SO2F2 Gas Research Articles

The gas-sensing mechanism of Nb2C monolayer for SF6 decomposition based on the DFT study

Abstract In addressing malfunctions in gas-insulated switchgear (GIS) systems, it is imperative to have a real-time tracking system for SF6 decomposition products to guarantee the safety and reliability of the equipment's operation. Although a variety of gas detection technologies are currently available on the market, low-power gas detection devices for SF6 decomposition products are still in the development stage, and technological advances in this area are of great significance for improving the reliability of GIS systems. Based on the density functional theory (DFT), the Nb2C crystal surface structure was established and six adsorption structures of SO2, H2S, SOF2, SO2F2, HF and CO gas molecules on Nb2C crystal surface were constructed by geometrical optimization in this paper. The gas-sensitive properties of each adsorption system were explored in terms of adsorption energy, charge transfer, electron density, density of states and recovery time. The results showed that the Nb2C crystal surface was unfit HF and CO gases detection, both of which showed weak physical adsorption; the adsorption energies of SO2, H2S, SOF2, and SO2F2 on the Nb2C crystal surface were -1.846 eV, -1.081 eV, -5.270 eV, and -10.582 eV, respectively, and all of them were strong chemical adsorption. It was further shown by theoretical recovery time calculations that the Nb2C crystal surface can act as SOF2 and SO2F2 gas scavengers, and are able to desorb H2S (4.69 s) and SO2 (2.26 s) gases by appropriately increasing the temperature, but the Nb2C crystal surface is more suitable for use as a low-power gas-sensitive material for H2S gas detection. Therefore, Nb2C is anticipated to be a promising material for high response, low-power consumption and fast recovery for H2S gas detection in SF6 decomposition gas.

DFT study of Cun (n = 1–3) cluster-modified WSe2 monolayers for the detection of SF6 decomposition gases (H2S, SO2, SOF2 and SO2F2)

The role of SF6 in gas-insulated equipment is crucial for insulation and arc extinction. When subjected to electrical faults, thermal faults, and mechanical failures in insulation devices, SF6 can decompose into H2S, SO2, SOF2, and SO2F2. This study conducted first-principles simulations to analyze the effect of Cun (n = 1–3) cluster-modified monolayer WSe2 on sensing H2S, SO2, SOF2, and SO2F2 gases during SF6 decomposition. The optimal doping positions of Cun-WSe2 clusters at n = 1, 2, and 3 were determined, showcasing their superiority over pure WSe2 in terms of band gap, frontier orbitals, and density of states. Subsequently, a detailed investigation was carried out on the adsorption effects of the four gases at the optimal doping positions, including parameters such as adsorption distance, adsorption energy, charge transfer, differential charge density, and density of states. It was found that when the number of copper atoms in the cluster increased to 3, the banding energy sharply rose to -2.395 eV. Simulation results demonstrated the adsorption behavior of H2S on Cun (n = 1–3)-WSe2 demonstrates remarkable affinity, with an increasing adsorption energy as the number of Cu atoms rises. Notably, Cun (n = 1–3)-WSe2 exhibits favorable desorption times for SO2. At 378 K, the desorption time for SO2@Cu3-WSe2 is 14.7 s. At 498 K, desorption times for SO2@Cu1-WSe2 and SO2@Cu2-WSe2 are 7.59 s and 2.85 s, respectively. When the number of copper atoms is 2, the cluster-modified system desorbs SOF2 at room temperature in only 0.89 s. Moreover, Cun (n = 1–3)-WSe2 displays strong adsorption towards SO2F2, characterized by prolonged desorption times, rendering it a promising adsorbent for SO2F2 removal. This study aims to highlight the adsorption effects of different numbers of Cu atomic clusters in the Cun-WSe2 system on SF6 decomposition gas, further advancing research for developing high-performance SF6 decomposition gas sensors.

