Publications by authors named "Souraya Goumri-Said"

11 Publications

  • Page 1 of 1

Impact of Bi Doping into Boron Nitride Nanosheets on Electronic and Optical Properties Using Theoretical Calculations and Experiments.

Nanoscale Res Lett 2021 May 12;16(1):82. Epub 2021 May 12.

Department of Physics, College of Science, King Faisal University, P.O. Box 400, Al-Ahsa, 31982, Saudi Arabia.

In the present work, boron nitride (BN) nanosheets were prepared through bulk BN liquid phase exfoliation while various wt. ratios (2.5, 5, 7.5 and 10) of bismuth (Bi) were incorporated as dopant using hydrothermal technique. Our findings exhibit that the optical investigation showed absorption spectra in near UV region. Density functional theory calculations indicate that Bi doping has led to various modifications in the electronic structures of BN nanosheet by inducing new localized gap states around the Fermi level. It was found that bandgap energy decrease with the increase of Bi dopant concentrations. Therefore, in analysis of the calculated absorption spectra, a redshift has been observed in the absorption edges, which is consistent with the experimental observation. Additionally, host and Bi-doped BN nanosheets were assessed for their catalytic and antibacterial potential. Catalytic activity of doped free and doped BN nanosheets was evaluated by assessing their performance in dye reduction/degradation process. Bactericidal activity of Bi-doped BN nanosheets resulted in enhanced efficiency measured at 0-33.8% and 43.4-60% against S. aureus and 0-38.8% and 50.5-85.8% against E. coli, respectively. Furthermore, In silico molecular docking predictions were in good agreement with in-vitro bactericidal activity. Bi-doped BN nanosheets showed good binding score against DHFR of E. coli (- 11.971 kcal/mol) and S. aureus (- 8.526 kcal/mol) while binding score for DNA gyrase from E. coli (- 6.782 kcal/mol) and S. aureus (- 7.819 kcal/mol) suggested these selected enzymes as possible target.
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http://dx.doi.org/10.1186/s11671-021-03542-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8116421PMC
May 2021

Liquid-phase exfoliated MoS nanosheets doped with -type transition metals: a comparative analysis of photocatalytic and antimicrobial potential combined with density functional theory.

Dalton Trans 2021 May;50(19):6598-6619

Department of Physics, College of Science, King Faisal University, P.O. Box 400, Al-Ahsa, 31982, Saudi Arabia.

MoS2 nanosheets were developed by undertaking the liquid-phase exfoliation of bulk counterparts. In order to enhance its photocatalytic properties, the host material was doped with p-type transition metals (i.e., Ag, Co, Bi, and Zr). The hydrothermal technique was used to produce samples doped with 7.5 wt% transition metals (TM). X-ray diffraction detected the existence of 2H-phase by mirroring its reflection at 2θ ∼ 14°, while the peak distribution revealed the degree of exfoliation in samples. Low PL intensities indicated a lower recombination of electron-hole pairs, as corroborated by a high degree of photocatalytic action. Raman analysis was undertaken to identify molecular vibrations. The A1g mode in Raman spectra consistently showed a blueshift in all samples and the E12g mode was only slightly affected, which is evidence of the p-type doping in the MoS2 nanosheets. In the XPS spectrum, two characteristic peaks of Mo 3d appeared at 229.87 and 233.03 eV assigned to Mo-3d5/2 and Mo-3d3/2, respectively. Furthermore, a microstructural examination with HR-TEM and FESEM divulged a thin-layered structure of MoS2 consisting of flat, gently curved or twisted nanosheets. Diverse morphologies were observed with a non-uniform distribution of the dopant. Photocatalytic action of the TM-doped products effectively degraded methylene blue (MB) concentrations of up to 94 percent (for Ag-MoS2). The synergistic effect of doped MoS2 nanosheets against S. aureus in comparison to E. coli bacteria was also evaluated. The efficacy % age improved from (0-31.7%) and (23.5-55.2%) against E. coli, and (0-34.2%) and (8.3-69.23%) against S. aureus. Moreover, results from first principles calculations indicate that substitutional doping of TM atoms is indeed advantageous. Theoretical calculations confirmed that doping with Ag, Co, Bi, and Zr leads to a decrease in the band gap to a certain degree, in which the conduction band edge shifts toward lower energy, while the valence band shifts closer to the high energy end. It can be concluded that Ag, Co, and Bi impurities can lead to beneficial p-type doping in MoS2 monolayered structures. With regards to doping with Zr, the acceptor levels are formed above the edge of the valence band, revealing an introduction of the p-type character.
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http://dx.doi.org/10.1039/d1dt00236hDOI Listing
May 2021

Experimental spectral characterization, Hirshfeld surface analysis, DFT/TD-DFT calculations and docking studies of (2Z,5Z)-5-(4-nitrobenzylidene)-3-N(2-methoxyphenyl)-2-N'(2-methoxyphenylimino) thiazolidin-4-one.

