Print ISSN: 1812-125X

Online ISSN: 2664-2530

Main Subjects : Materials science

Theoretical study of hydrogen adsorption on graphene nanostructures functionalized with nickel for solid state hydrogen storage

ameer albyatei; Issa Zainalabddeen assaflly

JOURNAL OF EDUCATION AND SCIENCE, 2021, Volume 30, Issue 2, Pages 19-32
DOI: 10.33899/edusj.2020.128376.1112

Hydrogen adsorption and storage on nickel- activated, pure graphene and boron-doped graphene was study using density functional theory simulations based on generalized gradient approximation methods (DFT-GGA). It was found that the nickel atoms tend to clustering on the surface of pure graphene due to the high cohesive energy of nickel compared to the energy of nickel binding to the surface of pure graphene, which decrease the storage capacity of hydrogen. It was also found that the storage capacity of seven hydrogen molecules on pure and activated graphene with a nickel atom is equal to (10.2 wt.%) With an average binding energy (0.27 eV), and the storage capacity for the same number of hydrogen molecules is (11.3 wt.%) With an average binding energy (0.22 eV), This indicates that the adsorption process will take place at ambient conditions. The process of inoculating graphene-doped boron and nickel activating is an effective strategy for improving the average binding energies and the storage capacity of hydrogen molecules in the graphene nanostructures.

An Overview of the Evolution of the Porous Silicon material: A review

Ghazwan Ghazi Ali; Marwan Hafeedh Younus; Ivan Karomi

JOURNAL OF EDUCATION AND SCIENCE, 2021, Volume 30, Issue 2, Pages 42-52
DOI: 10.33899/edusj.2020.128341.1111

Recently, the properties and applications of the porous became the main subject of several books and the vast numbers of review articles. Porous silicon has demonstrated significant versatility and promise for a wide range of optoelectronic applications thanks to its large surface area and intense photoluminescence at room temperature. In this review, we describe the fabrication techniques and experimental improvements made towards porous silicon (PSi) and we provide a full picture of realization and characterization of this material. We also highlight its important properties, such as chemical, structure and surface properties. We summarize the techniques that have been used, including Fourier transform infrared spectroscopy, X-ray diffraction measurements, atomic force microscope images (AFM) and a scanning probe microscope (SEM). Additionally, the effect of the current density and etching time are also documented in this review. In summary, porous silicon has undergone vast improvement in both fabrication and characterization methods, which makes it an attractive modern material.

A Study of Optical Properties of Tetraborate Glasses Containing CaO, MgO & BaO

Aynur Bahaaldeen Baha. kamal; Manaf A.Hassan al-azzawi

JOURNAL OF EDUCATION AND SCIENCE, 2021, Volume 30, Issue 1, Pages 10-23
DOI: 10.33899/edusj.2020.127127.1076

Glasses with compositions (100-x) % Na2B4O7–x % MO (X=10,20,30,40) where (M) is Ba, Mg and Ca, are prepared using conventional melt quenching method. X-rays diffractions are performed. The result of (XRD) confirm the amorphous nature of the samples. The measured density increases with increasing content of BaO, MgO & CaO in glass network. The position and shifting rate of absorption edge, optical band energy (Eopt) and band tails energy (Eo) were investigated. The Eopt and Eo values of all glasses studied in this work were found to be comparable with the values corresponding to some semiconductors. The structure of the glasses was investigated by means of IR spectroscopy. It found from the experimental results of IR spectra that the groups (BO3)- and (B2O7)- are dominant the structure of these glasses. Also It is found that the shifting in band position is small with increasing of (Ba, Mg, Ca) oxide in the glass network.

Studying the Parameter Gradient Energy Coefficient of Polyethylene Glycol as a Function of Molecular Weight in conjunction with Freed Contribution

Malak Jaafar Ali; Saygin Muhamed Nuri; Shany Muhamed Rajab

JOURNAL OF EDUCATION AND SCIENCE, 2020, Volume 29, Issue 2, Pages 201-215
DOI: 10.33899/edusj.2019.126025.1016

This work studies the gradient energy coefficient ( ) which has the main function in extracting the properties of the polymer, starting from the Simha-Somcynsky theory (SS) that describes the thermodynamic properties of both low and high molecular weights in terms of occupied site fraction (y). Cahn-Hilliard (CH) theory which clarifies the free energy profile of polymer surfaces or interfaces has been also adopted in this study. To gain accurate results, these two theories have been combined with that of Freed Bawendi, which gives the architecture structure for the polymers. Ultimately, the conjunction of these theories produces important properties of polymers such as; the molecular weight, surface tension, the gradient energy coefficient. This study has been performed in the temperature range (313 -473) K and up to about (150) Mpa of pressure according to the international condition of LaGrange for polymers. The success of our study can be clearly seen in the minimum and maximum deviations in (0.036) and (0.128) respectively, while the exact value of gradient energy coefficient has been proved in the high molecular weight polymers as in (PEG 18500). The gradient energy coefficient and the reduced surface tension are directly proportional to molecular weight, while the gradient energy coefficient is inversely proportional to both hole fraction and temperature. The study has been accurately proved by the obtained results and data given in the graphs.