scholarly journals [Au(CN)2]—Adsorption on a Graphite (0001) Surface: A First Principles Study

Minerals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 425 ◽  
Author(s):  
Xianhai Li ◽  
Qin Zhang ◽  
Jun Xie ◽  
Zhihui Shen
Keyword(s):  
Density Functional ◽  
Adsorption Mechanism ◽  
Physical Adsorption ◽  
Energy Levels ◽  
Mulliken Charge ◽  
Cyanide Leaching ◽  
Functional Theory ◽  
Electrostatic Adsorption ◽  
Bond Population ◽  
Valence Bands

Gold is mainly present in the form of [Au(CN)2]− during the cyanide leaching process, and this [Au(CN)2]− can be adsorbed by graphite in carbonaceous gold ore resulting in preg-robbing gold. In order to clarify the adsorption mechanism between the [Au(CN)2]− and graphite, the interaction between the [Au(CN)2]− and graphite (0001) surface was studied using density functional theory (DFT). The distance between [Au(CN)2]− and graphite (0001) decreased from (4.298–4.440 Å) to (3.123–3.343 Å) after optimization, and the shape of [Au(CN)2]− and graphite (0001) obviously changed from straight to curved, which indicated that the [Au(CN)2]− had been adsorbed on the graphite (0001) surface. A partial densities of state (PDOS) analysis revealed that there was little change in the delocalization and locality of the PDOS on the graphite (0001) surface after adsorption. However, the valence bands of the Au 5d orbital, C 2p orbital, and N 2p orbital near the Fermi level moved slightly towards lower energy levels; therefore, the adsorption configuration was stable. An analysis of the Mulliken charge population indicated that the Au, N, and C in [Au(CN)2]− obtained 0.26, 0.18, 0.04 electrons after adsorption, respectively, while C(surf) lost 0.03 electrons. [Au(CN)2]− changed to a conductor from an insulator after adsorption. Taking into account the surface electrical properties of [Au(CN)2]− and graphite (0001), there was still a slight electrostatic adsorption between them. The analysis of adsorption energy, electronic structure, PDOS, electron density, Mulliken charge population, and Mulliken bond population revealed that [Au(CN)2]− could be adsorbed to the graphite (0001) surface; the adsorption was a type of physical adsorption (including electrostatic adsorption) and mainly occurred on the two C≡N. These results contributed to the understanding of the mechanisms involved in preg-robbing gold formation by graphite and the optimization of this process during cyanide leaching.

scholarly journals DFT Calculations and Experimental Study to Inhibit Carbon Steel Corrosion in Saline Solution by Quinoline-2-One Derivative

2021 ◽  
Vol 18 (1) ◽  
pp. 0113
Author(s):  
Rehab Majid Kubba ◽  
Mustafa Alaa Mohammed ◽  
Luma S. Ahamed
Keyword(s):  
Carbon Steel ◽  
Density Functional ◽  
Adsorption Mechanism ◽  
Saline Solution ◽  
Physical Adsorption ◽  
Steel Corrosion ◽  
Equilibrium Geometry ◽  
Functional Theory ◽  
Carbon Steel Surface ◽  
Chemical Inhibition

A theoretical and protection study was conducted of the corrosion behavior of carbon steel surface with different concentrations of the derivative (Quinolin-2-one), namly (1-Amino-4,7-dimethyl-6-nitro-1H-quinolin-2-one (ADNQ2O)). Theoretically, Density Functional Theory (DFT) of B3LYP/ 6-311++G (2d, 2p) level was used to calculate the optimized geometry, physical properties and chemical inhibition parameters, with the local reactivity to predict both the reactive centers and to locate the possible sites of nucleophilic and electrophilic attacks, in vacuum, and in two solvents (DMSO and H2O), all at the equilibrium geometry. Experimentally, the inhibition efficiencies (%IE) in the saline solution (of 3.5%) NaCl were studied using potentiometric polarization measurements. The results revealed that the (%IE) for carbon steel corrosion by ADNQ2O is (89.88%). The obtained thermodynamic parameters support the physical adsorption mechanism. The adsorption followed the Langmuir isotherm. The surface change on carbon steel was studied using SEM (Scanning Electron Microscopy).

scholarly journals Theoretical and Experimental Study for Corrosion Inhibition of Carbon Steel in Salty and Acidic Media by A New Derivative of Imidazolidine 4-One

2020 ◽  
pp. 1842-1860
Author(s):  
Nada Mohammed Al-Joborry ◽  
Rehab Majed Kubba
Keyword(s):  
Carbon Steel ◽  
Density Functional ◽  
Adsorption Mechanism ◽  
Physical Adsorption ◽  
Equilibrium Geometry ◽  
Functional Theory ◽  
Force Microscopy ◽  
Atomic Force ◽  
Quantum Mechanical Method ◽  
Surface Changes

