-5, and COF-6 can spontaneously stimulate the hydrogen evolution reaction (HER) under their own light-induced bias without the need for sacrificial agents and co-catalysts. Among them, COF-4 and COF-5 show the best HER activity without light-induced bias, with ΔG values of 0.02 and −0.01 eV, respectively, whose excellent photocatalytic performance can be ascribed to their appropriate electronic band structures, pronounced optical absorption, and low work functions. This finding offers profound insights for exploring other highly efficient HER photocatalysts. Synopsis: Phosphorus-alkynyl COFs (COF-1, 2, 4, 5, 6), featuring varied benzene-based units, can spontaneously initiate HER under light-induced bias, eliminating the reliance on sacrificial agents or co-catalysts. [Display omitted] • The 2D COFs are constructed by phosphorus-alkynyl moieties and benzene-based units. • Varying the benzene-based units notably modulates the electronic structures of COFs. • COF-1, 2, 4, 5, 6 can spontaneously initiate HER under their own light-induced bias. • COF-4, 5 show superior HER activity in the absence of light-induced bias. [ABSTRACT FROM AUTHOR]

Bismuth oxyhalide (BiOX) represents a class of layered materials distinguished by unique physicochemical and optical characteristics. This study delivers an extensive investigation into the properties of BiOX crystals, employing first-principles calculations to analyze the electronic band structure, projected density of states (PDOS), Raman and infrared (IR) spectra, dielectric functions, alongside phonon and thermodynamic properties. The computed electronic band gaps BiOI, BiOBr, BiOCl, and BiOF crystals were determined to be 2.19 eV, 3.05 eV, 3.29 eV, and 3.43 eV, respectively. Furthermore, an analysis of the PDOS for each BiOX type indicates that the valence band maximum (VBM) primarily comprises dominant O 2p and halide X np states, while the conduction band minimum (CBM) predominantly features Bi 6p states. In addition, significant absorption edges for BiOI, BiOBr, BiOCl, and BiOF crystals, oriented along the [100] axis, were observed at wavelengths of 540 nm, 449 nm, 367 nm, and 320 nm, respectively. The Raman spectral analysis revealed a noticeable shift correlating with the increasing number of halogen atoms, with intensity enhancements observed at elevated temperatures. Phonon dispersion studies corroborated the geometric stability of the optimized structures of BiOX crystals. Thermodynamic evaluations suggested that BiOX materials exhibit qualities characteristic of hard materials at higher temperatures while displaying softer material attributes at lower temperatures. In summary, this research substantially enriches the current understanding of bismuth oxyhalides by detailing their structural, electronic, optical, phonon, and thermodynamic properties. The findings presented in this study provide a foundational basis for future advancements in photocatalytic applications and material development. [ABSTRACT FROM AUTHOR]

A density functional theory based calculations are performed to investigate structural, hydrogen storage, mechanical, electronic and thermodynamical properties of lead-free hydride perovskites XGeH 3 (X=Cs, Fr). The optimized lattice constant and hence volume against the minimum energy is obtained and found to be 4.176 Å and 4.184 Å for CsGeH 3 and FrGeH 3 respectively. The gravimetric and volumetric hydrogen storage capacity of 1.43% and 1.00%, 72.81 (g.H 2 / L) and 73.21 (g.H 2 / L) for CsGeH 3 and FrGeH 3 respectively. The density of states and electronic band structure predicted the metallic nature of both hydrides which was affirmed by the Fermi Surfaces. The calculation of Poisson's, Pugh's ratio and Cauchy's pressure suggested their brittle nature. The Debye temperature decreases with the increase of temperature while volume and entropy increase by increasing applied temperature. The present study shows the potential of lead-free hydride perovskites in hydrogen storage applications due to rather suitable gravimetric hydrogen capacity and high stability. • Hydrogen storage capacity of XGeH 3 (X = Cs, Fr) are investigated. • Gravimetric and volumetric hydrogen storage capacity of hydrides are calculated. • XGeH 3 (X = Cs, Fr) hydrides exhibit mechanical and thermodynamical stability. • Both compounds show metallic nature with 0 eV band gap. • Mechanical properties predict brittle nature of XGeH 3 (X = Cs, Fr). [ABSTRACT FROM AUTHOR]

Hydrogen production using the photocatalysis approach is considered a feasible option for achieving a sustainable future. In this work, we conducted a comprehensive investigation into the hydrogen evolution reaction (HER) performance of the XSeI monolayers (where X represents either Sb or Bi) using density functional theory (DFT) calculations. We simulate and optimize the structural properties of the 2D XSeI Janus monolayers in its H-phase, ensuring stability through cohesive energy and phonon analysis. For SbSeI, the computed cohesive energy is − 2.06 eV, and for BiSeI, it is − 2.14 eV. Subsequently, we explored the electronic characteristics, including density of states (DOS) and electronic band structure. The various machine learning (ML) models were integrated into our approach for predicting the band gap of Janus monolayers. Employing DFT calculations, we systematically examined the HER activity of the XSeI monolayers, assessing its responsiveness to doping, with a particular focus on Pt and Pd atoms. The calculated Gibbs free energy for Pd–SbSeI and Pd–BiSeI is 0.33 eV while for Pt–SbSeI and Pt–BiSeI, it is − 0.23 eV and − 0.21 eV, respectively. The study not only contributes insights into the fundamental electronic and catalytic properties of the XSeI monolayers but also investigate the potential for enhancing its hydrogen evolution performance through strategic doping strategies. The study demonstrates the stability and electronic properties of XSeI Janus monolayers using DFT calculations. Employing the random forest model, we predict the band gap at the HSE level for both Janus monolayers. We explored HER activity, finding promising results with Pt and Pd atom doping, especially for Pt-doped XSeI. [Display omitted] • We focused on pristine and doped XSeI (X = Sb, Bi) Janus monolayers in their H-phase. • ML models have the capability to predict the band gap of any Janus monolayer. • The examination of hydrogen evolution reaction (HER) activity within both pristine and doped Janus monolayers XSeI. • To explores the possibilities of improving their hydrogen evolution performance via strategic doping. [ABSTRACT FROM AUTHOR]

