| 1. |
- Amin, M. A., et al.
(författare)
-
Synthesis of Cyano-Benzylidene Xanthene Synthons Using a Diprotic Brønsted Acid Catalyst, and Their Application as Efficient Inhibitors of Aluminum Corrosion in Alkaline Solutions
- 2022
-
Ingår i: Molecules. - : MDPI AG. - 1420-3049. ; 27:17
-
Tidskriftsartikel (refereegranskat)abstract
- Novel cyano-benzylidene xanthene derivatives were synthesized using one-pot and condensation reactions. A diprotic Brønsted acid (i.e., oxalic acid) was used as an effective catalyst for the promotion of the synthesis process of the new starting xanthene–aldehyde compound. Different xanthene concentrations (ca. 0.1–2.0 mM) were applied as corrosion inhibitors to control the alkaline uniform corrosion of aluminum. Measurements were conducted in 1.0 M NaOH solution using Tafel extrapolation and linear polarization resistance (LPR) methods. The investigated xanthenes acted as mixed-type inhibitors that primarily affect the anodic process. Their inhibition efficiency values were enhanced with inhibitor concentration, and varied according to their chemical structures. At a concentration of 2.0 mM, the best-performing studied xanthene derivative recorded maximum inhibition efficiency values of 98.9% (calculated via the Tafel extrapolation method) and 98.4% (estimated via the LPR method). Scanning electron microscopy (SEM) was used to examine the morphology of the corroded and inhibited aluminum surfaces, revealing strong inhibitory action of each studied compound. High-resolution X-ray photoelectron spectroscopy (XPS) profiles validated the inhibitor compounds’ adsorption on the Al surface. Density functional theory (DFT) and Monte Carlo simulations were applied to investigate the distinction of the anticorrosive behavior among the studied xanthenes toward the Al (111) surface. The non-planarity of xanthenes and the presence of the nitrile group were the key players in the adsorption process. A match between the experimental and theoretical findings was evidenced. © 2022 by the authors.
|
|
| 2. |
- Mersal, G. A. M., et al.
(författare)
-
Study of half metallic ferromagnetism and thermoelectric properties of spinel chalcogenides BaCr2X4 (X 1/4 S, Se, Te) for spintronic and energy harvesting
- 2022
-
Ingår i: Journal of Materials Research and Technology-Jmr&T. - : Elsevier BV. - 2238-7854. ; 18:May–June 2022, s. 2831-2841
-
Tidskriftsartikel (refereegranskat)abstract
- The control of spin degree of freedom in electronics open new horizons to manipulate, transfer, and storage data at fasters speed. For this the structural, electronic, and magnetic characteristics of BaCr2X4 (X 1/4 S, Se, Te) spinels are addressed comprehensively. The more energy release in ferromagnetic states than antiferromagnetic states, and formation energy verified thermal stability in FM states. The Curie temperature, and spin polarization density have been reported for room temperature ferromagnetism. The detail and nature of ferromagnetism have illustrated by band structures, density of states, hybridization, double exchange mechanism, crystal field energy, exchange energies and exchange constants. The transfer of magnetic moment from Cr sites to other nonmagnetic sites (Ba, X)
|
|
| 3. |
- Amin, Mohammed A., et al.
(författare)
-
Elemental Variability of PM2.5 Aerosols in Historical and Modern Areas of Jeddah, Saudi Arabia
- 2022
-
Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 13:12
-
Tidskriftsartikel (refereegranskat)abstract
- Air particulate matter with a diameter of 2.5 µm (PM2.5) were assembled for a whole year from the historical Jeddah district. Additional PM2.5 aerosols were collected during the autumn and winter seasons from another newly constructed district in Jeddah city (Alnaeem). The annual concentration of the total mass of the PM2.5 aerosols from the historical Jeddah site was found to be 43 ± 6 µg/m3. In addition, the average of the total mass concentration at the Alnaeem site was 61 ± 14 µg/m3. These values were greater than the annual mass concentration of the air quality standards of the European Commission (25 µg/m3) and the World Health Organization (10 µg/m3). The elemental analysis of the collected fine atmospheric aerosols was achieved by energy dispersive X-ray fluorescence (EDXRF) with three secondary targets (CaF2, Ge, and Mo). Quantitative elemental analyses of twenty-two (22) elements were achieved starting from the low atomic number element (Na) up to the high atomic number element (Pb). Although the historical Jeddah site is not well organized, the elemental concentrations and total mass concentrations were lower than those of the other site. The statistical analyses including enrichment factors, correlation analysis, and the principal component analysis revealed more information about the source identification of the PM2.5 aerosols collected from both locations. It was recognized that the elements Al, Si, K, Ca, Ti, Mn, Fe, Rb, and Sr originated from a natural source. On the other hand, the elements Ta, Br, Pb, Sc, Ni, Cu, Zn, and S originated from anthropogenic sources. Finally, the elements Na, Cl, and Br came mainly from the sea spray source.
|
|
| 4. |
- Amin, Mohammed A., et al.
(författare)
-
Non-Covalent Functionalization of Graphene Oxide-Supported 2-Picolyamine-Based Zinc(II) Complexes as Novel Electrocatalysts for Hydrogen Production
- 2022
-
Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 12:4
-
Tidskriftsartikel (refereegranskat)abstract
- Three mononuclear 2-picolylamine-containing zinc(III) complexes viz [(2-PA)2ZnCl]2(ZnCl4)] (Zn1), [(2-PA)2Zn(H2O)](NO3)2] (Zn2) and [Zn(2-PA)2(OH)]NO3] (Zn3) were synthesized and fully characterized. Spectral and X-ray structural characteristics showed that the Zn1 complex has a square-pyramidal coordination environment around a zinc(II) core. The hydroxide complex Zn3 was non-covalently functionalized with few layers of graphene oxide (GO) sheets, formed by exfoliation of GO in water. The resulting Zn3/GO hybrid material was characterized by FT-IR, TGA-DSC, SEM-EDX and X-ray powder diffraction. The way of interaction of Zn3 with GO has been established through density functional theory (DFT) calculations. Both experimental and theoretical findings indicate that, on the surface of GO, the complex Zn3 forms a complete double-sided adsorption layer. Zn3 and its hybrid form Zn3/GO have been individually investigated as electrocatalysts for the hydrogen evolution reaction. The hybrid heterogenized form Zn3/GO was supported on glassy carbon (GC) with variable loading densities of Zn3 (0.2, 0.4 and 0.8 mg cm−2) to form electrodes. These electrodes have been tested as molecular electrocatalysts for the hydrogen evolution reaction (HER) using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in 0.1 M KOH. Results showed that both GC-Zn3 and GC-Zn3/GO catalysts for the HER are highly active, and with increase of the catalyst’s loading density, this catalytic activity enhances. The high catalytic activity of HER with a low onset potential of −140 mV vs. RHE and a high exchange current density of 0.22 mA cm−2 is achieved with the highest loading density of Zn3 (0.8 mg cm−2). To achieve a current density of 10 mA cm−2, an overpotential of 240 mV was needed.
|
|
