Electronic Structure Properties Research Articles

G-C3N4 coupled with GO accelerates carrier separation via high conductivity for photocatalytic MB degradation

Graphitic carbon nitride (g-C3N4) is widely utilized in photocatalysis due to its responsiveness to visible light, low cost, and non-toxicity. However, its efficiency is limited by factors such as the rapid recombination of photogenerated electron-hole pairs, slow electron transfer rates, and a limited number of active surface sites. In this study, g-C3N4 was synthesized through thermal polymerization, and varying amounts of graphene oxide (GO) were incorporated via physical blending to fabricate composite photocatalysts. The results indicated that the incorporation of GO not only increased the specific surface area and modified the pore size distribution of g-C3N4 but also affected the heptazine ring structure through chemical bonding, thereby enhancing the density of active sites. Photocatalytic degradation experiments with methylene blue (MB) indicated that g-C3N4 containing 2% GO exhibited photocatalytic activity 2.84 times greater than that of pristine g-C3N4. Kinetic simulations indicated that the Kapp value for the 2% GO-g-C3N4 composite was 0.00469min-1, which is 4.34 times higher than that of pure g-C3N4 (0.00108min-1). Furthermore, this composite maintained high photocatalytic activity after four cycles of reuse. An analysis of the photocatalytic degradation mechanism revealed that the incorporation of GO effectively promoted the separation and transfer of photogenerated electron-hole pairs, enhanced photocurrent density, and improved carrier separation efficiency. Electron spin resonance (ESR) and free radical scavenging experiments confirmed that the primary active species involved in the degradation of MB by the composite photocatalyst were ·O2- and h+. This study presents a novel approach for enhancing the photocatalytic performance of g-C3N4 by modifying its electronic structure and surface properties.

First-principles studies of strain-tunable InN monolayer: Applications for switching and optoelectronic devices

Abstract Two-dimensional (2D) materials are attracting significant attention for their potential applications in the post-Moore era. In this work, we systematically investigate the effect of strains on the electronic structure, transport and optoelectronic properties of 2D indium nitride (InN) monolayer using density functional theory and non-equilibrium Green’s function methods. The results show that strains can modulate the electronic properties. Specifically, biaxial strain triggers the transition from semiconductor to metal and indirect to direct band gap. On this basis, the constructed InN-based nanodevice exhibits current switching ratios up to 10^10. In addition, the optoelectronic device based on InN monolayer exhibits a robust photoelectric response in the red light. Meanwhile, biaxial strain can improve the optoelectronic performance of InN-based optoelectronic devices. The compressive strains blue-shift the photocurrent peaks of the InN monolayer, which effectively modulates its detection range in the visible light region. These findings underscore the potential applications in nanotechnology, particularly in nano-switches and optoelectronic devices.

Double exchange interaction in Mn-based topological kagome ferrimagnet

Recently discovered Mn-based kagome materials, such as RMn6Sn6 (R = rare-earth element), exhibit the coexistence of topological electronic states and long-range magnetic order, offering a platform for studying quantum phenomena. However, understanding the electronic and magnetic properties of these materials remains incomplete. Here, we investigate the electronic structure and magnetic properties of GdMn6Sn6 using x-ray magnetic circular dichroism, photoemission spectroscopy, and theoretical calculations. We observe localized electronic states from spin frustration in the Mn-based kagome lattice and induced magnetic moments in the nonmagnetic element Sn experimentally, which originate from the Sn-p\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p$$\\end{document} and Mn-d\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d$$\\end{document} orbital hybridization. Our calculations also reveal ferromagnetic coupling within the kagome Mn-Mn layer, driven by double exchange interaction. This work provides insights into the mechanisms of magnetic interaction and magnetic tuning in the exploration of topological quantum materials.

Pressure effects on the electronic structure and magnetic properties of infinite-layer nickelates

Pressure effects on the electronic structure and magnetic properties of infinite-layer nickelates

Impact of oxygen vacancies on the structural, electronic, and optical properties of Cu<i>2</i>O and nitrogen-doped Cu<sub>2</sub>O for optoelectronic applications: a first-principles study

This study utilizes Density Functional Theory (DFT) within the Quantum ESPRESSO framework to explore the effects of oxygen vacancies and nitrogen doping on the electronic structure and optical properties of cuprous oxide (Cu2O). Pristine Cu2O, an intrinsic p-type semiconductor, typically exhibits a direct band gap. Introducing an oxygen vacancy in the absence of a dopant broadens the band structure, leading to both direct and indirect band gap characteristics. In contrast, nitrogen doping transforms the band gap into a direct one, significantly reducing it from 1.97 eV to 1.09 eV, which deviates from previous findings due to potential variations in the initial state of the Cu2O host crystal. Furthermore, spin-polarization effects indicate spin-dependent behaviour within the material. The study also examines the absorption properties of pristine, defective, and nitrogen-doped Cu2O systems using the complex dielectric function. The results show distinct absorption peaks and transitions, with nitrogen-doped Cu2O exhibiting strong absorption in the visible light range, underscoring its potential for solar cell applications.

