Comparative DFT dual gas adsorption model of ZnO and Ag/ZnO with experimental applications as gas detection at ppb level

2021 ◽  
Author(s):  
Utkarsh Kumar ◽  
Shih-Ming Huang ◽  
Zen-In Deng ◽  
Cheng-Xin Yang ◽  
Wen-Min Huang ◽  
...  
Keyword(s):  
Density Functional ◽  
Reaction Rate ◽  
Gas Adsorption ◽  
Gas Detection ◽  
Adsorption Model ◽  
Ag Nps ◽  
Functional Theory ◽  
Peak Intensity ◽  
Homo Lumo ◽  
Good Agreement

Abstract By experimental and density functional theory (DFT) calculations, the toxic gases (O3 and NO2) sensing capability and mechanism of ZnO NRs and Ag/ZnO NRs have been comparatively studied in this work. The arrays of Ag NPs were employed as a templet for the growth of ZnO NRs. The experimental results show the response and adsorption rate towards the gases obviously change after adding Ag NPs in ZnO. From the TDOS plot, it has been observed that the HOMO-LUMO gap changes after interaction with different oxidizing gases similarly the peak intensity also decreases which confirms the electron has been transferred from ZnO to NO2 and O3. The response towards the gases decreases and the adsorption reaction rate has been calculated by the Eyring-Polanyi equation and found to be increased after adding Ag in the ZnO NRs which is very similar to our experimental data. We also find that the absorption coefficient is different for O3 and NO2. The mechanism of the gas sensor was explored. Finally, the findings of the response experiment and theoretical calculation were compared and found to be in good agreement.

Synthesis, optical characterization, and TD-DFT studies of novel mero/bis-mero cyanine dyes based on N-Bridgehead heterocycles

2019 ◽  
Vol 97 (3) ◽  
pp. 219-226
Author(s):  
Ahmed I. Koraiem ◽  
Islam M. Abdellah ◽  
Ahmed El-Shafei ◽  
Fathy F. Abdel-Latif ◽  
Reda M. Abd El-Aal
Keyword(s):  
Excitation Energy ◽  
Density Functional ◽  
Energy Gap ◽  
Solvent Polarity ◽  
Cyanine Dyes ◽  
Spectral Studies ◽  
Functional Theory ◽  
Td Dft ◽  
Homo Lumo ◽  
Good Agreement

Novel mero/bis-mero cyanine dyes based on N-Bridgehead imidazo[1,2-g]quinolino[2,1-a][2,6]naphthyridine have been synthesized and characterized to evaluate intramolecular charge transfer (ICT) effect on the energy gap (E0-0). The UV–vis and emission spectral studies revealed that dyes are absorbed in the region of λmax 485–577 nm and emitted at 567–673 nm. Their solvatochromic behavior in solvents of various polarities, CCl4, C6H6, H2O, CHCl3, acetone, and DMF, was studied to emphasize the effect of solvent polarity on the absorption maxima, molar extinction coefficients of the dyes, and excitation energy of the dyes. Their electron cloud delocalization in HOMO/LUMO levels were studied by DFT using Gaussian 09 software. Time-dependent density functional theory (TD-DFT) was applied to theoretically explore the first excitation energy (E0-0) of these dyes, which was in good agreement with experimental results.

ELECTRON TRANSFER MAKES D3h (78:5) CAGE EASY TO FORM M2@C78(M = La, Ce): A RELATIVISTIC DENSITY-FUNCTIONAL THEORY STUDY

2012 ◽  
Vol 11 (01) ◽  
pp. 197-207 ◽  
Author(s):  
CE HAO ◽  
HONGJIANG LI ◽  
GUORONG JIA ◽  
SHENMIN LI ◽  
JIESHAN QIU
Keyword(s):  
Density Functional Theory ◽  
Electron Transfer ◽  
Density Functional ◽  
Functional Theory ◽  
Endohedral Metallofullerenes ◽  
Metal Atoms ◽  
The Stability ◽  
Homo Lumo ◽  
Good Agreement ◽  
C Nmr

Applying relativistic density functional theory to isomers of C 78 and M 2@ C 78( M = La , Ce ), we calculate and analyze the relative energies and HOMO–LUMO gaps of neutral and hexaanion ( -6 charged) C 78 isomers. Our results indicate that the [Formula: see text] (5) isomer is the most stable, and it illustrate that electron transfer plays an important role in controlling the stability of endohedral metallofullerenes. We also calculate the electronic structures of there neutral isomers, and based on their LUMO + 2 and LUMO + 3 gaps, we explain why it is easier to encage two metal atoms in D3h′ (78:5). To further elucidate this issue, we theoretically characterize M 2@ C 78( M = La , Ce ) and compare the relative energies and the HOMO–LUMO gap of the two isomers M 2@ C 78 (4) and the M 2@ C 78 (5) ( M = La , Ce ). The results indicate that M 2@ C 78 (5) is more stable than M 2@ C 78 (4). Furthermore, the good agreement between the experimental and computed 13C NMR chemical shift of the isomer M 2@ C 78 (5) provided strong evidence that M 2@ C 78 forms a D3h′ (78:5) cage.

