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Density Functional Theory Study of Atomic Layer Deposition of Zinc Oxide on Graphene.

Ali AA, Hashim AM - Nanoscale Res Lett (2015)

Bottom Line: Furthermore, the relative energies of the various intermediates and products in the gas-phase radical mechanism were calculated at the B3LYP/6-311++G** and MP2/6-311 + G(2df,2p) levels of theory.The reaction energies were calculated, and the reaction mechanism was accordingly proposed.A simulation of infrared (IR) properties was performed using the same approach to support the proposed mechanism via a complete explanation of bond forming and breaking during each reaction step.

View Article: PubMed Central - PubMed

Affiliation: Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100, Kuala Lumpur, Malaysia, amgkhalil2@yahoo.com.

ABSTRACT
The dissociation of zinc ions (Zn(2+)) from vapor-phase zinc acetylacetonate, Zn(C5H7O2)2, or Zn(acac)2 and its adsorption onto graphene oxide via atomic layer deposition (ALD) were studied using a quantum mechanics approach. Density functional theory (DFT) was used to obtain an approximate solution to the Schrödinger equation. The graphene oxide cluster model was used to represent the surface of the graphene film after pre-oxidation. In this study, the geometries of reactants, transition states, and products were optimized using the B3LYB/6-31G** level of theory or higher. Furthermore, the relative energies of the various intermediates and products in the gas-phase radical mechanism were calculated at the B3LYP/6-311++G** and MP2/6-311 + G(2df,2p) levels of theory. Additionally, a molecular orbital (MO) analysis was performed for the products of the decomposition of the Zn(acac)2 complex to investigate the dissociation of Zn(2+) and the subsequent adsorption of H atoms on the C5H7O2 cluster to form acetylacetonate enol. The reaction energies were calculated, and the reaction mechanism was accordingly proposed. A simulation of infrared (IR) properties was performed using the same approach to support the proposed mechanism via a complete explanation of bond forming and breaking during each reaction step.

No MeSH data available.


Related in: MedlinePlus

a–f Potential energy profile showing the relative energies for the dissociation reaction calculated at the B3LYP/6-311 + G(d,p) level of theory
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Fig2: a–f Potential energy profile showing the relative energies for the dissociation reaction calculated at the B3LYP/6-311 + G(d,p) level of theory

Mentions: The relative energies for the transition states, intermediate, and products in the gas-phase reaction mechanism were calculated at the B3LYP/6-311++G** and MP2/6-311 + G(2df,2p) levels of theory. The calculated energy data are depicted in the reaction coordinate pathway in Fig. 2. The reaction starts when two H atoms approach the Zn(acac)2 complex. H atoms are then adsorbed, as shown by step (a) in the reaction pathway in Fig. 2. The chemical reactions involve several distinct steps including two transition states (steps (b) and (e)) and one intermediate step (step (d)). The first transition state (TS1) occurs when secondary bonds are constructed between the 2H atoms and the O atoms. The relative energy for TS1 was calculated to be 24.70 kcal/mol (Fig. 2). The initial transition reaction leads to twisted and stretched Zn–O bonds at a calculated energy of 19.66 kcal/mol (step (c)). This reaction cycle appears to be endothermic because the energy of the products is higher than the energy of the reactants. As the reaction proceeds, Zn2+ dissociates due to the breaking of Zn–O bonds; consequently, the O–H bonds become stronger, and TS2 is formed (step (d), Fig. 2). The calculated energy barrier for the dissociation of Zn2+ was found to be 61.78 kcal/mol. The reaction is terminated when the O–H bond is formed at a calculated energy of −95.18 kcal/mol (step (e)). The overall dissociation reaction can be then summarized as shown in Eq. (2).Fig. 2


Density Functional Theory Study of Atomic Layer Deposition of Zinc Oxide on Graphene.

Ali AA, Hashim AM - Nanoscale Res Lett (2015)

a–f Potential energy profile showing the relative energies for the dissociation reaction calculated at the B3LYP/6-311 + G(d,p) level of theory
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4510105&req=5

Fig2: a–f Potential energy profile showing the relative energies for the dissociation reaction calculated at the B3LYP/6-311 + G(d,p) level of theory
Mentions: The relative energies for the transition states, intermediate, and products in the gas-phase reaction mechanism were calculated at the B3LYP/6-311++G** and MP2/6-311 + G(2df,2p) levels of theory. The calculated energy data are depicted in the reaction coordinate pathway in Fig. 2. The reaction starts when two H atoms approach the Zn(acac)2 complex. H atoms are then adsorbed, as shown by step (a) in the reaction pathway in Fig. 2. The chemical reactions involve several distinct steps including two transition states (steps (b) and (e)) and one intermediate step (step (d)). The first transition state (TS1) occurs when secondary bonds are constructed between the 2H atoms and the O atoms. The relative energy for TS1 was calculated to be 24.70 kcal/mol (Fig. 2). The initial transition reaction leads to twisted and stretched Zn–O bonds at a calculated energy of 19.66 kcal/mol (step (c)). This reaction cycle appears to be endothermic because the energy of the products is higher than the energy of the reactants. As the reaction proceeds, Zn2+ dissociates due to the breaking of Zn–O bonds; consequently, the O–H bonds become stronger, and TS2 is formed (step (d), Fig. 2). The calculated energy barrier for the dissociation of Zn2+ was found to be 61.78 kcal/mol. The reaction is terminated when the O–H bond is formed at a calculated energy of −95.18 kcal/mol (step (e)). The overall dissociation reaction can be then summarized as shown in Eq. (2).Fig. 2

Bottom Line: Furthermore, the relative energies of the various intermediates and products in the gas-phase radical mechanism were calculated at the B3LYP/6-311++G** and MP2/6-311 + G(2df,2p) levels of theory.The reaction energies were calculated, and the reaction mechanism was accordingly proposed.A simulation of infrared (IR) properties was performed using the same approach to support the proposed mechanism via a complete explanation of bond forming and breaking during each reaction step.

View Article: PubMed Central - PubMed

Affiliation: Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100, Kuala Lumpur, Malaysia, amgkhalil2@yahoo.com.

ABSTRACT
The dissociation of zinc ions (Zn(2+)) from vapor-phase zinc acetylacetonate, Zn(C5H7O2)2, or Zn(acac)2 and its adsorption onto graphene oxide via atomic layer deposition (ALD) were studied using a quantum mechanics approach. Density functional theory (DFT) was used to obtain an approximate solution to the Schrödinger equation. The graphene oxide cluster model was used to represent the surface of the graphene film after pre-oxidation. In this study, the geometries of reactants, transition states, and products were optimized using the B3LYB/6-31G** level of theory or higher. Furthermore, the relative energies of the various intermediates and products in the gas-phase radical mechanism were calculated at the B3LYP/6-311++G** and MP2/6-311 + G(2df,2p) levels of theory. Additionally, a molecular orbital (MO) analysis was performed for the products of the decomposition of the Zn(acac)2 complex to investigate the dissociation of Zn(2+) and the subsequent adsorption of H atoms on the C5H7O2 cluster to form acetylacetonate enol. The reaction energies were calculated, and the reaction mechanism was accordingly proposed. A simulation of infrared (IR) properties was performed using the same approach to support the proposed mechanism via a complete explanation of bond forming and breaking during each reaction step.

No MeSH data available.


Related in: MedlinePlus