Effect of Vacancy Defects on the Electronic Structure and Optical Properties of Bi4O5Br2: First-Principles Calculations

First-principles calculations based on density functional theory are employed to investigate the impact of vacancy defects on the optoelectronic properties of Bi4O5Br2. The results indicate that vacancy defects induce minimal lattice distortion in Bi4O5Br2 without compromising its structural stability. Oxygen or bromine vacancies are more likely to occur than bismuth vacancies. The introduction of a bismuth vacancy leads to n-type semiconductor behavior in the Bi4O5Br2 system, while the creation of an oxygen vacancy reduces the bandgap and enhances the light absorption capacity. Bi4O5Br2 with three coordinated oxygen vacancies exhibits a higher effective electron–hole pair mass ratio, which is advantageous for the efficient separation of electron–hole pairs. Bi4O5Br2 with three coordinated oxygen vacancies exhibits enhanced absorption and reflection coefficients in the visible-light region compared to other systems, indicating that oxygen vacancy defects significantly promote visible-light absorption and electron–hole separation. This research provides new theoretical insights for understanding and optimizing the performance of photocatalysts based on Bi4O5Br2.

Emerging SiO2@ATO hierarchical submicron hollow microspheres with efficient photo-thermal shielding properties

Silicon dioxide/antimony doped tin oxide (SiO2@ATO) submicron hollow microspheres were prepared by hydrothermal method. The morphology and microstructure of the microspheres were characterized by XRD, SEM, EDS and HRTEM. The composite coatings were prepared by adding SiO2@ATO powders to acrylic matrix, and their photothermal shielding properties were investigated. In addition, the electronic structure and optical properties of SiO2@ATO heterojunction were calculated and analyzed using first principle. The results show that the interface binding energy of SiO2@ATO is ∼2.496 J/m2, which indicates that the interface can exist stably. The light transmittance of the acrylic matrix coating with 1.0 wt% submicron hollow SiO2@ATO microspheres can reach about 83 %. Moreover, it was found that the hollow double-shell SiO2@ATO/acrylic matrix coating lowered the indoor temperature of the homemade incubator by 11.5℃. In summary, the SiO2@ATO structure shows potential in the application of transparent thermal insulation coatings.

First−Principle Study on Electronic Structure and Magnetism in Doped Boron Phosphide Nanosheet

Based on the first‐principles calculation of density‐functional theory, the electronic structure and magnetic properties of hexagonal boron phosphide (h‐BP) with doping and applying strain to the transition‐metal (TM = Cr, Mn, Fe, Co, and Ni) elements are investigated. After the TM elements are introduced, the magnetism is induced. The magnetic moments are 3.00, 3.87, 1.00, 1.99, and 1.00 μB, respectively, which mainly contributed by the 3d orbitals of TM elements. In the case of magnetic coupling, Cr–Cr are mainly coupled antiferromagnetically at different distances. In addition, Fe–Fe performs a ferromagnetic state, and Co–Co represents an antiferromagnetic state with the distance of 3.213 Å. After applied strain, Co doped of the system shows the characteristics of semimetals under the application of 4% strain. It can be added that for h‐BP systems, doping Co and Mn increases its conductivity, which is beneficial to the study of spintronic materials.

The Influence of Pressure on the Electronic and Elastic Characteristics of GaP Nanocrystals using Density Functional Theory

The electronic structural and mechanical properties of III-V Gallium Phosphide (GaP) nano-crystals zinc-blende stable (ZB) phase under pressure dependence have been studied via the model of the density functional theory (DFT) in combination with the large unit cell (LUC) approach at (8, 16, 54 & 64) atoms. The exchanges and correlations (XC) energy has been defined in all approaches through generalized gradient approximations of the Perdew-Burke-Ernzerhof (GGA-PBE), and determination of GaP characteristics in the case where the pressure has been increased from 0GPa to ±50GPa. Elastic parameters like elastic constants (C11, C12 & C44), Kleinmann parameter (ξ), Zener anisotropic factor (A), shear modulus (G), Young's modulus (E), Poisson’s ratio (v), Bulk modules (B) of GaP-ZB structure have been calculated and showed systematic variation with a pressure increase. Our calculations show that Bulk modules and sound speed increase with an increase in the number of core atoms. In this systematic approach, it has been found that the B/G ratio is 1.58 for this compound and it exhibits a negative Cauchy pressure, classifying GaP as brittle. The results were discovered to be consistent with other theoretical as well as experimental results. The present study directly relates to the latest experimental works on the III-phosphide compounds. The current results provide information and direction for further investigation into the fundamentals and potential applications of gallium phosphate (GaP) nanocrystals. In addition, we attempted to compare the results of the investigation with some similar types of compounds that are already documented in the literature. We believe that our study will have a significant impact on both the field of research and contemporary technology based on semi-conducting materials.

