| 1. |
- Bouziani, I, et al.
(författare)
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Electronic and optical properties of ZnO nanosheet doped and codoped with Be and/or Mg for ultraviolet optoelectronic technologies : density functional calculations
- 2020
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Ingår i: Physica Scripta. - : IOP PUBLISHING LTD. - 0031-8949 .- 1402-4896. ; 95:1
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Tidskriftsartikel (refereegranskat)abstract
- Theoretically, the density functional calculations have been effectuated for investigating electronic and optical properties of zinc oxide nanosheet doped and codoped with Be and/or Mg utilizing the generalized gradient approximation modified Becke-Johnson (GGA-mBJ) approach. The computed results show that the ZnBeO, ZnMgO and ZnBeMgO in nanosheet structure, referring to their low formation energy values, are more stable than those in bulk one. Furthermore, the bandgap of ZnO monolayer can be effectively modulated through substitution of Zn atoms by Be and/or Mg. In addition to that, by incorporating Be and/or Mg, the absorption peaks of ZnO nanosheet shift into the shorter UV-wavelength side as well as its reflectivity becomes lower. These results indicate that doping and codoping process of ZnO monolayer with Be and/or Mg are two efficient ways to modulate electronic and optical properties for ultraviolet optoelectronic technologies.
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| 2. |
- Khossossi, Nabil, et al.
(författare)
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Hydrogen storage characteristics of Li and Na decorated 2D boron phosphide
- 2020
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Ingår i: Sustainable Energy & Fuels. - : Royal Society of Chemistry (RSC). - 2398-4902. ; 4:9, s. 4538-4546
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Solid-state systems serve as a candidate for clean energy applications driven by current technological demands. In this effort, density functional theory (DFT) has become a valuable asset to investigate the intrinsic electronic properties and holds a substantial promise for guiding the discovery of new materials. Herein, we have investigated the Li and Na decorated 2D boron phosphide (BP) monolayer as a potential candidate for hydrogen storage due to its lightweight and structural stability. Li and Na adatoms prefer to adsorb at the center of the hexagon with the binding energies 0.36 and 0.26 eV, respectively. The thermodynamic stabilities of BP monolayer in cases of 4Li@BP and 4Na@BP systems were evaluated at room temperature using ab initio molecular dynamics (AIMD) simulations. The study of the electronic structure revealed that the semiconducting BP sheets become metallic after the adatom adsorption. It was found that the dispersed Li and Na atoms on the monolayer surface significantly increase both the hydrogen binding energies and the hydrogen storage capacities. With one-sided coverage of Li and Na atoms, four H2 molecules were adsorbed with a gravimetric capacity of 4.917 and 4.558 wt%, respectively. For double-sided adatom coverage, a total of 16H2 molecules was captured around 4Li@BP and 4Na@BP complex with a gravimetric capacity of 7.402 and 6.446 wt%, respectively. These results suggest that boron phosphide (BP) can act as an effective substrate for H2 storage by carefully engineering it with metal decoration.
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| 3. |
- Khossossi, Nabil, et al.
(författare)
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Rational Design of 2D h-BAs Monolayer as Advanced Sulfur Host for High Energy Density Li-S Batteries
- 2020
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 3:8, s. 7306-7317
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Tidskriftsartikel (refereegranskat)abstract
- The emergence of compact lithium-sulfur (Li-S) batteries with improved performances is becoming one of the most desirable aspects of future energy technologies. Beyond Li-ion batteries, Li-S is of great relevance to follow as it adapts to the specificity of each application. It is among the most suitable elements for high-performance energy storage systems, given its high theoretical capacity (1674 mA h g(-1)) and energy density (2600 W h kg(-1)) relative to Li-ion batteries (300 W h kg(-1)). Nevertheless, the high-cell polarization and the shuttle effect constitute an enormous challenge toward the concrete applications of Li-S batteries. In the framework of this work, density functional theory calculations have been carried out to analyze the potential of h-BAs nanosheets as a promising host material for Li-S batteries. Binding and electronic characteristics of lithium polysulfides (LiPSs) adsorbed on h-BAs surface have been explored. Reported findings highlight the potential of the hBAs monolayer as a moderate host material, given that the binding energies of different LiPSs vary from 0.47 to 3.55 eV. More detailed analysis of the complex binding mechanisms is carried out by investigating the components of van der Waals physical/chemical interactions. The defected surface of the h-BAs monolayer has optimum binding energies with LiPSs for Li-S batteries. All these findings provide valuable insights into the binding and electronic characteristics of the h-BAs monolayer as a moderate host material for Li-S batteries.
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