Efficient photo‐ and piezoelectric‐induced molecular oxygen activation are both achieved by macroscopic polarization enhancement on a noncentrosymmetric piezoelectric semiconductor BiOIO3. The ...replacement of V5+ ions for I5+ in IO3 polyhedra gives rise to strengthened macroscopic polarization of BiOIO3, which facilitates the charge separation in the photocatalytic and piezoelectric catalytic process, and renders largely promoted photo‐ and piezoelectric induced reactive oxygen species (ROS) evolution, such as superoxide radicals (.O2−) and hydroxyl radicals (.OH). This work advances piezoelectricity as a new route to efficient ROS generation, and also discloses macroscopic polarization engineering on improvement of multi‐responsive catalysis.
Macroscopic polarization enhancement by V5+ replacement in the piezoelectric semiconductor BiOIO3 can greatly facilitate charge separation and provide efficient photo‐ and piezoelectric‐induced molecular oxygen activation. Powerful superoxide and hydroxyl radicals can be thereby produced in abundance.
As a starting point for our calculation of 3-methyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole we used the XRD data obtained by C. Liu, Z. Wang, H. Xiao, Y. Lan, X. Li, S. Wang, Jie Tang, Z. Chen, J. ...Chem. Crystallogr., 2009 39 881. The structure was optimized by minimization of the forces acting on the atoms keeping the lattice parameters fixed with the experimental values. Using the relaxed geometry we have performed a comprehensive theoretical investigation of dispersion of the linear and nonlinear optical susceptibilities of 3-methyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole using the full potential linear augmented plane wave method. The local density approximation by Ceperley-Alder (CA) exchange-correlation potential was applied. The full potential calculations show that this material possesses a direct energy gap of 3.4 eV for the original experimental structure and 3.2 eV for the optimized structure. We have calculated the complex's dielectric susceptibility ε(ω) dispersion, its zero-frequency limit ε(1)(0) and the birefringence. We find that a 3-methyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole crystal possesses a negative birefringence at the low-frequency limit Δn(0) which is equal to about -0.182 (-0.192) and at λ = 1064 nm is -0.193 (-0.21) for the non-optimized structure (optimized one), respectively. We also report calculations of the complex second-order optical susceptibility dispersions for the principal tensor components: χ(ω), χ(ω) and χ(ω). The intra- and inter-band contributions to these susceptibilities are evaluated. The calculated total second order susceptibility tensor components at the low-frequency limit |χ(0)| and |χ(ω)| at λ = 1064 nm for all the three tensor components are evaluated. We established that the calculated microscopic second order hyperpolarizability, β(ijk), the vector component along the dipole moment direction, at the low-frequency limit and at λ = 1064 nm, for the dominant component |χ(ω)| is 4.99 × 10(-30) esu (3.4 × 10(-30) esu) and 7.72 × 10(-30) esu (5.1 × 10(-30) esu), respectively for the non-optimized structure (optimized structure).
► A new package for calculating elastic constants of orthorhombic structure is released. ► The package called ortho-elastic. ► It is compatible with FP-(L)APW+lo method implemented in WIEN2k code. ► ...Several orthorhombic structure compounds were used to test the new package. ► Elastic constants calculated using this package show good agreement with experiment.
A new package for calculating the elastic constants of orthorhombic structure is released. The package called ortho-elastic. The formalism of calculating the ortho-elastic constants is described in details. The package is compatible with the highly accurate all-electron full-potential (linearized) augmented plane-wave plus local orbital FP-(L)APW+lo method implemented in WIEN2k code. Several orthorhombic structure compounds were used to test the new package. We found that the calculated elastic constants using the new package show better agreement with the available experimental data than the previous theoretical results used different methods. In this package the second-order derivative E″(ε) of polynomial fit E=E(ε) of energy vs strains at zero strain (ε=0), used to calculate the orthorhombic elastic constants.
Graphene/MoS2 heterostructure (G/MS-H) has distinctive and superlative electronic properties as it contains features of both graphene and MoS2. Our first-principles calculations reveal this ...heterostructure has a little bandgap (40 meV) and zero magnetic moment in the pristine form. In the present work, we have attempted to induce magnetism in the resultant heterostructure by adsorbing Cr atom at (i) Top (G-Top) (ii) Hollow (G-Hollow) configurations in the graphene layer and (iii) Top (S-Top) and (iv) Hollow (S-Hollow) in the MoS2 layer. However, only G-Top and S-Hollow are energetically favorable amid these configurations. Our results demonstrate that Cr-adsorption persuades the significant magnetic moment. Both the stable configurations (G-Top and S-Hollow) transpire metallicity with a Dirac point shift in the valence band. The magnetism originates from the interactions between Cr-3d states with C-2p and S-3p states. These results summarize that the resultant adsorbed heterostructure may serve as a phenomenal breakthrough for nanomagnetism.