Core‐Fluorinated BODIPYs – a New Family of Highly Efficient Luminophores

AbstractA modular synthesis of novel series of 1,7‐difluorinated BODIPYs has been elaborated. First, the acid‐catalyzed condensation of ethyl 3‐aryl‐4‐fluoro‐1H‐pyrrole‐2‐carboxylates with aromatic aldehydes gives the corresponding dipyrromethane‐1,9‐dicarboxylates. The latter are subjected to the exhaustive reduction with lithium aluminum hydride to transform the ester moieties into methyl groups. The subsequent oxidation of the resulting 1,9‐dimethylated dipyrromethanes followed by the boron difluoride complexation afforded a family of novel core‐fluorinated BODIPYs in up to 74 % yield. Photophysical properties of the resulting BODIPYs were tuned by varying of the starting fluoropyrroles and aromatic aldehydes and were studied by UV‐visible and fluorescence spectroscopy. As a result, the fluorescence quantum yields of the obtained compounds reached up to 99 %. In addition, their ability to generate singlet oxygen and electrochemical properties were also evaluated. As a result, a new promising family of fluorophores with a good combination of the fluorescence and photosensitizing properties was obtained. It was found that conversion of ester groups into methyl ones at the 3,5‐positions of the BODIPY core is a crucial step toward fluorescence enhancement. In addition, DFT calculations were performed to elucidate a relationship between electronic structure, geometry and photophysical properties of these BODIPYs.

Exploring Electron-Phonon Coupling Using Quantum Computing Methods

Abstract Quantum computing in the noisy intermediate-scale quantum (NISQ) era has foregrounded the importance of Variational Quantum Algorithms (VQAs). These algorithms are crucial for addressing complex quantum mechanical problems that challenge classical computers. One such problem is the electron-phonon (e–ph) interaction, which is essential for determining the zero-point renormalization (ZPR) of electronic structure properties. The calculation of ZPR of fundamental gap relies on the accurate computation of ionization potential (IP) and electron affinity (EA) energy levels in molecular systems, where the VQAs offer the promising solutions. Despite the critical importance of IP, EA energies and ZPR in quantum chemistry calculations, research into the application of quantum algorithms for these calculations remains limited. To address these challenges, we propose two quantum algorithms for ZPR of fundamental gap calculation using Variational Quantum Deflation (VQD) and Quantum Equation of Motion (QEOM) algorithm for several molecular systems. This work opens up new possibilities for the accurate and efficient study of e-ph interaction in electronic structure calculations, even with NISQ-era hardware.

A density functional study of type I to type II crossover in g-C3N4/CoN4 heterostructure in presence of external perturbation

Herein, we report the impact of external perturbation on the photocatalytic performance of g-C3N4/CoN4 heterojunction and concomitant transition from type-I to type-II. The state-of-the-art theoretical modeling presented here is the first study on dynamic role of strain and electric field on g-C3N4/CoN4 heterojunction and its potential application as a solar-driven water splitting reaction. Utilizing the density functional theory (DFT) calculation, V. N. et al. recently reported the photocatalytic activity of g-C3N4/MN4 (M = Mn, Fe and Co) heterojunction [J. Comput. Chem. 2024, 45, 2518-2529, https://doi.org/10.1002/jcc.2746412] and subsequently established g-C3N4/CoN4 as a type I heterojunction for photocatalytic water splitting reaction [Phys. Chem. Chem. Phys. 2024, 26, 21117–21133]. In the present study, we applied external perturbation in the form of mechanical strain, electric field and evaluated the electronic structure properties of the system along with the detailed examination of concomitant optical and magnetic properties of g-C3N4/CoN4 heterojunction. The switching of photocatalytic feature from type I to type II originates due to the crossover between valence band maxima (VBM) of g-C3N4 and CoN4 in presence of external perturbation. Notably, the resulting system acts as a type II photocatalyst for water splitting reaction while applying compressive (negative) strain of −2 to −6% and an electric field of −0.5 and +0.5 V/Å, respectively. Accumulation of photogenerated electrons and holes separately in g-C3N4 and CoN4 units confirms the perceptible separation of charge carriers and thereby reduces the recombination compared to un-perturbed system. A red-shifted absorption maximum (689 nm), superior charge transfer (0.9e), and clear separation of photogenerated electrons and holes are the origin of enhanced photocatalytic efficiency of g-C3N4/CoN4 heterojunction in the presence of external perturbation. We believe that our work will provide enough evidence to the experimentalists to achieve such a system in practice leading to human-friendly applications.