Heliyon 2020 Dec 22;6(12):e05754. Epub 2020 Dec 22.

College of Science, Physics Department, Alfaisal University, P.O. Box 50927, Riyadh, 11533, Saudi Arabia.

We reported an experimental and theoretical spectroscopic studies of (2Z,5Z)-5-(4-nitrobenzylidene)-3-N (2-methoxyphenyl)-2-N' (2-methoxyphenylimino) thiazolidin-4-one (CHNOS) molecule, using FT-IR, NMR spectroscopy, and density functional theory (DFT) via time-dependent schema (TD-DFT) respectively. The molecular inter-contacts were explored using Hirshfeld surfaces (HS) analysis method. Vibrational frequencies, gauge-independent atomic orbital (GIAO)H andC NMR chemical shift values and frontier molecular orbitals (FMOs) have been calculated from the optimized structure of the molecule by DFT/B3LYP functional with 6-31G(d, p) basis set. Our theoretical results show a good agreement with the experimental data. The calculated UV-visible spectrum employing TD-DFT shows electronic transitions at 388 nm and 495 nm. To get insight on the charge interaction happening inside the molecule, HOMO and LUMO were scrutinized and their calculated energy gap was found to be 2.96 eV. The molecular docking was analyzed via interplay study ofacetyl cholinesterase, and Butyrylcholinesterase using molecular docking methodology.
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http://dx.doi.org/10.1016/j.heliyon.2020.e05754DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7770550PMC
December 2020

Synthesis and Studies of Electro-Deposited Yttrium Arsenic Selenide Nanofilms for Opto-Electronic Applications.

Nanomaterials (Basel) 2020 Aug 8;10(8). Epub 2020 Aug 8.

Nano Research Laboratory, Department of Physics and Astronomy, University of Nigeria, Nsukka 410001, Nigeria.

Nanocomposite films grown by incorporating varying concentrations of Yttrium, a d-block rare-earth ion, into the binary chalcogenide Arsenic selenide host matrix is here presented. Films were grown via the wet-chemical electro-deposition technique and characterized for structural, optical, surface morphology, and photoluminescence (PL) properties. The X-ray Diffraction (XRD) result of the host matrix (pristine film) showed films of monoclinic structure with an average grain size of 36.2 nm. The composite films, on the other hand, had both cubic YAs and tetragonal YSe structures with average size within 36.5-46.8 nm. The fairly homogeneous nano-sized films are shown by the Scanning Electron Microscopy (SEM) micrographs while the two phases of the composite films present in the XRD patterns were confirmed by the Raman shifts due to the cleavage of the As-Se host matrix and formation of new structural units. The refractive index peaked at 2.63 within 350-600 nm. The bandgap energy lies in the range of 3.84-3.95 eV with a slight decrease with increasing Y addition; while the PL spectra depict emission bands across the Vis-NIR spectral regions. Theoretically, the density functional theory (DFT) simulations provided insight into the changes induced in the structure, bonding, and electronic properties. Besides reducing the bandgap of the AsSe, the yttrium addition has induced a lone pair -states of Se contributing nearby to Fermi energy level. The optical constants, and structural and electronic features of the films obtained present suitable features of film for IR applications as well as in optoelectronics.
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http://dx.doi.org/10.3390/nano10081557DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7466404PMC
August 2020

Insights into the Impact of Yttrium Doping at the Ba and Ti Sites of BaTiO on the Electronic Structures and Optical Properties: A First-Principles Study.

ACS Omega 2020 Jun 15;5(25):15502-15509. Epub 2020 Jun 15.

College of Science, Physics Department, Alfaisal University, P.O. Box 50927, Riyadh 11533, Saudi Arabia.