GeP3 monolayer as a promising 2D sensing materials in detecting SO2, H2S, SOF2 and SO2F2

The detection of SF6 decomposition components using gas-sensitive sensors is significantly important for characterizing internal insulation failures and assessing the operational status of SF6 gas-insulated equipment. In this paper, the adsorption properties of GeP3 monolayers for SO2, H2S, SOF2 and SO2F2 gases were investigated based on density functional theory. Four gas adsorption systems were constructed, and the adsorption mechanisms and sensing characteristics of GeP3 monolayers on target gases were investigated by calculating parameters such as adsorption energy, charge transfer, density of states, and recovery time, along with their potential application as resistive gas sensors and field-effect transistor sensors. It is demonstrated that GeP3 monolayers were suitable for the detection of SO2, H2S, SOF2 and SO2F2 gases, all of which exhibited good chemisorption with adsorption energies of −1.36 eV, −0.78 eV, −1.82 eV and −2.91 eV, respectively. The adsorption of SO2 and H2S is found to cause a significant change in the conductivity of the GeP3 monolayers, and desorption is achieved at the optimal operating temperature in only 54.428 s and 10.686 s, respectively. Also the adsorption of SOF2 and SO2F2 can make the work function of the GeP3 monolayers significantly larger. Consequently, the GeP3 monolayers have the potential to be used as a resistive gas sensor for SO2 and H2S gases, or as a field effect transistor sensor for SOF2 and SO2F2 gases. This study provides theoretical guidance for the development of GeP3-based sensors for monitoring the insulation status and operational conditions of SF6 gas-insulated equipment.

Ultrasensitive detection and sensitivity mechanism of SO2F2 in SF6 decomposition product based on TiO2-NiS heterojunction

SO2F2 is a typical fault product of SF6 electrical insulation equipment. Detecting SO2F2 can indicate whether the equipment is faulty. SO2F2 is a hazardous gas that can cause harm to the human body. This study reports on the development of the SO2F2 sensor using TiO2-NiS for the first time, and the investigation of its gas sensitivity to SO2F2 in SF6 background and air. The effective construction of the TiO2-NiS heterojunction was characterized via the XRD, SEM, and TEM. The TiO2-NiS heterojunction sensor for SO2F2 has a working temperature of 150°C in both SF6 and air environments with the response and recovery time of 6 s/2 s to 5 ppm SO2F2 in the air and 5 s/6 s in the SF6 environments, respectively. The sensor has a strong linear fit and a detection limit of 100 ppb. The long-term stability, selectivity, resistance to moisture, and responsiveness/recovery are features of this sensor. Furthermore, it was demonstrated that SO2F2 adsorption performance on the TiO2-NiS heterojunction outperformed that of TiO2 and NiS based on first principles, and density of states and differential charge density provided a more detailed description of the interaction between SO2F2 gas and the TiO2-NiS heterojunction. The oxygen competitive adsorption of SO2F2 and lattice oxygen molecules on the surface of TiO2-NiS heterojunction, as well as the interaction between adsorbed F2− on the TiO2-NiS heterojunction surface and SO2F2, may be used to characterise the sensing mechanism in the SF6. At the same time, the prepared SO2F2 sensor can effectively measure the concentration of SO2F2 through hardware, and give early warning when the concentration exceeds the safe value.

The design of CN/C3N2 heterostructures and the potential as gas sensor and scavenger for SF6 decomposed gases

The design, electronic and gas-sensing properties of the CN/C3N2 heterostructures with and without the adsorption of H2S, SO2, HF, SOF2, and SO2F2 were systematically investigated by using DFT calculations. All SF6 decomposition gases can physically adsorb on both sides of the CN/C3N2 heterostructure with significant adsorption strength and charge transfer. Although the adsorption of these gases, in general, hardly affects the electronic properties, but can remarkably tune the work function (Φ) of the heterostructure. The CN/C3N2 heterostructure as Φ-type gas sensors has an ultra-high sensitivity for SF6 decomposed gases (at least over 71.2 %), especially for the C3N2 side (at least over 568.7 %), and has relatively low recovery times for HF, H2S, SOF2, and SO2F2 gases at 300 K, indicating the reusability of the heterostructure at room temperature, but much more favorable at 350∼400 K for SO2 gas. Further, the heterostructure as adsorbents for the capture and scavenging of SF6 decomposition gases has high adsorption capacity and strength. Therefore, our findings reveal that the CN/C3N2 heterostructure is a promising candidate as Φ-type gas sensors with high sensitivity and reusability for the detection of SF6 decomposition gases, while as an optimal scavenger for removing these toxic gases.

