scholarly journals Pd-Doped SnO2-Based Sensor Detecting Characteristic Fault Hydrocarbon Gases in Transformer Oil

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Weigen Chen ◽  
Qu Zhou ◽  
Tuoyu Gao ◽  
Xiaoping Su ◽  
Fu Wan
Keyword(s):  
Molecular Orbital ◽  
Online Monitoring ◽  
Gas Sensing ◽  
Power Transformer ◽  
Transformer Oil ◽  
Orbital Energy ◽  
Hydrocarbon Gases ◽  
X Ray ◽  
Molecular Orbital Energy ◽  
Highest Occupied Molecular Orbital

Methane (CH4), ethane (C2H6), ethylene (C2H4), and acetylene (C2C2) are important fault characteristic hydrocarbon gases dissolved in power transformer oil. Online monitoring these gaseous components and their generation rates can present the operational state of power transformer timely and effectively. Gas sensing technology is the most sticky and tricky point in online monitoring system. In this paper, pure and Pd-doped SnO2nanoparticles were synthesized by hydrothermal method and characterized by X-ray powder diffraction, field-emission scanning electron microscopy, and energy dispersive X-ray spectroscopy, respectively. The gas sensors were fabricated by side-heated preparation, and their gas sensing properties against CH4, C2H6, C2H4, and C2H2were measured. Pd doping increases the electric conductance of the prepared SnO2sensors and improves their gas sensing performances to hydrocarbon gases. In addition based on the frontier molecular orbital theory, the highest occupied molecular orbital energy and the lowest unoccupied molecular orbital energy were calculated. Calculation results demonstrate that C2H4has the highest occupied molecular orbital energy among CH4, C2H6, C2H4, and C2H2, which promotes charge transfer in gas sensing process, and SnO2surfaces capture a relatively larger amount of electric charge from adsorbed C2H4.

scholarly journals QTAIM investigation of bis(pyrazol-1-yl)methane derivative and its Zn(II) complexes (ZnLX2, X=Cl, Br or I)

2015 ◽  
Vol 80 (8) ◽  
pp. 997-1008 ◽  
Author(s):  
Maryam Dehestani ◽  
Leila Zeidabadinejad
Keyword(s):  
Molecular Orbital ◽  
Critical Points ◽  
Structural Parameters ◽  
Frontier Molecular Orbital ◽  
Orbital Energy ◽  
Theory Approach ◽  
Topological Parameters ◽  
Molecular Orbital Energy ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

Topological analyses of the electron density using the quantum theory of atoms in molecules (QTAIM) have been carried out at the B3PW91/6-31g (d) theoretical level, on bis(pyrazol-1-yl)methanes derivatives 9-(4-(di (1H-pyrazol-1-yl)-methyl)phenyl)-9H-carbazole (L) and its zinc(II) complexes: ZnLCl2 (1), ZnLBr2 (2) and ZnLI2 (3). The topological parameters derived from Bader theory were also analyzed; these are characteristics of Zn-bond critical points and also of ring critical points. The calculated structural parameters are the frontier molecular orbital energies highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), hardness (?), softness (S), the absolute electronegativity (?), the electrophilicity index (?) and the fractions of electrons transferred (?N) from ZnLX2 complexes to L. The numerous correlations and dependencies between energy terms of the Symmetry Adapted Perturbation Theory approach (SAPT), geometrical, topological and energetic parameters were detected and described.

Discriminative modulation of the highest occupied molecular orbital energies of graphene and carbon nanotubes induced by charging

2015 ◽  
Vol 17 (11) ◽  
pp. 7248-7254 ◽  
Author(s):  
Hongping Yang ◽  
Chi-yung Yam ◽  
Aihua Zhang ◽  
Zhiping Xu ◽  
Jun Luo ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Molecular Orbital ◽  
First Principles ◽  
Orbital Energy ◽  
First Principles Calculations ◽  
Orbital Energies ◽  
Molecular Orbital Energy ◽  
Highest Occupied Molecular Orbital

First-principles calculations show that the increase in the highest occupied molecular orbital energy of a charged carbon nanotube is different from graphene.

scholarly journals Hydrothermal Synthesis and Structural Characterization of NiO/SnO2Composites and Hydrogen Sensing Properties

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Chao Wei ◽  
Bin Bo ◽  
Fengbo Tao ◽  
Yuncai Lu ◽  
Shudi Peng ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Power Transformer ◽  
Transformer Oil ◽  
Photoelectron Spectra ◽  
X Ray ◽  
Hydrogen Sensing ◽  
Sensing Material ◽  
P Type ◽  
Surface Morphologies ◽  
Gas Response