Context: Ammonium Tutton salts have been widely studied in recent years due to their thermostructural properties, which make them promising compounds for application in thermochemical energy storage devices. In this work, a detailed experimental study of the Tutton salt with the formula (NH4)2Zn(SO4)2(H2O)6 is carried out. Its structural, vibrational, and thermal properties are analyzed and discussed. Powder X-ray diffraction (PXRD) studies confirm that the compound crystallizes in a structure of a Tutton salt, with monoclinic symmetry and P21/a space group. The Hirshfeld surface analysis results indicate that the main contacts stabilizing the material crystal lattice are H···O/O···H, H···H, and O···O. In addition, a typical behavior of an insulating material is confirmed based on the electronic bandgap calculated from the band structure and experimental absorption coefficient. The Raman and infrared spectra calculated using DFT are in a good agreement with the respective experimental spectroscopic results. Thermal analysis in the range from 300 to 773 K reveals one exothermic and several endothermic events that are investigated using PXRD measurements as a function of temperature. With increasing temperature, two new structural phases are identified, one of which is resolved using the Le Bail method. Our findings suggest that the salt (NH4)2Zn(SO4)2(H2O)6 is a promising thermochemical material suitable for the development of heat storage systems, due to its low dehydration temperature (≈ 330 K), high enthalpy of dehydration (122.43 kJ/mol of H2O), and hydration after 24 h. Methods: Computational studies using Hirshfeld surfaces and void analysis are conducted to identify and quantify the intermolecular contacts occurring in the crystal structure. Furthermore, geometry optimization calculations are performed based on density functional theory (DFT) using the PBE functional and norm-conserving pseudopotentials implemented in the Cambridge Serial Total Energy Package (CASTEP). The primitive unit cell optimization was conducted using the Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm. The electronic properties of band structure and density of states, and vibrational modes of the optimized crystal lattice are calculated and analyzed. [ABSTRACT FROM AUTHOR]

Using first-principle calculations, metal–semiconductor (MS) contact of YX2 (Y=Ta, Nb; X=S, Se, Te) and MX2 (M=Mo, W; X=S, Se, Te) monolayers in the shape of YX2–MX2 van der Waals Heterostructures (vdWHs) are fabricated. Electronic structure, type of the Schottky contact and height of Schottky barrier at the interface of YX2–MX2 vdWHs are investigated. Stabilities of these systems confirmed via AIMD simulation and binding energies calculations. Electronic band structures confirm the metallic nature of YX2–MX2 MS vdWHs. Specific cases of the YX2–MX2 MS vdWHs have quite small (high) effective mass (carrier mobility), hence show potential for nanoelectronic devices. Workfunction and transfer of charges among the layers of YX2–MX2 MS vdWHs are also evaluated via electrostatic potential. A Schottky contact is established, while fabricating YX2–MX2 MS vdWHs. The calculated Schottky barrier height (SBH) show that YX2–MX2 (Y=Ta, Nb, M=Mo, W; X=S, Se, Te) vdWHs, initiate p-type of Schottky contact, while specifically, TaX2–MTe2 (M=Mo, W) and NbTe2–MoS2 and NbTe2–WS2 MS vdWHs initiate n-type of Schottky contact due to their higher Bn values. The SBH values are miniature compared to traditional MS contacts, but they are consistent with previous 2D based MS contacts. These observations indicates the potential of YX2–MX2 MS vdWHs for high-performance device application. [ABSTRACT FROM AUTHOR]

Based on density functional theory (DFT), a two-dimensional(2D) metal-organic framework (MOF) based on Co and Cu atoms were presented. Based on the phonon dispersion calculations, no imaginary mode is found in the phonon branches, which verifies that the crystal structures of MOF could be stable. Based on the calculation of electronic band structure, it is found that the Cu-based MOF is a metallic system by applying external electric field. While the Co-based MOF undergoes a transition from metal to semiconductor under external electric field. When the external electric field intensity reaches up to 0. 5 eV/Å, the band gap of Co-based MOF is around 0. 1 eV, while this does not happen in the Cu-based MOF. Furthermore, the N2 adsorption and the nitrogen reduction reaction (NRR) were investigated for the Co-based MOF, which shows that the NRR for the Co-based MOF exhibits good performance, and the electric field could enhance this effect of NRR. The free energy of NRR under external electric field of 0. 5 eV/Å is 0. 51 eV lower than that without electric field. Therefore, our study would prospectively guide the experimental researchers on the design of NRR. [ABSTRACT FROM AUTHOR]

