Intrinsic carbon nanotubes (CNTs) show limited toxic gas detection, thus, we need to develop a method to fabricate a novel CNT sensor that has good sensitivity. In this study, density functional theory (DFT) was applied to determine the adsorption behavior of Au-doped singlewalled carbon nanotubes (Au-SWCNTs) to SO 2 and H 2 S. The calculated results show that Au-SWCNTs have a high sensitivity to SO 2 and H 2 S. When SO 2 adsorbs on the surface of the nanotube, a large number of electrons transfer from the Au-SWCNT to SO 2 , which results in a decrease in the frontier orbital energy gap and an increase in electrical conductivity. On the other hand, when H 2 S adsorbs on the surface of the nanotube, the electrons transfer from H 2 S to the Au-SWCNT, the frontier orbital energy gap increases, and the electrical conductivity decreases. Thus, SO 2 and H 2 S could be detected by Au-SWCNTs. This conclusion is useful for the development of CNT-based gas sensors and provides a theoretical basis to fabricate Au-SWCNT-based gas sensors.

The detection of partial discharge by analyzing the components of SF6 gas in gas-insulated switchgears is important to the diagnosis and assessment of the operational state of power equipment. A gas sensor based on anatase TiO2 is used to detect decomposed gases in SF6. In this paper, first-principle density functional theory calculations are adopted to analyze the adsorption of SO2, SOF2, and SO2F2, the primary decomposition by-products of SF6 under partial discharge, on anatase (101) and (001) surfaces. Simulation results show that the perfect anatase (001) surface has a stronger interaction with the three gases than that of anatase (101), and both surfaces are more sensitive and selective to SO2 than to SOF2 and SO2F2. The selection of a defect surface to SO2, SOF2, and SO2F2 differs from that of a perfect surface. This theoretical result is corroborated by the sensing experiment using a TiO2 nanotube array (TNTA) gas sensor. The calculated values are analyzed to explain the results of the Pt-doped TNTA gas sensor sensing experiment. The results imply that the deposited Pt nanoparticles on the surface increase the active sites of the surface and the gas molecules may decompose upon adsorption on the active sites.

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Detection of partial discharge and analysis of SF 6 gas components in gas-insulated switchgear are important for diagnosis and operating state assessment of power equipment. The gas-sensing properties of the existing TiO 2 nanotube (TiO 2 NT) array-based and the Pt-doped TiO 2 NT-based sensors were investigated for the components of SF 6 decomposition. Four sensors with different amounts of Pt-doped TiO 2 NTs are prepared using constant current method. The sensing responses of the sensors to the main decomposition gases of SF 6 (i.e., SO 2 , SOF 2 , and SO 2 F 2 ) are examined, and the gas-sensing characteristic curves are comparatively analyzed. In addition, the mechanisms of the sensitive responses are discussed. Results show that a higher doping amount of Pt benefits the detection of SO 2 F 2 , whereas a lower doping amount is suitable for detecting SO 2 , which is similar with the capabilities of the intrinsic TiO 2 NT sensor. Moreover, the working temperature of the Pt-doped TiO 2 NT sensor is lower than that of the intrinsic TiO 2 NT sensor.Index Terms -Doping amount, TiO 2 nanotube array, SF 6 decomposition components, Sensor response.

In this paper, we discuss the potential of using virtual reality collaborative platforms for e-learning to improve the quality of online education. First, we explore the characteristics of existing online platforms that can be used for e-learning. Second, we present a method for creating a Virtual Reality Collaborative Environment (VRCE) for e-learning using an online platform, namely FrameVR. Third, an experiment is conducted to investigate participants' behavioural and emotional engagement when using Zoom and the VRCE for online learning. Valid survey data from twenty-two participants are analysed. Then, participants are interviewed about their perceptions of using a VRCE for e-learning. The results of the experiment confirm that using a VRCE can increase student engagement, especially emotional engagement compared to Zoom. However, the findings also suggest that there is still room for improvement in the use of VRCE for elearning. Therefore, further suggestions are made on the drawbacks of VRCE to improve the user experience. This paper provides insight into incorporating VRCE to enhance the e-learning experience and contribute to the development of online education.