Pure SnO2and NiO doped SnO2nanostructures were successfully synthesized via a simple and environment-friendly hydrothermal method. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectra (XPS) were used to investigate the crystalline structures, surface morphologies and microstructures, and element components and their valences of the as-synthesized samples. Furthermore, planar chemical gas sensors based on the synthesized pure SnO2and NiO/SnO2composites were fabricated and their sensing performances to hydrogen, an important fault characteristic gas dissolved in power transformer oil, were investigated in detail. Gas sensing experiments indicate that the NiO/SnO2composites showed much higher gas response and lower working temperature than those of pure SnO2, which could be ascribed to the formation of p-n heterojunctions between p-type NiO and n-type SnO2. These results demonstrate that the as-synthesized NiO/SnO2composites a promising hydrogen sensing material.

scholarly journals Estudo teórico da eficiência de inibidores orgânicos de corrosão derivados do benzimidazol

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Frederico Marcondes Da Silva ◽  
Lillian Weitzel Coelho Paes
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Basis Set ◽  
Orbital Energy ◽  
Molecular Orbital Energy ◽  
Highest Occupied Molecular Orbital ◽  
Fukui Indices ◽  
Lowest Unoccupied Molecular Orbital ◽  
Quantum Parameters

The objective of this work was to evaluate the efficiency of inhibition the corrosion of two organic molecules derived from benzimidazole, specifically 2-mercaptobenzimidazole (2Mcb) and 2-phenylbenzimidazole (2Fb). The calculations were performed using the Density Functional Theory (DFT) at the B3LYP with 6-311+G(d,p) basis set. The quantum parameters correlated with the inhibition efficiency such as the highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy (ELUMO) , energy gap (ΔE), electronegativity (χ), hardness (η), the fractions of electrons transferred (ΔN), electrophilicity (ω) and Fukui indices, were calculated. Calculations were performed in aqueous medium in both protonated and non-protonated forms. Theoretical results were compared with experimental data and a good correlation was found between the chemical quantum parameters and the efficiency of inhibition of the molecules. DOI: http://dx.doi.org/10.30609/JETI.2018-5270

scholarly journals Research on Acetylene Sensing Properties and Mechanism of SnO2Based Chemical Gas Sensor Decorated with Sm2O3

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Qu Zhou ◽  
Meiqing Cao ◽  
Wude Li ◽  
Chao Tang ◽  
Shiping Zhu
Keyword(s):  
Gas Sensing ◽  
Power Transformer ◽  
Transformer Oil ◽  
Optimum Operating ◽  
Optimum Operating Temperature ◽  
Hydrocarbon Gases ◽  
Promising Candidate ◽  
Analysis System ◽  
Fault Characteristic

Acetylene C2H2gas is one of the most important fault characteristic hydrocarbon gases dissolved in oil immersed power transformer oil. This paper reports the successful preparation and characterization of samarium oxide Sm2O3decorated tin oxide SnO2based sensors with hierarchical rod structure for C2H2gas detection. Pure and Sm2O3decorated SnO2sensing structures were synthesized by a facile hydrothermal method and characterized by XRD, FESEM, TEM, EDS, and XPS measurements, respectively. Planar chemical gas sensors with the synthesis samples were fabricated, and their sensing performances to C2H2gas were systematically performed and automatically recorded by a CGS-1 TP intelligent gas sensing analysis system. The optimum operating temperature of the Sm2O3decorated SnO2based sensor towards 50 μL/L of C2H2is 260°C, and its corresponding response value is 38.12, which is 6 times larger than the pure one. Its response time is about 8–10 s and 10–13 s for recovery time. Meanwhile good stability and reproducibility of the decorated sensor to C2H2gas are also obtained. Furthermore, the proposed sensor exhibits excellent C2H2selectivity among some potential interface gases, like H2and CO gas. All sensing results indicate the sensor fabricated with oxide Sm2O3decorated SnO2nanorods might be a promising candidate for C2H2detection in practice.

Semi-empirical Molecular Orbital Energy Levels of the Hexammine and Chloroammine Complexes of Co(IV)

1967 ◽  
Vol 22 (2) ◽  
pp. 170-175 ◽  
Author(s):  
Walter A. Yeranos ◽  
David A. Hasman
Keyword(s):  
Molecular Orbital ◽  
Energy Levels ◽  
Empirical Evaluation ◽  
Wave Functions ◽  
Electronic Transitions ◽  
Orbital Energy ◽  
Molecular Orbital Energy ◽  
The One ◽  
Semi Empirical

Using the recently proposed reciprocal mean for the semi-empirical evaluation of resonance integrals, as well as approximate SCF wave functions for Co3+, the one-electron molecular energy levels of Co (NH3) 3+, Co (NH3) 5Cl2+, and Co (NH3) 4Cl21+ have been redetermined within the WOLFSBERG–HELMHOLZ approximation. The outcome of the study fits remarkably well with the observed electronic transitions in the u.v. spectra of these complexes and prompts different band assignments than previously suggested.

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