A new imidazolidine 4-one derivative, of namly 2-[2-(4-Bromo-phenyl)-imidazo [1,2-a] pyridine-3-yl]-3-(4-nitro-phenyl)-imidazolidine-4-one (BPIPNP) was investigated as corrosion inhibitor for carbon steel in salty (3.5% NaCl) and acidic (0.5M HCl) solutions using potentiometric polarization measurements. The results revealed that the percentage inhibition efficiencies (%IE) in the salty solution (90.67%) are greater than that in the acidic solution (83.52%). Experimentally, the thermodynamic parameters obtained have supported a physical adsorption mechanism and which followed Langmuir adsorption isotherm. Density Functional Theory (DFT) of quantum mechanical method with B3LYP 6-311++G (2d, 2p) level was used to calculate geometrical structure, physical properties and inhibition efficiency parameters, in vacuum and two solvents (DMSO and H2O), all at the equilibrium geometry. The surface changes of carbon steel were studied using  Scanning Electron Microscopy SEM and Atomic Force Microscopy (AFM) techniques.

scholarly journals Unraveling the electrochemical and spectroscopic properties of neutral and negatively charged perylene tetraethylesters

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Christian Wiebeler ◽  
Joachim Vollbrecht ◽  
Adam Neuba ◽  
Heinz-Siegfried Kitzerow ◽  
Stefan Schumacher
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Energy Levels ◽  
Spectroscopic Properties ◽  
Absorption Bands ◽  
Functional Theory ◽  
Vertical Excitation ◽  
Hartree Fock ◽  
Tauc Plot ◽  
Electrochemical Approach

AbstractA detailed investigation of the energy levels of perylene-3,4,9,10-tetracarboxylic tetraethylester as a representative compound for the whole family of perylene esters was performed. It was revealed via electrochemical measurements that one oxidation and two reductions take place. The bandgaps determined via the electrochemical approach are in good agreement with the optical bandgap obtained from the absorption spectra via a Tauc plot. In addition, absorption spectra in dependence of the electrochemical potential were the basis for extensive quantum-chemical calculations of the neutral, monoanionic, and dianionic molecules. For this purpose, calculations based on density functional theory were compared with post-Hartree–Fock methods and the CAM-B3LYP functional proved to be the most reliable choice for the calculation of absorption spectra. Furthermore, spectral features found experimentally could be reproduced with vibronic calculations and allowed to understand their origins. In particular, the two lowest energy absorption bands of the anion are not caused by absorption of two distinct electronic states, which might have been expected from vertical excitation calculations, but both states exhibit a strong vibronic progression resulting in contributions to both bands.

scholarly journals Tuning Bandgaps of Mixed Halide and Oxide Perovskites CsSnX3 (X=Cl, I), and SrBO3 (B=Rh, Ti)

2021 ◽  
Vol 11 (15) ◽  
pp. 6862
Author(s):  
Hongzhe Wen ◽  
Xuan Luo
Keyword(s):  
Solar Energy ◽  
Electronic Properties ◽  
Density Functional ◽  
Photovoltaic Cell ◽  
Photovoltaic Properties ◽  
Functional Theory ◽  
New Approach ◽  
Energy Applications ◽  
Valence Bands ◽  
The Ideal

Perovskites have recently attracted interest in the field of solar energy due to their excellent photovoltaic properties. We herein present a new approach to the composition of lead free perovskites via mixing of halide and oxide perovskites that share the cubic ABX3 structure. Using first-principles calculations through Density Functional Theory, we systematically investigated the atomic and electronic structures of mixed perovskite compounds composed of four cubic ABX3 perovskites. Our result shows that the B and X atoms play important roles in their band structure. On the other hand, their valence bands contributed by O-2p, Rh-4p, and Ti-3p orbitals, and their electronic properties were determined by Rh-O and Ti-O bonds. With new understandings of the electronic properties of cubic halide or oxide perovskites, we lastly combined the cubic perovskites in various configurations to improve stability and tune the bandgap to values desirable for photovoltaic cell applications. Our investigations suggest that the mixed perovskite compound Cs2Sn2Cl3I3Sr2TiRhO6 produced a bandgap of 1.2 eV, which falls into the ideal range of 1.0 to 1.7 eV, indicating high photo-conversion efficiency and showing promise towards solar energy applications.

scholarly journals Taguchi-Assisted Optimization Technique and Density Functional Theory for Green Synthesis of a Novel Cu-MOF Derived From Caffeic Acid and Its Anticancerious Activities