Electronic structure and optical properties of halide double perovskites from a Wannier-localized optimally-tuned screened range-separated hybrid functional

Electronic structure and optical properties of halide double perovskites from a Wannier-localized optimally-tuned screened range-separated hybrid functional

Catalytic behavior, electronic structure and spectroscopic (FT-IR, Raman, UV–vis) properties for the new ionic liquid imidazolium hydrogen sulfate

Catalytic performance, chemical reactivity, vibrational modes and electronic transitions of the ion pair [H–Im]+[HSO4]– were investigated in the current paper. Hence, a combined experimental (Hammett acidity function, infrared, Raman and ultraviolet-visible spectroscopies) and theoretical (molecular electrostatic potential surface, reduced density gradient, frontier molecular orbital analysis, quantum theory of atoms in molecules, net atomic charges, global and local reactivity descriptors) study was conducted. In terms of the catalytic performance, the acetic acid esterification with butanol was evaluated. Important kinetic (rate constant, activation energy, pre-exponential factor) and thermodynamic (enthalpy, entropy, Gibbs free energy barrier) factors for ester production as a function of the temperature and catalyst loading have been determined. Results revealed intensive electron density distribution in [H–Im]+[HSO4]– due to chemical interactions between the cationic and anionic moieties. These bonds were established as electrostatic in nature. The pronounced charge transfers within [H–Im]+[HSO4]– managed the title compound acidity (H0) and its catalytic behavior towards butyl acetate synthesis. Using the thermodynamic and kinetic measurements, a mechanism for acetic acid esterification with butanol in the presence of imidazolium hydrogen sulfate ionic liquid was offered.

Unraveling Oxygen Vacancies Effect on Chemical Composition, Electronic Structure and Optical Properties of Eu Doped SnO2.

The influence of Eu doping (0.5, 1 and 2 mol.%) and annealing in an oxygen-deficient atmosphere on the structure and optical properties of SnO2 nanoparticles were investigated in relation to electronic structure. The X-ray diffraction (XRD) patterns revealed single-phase tetragonal rutile structure for both synthesized and annealed Eu-doped SnO2 samples, except for the annealed sample with 2 mol.% Eu. The results of X-ray photoelectron spectroscopy (XPS) emphasized that europium incorporated into the SnO2 host lattice with an oxidation state of 3+, which was accompanied by the formation of oxygen vacancies under cation substitution of tetravalent Sn. Moreover, XPS spectra showed the O/Sn ratio, which has been reduced under annealing for creating additional oxygen vacancies. The pulse cathodoluminescence (PCL) demonstrated the concentration dependence of Eu site symmetry. Combination of XRD, XPS and PCL revealed that Eu doping and following annealing induce strongly disordering of the SnO2 crystal lattice. Our findings provide new insight into the interaction of rare-earth metals (Eu) with host SnO2 matrix and new evidence for the importance of oxygen vacancies for optical and electronic structure formation.

Computational Design of 3D Lantern Organic Framework.

This study employed a computational approach, particularly Density Functional Theory at B3LYP-D3/6-31+G(d) level to design two new classes of three-dimensional (3D) Lantern Organic Frameworks (LOFs) materials based on trisilasumanene and porphyrin core building units. Particularly, we detail strategies for transitioning from 1D-LOF nanowires to extended 3D structures: first by connecting planar-molecule base units of trisilasumanene or porphyrin using benzene-based linkers, and then connecting silicon anchoring atoms on the bases with other bases that are vertically stacked by sp3-hydrocarbon chains. The 3D-LOF structures are designed to have different pore sizes through the use of various bases, bridges, and linkers. Comparisons of electronic properties of these 3D structures lead to one designing rule. That is, the gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the 3D materials depends only on its base and is nearly independent of the stack size or the length of the sp3-hydrocarbon bridges. Additionally, connecting base units with linkers also extends π-electron conjugation system leading to a reduction in HOMO-LUMO gap. For instance, linking two trisilasumanene molecules significantly narrows HOMO-LUMO gap by 1.75 eV while stacking these bases vertically and connecting them by linear pentane-based bridges yield insignificant change to the gap.

