Two-dimensional transition metal disulfides (TMDs) has attracted considerable attention due to its excellent physicochemical properties. In order to detect the SF6 decomposition products, transition ...metal Pt cluster doping was chosen to enhance the adsorption property of intrinsic WSe2 monolayer. The adsorption of SO2, SOF2 and SO2F2 on Ptn (n=1–3) doped WSe2 monolayer is studied based on the first-principle calculation. The adsorption energy, charge transfer, and density of states of the interaction between the target gas molecules and Ptn-WSe2 were studied. The calculation results showed that Pt3 doping dramatically enhances the adsorption of WSe2 to SO2 and SOF2 and SO2F2 molecules. Meanwhile, electrons transfer from Ptn-WSe2 surface to these three kinds of target gas molecules, reducing the conductivity of the adsorption system in different degrees. The results of this study not only have important significance for explaining the sensing mechanism of Ptn-WSe2 adsorption to SF6 gas decomposition products, but also provide a potential material for further development of gas sensing sensors.
Carbon nanotubes (CNTs) have aroused extensive attentions as a new category of gas sensor materials owing to their outstanding performance for detecting specific gas among a variety of ones through ...diverse gas responses. This review summarizes the adsorption mechanism of CNTs and their properties related to the detection of sulfur hexafluoride (SF
6
) decomposed gases that generated in gas insulation switchgear (GIS) of power system. Their performances as sensors of both experimental analysis and theoretical calculation for various kinds of decomposed gases are summarized, and the further research trend on CNTs in the detection of SF
6
decomposition components is also put forward.
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Poultry feeding will lead to a large amount of ammonia(NH3) emissions, which will seriously affect the quality of meat. Herein, we report a resistive sensor based on NiO/Ti3C2Tx ...sensitive nanocomposites for NH3 detection in a natural environment. The nanocomposites were prepared by modifying two-dimensional（2D） Ti3C2Tx MXene with nickel oxide (NiO) nanoparticles (NPs) by a simple ultrasonic self-assembly method. The results show that the NiO/Ti3C2Tx MXene nanocomposite sensor exhibits a high sensitivity of 6.13 % to 50 ppm NH3 at room temperature (RT), which is 8.7 times higher than that of the pure Ti3C2Tx MXene sensor. In other words, the addition of NiO NPs can significantly enhance the gas-sensing response of pure Ti3C2Tx MXene to NH3 at RT. Meanwhile, the response and recovery time were also effectively improved (63 s/19 s) due to the addition of NiO NPs. Furthermore, the response of the nanocomposite sensor to volatile organic compounds (VOCs) was investigated, and the results showed its prospective and high selectivity. On the other hand, the nanocomposite sensor exhibits good repeatability and long-term stability. Finally, a possible sensing mechanism is proposed to improve sensor performance.
In this study, the adsorption behavior of CuO-GeSe, NiO-GeSe, and Ag2O-GeSe towards the main dissolved gases CO, CH4, C2H2, and C2H4 in transformer oil was systematically studied based on DFT. The ...adsorption structure, band structure, density of states, deformation charge density, and molecular orbit were analyzed to explore the interaction between the modified monolayers and gases. The results show that the adsorption of the four target gases on pristine GeSe belongs to weak physical adsorption. Metal oxides modification improves the conductivity of GeSe, and the formation of numerous triangular structures makes the modified substrates hard to deform during gas adsorption. Due to the poor gas sensitivity and extremely short recovery time of CH4 on CuO-GeSe, NiO-GeSe, and Ag2O-GeSe, these three modified structures are not suitable to be used as a material for detecting CH4. The conductivity of MO-GeSe changes in different degrees after adsorbing CO, C2H2, and C2H4. The gases can be detected according to the different change rule of conductivity upon adsorption. In addition, gas desorption from the substrate can be achieved by controlling the temperature. This study provides a theoretical basis for the application of gas sensors used in DGA.
In this paper, a Ni-doped MoS₂ monolayer (Ni-MoS₂) has been proposed as a novel gas adsorbent to be used in SF₆-insulated equipment. Based on the first-principles calculation, the adsorption ...properties of Ni-MoS₂ to SO₂ and H₂S molecules, the main decomposition components of SF₆ under a partial discharge (PD) condition have been studied. The adsorption energy, charge transfer, and structural parameters have been analyzed to find the most stable gas-adsorbed Ni-MoS₂. Furthermore, the density of states (DOS), projected density of states (PDOS), and electron density difference were employed to explore the interaction mechanism between SO₂, H₂S, and the Ni-MoS₂ surface. It is found that the H₂S molecule and SO₂ molecule interact with the Ni-MoS₂ surface by strong adsorption energy. Therefore, we conclude that the interaction between these two kinds of gases and the Ni-MoS₂ monolayer belongs to chemisorption, and the Ni-MoS₂ monolayer might be a promising gas adsorbent for the fault recovery of SF₆-insulated equipment. Additionally, we have to point out that all of the conclusions only considered the final adsorption energy, the barrier in the transition state has not been analyzed in this paper.
•To the best of our knowledge, it is the first time that Pd-doped SWCNTs are applied to detect decomposition of SF6.•The Pd doping method has effectively improved the sensitivity of SWCNTs to detect ...decomposition of SF6.•The Pd-doped SWCNTs realize the selective detection of SF6 decomposition.
