Islamic Azad University at Qaemshahr

www.qaemshahriau.ac.ir
Mazandaran, Iran
SEARCH FILTERS
Time filter
Source Type

Rad A.S.,Islamic Azad University at Qaemshahr
Applied Surface Science | Year: 2015

We studied the first principles adsorption phenomena of nitrogen dioxide (NO2) and nitrous oxide (N2O) molecules on the surface of pristine graphene and Al-doped graphene using density functional theory (DFT) calculations. The adsorption energies have been calculated for different possible configurations of the molecules on the surface of pristine and Al-doped graphene. Our calculations reveal that the Al-doped graphene has significant adsorption energy, elevated net charge transferring values and smaller bond distances to gases than that of pristine graphene because of the chemical interaction of the mentioned molecules. Furthermore, the calculated density of states (DOS) show the existing of noteworthy orbital hybridization between NO2 as well as N2O and Al-doped graphene during adsorption process which is proving to strong interaction while there is no evidence for hybridization between the those molecules and the pristine graphene. Our calculated adsorption energies for the most stable states for NO2 and N2O was -62.2 kJ mol-1 (-48.5 kJ mol-1 BSSE corrected energy) and -33.9 kJ mol-1 (-22.7 kJ mol-1 corrected energy), which are correspond to chemisorption process. These results point to the suitability of Al-doped graphene as a powerful sensor for practical applications. © 2015 Elsevier B.V. All rights reserved.


Rad A.S.,Islamic Azad University at Qaemshahr | Kashani O.R.,Islamic Azad University at Qaemshahr
Applied Surface Science | Year: 2015

We have scrutinized the adsorption energy, electronic structure, natural bond analysis (NBO), density of state (DOS) and global indices for adsorption of acetyl chloride (AC) and acetyl fluoride (AF) on the surface of pristine graphene as well as Al-doped graphene. The adsorption energies have been calculated for the most stable configurations of the molecules on the surface of pristine and Al-doped graphene. According to the calculated parameters, there is very weak physical adsorption of AC and AF on pristine graphene while strong adsorption takes place in the case of Al-doped graphene. The charge transfer from adsorbed molecules to Al-doped graphene surface was confirmed by the natural bond orbital as well as the Mulliken population analysis while there is no charge transfer with pristine graphene. Additionally, the density of states results reveal that orbital hybridization takes place between above-mentioned molecules and Al-doped graphene sheet, whereas there is no hybridization between the molecules and the pristine graphene. Our calculated adsorption energies for the most stable position configurations of AC and AF on Al-doped graphene were -68.8 kJ mol-1 (-52.6 kJ mol-1 BSSE corrected energy) and -78.4 kJ mol-1 (-64.3 kJ mol-1 BSSE corrected energy) which are correspond to chemisorptions process respectively. These results point to the appropriateness of Al-doped graphene as a powerful adsorbent for practical applications. © 2015 Elsevier B.V. All rights reserved.


Shokuhi Rad A.,Islamic Azad University at Qaemshahr
Journal of Alloys and Compounds | Year: 2016

We used first principles density functional theory (DFT) to study the adsorption of mercaptopyridine molecule (as an important intermediate) on the surface of pristine as well as Al- and B-doped graphene sheets. Different possible configurations have been considered for adsorption on both sheets. The resulted electronic structure of each adsorbed system is noticeably different. Our results revealed very weak adsorption on the surface of pristine graphene while relatively high adsorption was achieved by using Al-doped graphene at proper configuration. The adsorption on the surface of B-doped graphene is considerable at proper configuration but is lower than that of Al-doped graphene. Furthermore we analyzed the parameters of electronic structures, the net charge transfer, and orbital analyses including the HOMO-LUMO distributions and also density of states (DOSs) for all possible configurations. As a result, we introduce Al- and B-doped graphenes as hopeful surfaces for adsorption of MP molecule for different purpose. © 2016 Elsevier B.V. All rights reserved.


Rad A.S.,Islamic Azad University at Qaemshahr
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2016

The adsorption energies and orientation of single alcohol molecule (methanol and ethanol) on the surface of Pt-decorated graphene (PtG) were determined from first-principles density functional (DFT) calculations. We found the same adsorption energies as well as connecting distances upon adsorption of MeOH and EtOH on PtG surface, in which at their relaxed structures, the O atom of alcohol is closed to the Pt of PtG surface. We found high adsorption energies, low connecting distances, and high orbital hybridizing upon adsorption of EtOH and MeOH molecules on PtG surface. There are significant shifts in the location of both the HOMO and LUMO, in addition to variation in the charge transfer when the MeOH and EtOH are adsorbed on PtG surface. © 2016 Elsevier B.V. All rights reserved.