Heterostructures are highly promising photocatalyst candidates for water splitting due to their advanced properties than those of pristine components. The ZnO/Sc2CF2 heterostructure was designed in this work, and its electronic structure was investigated to explore its potential for water splitting. The assessments of binding energy, phonon spectrum, ab initio molecular dynamics, and elastic constants provide strong evidence for its stability. The ZnO/Sc2CF2 heterostructure has an indirect band gap of 1.93 eV with a type-Ⅰ band alignment. The electronic structure can be modified with strain, leading to a transition in band alignment from type-Ⅰ to type-Ⅱ. The heterostructure is suitable for water splitting since its VBM and CBM stride over the redox potential. The energy barrier and built-in electric field, resulting from the charge transfer, facilitate the spatial separation of photogenerated carriers, enhancing their utilization efficiency for redox processes. The photogenerated carriers in the heterostructures with lattice compression greater than 6% follow the direct-Z transfer mechanism. The ZnO/Sc2CF2 heterostructure is confirmed with high photocatalytic activity by a Gibbs free energy change of HER, which is 0.89 eV and decreases to −0.52 eV under an 8% compressive strain. The heterostructure exhibits a remarkable enhancement in both absorption range and intensity, which can be further improved with strains. All these findings suggest that the ZnO/Sc2CF2 heterostructure is an appreciated catalyst for efficient photocatalytic water splitting. [ABSTRACT FROM AUTHOR]

The method of linearized full-potential augmented plane waves based on density functional theory (DFT) is employed to investigate the structural, elastic, magnetic electronic, and thermoelectric properties of the cerium-based half-Heusler alloy FeCeSi. The exchange correlation functional is treated with the generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE) and the Tran-Blaha-modified Beck-Johnson (TB-mBJ) as implemented in the Wien2k package. According to our results, we have discovered that the material studied is mechanically stable, which means that this compound can be synthesized experimentally. Furthermore, FeCeSi exhibits a half-metallic behavior obeying the Slater-Pauling rule with an integer magnetic moment of 2 μB. The electronic band structures and density of states confirm the half-metallic character with an indirect band gap equals to 0.51 eV and 0.59 eV for GGA-PBE and TB-mBJ approximation, respectively. For the study of the thermoelectric parameters, such as Seebeck coefficient (S), electrical conductivity (σ), thermal conductivity (κ), and figure of merit (ZT), the Boltzmann transport equations within the framework of DFT have been used. Significant values for the figure of merit and Seebeck coefficient indicate promising candidate for useful thermoelectric applications for FeCeSi alloy. So far, no experimental or theoretical investigations have been carried out on the half-Heusler alloy FeCeSi. Accordingly, our theoretical results concerning structural, elastic, electronic, magnetic, and thermoelectric properties will probably be confirmed by experimental investigations. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) are important new energy storage devices. Due to the abundance of sodium and the similar operating principles of SIBs to lithium-ion batteries (LIBs), SIBs are considered as an important complementary technology to LIBs that will dominate the next generation of energy storage. However, large-scale application of SIBs is hindered by severe capacity decay and low rate capability. The actual capacity of batteries is closely related to the specific capacity of anode materials. Therefore, the development of high-capacity anode materials has become a key area of research for SIBs. Transition metal compounds can improve these problems due to their unique electronic band structure, good chemical adsorption ability, and excellent catalytic ability. Cobalt-based phosphide anode materials have the characteristics of high theoretical capacity, abundant reserves, and low prices, making them become promising anode materials for SIBs. Furthermore, adjusting the size and structure and combining with carbon-based or non-carbon-based materials can effectively alleviate the defects of cobalt-based phosphide electrodes, thereby improving the specific capacity, cyclic stability, and rate capability of SIBs. This review summarizes the recent research progress on cobalt-based phosphide anode materials for SIBs, including the current research status and future development prospects. [ABSTRACT FROM AUTHOR]

In this work, nitrogen‐defective g‐C3N4 with different nitrogen defect densities is synthesized for ciprofloxacin photocatalytic degradation. Compared with pristine g‐C3N4, g‐C3N4 etched with NaBH4 for 1 h exhibits an approximately ten‐fold increase in the rate constant of ciprofloxacin (CIP) degradation. The combined experimental analysis and theoretical calculations reveal that nitrogen defects can be incorporated into g‐C3N4 in all nitrogen sites and that C─N═C is the most susceptible site. By incorporating nitrogen defects to induce defect states between the conduction band (CB) and valence band (VB), the electronic and band structures are tuned. The induced defect states can be downshifted to approach the valance band, reaching increased nitrogen defect density within optimum ranges to accommodate excited electrons to narrow the bandgap, extend the light absorption capability, and enhance the charge carrier separation and transfer efficiency. The g‐C3N4 etched by NaBH4 for 2 h with over‐introduced nitrogen defects exhibits a declined performance due to a deteriorated structure, and the over‐downshifted defect states turn out to be a new recombination center for charge carriers. [ABSTRACT FROM AUTHOR]