Engineering of in-plane SnS2–SnO2 nanosheets heterostructures for enhanced H2S sensing

In-plane heterostructures has attracted considerable interest due to exceptional electron transport properties, high specific surface area, and abundant active sites. However, synthesis of in-plane SnS2–SnO2 heterostructures are rarely reported, and the deep investigation of the fine structure on reactivity is of great significance. Here, we propose partial in-situ oxidation strategy to construct the in-plane SnS2–SnO2 heterostructures and the surface properties, the ratio of two components can be finely tuned by precisely adjusting the treatment temperature. In particular, the SnS2–SnO2 heterostructures formed after annealing of SnS2 nanosheets at 350 °C exhibits a unique electronic structure and surface properties due to rich grain boundaries, which exhibits excellent gas sensing performance to H2S (Ra/Rg = 169.81 for 5 ppm H2S at 160 °C, fast response and recovery dynamic (41/101 s), excellent reliability (σ = 0.01) and sensing stability (φ = 0.11 %)). Notably, the in-plane heterostructures endow the material with abundant grain boundaries and effectively regulates the electronic structure of the Sn p-orbital, which facilitate the formation of active oxygen species (O−(ad)), thus contributing to the sensing performance. Our work provides a promising platform to design in-plane heterostructures for various advanced applications.

Probing Surface-Mediated Electronic Coupling in Flat Hexagonal Phosphorus Nanostructures and Monolayer on Au(111).

Due to its diverse allotropes and intriguing properties, 2D phosphorus, also known as phosphorene, is a material of great interest. Here, the successful growth of flat hexagonal 2D phosphorus on Au(111) is reported. Starting from phosphorus linear chains at low coverage, a porous network and finally an extended 2D flat hexagonal (HexP) layer while increasing phosphorus deposition is formed. Using scanning tunneling microscopy/spectroscopy combined with ab initio calculations, the structure and electronic properties of the as-grown phosphorus structures are followed. The progressive formation of a phosphorus electronic band in the conduction band region is followed. More strikingly, a partial flatband that appears only on the HexP phase characterized by a sharp peak in the electronic spectrum is observed. These bands arise from the hybridization of phosphorus and gold atoms. This novel phosphorus-based structure exhibits remarkable electronic properties due to gold mediated phosphorus-phosphorus electronic coupling. This work paves the way for new interface material developments with attractive electronicproperties.

The influence of spin-orbit coupling on the electronic structure and optical properties of α-BiB3O6 crystals: a first-principles investigation

The α-BiB3O6 (BIBO) crystal is highly regarded in the field of nonlinear optical (NLO) due to its excellent ultraviolet (UV) NLO properties, including a short ultraviolet cutoff edge (270 nm), appropriate birefringence (Δn = 0.175@546 nm), and strong second harmonic generation (deff = 3.20 pm V−1). In this study, the first-principles computational software PWmat was employed to conduct theoretical calculations on BIBO crystals, including the non-negligible spin-orbit coupling (SOC) effects induced by the presence of the heavy element bismuth (Bi). The results show that after the inclusion of the SOC, the calculated birefringence (0.173@546 nm) and effective second harmonic generation (SHG) coefficient (deff = 3.16 pm V−1) are in good agreement with experimental data. Furthermore, comparative analysis has demonstrated that the changes in the band structure induced by the SOC effect are significant factors influencing the optical properties of the material.

Structure and optical properties of alkali rare-earth double phosphates of M3RE(PO4)2 (M = K, Rb; RE = Y, La, and Lu)

Designing and synthesizing phosphate nonlinear optical materials with novel structures and excellent properties remains challenging. In this work, the electronic structure and optical properties (second harmonic generation (SHG) response or birefringence) of alkali rare-earth double phosphates M3RE(PO4)2 (M = K, Rb; RE = Y, La, and Lu) are systematically investigated. It is worth mentioning that P31m-Rb3Lu(PO4)2 was successfully synthesized by a flux-method, and the UV–vis–NIR diffuse reflectance spectroscopy showed that Rb3Lu(PO4)2 exhibits a short absorption edge at 207 nm and a high transmittance of 77.9 %. Based on first-principles calculations, the results show that the birefringence of the M3RE(PO4)2 series of crystals exhibits significant differences (0.009-0.028@1064 nm). Subsequently, analysis of the electronic structure and the real-space atom cutting method reveals that rare-earth polyhedra play a major role in enhanced birefringence. Overall, this work enriches the study of nonlinear optical crystals of rare earth phosphates and provides a case for further exploration.