scholarly journals Crystal structures, DFT studies and UV–visible absorption spectra of two anthracenyl chalcone derivatives

2018 ◽  
Vol 74 (10) ◽  
pp. 1491-1496 ◽  
Author(s):  
Dian Alwani Zainuri ◽  
Ibrahim Abdul Razak ◽  
Suhana Arshad
Keyword(s):  
Crystal Structures ◽  
Density Functional ◽  
Crystal Packing ◽  
Density Functional Theory Calculations ◽  
Ring System ◽  
Basis Set ◽  
Visible Absorption ◽  
Functional Theory ◽  
Homo Lumo ◽  
Good Agreement

The crystal structures of (E)-1-(anthracen-9-yl)-3-(3H-indol-2-yl)prop-2-en-1-one, C25H17NO, and (E)-1-(anthracen-9-yl)-3-[4-(dimethylamino)naphthalen-1-yl]prop-2-en-1-one, C29H23NO, are reported. In each case the anthracene ring system and pendant ring system are almost perpendicular to each other [dihedral angles = 75.57 (7)° and 70.26 (10)°, respectively]. In the extended structures, weak N—H...O, C—H...O and C—H...π interactions influence the centrosymmetric crystal packing. Density functional theory calculations were carried out using a 6–311 G++(d,p) basis set and the calculated structures are in good agreement with the crystal structures. The compounds were also characterized by UV–Vis absorption spectroscopy and the smallest (HOMO–LUMO) energy gaps of 2.89 and 2.54 eV indicate the enhanced non-linear responses (intermolecular charge transfers) of these systems.

A van der WAALS CORRECTED DFT STUDY OF CHEMICAL SENSING OF SULFUR DIOXIDE MOLECULE BY NITROGEN-DOPED Au DECORATED TiO2 NANOPARTICLES

2018 ◽  
Vol 25 (06) ◽  
pp. 1950003
Author(s):  
AMIRALI ABBASI ◽  
JABER JAHANBIN SARDROODI
Keyword(s):  
Binding Sites ◽  
Density Functional ◽  
Nitrogen Doping ◽  
Van Der Waals ◽  
Gas Detection ◽  
Functional Theory ◽  
Net Charge ◽  
Nitrogen Doped ◽  
Interacting Atoms ◽  
Homo Lumo

We have studied the adsorption of SO2 molecule on the pristine and nitrogen-doped Au decorated TiO2 nanoparticles using density functional theory (DFT) calculations, taking into attention van der Waals (vdW) interactions. Theoretically, it was found that SO2 molecule adsorbs on the Au decorated TiO2 in a bridge geometry. The adsorption of SO2 molecule on both the Au and TiO2 sides were considered. On the TiO2 side, the fivefold coordinated titanium sites were found to be the most stable binding sites, providing double contacting point between the nanoparticle and SO2. The results suggest that the adsorption of SO2 on the N-doped Au decorated TiO2 is more energetically favorable than the adsorption on the pristine one. Thus, nitrogen doping is dominant during the adsorption of SO2. The changes in the electronic structure of the system and the net charge transfer upon adsorption of SO2 molecule were studied in detail. Also, HOMO–LUMO isosurfaces of the adsorption systems were presented for discussion of results. By considering large overlaps in the projected density of states (PDOSs) of the interacting atoms, we found that the molecule is bound most strongly to the Au and fivefold coordinated titanium positions. The inclusion of vdW interactions is important for obtaining final equilibrium adsorption configurations of SO2 on Au decorated TiO2 nanoparticles. Our results thus suggest that N-doped Au decorated TiO2 would be an efficient sensor for SO2 gas detection in the environment.