Two new salts of l-proline containing triiodide anions were obtained and investigated: (l-ProH···l-Pro)(I3) (I) and [(l-ProH)3(l-Pro)](I3)3 (II). Both compounds crystallize in the polar monoclinic space group P21. Crystal structure determinations showed that (I) contains a dimeric cation formed by an O-H···O hydrogen bond with an O···O distance of 2.458(4) Å, while (II) features a peculiar tetrameric cation [l-ProH···(l-Pro-H-l-Pro)···l-ProH], where (l-Pro-H-l-Pro) is a pseudocentrosymmetric dimer with a very short hydrogen bond with an O···O distance of 2.427 Å. Infrared spectra of both crystals were registered and interpreted based on their structures. Electronic band structures were determined by quantum chemical calculations. The CASTEP code was used to calculate the band structures, total and partial density of states (TDOS, PDOS). Bandgaps were also measured by the diffuse reflectance method. [ABSTRACT FROM AUTHOR]

The growing interest in a material composed of Cu single atoms and/or their sub-nanometric clusters deposited on titania prompted us to perform systematic theoretical studies on the system comprising the anatase phase of titania, modelled by a (TiO2)34 cluster with copper particles of 1–7 atoms on top of it. The ground-state geometric structures were proposed and compared with the available literature data derived from EXAFS experiments done for Cu-TiO2 materials. Copper atoms prefer to aggregate and form larger clusters on TiO2, as seen from the computed nucleation energies. The models were characterised by the following electronic properties: electronic band structure, natural population charges, and frontier orbitals (HOMO, LUMO, and SOMO). The copper phase becomes oxidised once it is deposited on titania. The charge distribution in the resulting structures indicates that the atoms that are the closest to the Cu-TiO2 interface would become the active sites for catalytic processes; copper atoms would act as electrophilic, while oxygen atoms would act as nucleophilic. The calculated binding energies between the two phases show that the formation of the composite system is favourable from the thermodynamic point of view, and the interaction between the small copper clusters and the titania surface is mostly of electrostatic nature. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) have rapidly become a hot topic in photocatalytic research due to their unique physical and chemical properties, high activity, and high selectivity. Among many semiconductor carriers, the special structure of carbon nitride (C3N4) perfectly meets the substrate requirements for stabilizing SACs; they can also compensate for the photocatalytic defects of C3N4 materials by modifying energy bands and electronic structures. Therefore, developing advanced C3N4‐based SACs is of great significance. In this review, we focus on elucidating efficient preparation strategies and the burgeoning photocatalytic applications of C3N4‐based SACs. We also outline prospective strategies for enhancing the performance of SACs and C3N4‐based SACs in the future. A comprehensive array of methodologies is presented for identifying and characterizing C3N4‐based SACs. This includes an exploration of potential atomic catalytic mechanisms through the simulation and regulation of atomic catalytic behaviors and the synergistic effects of single or multiple sites. Subsequently, a forward‐looking perspective is adopted to contemplate the future prospects and challenges associated with C3N4‐based SACs. This encompasses considerations, such as atomic loading, regulatory design, and the integration of machine learning techniques. It is anticipated that this review will stimulate novel insights into the synthesis of high‐load and durable SACs, thereby providing theoretical groundwork for scalable and controllable applications in the field. [ABSTRACT FROM AUTHOR]

The full electronic band structure of the Al doped ZnO films have been characterized using the TNL-FB™ (full band) simulator from Tech Next Lab. The bandgaps obtained through simulation studies were matched against the experimental bandgap and compared with the results obtained through DFT-based techniques. It was observed that the bandgap value at the Γ-valley increases with the increase in the Al dopant content from 0 at% to 5 at%. The extracted cut-off absorption wavelength was shifted to a shorter wavelength by increasing the Al content, and justifies the Burstein–Moss shift effect. In the present study, the dependency of the topology of the shape of the nanostructure films was taken care of through the lattice disorder effect. The influence of thickness and plane orientation on the various features has been carefully studied. The full electronic band structures of ZnO and AZO samples predicted that the bandgap value is strongly dependent on the internal structure parameter, u. The value of u is significantly affected by lattice disorder generated due to bond angle or length alteration dependent on the topology of the structure and impurity addition. Good agreement was found between the reported and experimental optical bandgap results. [ABSTRACT FROM AUTHOR]