2021 ◽  
Vol 9 ◽  
Author(s):  
Malihe Zeraati ◽  
Ali Mohammadi ◽  
Somayeh Vafaei ◽  
Narendra Pal Singh Chauhan ◽  
Ghasem Sargazi
Keyword(s):  
Density Functional Theory ◽  
Caffeic Acid ◽  
Density Functional ◽  
Energy Levels ◽  
Optimization Technique ◽  
Nitrogen Adsorption ◽  
High Porosity ◽  
Anticancer Activities ◽  
Functional Theory ◽  
Sem Analyses

In this paper, we have reported an innovative greener method for developing copper-metal organic frameworks (Cu-MOFs) using caffeic acid (CA) as a linker extracted from Satureja hortensis using ultrasonic bath. The density functional theory is used to discuss the Cu-MOF-binding reaction mechanism. In order to achieve a discrepancy between the energy levels of the interactive precursor orbitals, the molecules have been optimized using the B3LYP/6–31G method. The Taguchi method was used to optimize the key parameters for the synthesis of Cu-MOF. FT-IR, XRD, nitrogen adsorption, and SEM analyses are used to characterize it. The adsorption/desorption and SEM analyses suggested that Cu-MOF has a larger surface area of 284.94 m2/g with high porosity. Cu-MOF has shown anticancer activities against the human breast cancer (MDA-MB-468) cell lines, and it could be a potent candidate for clinical applications.

Adsorption mechanism of CO molecule on Al(111) surface: periodic DFT investigation

2018 ◽  
Vol 96 (12) ◽  
pp. 993-999 ◽  
Author(s):  
Chenhong Xu ◽  
Suqin Zhou ◽  
Jing Chen ◽  
Yuxiang Wang ◽  
Lei He
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Adsorption Mechanism ◽  
Bond Activation ◽  
Aluminum Surface ◽  
Hollow Site ◽  
Functional Theory ◽  
Wide Range ◽  
Adsorption Of Co ◽  
Adsorption Energies

The adsorption mechanism of the CO molecule on Al(111) surface has been investigated systematically at the atom-molecule level by the method of periodic density functional theory. The adsorption energies, adsorption structures, charge transfer, and density of states have been calculated in a wide range of coverage. It is found that the hcp-hollow site is the energetically favorable site. A significant positive correlation has been found between the adsorption energy (Eads) and coverage. The adsorbed CO molecules are almost perpendicular on the surface with the C atom facing the surface. There is an obvious charge transfer from Al atoms to the C atom; the Al atoms that have interaction with the C atom offer the most charge. The 4σ, 1π, and 5σ molecular orbitals of CO are found to contribute to bonding with the Al. The charges filling in the 2π molecular orbital contribute to C–O bond activation. In conclusion, the passivation of aluminum surface and the activation of CO molecule occur simultaneously in the adsorption of CO on Al surface.

scholarly journals First Principles Predictions of Intrinsic Defects in Aluminum Arsenide, AlAs

2011 ◽  
Vol 1370 ◽  
Author(s):  
Peter A. Schultz
Keyword(s):  
Point Defects ◽  
First Principles ◽  
Density Functional ◽  
Semiconductor Device ◽  
Energy Levels ◽  
Aluminum Arsenide ◽  
Functional Theory ◽  
Eigenvalue Gap ◽  
Rigorous Treatment ◽  
Simulation Results

ABSTRACTThe structures, energies, and energy levels of a comprehensive set of simple intrinsic point defects in aluminum arsenide are predicted using density functional theory (DFT). The calculations incorporate explicit and rigorous treatment of charged supercell boundary conditions. The predicted defect energy levels, computed as total energy differences, do not suffer from the DFT band gap problem, spanning the experimental gap despite the Kohn-Sham eigenvalue gap being much smaller than experiment. Defects in AlAs exhibit a surprising complexity—with a greater range of charge states, bistabilities, and multiple negative-U systems—that would be impossible to resolve with experiment alone. The simulation results can be used to populate defect physics models in III-V semiconductor device simulations with reliable quantities in those cases where experimental data is lacking, as in AlAs.

scholarly journals Study on the adsorption mechanism of benzoylurea insecticides onto modified hyperbranched polysilicon materials

RSC Advances ◽  
2020 ◽  
Vol 10 (48) ◽  
pp. 28664-28673
Author(s):  
Chaoran Liu ◽  
Xiaodong Huang ◽  
Zilin Meng ◽  
Heng Qian ◽  
Xinya Liu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Adsorption Mechanism ◽  
Functional Theory ◽  
Adsorption Studies ◽  
The Density Functional Theory ◽  
Benzoylurea Insecticides ◽  
End Group

Several hyperbranched polysilicon with different end group modifications were prepared, and the adsorption mechanism of benzoylureas onto the obtained materials were investigated based on the density functional theory and adsorption studies.

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