Carbon-nanotube doping is extensively researched. This work aims to investigate a novel sensor for detecting the five gas components of SF6 decomposition (i.e., SO2, H2S, SOF2, SO2F2, and CF4) using Pd-doped zigzag (8, 0) single-wall carbon nanotubes (Pd-SWCNTs). We compute the preferential adsorption sites, bonding configurations, and adsorption geometry for molecular adsorption. Results of electrical characteristics analysis reveal that Pd-SWCNTs show different responses to the five gases. After SO2, H2S, and SOF2 adsorbed onto Pd-SWCNTs, the conductivity of Pd-SWCNTs increases in the following order: SO2>SOF2>H2S. SO2F2 adsorption onto Pd-SWCNTs slightly decreases conductivity. Conversely, Pd-SWCNTs are not sensitive to the other gas molecule CF4. We conclude that Pd-SWCNTs have good sensitivity and selectivity to SO2, H2S, SOF2, SO2F2, and CF4.
Graphene-based materials have aroused enormous focus on a wide range of engineering fields because of their unique structure. One of the most promising applications is gas adsorption and sensing. In ...electrical engineering, graphene-based sensors are also employed as detecting devices to estimate the operation status of gas insulated switchgear (GIS). This paper reviews the main synthesis methods of graphene, gas adsorption, and sensing mechanism of its based sensors, as well as their applications in detecting SF6 decomposing products, such as SO2, H2S, SO2F2, and SOF2, in GIS. Both theoretical and experimental researches on gas response of graphene-based sensors to these typical gases are summarized. Finally, the future research trend about graphene synthesis technique and relevant perspective are also given.
The adsorption capacity of intrinsic SnS2 to NH3, Cl2 and C2H2 is very weak. However, non-metallic elements B and N have strong chemical activity, which can significantly improve the conductivity and ...gas sensitivity of SnS2. Based on density functional theory, SnS2 was modified with B and N atoms to analyze its adsorption mechanism and gas sensitivity for NH3, Cl2 and C2H2 gases. The optimal structure, adsorption energy, state density and frontier molecular orbital theory are analyzed, and the results are in good agreement with the experimental results. The results show that the adsorption of gas molecules is exothermic and spontaneous. Only the adsorption of NH3 and Cl2 on B-SnS2 belongs to chemical adsorption, whereas other gas adsorption systems belong to physical adsorption. Moderate adsorption distance, large adsorption energy, charge transfer and frontier molecular orbital analysis show that gas adsorption leads to the change of the conductivity of the modified SnS2 system. The adsorption capacity of B-SnS2 to these gases is Cl2 > NH3 > C2H2. The adsorption capacity of N-SnS2 is NH3 > C2H2 > Cl2. Therefore, according to different conductivity changes, B-SnS2 and N-SnS2 materials can be developed for greenhouse gas detection of gas sensors.
In the long-running of sulphur hexafluoride (SF(6))-insulated equipment, SF(6) inevitably decomposes to various decomposition products under electric discharge, including SOF(2) and SO(2)F(2). In ...this work, single Pt modified molybdenum disulphide (Pt-MoS(2)) monolayer, and double Pt modified molybdenum disulphide (Pt(2)-MoS(2)) monolayer are proposed to analyse its adsorption and sensing properties to SOF(2) and SO(2)F(2) with single and double gas molecules adsorption based on density functional theory. The adsorption energy, density of states, and molecular orbit theory are employed to analyse the adsorption and sensing mechanism. It turns out that the Pt-MoS(2) and Pt(2)-MoS(2) present outstanding adsorption capacity to gas molecules. Specifically, double SOF(2) adsorption on Pt(2)-MoS(2) shows the best adsorption performance, and the conductivity of the adsorption system changes the most in the adsorption process. Overall, both Pt-MoS(2) and Pt(2)-MoS(2) perform as an excellent gas sensor. This study provides a theoretical basis to develop Pt-MoS(2) and Pt(2)-MoS(2) based materials for SOF(2) and SO(2)F(2) detection in SF(6)-insulated equipment.
GIS plays an irreplaceable role in the modern electrical system. However, partial discharge will inevitably occur under insulation defect conditions and may lead to serious insulation malfunction. ...The online monitoring method based on gas sensor is a feasible method to diagnose the severity of partial discharge in GIS. In this paper, metal oxide (TiO2, Fe2O3, NiO) cluster-modified single-layer graphene was proposed as a novel gas sensor to detect the characteristic components of SF6 decomposition products, SOF2 and SO2F2. Density functional theory calculations were carried out to study the gas adsorption and sensing mechanisms. The adsorption structures of gas molecules and the metal oxide cluster-modified single-layer graphene were built and optimized. Then, the most stable structure was selected to analyze the corresponding adsorption parameters. Calculation results showed that metal oxides decoration reduces the energy gap, improving the electrical conductivity and enhancing the adsorption activity of the graphene surface. According to DOS and CDD analyses, TiO2 modification obtained the best adsorption effect. Calculation results show that the metal-oxide-modified graphene sensor provides an effective method for effectively estimating the operating state of GIS by detecting SF6 decomposition products.
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