Using density functional theory (DFT) combined with semi‐classical Boltzmann transport theory, the electronic and thermoelectric properties of binary skutterudite CoAs3 material are investigated up to 30 GPa. Elastic properties calculations confirm the mechanical stability at 0 GPa and under varying hydrostatic pressures, with ductility influenced by pressure. To ensure dynamical stability, the phonon dispersion frequencies are computed at both 0 and 30 GPa. Electronic band structure calculations, using the GGA + TB‐mBJ approximation, indicate that CoAs3 initially exhibits a direct band gap at its equilibrium lattice constant, which shifts to become indirect under increasing pressure. To assess the impact of pressure on the thermoelectric properties of CoAs3, the Seebeck coefficient, thermal conductivities, and figure of merit (ZT) are calculated at pressures of 5, 10, 20, and 30 GPa for various temperatures (300, 600, 900, and 1200 K). These computations provide valuable insights into how varying pressures influence the material's thermoelectric performance. The optimal thermoelectric properties in CoAs3 material are achieved at 5 GPa and 1200 K for n‐doping (20 GPa and 600 K for p‐doping), with an ideal doping concentration of 1.5 × 1021 cm−3 (5.5 × 1018 cm−3). Under these conditions, the material reaches a high figure of merit (ZT) value of 0.52 for n‐doping and 0.49 for p‐doping. These findings underscore CoAs3 as a promising candidate for applications in energy harvesting and optoelectronic systems, showcasing its robust thermoelectric performance under precise pressure and temperature conditions. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, we investigate a twisted bilayer graphene on an h‐BN substrate. The graphene is grown using high‐quality chemical vapor deposition (CVD) and subsequently transferred onto the h‐BN substrate. Our focus is on the stacking transition within the bilayer system, based on fluctuations in both intralayer and interlayer processes. Our findings reveal that post‐annealing induces alterations in the electron–phonon interaction, corresponding to the spatially dependent stacking changes in the bilayer structure. This makes it possible to modify the electronic band structure of graphene and subsequently all its optoelectronic properties. [ABSTRACT FROM AUTHOR]

A novel two-dimensional (2D) half-Heusler ZrNiSn nanosheet for thermoelectric applications was designed from bulk half-Heusler ZrNiSn through first-principles calculation. Investigation of bulk half-Heusler and 2D nanosheet ZrNiSn was performed with the Quantum Espresso code based on a density functional theory plane wave basis set. Electronic band structure and density of states calculations were used to study the confinement effects. On moving from bulk to 2D a change of structure is observed from face-centered cubic to trigonal due to confinement effects. The semiconducting nature of bulk ZrNiSn is undisturbed while moving to a 2D nanosheet; however, the band gap is widened from 0.46 to 1.3 eV due to the restricted motion of electrons in one direction. Compared with bulk ZrNiSn, 2D nanosheets were found to have a higher Seebeck coefficient a lower thermal conductivity and higher figure of merit, which makes 2D ZrNiSn nanosheets suitable for thermoelectric applications. Atomically thin 2D structures with a flat surface have the potential to form van der Waals heterojunctions, paving the way for device fabrication at the nanoscale level. [ABSTRACT FROM AUTHOR]

Searching for novel carbon allotropes holds paramount importance for both condensed matter physics and materials science. Using the combination of structure searching and first-principles calculations, we identified a carbon allotrope with orthorhombic symmetry (Pmm2, 10 atoms/cell), termed O–C10. The energetic, dynamical, mechanical, and thermal stabilities of O–C10 have been validated through energy analysis, phonon dispersion curves calculations, evaluation of elastic constants, and ab initio molecular dynamics simulations. In addition, the bulk modulus and Vickers hardness of O–C10 are calculated to be 410 and 79 GPa, respectively, which are higher than those of c-BN. The predicted B/G ratio for O–C10 is 0.90 (< 1.750), indicating that O–C10 possesses brittle nature. The simulated X-ray diffraction (XRD) patterns are also provided to facilitate potential future experimental endeavors. The calculated electronic band structures by the Heyd–Scuseria–Ernzerhof (HSE06) hybrid functional unveiled that O–C10 is an insulator with a large indirect band gap of 5.29 eV. These results regarding this novel carbon allotrope may broaden the scope of the carbon family, advance the practical uses of carbon-based materials, and stimulate the development of distinctive crystalline carbon structures. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDs) possess a wide range of functionalities due to their highly tunable chemical, physical, and electronic properties. In this study, we systematically explore the structural, electronic, and phonon characteristics of six TMD systems using density functional theory (DFT) simulations. Our analysis covers both the semiconducting (2H) and metallic (1T) phases of these TMD systems. Specifically, we investigate group-V TMDs (AB2, where A = Nb, Ta, and B = S, Se, Te), examining their structure–property relationships and electronic behaviors to validate the accuracy of various exchange–correlation (XC) functionals, including van der Waals density functionals (vdW-DFs). Our calculations account for both spin–orbit coupling (SOC) and non-SOC (NSOC) scenarios. The results reveal significant impacts on vdW gaps, lattice parameters, and electronic band structures in both the 2H and 1T phases, highlighting their potential for conventional applications. [ABSTRACT FROM AUTHOR]

Strain engineering is a powerful technique for controlling the performance of semiconductor ceramic systems. In this article, the effect of strain engineering, specifically biaxial compressive and tensile strains, on the bonding characteristics, structure, electronic, and optical properties of nonplanar phosphorene‐like (NPP) ZnS ceramic nanolayers was investigated using density functional theory. It was observed that this ceramic exhibits greater stability under significant tensile strains. The structural stability of NPP‐ZnS ceramic, both with and without biaxial strain, was confirmed by its negative formation energy. Biaxial strain strongly influences the electronic band structure of NPP‐ZnS ceramic nanolayers, leading to a transformation from a direct band gap to an indirect gap under tensile strain. Additionally, the bandgap decreases under compressive strain, while it slightly increases under tensile strain. Various optical properties, including refractive index, extinction coefficient, absorption, reflectivity, optical conductivity, and optical susceptibility, were calculated. Biaxial compressive and tensile strains alter the optical properties, shifting them to higher or lower frequencies. NPP‐ZnS ceramic nanolayers exhibit high optical absorption in the UV range, which can be further enhanced by biaxial strain. Furthermore, under increasing compressive strain, the absorption edge moves toward higher energies. This improvement in optical absorption expands the potential applications of NPP‐ZnS ceramic nanolayers in optoelectronic devices. [ABSTRACT FROM AUTHOR]