Shokuhi Rad A.,Islamic Azad University at Qaemshahr
Journal of Molecular Modeling | Year: 2015

The interaction of methanol with terthiophene (3PT; a model of polythiophene) was investigated using density functional theory (DFT) at the BLYP-D3/6-31+G(d,p) level of theory. The computed density of states (DOS) pointed to considerable orbital hybridization upon the interaction of methanol with 3PT. Natural population analysis (NPA) was used to determine the charge distribution as well as the net charge transfer within the 3PT–methanol system, and thus to assess the sensing ability of terthiophene. The computed dipole moment revealed that the dielectric μD changes upon the interaction of methanol with 3PT. Using calculated changes in the HOMO-LUMO energy gap, it was deduced that the electronic properties of 3PT are sensitive to the interaction of 3PT with methanol. After full energy relaxation, the interaction energy of methanol with 3PT in the most stable configuration was calculated to be −16.4 (counterpoise-corrected energy: −13.5) kJ mol−1, providing proof that methanol is physisorbed by 3PT. [Figure not available: see fulltext.] © 2015, Springer-Verlag Berlin Heidelberg.


Rad A.S.,Islamic Azad University at Qaemshahr
Surface Science | Year: 2016

We have studied the electronic structure and property of pristine as well as Al-doped graphene sheets towards adsorption of some halomethane compounds (trichloromethane, dichloromethane, and difluoromethane) using density functional theory (DFhsT) calculations. The adsorption energies have been calculated for each adsorbed-adsorbent system. Based on our results, compared to pristine graphene, the Al-doped graphene causes significant adsorption energy, higher charge transferring, and smaller bond distances to halomethane compounds. Our calculated adsorption energies of trichloromethane, dichloromethane, and difluoromethane on Al-doped graphene were - 54.1, - 68.3, and - 123.2 kJ mol- 1, respectively, which are categorized in the chemisorption region while the adsorption of these molecules on pristine graphene release insignificant energies which correspond to very weak adsorption on it. Furthermore, we used charge transfer analysis to search the amount of electron allocation. Orbital analysis including the density of states (DOS) was done to find the possible orbital hybridization between adsorbates and two graphene sheets. These results imply the suitability of Al-doped graphene as a good adsorbent/sensor for halomethane compounds. © 2015 Elsevier B.V. All rights reserved.


Ebrahimnejad A.,Islamic Azad University at Qaemshahr
Applied Soft Computing Journal | Year: 2014

In a recent paper, Kaur and Kumar (2012) proposed a new method based on ranking function for solving fuzzy transportation problem (FTP) by assuming that the values of transportation costs are represented by generalized trapezoidal fuzzy numbers. Here it is shown that once the ranking function is chosen, the FTP is converted into crisp one, which is easily solved by the standard transportation algorithms. The main contribution here is the reduction of the computational complexity of the existing method. By solving two application examples, it is shown that it is possible to find a same optimal solution without solving any FTP. Since the proposed approach is based on classical approach it is very easy to understand and to apply on real life transportation problems for the decision makers. © 2014 Elsevier B.V.


Ebrahimnejad A.,Islamic Azad University at Qaemshahr
Mathematical and Computer Modelling | Year: 2011

In this paper, we generalize the concept of sensitivity analysis in fuzzy number linear programming (FLNP) problems by applying fuzzy simplex algorithms and using the general linear ranking functions on fuzzy numbers. The purpose of sensitivity analysis is to determine changes in the optimal solution of FNLP problem resulting from changes in the data. If the change affects the optimality of the basis, we perform primal pivots to achieve optimality by use of the fuzzy primal simplex method. Whenever the change destroys the feasibility of the optimal basis, we perform dual pivots to achieve feasibility by use of the fuzzy dual simplex method. © 2011 Elsevier Ltd.


Rad A.S.,Islamic Azad University at Qaemshahr
Synthetic Metals | Year: 2016

Adsorption properties of C2H2 and C2H4 gas molecules on Pt-decorated graphene (PtG) have been examined using first-principles density functional theory (DFT) calculations. A particular interesting aspect of PtG is that the Pt atom influences the electronic structure of graphene through coulombic charge-transferring. Upon adsorption of C2H2 and C2H4 on PtG, the C-C axis remains essentially parallel to the surface. We found high values of adsorption energy, low connecting distance, and high orbital hybridizing upon adsorption of C2H2 and C2H4 gas molecules on PtG. There are significant shift in both the HOMO and LUMO locations. Moreover there are significant changes in charge transfer upon adsorption of C2H2 and C2H4 on PtG. Our studies support the efficacy of graphene including Pt atom toward adsorption of C2H2 and C2H4 which is applicable for different targets such as study on heterogeneous reactions. © 2015 Elsevier B.V.


Zareyee D.,Islamic Azad University at Qaemshahr | Serehneh M.,Islamic Azad University at Qaemshahr
Journal of Molecular Catalysis A: Chemical | Year: 2014

Sulfonic acid modified nanostructured CMK-5 is used as an alternative to conventional acid catalysts in the von Pechmann condensation of a neat mixture of substituted phenols with ethyl acetoacetate leading to the formation of coumarin derivatives at 130 °C. In comparison, CMK-5-SO3H showed a greater activity than some other homogeneous and heterogeneous catalysts. Additionally, the catalyst is reused repeatedly for 6 reaction cycles without any evidence of loss of activity, confirming the stability of the covalent bonding of acidic centers. The methodology presented offers reusable strategy for the efficient synthesis of coumarin, simplicity in operation, and green aspects by avoiding toxic conventional catalysts and solvents. © 2014 Elsevier B.V.

Loading Islamic Azad University at Qaemshahr collaborators
Loading Islamic Azad University at Qaemshahr collaborators