We reported a systematic study of the effects of Y doping BaTiO at Ba and Ti sites. We assessed the structural, electronic, and optical properties by employing first-principles calculations within the Tran-Blaha-modified Becke-Johnson (TB-mBJ) potential and generalized gradient approximation + approaches. We calculated the lattice constants and bond lengths for pure and Y-doped BaTiO. We explored the consequences of electronic structure and optical property modification because of Y doping in BaTiO. Indeed, Y doping has led to various modifications in the electronic structures of BaTiO by inducing a shift of the conduction band through lower energies for the Ba site and higher energies for the Ti site. It was found that Y doping, either at Ba or at Ti sites, strongly enhanced the BaTiO dielectric constant properties. The transformation in bonding was explored via the charge density contours and Born effective charges. We used the state of art of polarization theory based on finite difference and Berry-phase approaches to investigate piezoelectricity. Y doping has increased the dielectric constants but canceled the piezoelectricity as they changed to metallic nature. We could look into the future for potential doping, preserving the semiconductor nature of BaTiO and increasing the permittivity with large dielectric loss.
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http://dx.doi.org/10.1021/acsomega.0c01638DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7331034PMC
June 2020

Revealing the optoelectronic properties of Re-based double perovskites using the Tran-Blaha modified Becke-Johnson with density functional theory.

J Mol Model 2020 May 28;26(6):158. Epub 2020 May 28.

School of Physical Science and Technology, Southwest University, Chongqing, 400715, China.

Density functional theoretical (DFT) calculations were carried out to explore the electronic and optical properties of double ordered BaNaReO, BaLiReO, and SrLiReO perovskites by employing the state-of-the-art exchange-correlation potential, i.e., Tran-Blaha modified Becke-Johnson for the electronic system. The calculated electronic band structures show an indirect band gap along with a semiconductor nature. Total and partial densities of state peaks were analyzed in light of effective contributions of various electronic states. The significant optical parameters, including the components of dielectric constant, the energy loss function, the absorption coefficient, the reflectivity spectra, the refractive index, and the extinction coefficient, were computed and discussed in details for radiation up to 14 eV. Finally, we studied the inter-band contributions from the optical characteristics. Our present study might be considered as first theoretical quantitative calculations of the optical and electronic behavior in the cubic phase of double perovskite materials based on rhenium.
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http://dx.doi.org/10.1007/s00894-020-04421-5DOI Listing
May 2020

Toward a better understanding of the enhancing/embrittling effects of impurities in Nickel grain boundaries.

Sci Rep 2019 Oct 1;9(1):14024. Epub 2019 Oct 1.

College of Science, Physics department, Alfaisal University, P.O. Box 50927, Riyadh, 11533, Saudi Arabia.

The fracture path follows grain boundaries (GB) in most metallic system under tensile test. In general, impurities, even in ppm concentration, that segregate to these boundaries can remarkably change materials mechanical properties. Predicting impurities segregation effects in Nickel super-alloys might not be seen as intuitive and perhaps more fundamental understanding is needed. We performed a density functional theory calculation to elucidate the effect of eight light elements (B, C, N, O, Al, Si, P and S) and twelve transition metal elements (Tc, Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, Ta, W, Re) on Nickel ∑5(210) grain boundary formation and its Ni free surface. The effect of impurities was carefully examined by calculating different properties such as segregation, binding and cohesive energies, strengthening/embrittling potency and the theoretical tensile strength. Additionally, we employed the electron density differences and magnetic effects to explain why and how impurities such as B, S, V, Nb, Mn and W affect Nickel ∑5 GB. We used the generated data calculated on equal footing, to develop a fundamental understanding on impurity effect. A clear and strong correlation is found between difference in magnetic moment change between isolated and imbedded impurity atom on one hand and the tensile strength on the other hand. The higher the loss of the magnetic moment, the more the impurity consolidates the GB.
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http://dx.doi.org/10.1038/s41598-019-50361-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6773772PMC
October 2019

Electronic and optical properties of functionalized zigzag ZnO nanotubes.

J Mol Model 2018 Feb 4;24(2):48. Epub 2018 Feb 4.

College of Science, Physics department, Alfaisal University, Riyadh, 11533, Saudi Arabia.