The structural, electronic, elastic, optical, phonon, and thermo-physical properties of the tetragonal X 2 CoH 5 (X = Ca, Sr) hydrogen storage compounds were thoroughly examined using first-principles calculations. The negative formation enthalpies (−76.03 kJ/mol.H 2 for Ca 2 CoH 5 and −72.55 kJ/mol.H 2 for Sr 2 CoH 5) highlight the structural stability of these materials. Phonon calculations revealed no imaginary frequency modes, confirming the dynamic stability of X 2 CoH 5. The mechanical stability of Ca 2 CoH 5 and Sr 2 CoH 5 was evidenced by the compliance of the elastic constants with Born stability criteria. The electronic band structure indicates that Ca 2 CoH 5 and Sr 2 CoH 5 are direct bandgap semiconductors with narrow bandgaps of ∼ 0.27 and 0.34 eV, respectively. The appraisal of Poisson's ratio (ν = 0.22 for X = Ca and 0.23 for Sr) and Pugh's ratio (B/G = 1.47 for X = Ca and 1.56 for Sr) suggests that both metal hydrides exhibit brittle mechanical behavior. Moreover, 3D plots of Young's modulus (E), shear modulus (G), linear compressibility (β), and Poisson's ratio (ν) uncover anisotropy within X 2 CoH 5. The hydrogen storage capabilities were scrutinized, and the present materials feature excellent volumetric hydrogen density (95.65 gH 2 l −1 for Ca 2 CoH 5 and 80.24 gH 2 l −1 for Sr 2 CoH 5), moderate gravimetric hydrogen density (3.38 wt% for Ca 2 CoH 5 and 2.06 wt% for Sr 2 CoH 5) and high hydrogen desorption temperature (584 K for Ca 2 CoH 5 and 558 K for Sr 2 CoH 5). Notably, the obtained volumetric hydrogen densities are in line with the volumetric capacity criteria set by the U.S. Department of Energy (DOE) for 2025. Finally, the optical and thermo-physical characteristics of X 2 CoH 5 compounds were also investigated in this work. • New X 2 CoH 5 (X = Ca and Sr) hydrides were studied using first-principles calculations. • The X 2 CoH 5 compounds are thermodynamically, dynamically and mechanically stable. • X 2 CoH 5 hydrides display semiconductor behavior, brittleness, and elastic anisotropy. • The Gravimetric capacity was calculated as 3.38 wt% for Ca 2 CoH 5 2.06 wt% for Sr 2 CoH 5. [ABSTRACT FROM AUTHOR]

Ternary metal oxide materials are being explored as potential electrode materials for dye-sensitized solar cells due to their adjustable electronic band structures through elemental composition modifications. Perovskite materials based on zinc and titanium have been utilised in DSSC and show moderate performance. Considerable research has been dedicated to this field to improve their performances. The focus was primarily on the synthetic variabilities due to their impact on performance under varying synthetic conditions. According to this perspective, no comparative studies have found superior methodologies for utilising zinc titanate as a potential photoanode in DSSC. We synthesised a zinc titanate material using thermal, sol-gel, and plasma irradiation techniques. The materials' structural variability was analysed using PXRD and FT-IR techniques. A mixed-phase composition of spinel cubic and hexagonal has been identified. The SEM images provide insights into the particle distribution and morphology of the zinc titanate materials. Investigating absorption properties, band gap energy levels and aggregation behaviours provided initial insights into the potential use of the three zinc titanate materials. The DSSC devices were fabricated using zinc titanate materials with varying properties, and the results are detailed in this discussion. Based on the findings, the plasma and thermal irradiation techniques yielded more favourable zinc titanate materials for dye-sensitized solar cell use. The efficiency reached 0.04 % when operating with polymeric gel electrolytes. [Display omitted] [ABSTRACT FROM AUTHOR]

Nitridophosphates are in the focus of current research interest due to their structural versatility and properties, such as ion conductivity, ultra‐incompressibility and luminescent properties when doped with suitable activator ions. Multinary representatives often require thorough investigation due to the competition with the thermodynamically more stable binary and ternary compounds. Another point of concern is the synthetic control of structural details, which is usually limited by conventional bottom‐up syntheses. In this study, we report on the synthesis and characterization of the quaternary nitridophosphate CaLi2PN3. Various synthesis protocols were used for the preparation of CaLi2PN3, including the novel nitridophosphate double salt approach. The crystal structure was solved and refined from single‐crystal X‐ray diffraction data and confirmed by Rietveld refinement, solid‐state NMR spectroscopy, EDX measurements and low‐cost crystallographic calculations. The experimental results were corroborated by DFT calculations, which revealed the electronic band structure. Formation energy calculations allowed conclusions to be drawn about the stability in comparison to the initial ternary nitridophosphates. The synthesis of CaLi2PN3 exemplifies the enormous potential of medium‐pressure syntheses in the field of nitridophosphate research. Furthermore, the presented new synthesis route allows a certain degree of structural control, which is a promising addition to previous synthesis strategies in nitridophosphate chemistry. [ABSTRACT FROM AUTHOR]