DFT investigation of Pt-doped CTF-1 covalent triazine frameworks for adsorption and sensing of SF6 decomposition products

We report a computational investigation of the gas adsorption and sensing properties of pristine covalent triazine framework CTF-1 and its platinum atom (Pt)-doped counterpart towards SF6 decomposition products (i.e., H2S, SO2, SOF2, and SO2F2 gases). For this purpose, density-functional theory calculations are employed with the TPSS exchange-correlation functional (with the Grimme-D3 empirical dispersion correction) and a 6-31+G**/Lanl2DZ mixed basis set. Pt was found to interact with a nitrogen atom, distorting the planar structure. Our results reveal that the electronic bandgap of the pristine CTF-1 lowers noticeably following surface doping with a Pt atom (3.48 vs. 1.06 eV for pristine vs. Pt-doped CTF-1, respectively), enhancing the electrical conductivity of the gas sensor. In contrast to pristine CTF-1, which displays weak adsorption performance (with adsorption energies of −0.25, −0.27, −0.31, and −0.18 eV for H2S, SO2, SOF2, and SO2F2, respectively), Pt-doped CTF-1 exhibits strong interactions with the gas species (with adsorption energies of −1.93, −2.41, −6.27, and −7.98 eV for H2S, SO2, SOF2, and SO2F2, respectively) and high sensitivity in detecting the target gas species under study. Moreover, a density of states (DOS) analysis is conducted to further characterize the mechanisms involved in gas adsorption and sensing. All four degradation products decrease the bandgap of pristine CTF-1 and increase the bandgap in Pt-doped CTF-1. The latter is generally more pronounced. We conclude that Pt-doped CTF-1 could be a novel SF6 decomposition gas adsorbent and sensor and provide experimentalists with the essential physicochemical characteristics of the designed materials for future work.

Pd-Adsorbed SiN3 Monolayer as a Promising Gas Scavenger for SF6 Partial Discharge Decomposition Components: Insights from the First-Principles Study.

Gas-insulated switchgear (GIS) equipment must be protected by detecting and eliminating the toxic SF6 partial discharge decomposition components. This study employs first-principles calculations to thoroughly investigate the interaction between a Pd-adsorbed SiN3 monolayer (Pd-SiN3) and four typical SF6 decomposition gases (H2S, SO2, SOF2, and SO2F2). The study also investigates the associated geometric, electrical, and optical characteristics along with the sensing sensitivity and desorption efficiency. The ab initio molecular dynamics (AIMD) simulations demonstrated the favorable stability of the Pd-SiN3 monolayer. Furthermore, the Pd-SiN3 monolayer exhibited strong chemisorption behavior toward H2S, SO2, SOF2, and SO2F2 gases because of the higher adsorption energies of -2.717, -2.917, -2.457, and -2.025 eV, respectively. Furthermore, significant changes occur in the electronic and optical characteristics of the Pd-SiN3 monolayer following the adsorption of these gases, resulting in remarkable sensitivity of the Pd-SiN3 monolayer in relation to electrical conductivity and optical absorption. Meanwhile, all of these gas adsorption systems exhibited extremely long recovery times. The aforementioned theoretical findings suggest that the Pd-SiN3 monolayer has the potential to be an effective gas scavenger for the storage or removal of the SF6 decomposition components. Additionally, it might function as a reliable one-time sensor for detecting these gases. The results potentially provide valuable theoretical guidance for maintaining the normal operation of the SF6 insulation devices.

First Principles Calculation of Gas Sensitive Properties of Pd3‐Modified Monolayer PtSe2 to SF6 Decomposition Products