The present paper reports the analysis of surface decoration on the structural, electronic, and optical properties of (n,0) ZnO nanotubes, performed by means of a density function theory based ab-initio approach. Fe functionalization induced buckling in ZnO nanotubes affects its electronic and optical properties. Increase in Fe functionalization leads to better stability of ZnO nanotube and shows enhanced metallic character. The possibility of its use in optoelectronics has been analyzed in terms of dielectric constant, absorption coefficient, and refractive index. In another observation, the high sensitivity of the HCN molecule for the Fe-incorporated ZnO nanotube suggests it as a potential gas sensor. Graphical abstract HCN-adsorbed Fe-ZnO nanotube, electron difference density, and PDOS analysis of different orbitals.
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http://dx.doi.org/10.1007/s00894-017-3556-9DOI Listing
February 2018

Structure-dependent optoelectronic properties of perylene, di-indenoperylene (DIP) isolated molecule and DIP molecular crystal.

Chem Cent J 2017 Dec 2;11(1):125. Epub 2017 Dec 2.

College of Science, Physics Department, Alfaisal University, P.O. Box 50927, Riyadh, 11533, Saudi Arabia.

Theoretical simulations were designed by first principles approach of density functional theory to investigate the structural and optoelectronic properties of different structural classes of perylene; isolated perylene, diindeno[1,2,3-cd:1',2',3'-lm]perylene (DIP) molecule and DIP molecular crystal. The presence of molecular interactions in DIP crystal proved its structure-dependent behaviours. The herringbone molecular arrangement of DIP crystal has influenced the electronic properties by triggering the intermolecular interactions that reduced the energy gaps between HOMO and LUMO of the crystal. Strong hybridization resulting from dense charges population near zero Fermi energy has pushed valence band maxima in the density of states of all perylene structures to higher energies. Under small energy input, charges are transferred continuously as observed in the spectra of conductivity and dielectric. The existence of strong absorption intensities are consistent with the former works and supported by the obtained polarized reflectivity and loss spectra.
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http://dx.doi.org/10.1186/s13065-017-0352-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5712299PMC
December 2017

First principles investigations of vinazene molecule and molecular crystal: a prospective candidate for organic photovoltaic applications.

J Mol Model 2015 Feb 29;21(2):27. Epub 2015 Jan 29.

Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, UTM, Skudai, 81310, Johor, Malaysia.

Escalating demand for sustainable energy resources, because of the rapid exhaustion of conventional energy resources as well as to maintain the environmental level of carbon dioxide (CO2) to avoid its adverse effect on the climate, has led to the exploitation of photovoltaic technology manifold more than ever. In this regard organic materials have attracted great attention on account of demonstrating their potential to harvest solar energy at an affordable rate for photovoltaic technology. 2-vinyl-4,5-dicyanoimidazole (vinazene) is considered as a suitable material over the fullerenes for photovoltaic applications because of its particular chemical and physical nature. In the present study, DFT approaches are employed to provide an exposition of optoelectronic properties of vinazene molecule and molecular crystal. To gain insight into its properties, different forms of exchange correlation energy functional/potential such as LDA, GGA, BLYP, and BL3YP are used. Calculated electronic structure of vinazene molecule has been displayed via HOMO-LUMO isosurfaces, whereas electronic structure of the vinazene molecular crystal, via electronic band structure, is presented. The calculated electronic and optical properties were analyzed and compared as well. Our results endorse vinazene as a suitable material for organic photovoltaic applications.
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http://dx.doi.org/10.1007/s00894-015-2582-8DOI Listing
February 2015

The origin of magnetism in transition metal-doped ZrO2 thin films: experiment and theory.

J Phys Condens Matter 2013 Oct 4;25(43):436003. Epub 2013 Oct 4.

Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 151-747, Korea.

We have investigated the magnetic properties of Fe/Co/Ni-doped ZrO2 laser ablated thin films in comparison with the known results of Mn-doped ZrO2, which is thought to be a promising material for spintronics applications. It is found that doping with a transition metal can induce room temperature ferromagnetism in 'fake' diamond. Theoretical analysis based on density functional theory confirms the experimental measurements, by revealing that the magnetic moments of Mn- and Ni-doped ZrO2 thin films are much larger than that of Fe- or Co-doped ZrO2 thin films. Most importantly, our calculations confirm that Mn- and Ni-doped ZrO2 show a ferromagnetic ground state in comparison to Co- and Fe-doped ZrO2, which favor an antiferromagnetic ground state.
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http://dx.doi.org/10.1088/0953-8984/25/43/436003DOI Listing
October 2013