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•Cr-adsorption introduces significant magnetic moment and metallic character in the resultant graphene/MoS2 heterostructure.•Magnetic behavior originates due to strong admixture of C-3d states with C/S-2p/3p states in graphene/MoS2 layers.•The resultant heterostructure after adsorption is a promising candidate in the fabrication of nano magnetic devices.
When modeling complex systems, we usually encounter the following difficulties: partiality, large amount of data, and uncertainty of conclusions. It can be said that none of the known approaches ...solves these difficulties perfectly, especially in cases where we expect emergences in the complex system. The most common is the physical approach, sometimes reinforced by statistical procedures. The physical approach to modeling leads to a complicated description of phenomena associated with a relatively simple geometry. If we assume emergences in the complex system, the physical approach is not appropriate at all. In this article, we apply the approach of structural invariants, which has the opposite properties: a simple description of phenomena associated with a more complicated geometry (in our case pregeometry). It does not require as much data and the calculations are simple. The price paid for the apparent simplicity is a qualitative interpretation of the results, which carries a special type of uncertainty. Attention is mainly focused (in this article) on the invariant matroid and bases of matroid (M, BM) in combination with the Ramsey graph theory. In addition, this article introduces a calculus that describes the emergent phenomenon using two quantities—the power of the emergent phenomenon and the complexity of the structure that is associated with this phenomenon. The developed method is used in the paper for modeling and detecting emergent situations in cases of water floods, traffic jams, and phase transition in chemistry.
This research explores the synthesis, characterization, and application of Vanadium Pentoxide nanoparticles (V2O5 NPs), focusing on their efficacy in the photocatalytic degradation of organic dyes ...under visible light. Utilizing a co-precipitation method, we synthesized V2O5 NPs characterized by an orthorhombic crystal structure with a consistent average particle size of 28 nm. The optical properties of V2O5 NPs, including their band gap, were thoroughly investigated to understand their light absorption capabilities, which are crucial for photocatalytic activity. In our study, Methyl Violet (MV) dye was employed as a model organic pollutant to assess the photocatalytic performance of the nanoparticles. Under visible light irradiation, the V2O5 nanoparticles demonstrated an exceptional photocatalytic degradation efficiency, achieving up to 85% degradation of the MV dye within 100 min. This high level of efficiency is attributed to the nanoparticles' ability to effectively absorb visible light and generate electron-hole pairs, thereby facilitating a robust degradation process. Further analysis revealed that the photocatalytic activity led to the generation of reactive oxygen species (ROS) such as superoxide and hydroxyl radicals, which are integral to the dye degradation mechanism. These ROS play a critical role in breaking down the dye molecules, significantly contributing to the overall effectiveness of the photocatalytic process. The results of this study highlight the potential of V2O5 nanoparticles as a sustainable and effective photocatalytic material for environmental remediation applications, particularly in the treatment of wastewater containing organic dyes. This research not only advances our understanding of the photocatalytic properties of V2O5 nanoparticles but also demonstrates their practical application in addressing environmental pollution through innovative and efficient degradation of hazardous substances.This research explores the synthesis, characterization, and application of Vanadium Pentoxide nanoparticles (V2O5 NPs), focusing on their efficacy in the photocatalytic degradation of organic dyes under visible light. Utilizing a co-precipitation method, we synthesized V2O5 NPs characterized by an orthorhombic crystal structure with a consistent average particle size of 28 nm. The optical properties of V2O5 NPs, including their band gap, were thoroughly investigated to understand their light absorption capabilities, which are crucial for photocatalytic activity. In our study, Methyl Violet (MV) dye was employed as a model organic pollutant to assess the photocatalytic performance of the nanoparticles. Under visible light irradiation, the V2O5 nanoparticles demonstrated an exceptional photocatalytic degradation efficiency, achieving up to 85% degradation of the MV dye within 100 min. This high level of efficiency is attributed to the nanoparticles' ability to effectively absorb visible light and generate electron-hole pairs, thereby facilitating a robust degradation process. Further analysis revealed that the photocatalytic activity led to the generation of reactive oxygen species (ROS) such as superoxide and hydroxyl radicals, which are integral to the dye degradation mechanism. These ROS play a critical role in breaking down the dye molecules, significantly contributing to the overall effectiveness of the photocatalytic process. The results of this study highlight the potential of V2O5 nanoparticles as a sustainable and effective photocatalytic material for environmental remediation applications, particularly in the treatment of wastewater containing organic dyes. This research not only advances our understanding of the photocatalytic properties of V2O5 nanoparticles but also demonstrates their practical application in addressing environmental pollution through innovative and efficient degradation of hazardous substances.