Based on density functional theory (DFT), the effect of Pd3 cluster modification on the surface properties of PtSe2 monolayer and the gas sensitive detection performance of PtSe2/Pd3–PtSe2 on sulfur hexafluoride (SF6) decomposition is studied, in terms of the adsorption energy, density of states (DOS), and sensing characteristic. It is found that that the Pd3 cluster exhibit stable modified structure on monolayer PtSe2, the adsorption capacity of Pd3–PtSe2 monolayer is the highest, significantly improves the surface activity and sensing performance of PtSe2 monolayer. Further, the large charge transfer, bandgap, and conductivity changes indicate that the monolayer Pd3–PtSe2 has strong chemical interaction and high sensitivity to SO2, H2S, and SO2F2 gas molecules. Pd3–PtSe2 can be used as a potential candidate for gas sensors. Finally, the sensing performance analysis of the system shows that the recovery time of Pd3–PtSe2 for SO2F2 is only 10.7 s, which can be repeated for a long time. These analyses illustrate the potential application of Pd3–PtSe2 in the detection and removal of harmful gases in gas insulated switch‐gear (GIS). The calculations may provide new insights for researchers to explore gas‐sensitive materials based on PtSe2.

Density function theory study of TM (Pt,Pd,Ag) decorated ZrSSe for SF6 decomposition products

The detection of the main decomposition products of SF6 can effectively prevent the failure of GIS. In this work, three metals (Pt, Pd, and Ag) doped on ZrSSe monolayer are used to detect three gases of SF6 decomposition, namely SO2, H2S, and SO2F2. The results obtained through systematic analysis show that metals tend to be doped on the S surface of ZrSSe, and the gases adsorption systems of the original ZrSSe are all physical adsorption. After metals doping, SO2 and H2S are chemically adsorbed, and SO2F2 gas systems are still weakly physically adsorbed, and the same results as above can be obtained from DCD and DOS analysis. In terms of recovery time, the time of the SO2F2 adsorption systems is extremely short, indicating that the modified monolayer formed on ZrSSe doped with three metals is not suitable as a material for detecting SO2F2 gas, the gases can be detached from the substrate by changing the temperature. This research provides a theoretical basis for ZrSSe materials in gas sensors.

Adsorption properties of nCu2O-graphene (n = 1, 2, 3) for SOF2 and SO2F2 gas molecules

This study analyzed the adsorption and gas-sensing properties of nCu2O-graphene (n = 1, 2, 3) to SF6 characteristic decomposition products (SOF2 and SO2F2) based on the first-principles calculations. The interaction between the modified graphene monolayer and SOF2 or SO2F2 gas molecules was explored by analyzing adsorption structure, energy, distance, charge transfer, DOS, PDOS, and band gap. The results showed that Cu2O modification improved the conductivity and surface activity of the graphene substrate, and the gas sensitivity of nCu2O-graphene to SOF2 and SO2F2 enhanced. Except for the 2SO2F2/3Cu2O-graphene system, the conductivity of the other system decreased to different degrees. In contrast, the adsorption performance to SOF2 improved more, and the conductivity after the adsorption of SOF2 changed more obviously. Moreover, calculations showed that the recovery time of the SO2F2/Cu2O-graphene system is too short to build stable adsorption. Thus, Cu2O-graphene modified system was not suitable for SO2F2 gas detection. The other gas adoption systems can easily realize adsorption and desorption under suitable conditions. The study results provide a potential material for developing gas sensors using in Gas-insulated switchgear.

Sensing properties of SF6 decomposition gas sensor based on Rh doped α-AsP monolayer

The detection of decomposition components of SF6 insulating gas in gas-insulated switchgear (GIS) is of great significance to evaluating GIS's operating state and ensuring the equipment's safety. In order to detect and diagnose the main decomposition gases SO2, SOF2, and SO2F2 of SF6, this work systematically analyses the intrinsic α-AsP monolayer and two Rh-modified α-AsP monolayers. Specifically, the adsorption structure, energy, charge transfer and deformed charge density, the total density of states, the partial density of states, and recovery time were discussed and calculated in detail, and the internal mechanism of the entire adsorption process was clarified. Meanwhile, the results show that Rh adsorbed on α-AsP monolayer (Rh-AsP-O) has a good adsorption effect on SO2, SOF2, and SO2F2 gases. From the sensor's perspective, the Rh-AsP-O monolayer has potential applications in the gas-sensing field of SO2, SOF2, and SO2F2.