Theoretical and experimental results exploring a half‐Heusler compound TmPdSb with unusual band order and metallic surface states are presented. Typically, the half‐Heusler systems exhibit topological features in a semimetallic state, and trivial ones in an insulating state. Topological properties of the most of half‐Heusler systems are related to the band inversion around the Fermi level, similar to this observed in CdTe/HgTe systems. In the case of TmPdSb, the gapped electronic band structure with "band inversion" in the conductance band is observed, while the slab‐like system realized metallic surface states. The bulk insulating nature of the compound is corroborated by means of electrical transport measurements. The experimental data reveal several features due to the presence of metallic surface states, such as linear magnetoresistance and weak‐antilocalization effect, characterized by enhanced coherence length and a very large number of surface conductive channels. The findings reveal new features of the rare‐earth bearing half‐Heusler. [ABSTRACT FROM AUTHOR]

Transition metal oxides (TMOs) have emerged as promising candidates for spintronic applications due to their unique electronic properties and novel quantum states. The intricate interplay between strong spin-orbit coupling and electronic correlations in TMOs gives rise to distinct spin and orbital textures, leading to enhanced spin-momentum locking and efficient charge-spin interconversion. Remarkably, recent researches have unveiled the significant and highly tunable nature of charge-spin interconversion efficiency in TMOs, which can be manipulated through strategies such as electric field gating, epitaxial strain, and heterostructure engineering. This review provides a comprehensive overview of the recent advances in understanding the electronic band structures of TMOs and their correlation with charge-spin interconversion mechanisms. We summarize the tunability of these properties through various experimental approaches and discuss the potential implications for spintronic device applications. The insights gained from this review can guide future research efforts towards the development of high-performance, energyefficient spintronic devices based on TMOs. [ABSTRACT FROM AUTHOR]

Zero-dimensional organic–inorganic hybrid metal halides are unique semiconductors with fruitful physical properties. Usually, only the inorganic polyhedrons dominate the band edge electronic and photophysical properties of such hybrid semiconductors, whereas the organic components mainly act as structure-stabilizing units. Herein, we study the electronic structures and photodynamics of isoelectronically Br-substituted (I) zero-dimensional organic–inorganic copper halide semiconductors (C9H14N)3Cu3(BrxI1−x)6. They are composed of both inorganic [Cu3(BrxI1−x)6]3− units and organic C9H14N+ skeletons. It is surprising to find that unlike usual organic–inorganic metal halides, although the heavily isoelectronic substitution of halogen atoms in the (C9H14N)3Cu3I6 crystal leads to significant shrinkage of the lattice, it does not remarkably alter the bandgap and luminescence peak owing to the site-projected density of states as revealed by the density functional theory calculation. The inorganic units dominate the valence band edge quantum states, whereas the organic skeletons dominate the conduction-band edge states. However, the isoelectronic substitution significantly lowers the symmetry of the crystal, and as a result, the quantum transition probability at the band edge increases first and decreases then with increasing concentration of substituting bromine atoms. The (C9H14N)3Cu3(BrxI1−x)6 crystals exhibit dual-band luminescence with large Stokes shift and near-unity quantum yield. It arises from the excitons trapped by two kinds of centers. The critical participation of the organic skeletons in the electronic structures and band edge photodynamics refresh our knowledge of their roles in the hybrid semiconductors. [ABSTRACT FROM AUTHOR]

The structural, mechanical, optical, thermo-physical, and electronic properties of the monoclinic XGaH 5 (X = Ba, Ca, and Mg) used as hydrogen storage material were investigated in detail using the ab initio technique. Gravimetric hydrogen densities (5.1 wt % for the MgGaH 5 , 4.4 wt % for the CaGaH 5 , and 2.38 wt % for the BaGaH 5), hydrogen desorption temperatures (29.05 K for the MgGaH 5 , 175.56 K for the CaGaH 5 , and 218.36 K for the BaGaH 5) and enthalpies of formation (−0.039 eV/atom for the MgGaH 5 , -0.237 eV/atom for the CaGaH 5 and -0.296 eV/atom for the BaGaH 5) of these compounds were also calculated. As a result of electronic band structure calculations, band gap values for BaGaH 5 , CaGaH 5 , and MgGaH 5 were obtained as 3.08 eV, 4.05 eV, and 3.61 eV, respectively. It is clear from the high band gap values that all three materials have insulator character. The second-order independent elastic constant values, which provide information about the hardness and mechanical stability of the materials, were calculated. The elastic constant values showed that XGaH 5 is mechanically stable. Hardness parameters such as bulk modulus, shear modulus, B/G ratio (1.19 for the MgGaH 5 , 1.11 for the CaGaH 5 , and 1.68 for the BaGaH 5), Young's modulus, and Poisson's ratio were also calculated using elastic constant values. According to the B/G ratio, all three structures were found to be brittle materials. From Poisson's ratio (0.17 for the MgGaH 5 , 0.15 for the CaGaH 5 , and 0.25 for the BaGaH 5), the atoms in XGaH 5 compounds are connected by covalent bonds. Besides, the formation enthalpies of the materials were calculated, and it was concluded that all three compounds could be synthesized in the laboratory. In addition, some optical properties of XGaH 5 such as dielectric function, conductivity, reflectivity, and absorption were also calculated. Finally, thermo-physical properties were calculated for XGaH 5 compounds. • First-principles calculations to investigate XGaH 5 materials for hydrogen storage applications. • XGaH 5 (X = Ba, Ca, and Mg) compounds are found to be mechanically stable and brittle. • The desorption temperature values for MgGaH 5 , CaGaH 5 , and BaGaH 5 are 29.05 K, 175.56 K, and 218.36 K, respectively • MgGaH 5 5.1 wt % has a higher gravimetric hydrogen densities. [ABSTRACT FROM AUTHOR]

