DFT calculations on the adsorption of component SF6 decomposed under partial discharge onto carbon nanotubes modified by -OH

Zhang, Xiaoxing; Meng, Fansheng; Tang, Ju; Bing, Yang

doi:10.7498/aps.61.156101

Cited by 3 publications

(1 citation statement)

References 16 publications

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“…Nanotubes which can be formed by rolling up twodimensional materials, such as graphene and transition-metal dichalcogenides (TMDs), have attracted a great deal of attention due to their distinct physical and chemical properties. [1][2][3][4][5] Nanotubes based on TMDs are semiconductors with wide applications including field-effect transistors, [6][7][8] photodetectors, [9] and solid lubricants. [10] Similar to carbon nanotubes (CNTs), the properties of TMD nanotubes, such as band gap, [11,12] mechanic property, [13,14] carrier mobility, [15] and optical conductivity, [16] are predicted to be diameterdependent.…”

Section: Introductionmentioning

confidence: 99%

Band engineering of double-wall Mo-based hybrid nanotubes

et al. 2018

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Hybrid transition-metal dichalcogenides (TMDs) with different chalcogens on each side (X-TM-Y ) have attracted attention because of their unique properties. Nanotubes based on hybrid TMD materials have advantages in flexibility over conventional TMD nanotubes. Here we predict the wide band gap tunability of hybrid TMD double-wall nanotubes (DWNTs) from metal to semiconductor. Using density-function theory (DFT) with HSE06 hybrid functional, we find that the electronic property of X-Mo-Y DWNTs (X = O and S, inside a tube; Y = S and Se, outside a tube) depends both on electronegativity difference and diameter difference. If there is no difference in electron negativity between inner atoms (X) of outer tube and outer atoms (Y ) of inner tube, the band gap of DWNTs is the same as that of the inner one. If there is a significant electronegativity difference, the electronic property of the DWNTs ranges from metallic to semiconducting, depending on the diameter differences. Our results provide alternative ways for the band gap engineering of TMD nanotubes.

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Section: Introductionmentioning

confidence: 99%

Band engineering of double-wall Mo-based hybrid nanotubes

et al. 2018

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Electrical Conductivity of Multiwall Carbon Nanotube Bundles Contacting with Metal Electrodes by Nano Manipulators inside SEM

Yang

Xiao

et al. 2021

Nanomaterials

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Determining the metallicity and semiconductivity of a multi-walled carbon nanotube (MWCNT) bundle plays a particularly vital role in its interconnection with the metal electrode of an integrated circuit. In this paper, an effective method is proposed to determine the electrical transport properties of an MWCNT bundle using a current–voltage characteristic curve during its electrical breakdown. We established the reliable electrical nanoscale contact between the MWCNT bundle and metal electrode using a robotic manipulation system under scanning electron microscope (SEM) vacuum conditions. The experimental results show that the current–voltage curve appears as saw-tooth-like current changes including up and down steps, which signify the conductance and breakdown of carbon shells in the MWCNT bundle, respectively. Additionally, the power law nonlinear behavior of the current–voltage curve indicates that the MWCNT bundle is semiconducting. The molecular dynamics simulation explains that the electron transport between the inner carbon shells, between the outermost carbon shells and gold metal electrode and between the outermost carbons shells of two adjacent individual three-walled carbon nanotubes (TWCNTs) is through their radial deformation. Density functional theory (DFT) calculations elucidate the electron transport mechanism between the gold surface and double-wall carbon nanotube (DWCNT) and between the inner and outermost carbon shells of DWCNT using the charge density difference, electrostatic potential and partial density of states.

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Design and optimization of photoacoustic CO gas sensor for fault diagnosis of SF6 gas insulated equipment

Yin¹,

Wu²,

Lixian³

et al. 2021

Acta Phys. Sin.

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Trace gas analysis for SF6 decomposition is a powerful diagnostic method to identify partial discharge problem occurring in electrical equipment. In particular, it is recognized that the SF6 decomposition gases (such as CO, H2S, SO2 and CF4) can effectively determine the inner insulation condition of the electrical equipment. Currently, most of researches of diagnostic methods cannot meet the online high-precision detection of gas derivatives in SF6 electrical insulation equipment. Therefore, there is a need of developing a sensitive, selective and cost-effective sensor system for CO detection in an SF6 buffer gas environment due to the fact that the power system is filled with pure SF6 as the dielectric gas, which means that the concentration of SF6 is usually > 99.8%. The traditional photoacoustic CO gas sensors cannot be directly used in power system, since several SF6 physical constants strongly differ from those of N2 or air. In addition, SF6 molecule reveals uninterrupted and strong absorption lines in the mid-infrared spectral region. In this work, a CO gas sensor working in high concentration SF6 background gas is designed by using a distributed feedback (DFB) laser as an excitation source with a center wavelength of 2.3 μm. The absorption line strength of 2.3 μm is ~ two orders of magnitude higher than the absorption line strength around 1.56 μm, which can improve the sensor detection performance. A background-gas-induced high-Q differential photoacoustic cell is simulated numerically and tested experimentally. The quality factor of the designed photoacoustic cell in pure SF6 gas is 85, which is ~ 4 times higher than that in N2 carrier gas. The experimental results show that the maximum gas flow rate of the differential structure photoacoustic cell is ~ 6 times higher than that of the single resonant cavity photoacoustic cell. After optimizing the resonance frequency, gas velocity and working pressure of the sensor system, the detection sensitivity of the volume fraction of 1.85 × 10–6 is achieved. In the case of the volume fraction of 50 × 10–6 CO/SF6 gas mixture, the maximum photoacoustic signal amplitude of 19.6 μV is obtained, the corresponding normalized noise equivalent concentration (1σ) is 3.68 × 10–8 cm–1·W·Hz1/2 in 1 s integration time. A linear fitting is implemented to evaluate the response of the sensor from 50 × 10–6 to 1000 × 10–6, resulting in an R square value of 0.9997. The CO photoacoustic gas sensor has high sensitivity, good selectivity and strong noise immunity, which can provide an on-line detection technology for potential insulation fault diagnosis in the power system. The capability of CO gas sensor can be improved by using a higher excitation optical output power and/or reducing the PAC resonator volume to increase the cell constant.

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DFT calculations on the adsorption of component SF6 decomposed under partial discharge onto carbon nanotubes modified by -OH

Cited by 3 publications

References 16 publications

Band engineering of double-wall Mo-based hybrid nanotubes

Band engineering of double-wall Mo-based hybrid nanotubes

Electrical Conductivity of Multiwall Carbon Nanotube Bundles Contacting with Metal Electrodes by Nano Manipulators inside SEM

Design and optimization of photoacoustic CO gas sensor for fault diagnosis of SF<sub>6</sub> gas insulated equipment

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