Improvement of sensing performance of SO2, SOF2, and SO2F2 gases on monolayer and bilayer HfSe2 under electric field

In this contribution, we use DFT simulations to gain a systematic understanding of how an external vertical electric field (E-field) affects the improvement of the sensing performance of SF6 gases on monolayer and bilayer HfSe2. The individual layered HfSe2 nanosheets' predicted band gaps and lattice constants agree with previously published results, demonstrating the validity of our theoretical framework and computational details. In the current study, it is examined the viability of stacked HfSe2 nanosheets as a candidate for detection SO2, SOF2, and SO2F2. An external E-field can facilitate the adsorption and the stability of SF6 products onto monolayer and bilayer HfSe2 nanosheets. The highest adsorption energies of SO2, SOF2, and SO2F2 on bilayer HfSe2 occurred at an E-field intensity of roughly −0.41 V/A0, with values −1.46, −1.39, and −1.16 eV, respectively. The electronic structures of the layered HfSe2 systems were seen to change as a result of the adsorption of gas molecules, where all the monolayer HfSe2 systems containing adsorbed molecules exhibited semiconductor properties with various band gaps, barring the monolayer HfSe2/SO2 system. Also, all bilayer HfSe2 systems exhibit metallic behavior in all values of E-field. Overall, these study's findings demonstrated that monolayer and bilayer HfSe2 might be utilized in techniques for the adsorption and detection of SF6 products. That bilayer HfSe2 also works to remove these gases.

FeN4-embedded warped nanographene as a potential candidate for scavenging and detecting sulfur-based gases: A DFT study

To bringing more safety to the working and living environment, effectively monitoring and purification of hazardous sulfur-based gases (H2S, SO2, SO3, SOF2 and SO2F2) are strongly required. In this study, the sensing mechanism of pristine and four-nitrogen coordinated iron (FeN4) embedded warped nanographene (WNG) towards sulfur-based gases systematically investigated from a theoretical perspective. The results show that FeN4 embedded WNG can greatly enhance the adsorption ability and exhibits considerable sensitivity towards the H2S, SO2, SO3, SOF2 and SO2F2 gases due to the synergistic effect of N and Fe atoms. Meanwhile, FeN4-WNG sensor has good stability and can effectively detect sulfur-based gases in a humid environment. The electrical conductivity of FeN4-WNG system changed significantly after SO3 gas adsorption, which is conducive to the improvement of detection accuracy. FeN4-WNG is more suitable as a disposable gas sensor or gas scavenger for SO3 gas due to its strong adsorption capacity. In contrast, FeN4-WNG can be regarded as the excellent reusability sensor towards H2S, SO2 and SOF2 gases. Furthermore, applying positive and negative electric fields can further enhance the selectivity and sensitivity of H2S and SO3 gases. This work is meaningful to illuminate the gas-sensitive mechanism for experimentalists to realize the potential application of FeN4-WNG in the field of detecting and removing sulfur-based gases.

Adsorption and sensing properties of SF6 decomposed gases on Mg-MOF-74

Using the framework of density functional theory (DFT), this work investigated the adsorption properties of SF6 decomposed H2S, SO2, SOF2, and SO2F2 gases on a magnesium-based metal-organic framework (Mg-MOF-74). Further, the possible application of this MOF as a suitable sensor for the detection of these gas molecules is discussed through the analysis of adsorption energies, electronic properties, charge transfer, selectivity and sensitivity features and recovery time. The study revealed that the SO2 molecule possesses relatively high adsorption energy (−1.26 eV) compared to H2S (−0.10 eV), SOF2 (−0.08 eV), and SO2F2 (−0.04 eV) molecules. Results show that all the molecules are physisorbed on the semiconducting Mg-MOF-74 and the adsorption energy has a strong correlation with the electronic properties. This reflects in the bandgap and the density of states analysis shows that the adsorption of H2S, SOF2, and SO2F2 molecules leads to insignificant changes in the bandgap, whereas the adsorption of SO2 reduces the bandgap by almost 50%. The recovery time analysis also ensures that Mg-MOF-74 has a fast desorption ability for H2S, SOF2, and SO2F2 molecules, suitable for resistive and reusable chemical sensors for industrial applications.