The structural stability, electronic structure, and optical properties of the novel YxGd1-xN ternary alloys were studied using the FP-LAPW method with the generalized gradient approximation + Hubbard U (GGA + U). Our results reveal that YxGd1-xN alloys can be experimentally synthesized because they exhibit energetic and mechanical stability. All these systems present semiconducting behavior. Both GdN and YN are indirect band gap semiconductors while YxGd1-xN alloys are direct band gap semiconductors for $x = 0.25\comma \; 0.5\comma \; 0.75$ x = 0.25 , 0.5 , 0.75 because of hybridization between d (Y) and Gd(f) orbitals in the vicinity of the Fermi energy level. The f-d coupling induces the major magnetic moments on the Gd atom. The absorption spectra are reasonably high (>105 cm−1) and the bandgap energy and structure spacing match between YN and GaN which made YxGd1-xN alloys suitable for optoelectronic applications. In the absence of experimental work, our results can be useful for further studies. [ABSTRACT FROM AUTHOR]

Potassium-based perovskites hold the potential to substantially modify renewable technology by developing eco-friendly devices. A thorough analysis of structural, electronic, optical, transport, and mechanical characteristics of the double perovskites K2AgGaZ6 (Z = Cl, Br) has been executed using the Wein2K code. The stability has been verified by analyzing optimization curves, tolerance factor, and the enthalpy of formation energy. The AIMD simulation further confirms the thermodynamic stability of both compounds. The analysis of electronic band structures indicates that the perovskite K2AgGaCl6 has a bandgap of 1.85 eV, which is reduced to 1.14 eV for K2AgGaBr6. The Kramer-Kronig relation is used to evaluate optical characteristics, which exhibit extensive absorption within the visible spectrum for both materials, enabling their utilization in photovoltaics and optoelectronics. The Boltzmann semi-classical framework is employed to calculate thermoelectric properties. These materials have great potential for renewable energy applications due to their high ZT values, supported by their high Seebeck coefficients and electrical conductivities. The demonstrated mechanical attributes confirm ductility, stiffness, anisotropy, and higher melting temperature. Hence, this study provides theoretical evidence that these perovskite compounds are well-suited for green energy harvesting. [ABSTRACT FROM AUTHOR]

Tetragonal and hexagonal hybrid sp3/sp2 carbon allotropes C5 were proposed based on crystal chemistry and subsequently used as template structures to identify new binary phases of the B–N system, specifically tetragonal and hexagonal boron nitrides, B2N3 and B3N3. The ground structures and energy-dependent quantities of the new phases were computed within the framework of quantum density functional theory (DFT). All four new boron nitrides were found to be cohesive and mechanically (elastic constants) stable. Vickers hardness (HV), evaluated by various models, qualified all new phases as superhard (HV > 40 GPa). Dynamically, all new boron nitrides were found to be stable from positive phonon frequencies. The electronic band structures revealed mainly conductive behavior due to the presence of π electrons of sp2-like hybrid atoms. [ABSTRACT FROM AUTHOR]

Using the first-principles density functional theory calculations, we examined the effect of uniaxial strain on the electronic and magnetic properties of full-Heusler alloy N2SrRb. Our results show that N2SrRb is a ferromagnetic full-Heusler alloy, and it exhibits half metallic properties with 100% spin polarisation when no strain is applied. The half-metallic and magnetic properties of N2SrRb were retained under the ranges of tensile and compressive strain applied. The spin flip gap was found to increase as the tensile strain increases, while it decreases as the compressive strain increases. The mechanical properties show that the full-Heusler alloy is mechanically stable and having a ductile characteristics [ABSTRACT FROM AUTHOR]

Using state-of-the-art first-principles electronic-band-structure calculations alongside density functional theory, we investigated the structural, elastic, electronic, and magnetic properties of LiMnZ2 (Z = Se, Te) compounds with a trigonal structure. Initially, we determined the equilibrium lattice structure and atomic positions, which aligned well with experimental values. Ferromagnetism was shown to be more favorable than the non-magnetic state. The elastic constants, cohesive energies, and formation energies indicated that the studied compounds were mechanically stable in the experimentally determined trigonal lattice. The analysis of spin-polarized band structures and density of states revealed that both LiMnZ2 compounds exhibited perfect half-metallic characters. The total spin magnetic moment per formula unit adhered to the Slater–Pauling rule, being exactly 4 μΒ, mainly concentrated at the Mn atoms due to the strong spin polarization of the Mn d orbitals. We anticipate that our results will prompt further experimental and computational studies for the application of these layered materials in practical devices. [ABSTRACT FROM AUTHOR]