•A new quaternary Heusler alloy FeCrMnSb is identified with robust half metallicity.•The stability of FeCrMnSb has been examined using elastic constants.•Effect of uniform and tetragonal strains on ...half metallicity has been studied.
A new quaternary Heusler alloy FeCrMnSb is identified by employing ab initio electronic structure calculations. It is stable in Y-structure which is also verified by various conditions governed by elastic constants cij. It is a true half-metallic (HM) ferromagnet with integer magnetic moment of 2.00μB per formula unit. The values of minority band gap and HM gap are found to be 0.65eV and 0.1eV, respectively. The HM character of FeCrMnSb sustains for −6% to 9% of uniform strain and −9% to 12% of tetragonal strain. This new quaternary Heusler alloy can be proved as an ideal candidate for spin valves and magnetic tunnel junction applications (MTJs).
Rare-earth zirconate pyrochlores (RE2Zr2O7) are of much fundamental and technological interest as optoelectronic, scintillator and thermal barrier coating materials. For the first time, we report the ...detailed optoelectronic properties of rare-earth zirconates Nd2Zr2O7 in both, i.e., for spin up and spin down states, via the use of first-principles density functional theory (DFT) procedure. To obtain the desired optoelectronic properties, we used a highly accurate method called full-potential linearized augmented plane wave (FPLAPW) within the generalized gradient approximation (GGA), parametrized with Hubbard potential U as an exchange-correlation function. The band gaps predicted for Nd2Zr2O7 were of the order 2.4 eV and 2.5 eV in Fd-3m and Pmma symmetrical phases, respectively. For both the phases, our research involved a complete examination of the optical properties of Nd2Zr2O7, including extinction coefficient, absorption coefficient, energy loss, function, reflectivity, refractive index, and real optical conductivity, analyzed in the spectral range from 0.0 eV to 14 eV. The calculated optical properties in both phases showed a considerable spin-dependent effect. The electronic bonding characteristics of different species in Nd2Zr2O7 within the two crystal symmetries were explored via the density distribution mapping of charge.
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•The novel compound LiMoO3(IO3) is an active photocatalyst under visible light irradiation.•LiMoO3(IO3) possesses a direct energy band gap of 2.73eV.•Two crystallographic planes were ...mapped to explore the charge transfer.
The electronic structure of the novel molybdenyl iodate LiMoO3(IO3) based on WO3-type sheets is calculated in order to understand to its usage as a photocatalyst. Using X-ray diffraction data as the initial input, we have optimized the atomic positions by minimizing the force on each atom. Calculations are performed using the generalized gradient approximation (PBE-GGA) within the full-potential linear augmented plane wave method. The optimized structure is used to calculate the electronic band structure and the related properties with PBE-GGA and the recently modified Becke–Johnson potential (mBJ). The top of the valence band (VBM) and the bottom of the conduction band (CBM) are located at the Γ point of the Brillouin zone (BZ), resulting in a direct energy band gap of 2.15eV (PBE-GGA) or 2.73eV (mBJ). It is clear that mBJ succeeds by a large amount in bringing the calculated energy gap into close agreement with the measured one (2.80eV). Thus, LiMoO3(IO3) could be an active visible-light photocatalyst. The angular-momentum-resolved projected density of states reveals that the energy gap value is mainly controlled by O2p (valence bands) and Mo4d (conduction bands) states. The electronic charge density distribution is calculated in two crystallographic planes to explore the chemical bonding characters. The free end Li atom forms ionic bonds, whereas the I atom forms partial valence and dominant ionic bonds with two O atoms. Mo and Li atoms form very weak covalent bonds with O atoms. The calculated chemical bond lengths and angles are in good agreement with the experimental values.
We performed a comprehensive ab inito calculation to investigate the influence of substitution of Ca2+ (180 pm) by larger Sr2+ (200 pm) in MZnSO (M = Ca or Sr) on the structural properties and, ...hence, on the linear and nonlinear optical properties. The substitution of Ca2+ by Sr2+ in MZnSO causes a band gap reduction resulting in an influence on the photophysical properties and enhances the optic activity toward the visible region. The observation of linear optical properties reveals a band gap reduction on moving from Ca to Sr, and the whole spectral structure shifts toward lower energies. The substitution of Ca2+ by Sr2+ introduces an obvious enhancement in the anisotropy between the extraordinary and ordinary tensor components, as confirmed by the uniaxial anisotropy and birefringence favoring an important role in second harmonic generation (SHG) and optical parameter oscillator due to better fulfilling of phase-matching conditions. The calculations show that SrZnSO exhibits larger SHG and microscopic first hyperpolarizability (βijk) than CaZnSO.
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