Mohammed Benaissa

Adsorption and diffusion on a phosphorene monolayer: a DFT study

A computational study of the adsorption and diffusion behavior of alkali and alkaline earth metal atoms on a phosphorene monolayer is reported. Our calculations were performed within the framework of density functional theory using the Perdew–Burke–Ernzerhof functional and projector augmented wave potentials, as derived from the generalized gradient approximation. Our binding energy calculations for various potential adsorption sites showed that the site located above the center of a triangle formed by three surface phosphorus atoms is the most attractive to all adatoms. In addition, simulation of the diffusion of adatoms across the surface of the phosphorene monolayer showed that the diffusion is anisotropic, with K having the lowest diffusion barrier (0.02xa0eV along the zigzag pathway). To the best of our knowledge, this is the lowest diffusion barrier of any metal adatom on a single layer of phosphorene. While phosphorene exhibited significantly better adatom adsorption and diffusion than graphene, it also showed a reduced storage capacity compared to graphene, most probably due to the structural distortion induced by the oversaturated phosphorene surface. This finding strongly suggests that a phosphorene–graphene hybrid system could be employed as a promising high-capacity ion anode.

Simple preparation of high transparent tin dioxide thin films by spin coating method: Effect of sol concertation

Successful simple preparation of nanocrystalline SnO2 films was performed by the Sol-Gel spin coating method in an alcoholic medium without any complexing agent. The precursor concentration effect on structural, optical and electrical properties was examined. The X-ray Diffraction (XRD) characterization shows the formation of single tetragonal rutile phase with (110) plan as preferential orientation. Excellent high transmittance greater than 97% in visible was measured by Ultraviolet-visible spectroscopy (UV-Vis). The presence of the interference fringes reflects that the obtained films are thick enough. The results reveal that increasing in precursor concentration leads peak intensity (110), particle size, film thickness and absorbance to increase as well. While the optical transmittance decrease when increasing the precursor concentration.

Phosphorene as a promising anode material for lithium-ion batteries: A first-principle study

Density functional theory calculations (DFT), including van der Waals interactions, have been carried out to evaluate the prospects of a novel 2D nanomaterial, phosphorene as a promising anode material for Li-ion batteries. We determined adsorption energies and diffusion barriers on different paths of a single layer phosphorene. Our results showed that at low coverage, Li binds strongly with phosphorene with a significant charge transfer. After lithiation of phosphorene, a semiconductor-to-conductor transition is observed. We also found that a single Li-ion diffuses more easily along the open channel (a barrier of 90 meV) against a high barrier (close to 0.5 eV) across channels. In addition, the average voltage of the Li intercalation is estimated to be 4.4 V, suitable for high charging voltage applications in LIBs. Our investigation suggests that phosphorene could make a competitive candidate for battery applications as an anode material compared to other classical materials such as graphite.

A new methodology to select the thermal solar collectors by localizations and applications

The temperature requirements of the majority of solar thermal collectors applications is between 40°C and 260°C. The characteristics of low to medium-high temperature solar collectors are given and an overview of the relation between the efficiency and operating temperature of existing technologies is presented. Four thermal collectors have been considered in this study varying from the simple stationary flat plate to a movable parabolic trough one. Based on theoretical studies of solar systems, a mapping for various solar technologies was performed to different climate zones and different heat demand. The study was based on three criteria. Firstly, the industrial process heat demand, secondly, the efficiency of the solar thermal collectors (STC) and at last, the solar potential in different localizations. The viabilities of the systems depend primarily on these criteria.

Accurate band gaps for earth-abundant photovoltaic absorber from density functional theory

First-principles calculations of the electronic and optical properties of Cu₂ZnSnSe₄ (CZTSe) and Cu₂ZnSnS₄ (CZTS) are simulated within the framework of the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) a sufficiently adequate approach, namely self-interaction-corrected local-density-approximation (SIC-LDA) exchange correlation potential is employed for calculating the energy band gap and electronic structure of Cu₂ZnSnSe₄ and Cu₂ZnSnS₄ based solar cells systems. This work presents detailed information about total and atom projected density of states functions, for different atoms in Cu₂ZnSnSe₄ and Cu₂ZnSnS₄. We show that density functional theory is a very powerful tool for: studying the local doping effects, defects effect, size and disorder effect on optical and electronic properties of these materials, and predicting properties of new materials.