Synthesis of New α-Amino Phosphonates Containing 3-Amino-4(3H) Quinazolinone Moiety as Anticancer and Antimicrobial Agents: DFT, NBO, and Vibrational Studies

2018 ◽  
Vol 15 (2) ◽  
pp. 286-296 ◽  
Author(s):  
Mohamed K. Awad ◽  
Mahmoud F. Abdel-Aal ◽  
Faten M. Atlam ◽  
Hend A. Hekal
Keyword(s):  
Biological Activity ◽  
Cell Line ◽  
Quantum Chemical ◽  
Density Functional ◽  
Carcinoma Cell ◽  
Liver Carcinoma ◽  
Anticancer Activities ◽  
Functional Theory ◽  
Ft Ir ◽  
Good Agreement

Aim and Objective: Synthesis of new .-aminophosphonates containing quinazoline moiety through Kabachnik-Fields reaction in the presence of copper triflate catalyst [32], followed by studying their antimicrobial activities and in vitro anticancer activities against liver carcinoma cell line (HepG2) with the hope that new anticancer agents could be developed. Also, the quantum chemical calculations are performed using density functional theory (DFT) to study the effect of the changes of molecular and electronic structures on the biological activity of the investigated compounds. Materials and Method: The structures of the synthesized compounds are confirmed by FT-IR, 1H NMR, 13C NMR, 31P NMR and MS spectral data. The synthesized compounds show significant antimicrobial and also remarkable cytotoxicity anticancer activities against liver carcinoma cell line (HepG2). Density functional theory (DFT) was performed to study the effect of the molecular and electronic structure changes on the biological activity. Results: It was found that the electronic structure of the substituents affects on the reaction yield. The electron withdrawing substituent, NO2 group 3b, on the aromatic aldehydes gave a good yield more than the electron donating substituent, OH group 3c. The electron deficient on the carbon atom of the aldehydic group may increase the interaction of the Lewis acid (Cu(OTf)2) and the Lewis base (imine nitrogen), and accordingly, facilitate the formation of imine easily, which is attacked by the nucleophilic phosphite species to give the α- aminophosphonates. Conclusion: The newly synthesized compounds exhibit a remarkable inhibition of the growth of Grampositive, Gram-negative bacteria and fungi at low concentrations. The cytotoxicity of the synthesized compounds showed a significant cytotoxicity against the liver cancer cell line (HepG 2). Also, it was shown from the quantum chemical calculations that the electron-withdrawing substituent increases the biological activity of the α-aminophosphonates more than the electron donating group which was in a good agreement with the experimental results. Also, a good agreement between the experimental FT-IR and the calculated one was found.

A DFT study of spherands containing five anisyl groups — Highly preorganized to bind the alkali metal

2006 ◽  
Vol 84 (8) ◽  
pp. 1045-1049 ◽  
Author(s):  
Shabaan AK Elroby ◽  
Kyu Hwan Lee ◽  
Seung Joo Cho ◽  
Alan Hinchliffe
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Ionic Radius ◽  
Binding Energies ◽  
Cavity Size ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Good Agreement

Although anisyl units are basically poor ligands for metal ions, the rigid placements of their oxygens during synthesis rather than during complexation are undoubtedly responsible for the enhanced binding and selectivity of the spherand. We used standard B3LYP/6-31G** (5d) density functional theory (DFT) to investigate the complexation between spherands containing five anisyl groups, with CH2–O–CH2 (2) and CH2–S–CH2 (3) units in an 18-membered macrocyclic ring, and the cationic guests (Li+, Na+, and K+). Our geometric structure results for spherands 1, 2, and 3 are in good agreement with the previously reported X-ray diffraction data. The absolute values of the binding energy of all the spherands are inversely proportional to the ionic radius of the guests. The results, taken as a whole, show that replacement of one anisyl group by CH2–O–CH2 (2) and CH2–S–CH2 (3) makes the cavity bigger and less preorganized. In addition, both the binding and specificity decrease for small ions. The spherands 2 and 3 appear beautifully preorganized to bind all guests, so it is not surprising that their binding energies are close to the parent spherand 1. Interestingly, there is a clear linear relation between the radius of the cavity and the binding energy (R2 = 0.999).Key words: spherands, preorganization, density functional theory, binding energy, cavity size.

scholarly journals Changes in CO2 Adsorption Affinity Related to Ni Doping in FeS Surfaces: A DFT-D3 Study

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 486
Author(s):  
Aleksandar Zivković ◽  
Michiel Somers ◽  
Eloi Camprubi ◽  
Helen E. King ◽  
Mariette Wolthers ◽  
...  
Keyword(s):  
Density Functional ◽  
Organic Molecules ◽  
Ni Doping ◽  
Functional Theory ◽  
Small Organic Molecules ◽  
Adsorption Affinity ◽  
The Origin Of Life ◽  
Carbon Dioxide Co2 ◽  
Partial Desorption ◽  
Good Agreement

