Results 1 - 3 of 3
Results 1 - 3 of 3. Search took: 0.013 seconds
|Sort by: date | relevance|
[en] This article reports the electronic, optical and structural properties of XPN 2 (X = H, Cu) chalcopyrite semiconductors by implying the density functional theory (DFT) with full potential linearized augmented plane wave plus local orbitals (APW+lo) method. The calculated electronic and structural parameters such as energy band gap, anion displacement, tetragonal ratio and lattice parameters have shown good agreement with the previous experimental and theoretical results. The optical properties are described by calculating the absorption coefficients, dielectric function along with real and imaginary part of the dielectric function. Voigt-Reuss-Hill approximations are used to calculate the set of macroscopic elastic moduli including average elastic wave velocity, Young, shear and bulk moduli, Debye temperature and Poisson’s coefficient for chalcopyrite CuPN 2 and HPN 2. Finally, the semi-classical Bolzmann theory is applied with BolzTrap code to compute the transport properties such as thermal electrical conductivity, figure of merit and Seebeck coefficient for these materials. (paper)
[en] This study aims to investigate the photocatalytic degradation performance, mechanism, and dynamics of methyl orange (MO) which is a widely used organic dye in textile industries as well a hazardous wastewater pollutant. The degradation process was catalyzed by employing a synthesized Fe3O4 magnetic nanoparticle (NP) using the coprecipitation method. The structural and morphological properties of the synthesized Fe3O4 NPs were investigated by employing XRD, HR-SEM, and XPS, which proved that acquired Fe3O4 NPs were in a pure phase. Moreover, the crystallite sizes fall in the range of 28–31.8 nm and were estimated by applying the Scherrer equation on the XRD spectrum as well as calculated independently by applying a statistical approach on the SEM micrographs. The UV–Vis maximum in the visible range at 468.8 nm consists of two absorption frequency bands due to the effect of the hydrogen-bond interaction between water and the azo nitrogens in the MO. A non-monotonic spectral dynamic accompanied by peak wavelength shifts, as well as the absolute signal amplitude and signal area of the MO band, suggests that a cleavage of the azo bond is not the only and/or the dominant process in the photocatalytic oxidization of the MO in a protic solvent. The overall absorbance process is a complicated response to a combination of nonspecific and specific solute-solvent interactions, dipole-dipole interactions, hydrogen-bonding networks, and other possible intermolecular interactions such as hydrophobic/hydrophilic interactions. A bi-exponential decay was found to be the best fitting function to model the decay of the time-dependent electrical conductivity of the MO aqueous solution under photocatalytic oxidization. The Fe3O4 NPs exhibited a 98.3% removal of MO within 110 min. Photocatalytic degradation of methyl orange can be modeled to the first-order model with a rate constant k of 0.037 min−1 taking into account the initial concentration of 1175 ppm of MO. The degradation/decolorization efficiency deduced from the low-frequency band of the visible spectra is around 99.4% after 110 min. The real-time degradation/decolorization efficiencies deduced from the overall absorbance maxima and the low-frequency band have a discrepancy of 50.1% at 20 min and 12.3% at 60 min representing the progressive attenuation of the H-bond impact dissociation of MO (degradation/decolorization).