Comparison of Gas-sensitive properties of Au, Ag and Cu Metal-doped GaNNT for SF6 decomposition gases

SF6 gas will produce various decomposition products When the partial discharge fault occurs in SF6 gas-insulated equipment, resulting in significantly reduced insulation performance of the insulated equipment. Early latent insulation faults in gas-insulated equipment can be diagnosed by monitoring the concentration of SF6 typical decomposition products (H2S, SO2, SO2F2 and SOF2) inside the insulated equipment. Gallium nitride nanotubes (GaNNT) have shown promising applications as gas-sensitive materials for sensors, and the gas-sensitive properties of the materials can be better improved by doped-metal. Therefore, the Density functional theory (DFT) calculation approach is proposed to compare with the gas-sensitive response characteristics of Au, Ag and Cu metal-doped GaNNT (M−GaNNT) to SF6 typical decomposition gases in the paper. The adsorption mechanism is analyzed by band structure, density of states, frontier molecular orbital theory and differential charge density, and the results are in high consistency. The metal-doped GaNNT introduces a large number of impurity bands which makes the probability of electrons crossing the forbidden band to reach the conduction band larger, and thus the gas-sensitive characteristics are improved. The adsorption of gases by M−GaNNT causes the resistivity of the system to vary, and sensing response (SR) and response time (RT) of M−GaNNT adsorbs gases are also analyzed. The results show that the ability of metal-doped GaNNT is Ag-GaNNT>Cu-GaNNT>Au-GaNNT, and the average values of SR are 516.9, 29.3 and 8.7, respectively. Ag-GaNNT has higher selectivity for SO2F2 gas. In summary, it shows that Ag-GaNNT is a potential gas-sensitive material that can be a new material for the online monitoring of fault gas content in gas-insulated equipment.

Hybrid nanogenerator driven self-powered SO2F2 sensing system based on TiO2/Ni/C composites at room temperature

The application of conventional sensors is limited due to energy supply issues and environmental problems, and current triboelectric nanogenerator (TENG) based self-powered sensing systems is hard to meet the specific requirement. In this paper, TiO2/Ni/C composites were prepared using MOF-derived Ni/C materials for SO2F2 detection at room temperature. The excellent pore structure and high electrical conductivity of Ni/C material greatly improve the sensitivity properties of TiO2. The TiO2/Ni/C composites-based SO2F2 sensor exhibits a wide detection range of 5–200 ppm concentration and a fast response/recovery time of 26 s/9 s, while its response value for 200 ppm SO2F2 is 18.34 times higher than that of the pure TiO2-based sensor. Furthermore, by modifying the PVDF film with TiO2, the permittivity of PVDF is greatly improved, and the surface potential is 2.6 times higher than that of pure PVDF film. Eventually, a dual-layer hybrid TENG based on TiO2/PVDF composite film was constructed. Its upper TENG powers the TiO2/Ni/C composite sensor, and the lower hybrid TENG drives the thermohygrometer to realize a self-powered temperature and humidity-corrected SO2F2 sensing system, which can accurately implement SO2F2 gas concentration alarms at 10 ppm, 50 ppm, and 100 ppm at different humidity levels. This work broadens the application of TENG in the field of self-powered gas sensing while providing a new idea to achieve the trace detection of SO2F2 at room temperature.

A DFT Based Approach to Sense the SF6 Decomposed Gases Using Ni-doped WS2 Monolayer

In this paper, we investigated Ni-doped WS2 (Ni@WS2) to detect the H2S, SO2, SOF2, and SO2F2 gases, which are also decomposition gases of SF6 (sulphur hexafluoride). Hence, Electron Difference density, adsorption length and energy, band structure (B.S.), charge transfer, and density of states (DOS) are detailed and studied in depth. The adsorption energy of SF6 decomposition gases i.e. H2S, SO2, SOF2, SO2F2 on Ni@WS2 are found to be −1.3, −1.46, −1.64, and −1.8 eV, respectively, which is superior as compared to other materials. It has been observed through the band structure analysis that after adsorption of SF6 decomposed gas on Ni modified WS2 bandgap reduces, and as a result, conductivity also changes. The dip in bandgap after adsorption of H2S, SO2, SOF2, and SO2F2 on Ni decorated WS2 can be arranged as Ni@WS2@SO2F2> Ni@WS2@SOF2> Ni@WS2@H2S > Ni@WS2@SO2. In brief, these investigations are very efficacious for detecting H2S, SO2, SOF2, and SO2F2 gases, by Ni-doped WS2 monolayer.