Metal sulphides constitute cheap, naturally abundant, and environmentally friendly materials for energy storage applications and chemistry. In particular, iron (II) monosulphide (FeS, mackinawite) is a material of relevance in theories of the origin of life and for heterogenous catalytic applications in the conversion of carbon dioxide (CO2) towards small organic molecules. In natural mackinawite, Fe is often substituted by other metals, however, little is known about how such substitutions alter the chemical activity of the material. Herein, the effect of Ni doping on the structural, electronic, and catalytic properties of FeS surfaces is explored via dispersion-corrected density functional theory simulations. Substitutional Ni dopants, introduced on the Fe site, are readily incorporated into the pristine matrix of FeS, in good agreement with experimental measurements. The CO2 molecule was found to undergo deactivation and partial desorption from the doped surfaces, mainly at the Ni site when compared to undoped FeS surfaces. This behaviour is attributed to the energetically lowered d-band centre position of the doped surface, as a consequence of the increased number of paired electrons originating from the Ni dopant. The reaction and activation energies of CO2 dissociation atop the doped surfaces were found to be increased when compared to pristine surfaces, thus helping to further elucidate the role Ni could have played in the reactivity of FeS. It is expected that Ni doping in other Fe-sulphides may have a similar effect, limiting the catalytic activity of these phases when this dopant is present at their surfaces.

The Quantum Length Dependence of Conductance in Molecular Device: An Ab Initio Study

2010 ◽  
Vol 663-665 ◽  
pp. 519-522
Author(s):  
Cai Juan Xia ◽  
Han Chen Liu ◽  
Ying Tang Zhang
Keyword(s):  
Electronic Transport ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Molecular Device ◽  
Functional Theory ◽  
Length Dependence ◽  
Molecular Conductance ◽  
Homo Lumo ◽  
Molecular Compounds

By Applying Nonequilibrium Green’s Function Formalism Combined First-Principles Density Functional Theory, we Investigate the Electronic Transport Properties of Thiophene and Furan Molecules with Different Quantum Length. the Influence of HOMO-LUMO Gaps and the Spatial Distributions of Molecular Orbitals on the Electronic Transport through the Molecular Device Are Discussed in Detail. the Results Show that the Transport Behaviors Are Determined by the Distinct Electronic Structures of the Molecular Compounds. the Length Dependence of Molecular Conductance Exhibits its Diversity for Different Molecules.

Theoretical Investigations on Mechanical Stability and Electronic Structure of NbN under Pressures

2011 ◽  
Vol 90-93 ◽  
pp. 1264-1271
Author(s):  
Xiao Feng Li ◽  
Jun Yi Du
Keyword(s):  
Debye Temperature ◽  
Density Functional ◽  
Mechanical Stability ◽  
Structural Parameters ◽  
Theoretical Data ◽  
Hexagonal Structure ◽  
Functional Theory ◽  
Theoretical Investigations ◽  
Crystallographic Structures ◽  
Good Agreement

The ground structure, elastic and electronic properties of several phases of NbN are determined based on ab initio total-energy calculations within the framework of density functional theory. Among the five crystallographic structures that have been investigated, the hexagonal phases have been found to be more stable than the cubic ones. The calculated equilibrium structural parameters are in good agreement with the available experimental results. The elastic constants of five structures in NbN are calculated, which are in consistent with the obtained theoretical and experimental data. The corresponding Debye temperature and elastic ansitropies are also obtained. The Debye temperature of NbN in various structures consistent with available experimental and theoretical data, in which the Debye temperature of δ-NbN is highest. The anisotropies of ZB-NbN, NaCl-NbN, CsCl-NbN gradually increases. For hexagonal structure, the anisotropies of ε-NbN are stronger than that of δ-NbN. The electronic structures of NbN under pressure are investigated. It is found that NbN have metallization and the hybridizations of atoms in NbN under pressure become stronger.

First-Principles Study of Triangle Terarylene as a Possible Optical Molecular Switch

2011 ◽  
Vol 311-313 ◽  
pp. 526-529
Author(s):  
Cai Juan Xia ◽  
Han Chen Liu ◽  
Ji Xin Yin
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Molecular Switch ◽  
Optical Switches ◽  
Functional Theory ◽  
Closed Ring ◽  
Potential Applications ◽  
Homo Lumo ◽  
Non Equilibrium Green’S Function ◽  
Theoretical Results

Using non-equilibrium Green’s function formalism combined with first-principles density functional theory, we investigate the electronic transport properties of a triangle terarylene(open- and closed-ring forms) optical molecular switch. The influence of the HOMO-LUMO gaps and the spatial distributions of molecular orbitals on the quantum transport through the molecular device is discussed. Theoretical results show that the conductance of the closed-ring is 3-8 times larger than that of open-ring, which expect that this system can be one of good candidates for optical switches due to this unique advantage, and may have some potential applications in future molecular circuit.

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