Simulation and experimental study on adsorption of SF6 decomposition components and optical gas cell materials

Fourier transform infrared spectroscopy (FTIR) is widely used in gas detection of SF6 decomposition components. A gas cell is an important element in the detection system, which can directly affect the accuracy and sensitivity of detection. During the long-term use of the gas cell, SF6 decomposition components may be adsorbed on the inner wall of the gas cell, which affects the detection results and the life of the gas cell. Therefore, the study on the adsorption between the gas cell material and the SF6 decomposition component is of great significance for improving the accuracy of detection. In this paper, based on the density functional theory, the adsorption process and adsorption degree of SF6 decomposition components (SOF2, SO2F2, CO, SO2, and H2S) with three typical main gas cell materials (Al, Cu, and Fe) and two gas cell coating materials (Teflon and Au) were simulated. It was found that the adsorption of Teflon and Au with gas was weak in the five materials and that of Teflon was the weakest. The adsorption energy of the three main gas cell materials was 2.65–6.31 times that of Teflon. The simulation results were also verified by FTIR and the GC-Materials Studio (MS) method. FTIR results showed that Teflon and Au had the weakest influence on the infrared spectral absorption peak and the effect of the two materials on SOF2 and SO2F2 gas absorption peaks is only less than 0.1. The results of gas chromatograph-mass spectrometer (GC-MS) showed that the effects of Teflon materials and Au on gas concentration were 2%–9.41% and the effects of Cu, Fe, and Al on gas concentration were 4.48%–65.43%. Therefore, Au and Teflon are suitable as coating materials for gas cells, which can reduce the adsorption of gas and improve the accuracy of infrared spectroscopy measurement. The results of this paper provide a reference for the development of application of optical gas detection technology in SF6 decomposition component detection.

Sensing performance of CdPc monolayer toward the SF6 decomposition gases: A DFT study

The rapid and effective detection of SF6 decomposition species is beneficial to diagnose the faults type and severity of gas insulated switchgear (GIS). In this work, the adsorption behaviors of SF6 decomposition products (HF, H2S SO2, SOF2 and SO2F2) on the Cd decorated phthalocyanine (CdPc) monolayer were systematically studied by using the first-principles calculations, the electronic properties of different adsorption systems and their sensing characteristics were also discussed in detail. The results show that the CdPc monolayer is both thermodynamically and dynamically stable, the H2S and SO2 are all chemically adsorbed on the CdPc monolayer, but the large adsorption strength restrict its application in gas sensor. By contrast, the CdPc monolayer has the appropriate adsorption strength for HF, SOF2 and SO2F2 gases with the Wads of −0.60 to −0.71 eV, as proved by the analysis of charge transfer, charge density difference and density of state. Besides, the work function of CdPc monolayer undergoes remarkable change after HF, SOF2 and SO2F2 adsorption, and the corresponding recovery time is predicted to be 0.01 s, 1.01 s and 0.46 s at room temperature. Therefore, CdPc monolayer has a great potential to be a chemi-resistive material with high sensitivity for HF, SOF2 and SO2F2 detection in GIS.

As-Doped h-BN Monolayer: A High Sensitivity and Short Recovery Time SF6 Decomposition Gas Sensor.

SF6 is a common insulating medium of gas-insulated switchgear (GIS). However, it is inevitable that SF6 will be decomposed due to partial discharge (PD) in GIS, which will cause hidden dangers to the safe and stable operation of equipment. Based on the DFT method, the two-dimensional nano-composite As-doped h-BN (As-BN) monolayer was proposed. By modeling and calculating, the ability of an As-BN monolayer as a specific sensor for SO2F2 (compared with an H2O adsorption system and CO2 adsorption system) was evaluated by parameters such as the binding energy (Eb), adsorption energy (Eads), transfer charge (ΔQ), geometric structure parameters, the total density of states (TDOS), band structure, charge difference density (CDD), electron localization function (ELF), sensitivity (S), and recovery time (τ). The results showed that an As-BN monolayer showed strong adsorption specificity, high sensitivity, and short recovery time for SO2F2 gas molecules. Therefore, the As-BN monolayer sensor has great application potential in the detection of SF6 decomposition gases.