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Under partial discharge, air would be converted into O 3 and NO 2 in air-insulated switchgears, therefore, the detection of such two gases can be used to evaluate the operation status of such electrical equipment. In this study, first-principles simulations are implemented to investigate the Ni-doping behavior on the pristine PtTe 2 monolayer, and the adsorption and sensing performances of the Ni-doped PtTe 2 (Ni-PtTe 2 ) monolayer upon O 3 and NO 2 in air-insulated switchgears. The formation energy ( E form ) of Ni-doping on the PtTe 2 surface was calculated to be -0.55 eV, which indicates the exothermicity and spontaneity of the Ni-doping process. Strong interactions occurred in the O 3 and NO 2 systems given the significant adsorption energy ( E ad ) of -2.44 and -1.93 eV, respectively. Using the band structure and frontier molecular orbital analysis, the sensing response of the Ni-PtTe 2 monolayer upon such two gas species is quite close and large enough for gas detections. Combined with the extremely long recovery time for gas desorption, it is presumed that the Ni-PtTe 2 monolayer is a promising one-shot gas sensor for O 3 and NO 2 detection with a strong sensing response. This study aims at proposing a novel and promising gas sensing material for the detection of the typical fault gases in air-insulated switchgears, so as to ensure their good operation in the whole power system., Competing Interests: The authors declare no conflicts of interest., (This journal is © The Royal Society of Chemistry.)

The first-principles theory is conducted in this paper to investigate the adsorption and electronic properties of a Ni-decorated PtS 2 (Ni-PtS 2 ) monolayer upon two dissolved gas species (CO and C 2 H 2 ) in the transformer oil, thus illustrating its sensing performance and related potential to evaluate the working condition of the oil-immersed transformers. We then highlight the effect of the biaxial strain on the configuration, charge transfer, and bandgap of the adsorbed systems to expound its potential as a strain-modulated gas sensor. Results indicate that the Ni-PtS 2 monolayer undergoes chemisorption upon two species, with an E ad value of -1.78 eV for the CO system and -1.53 eV for the C 2 H 2 system. The reduced bandgap by 0.164 eV (20.05%) in the CO system and 0.047 eV (5.74%) in the C 2 H 2 system imply the large feasibility of the Ni-PtS 2 monolayer to be a resistance-type sensor for CO and C 2 H 2 detection, which is also verified by the I - V analysis of these systems. Besides, the applied biaxial strain can exert geometric activations on the Ni-PtS 2 monolayer, and specifically, the compressive force can further reduce the bandgap in two systems, thus promoting its sensing response upon two gases. Our work is meaningful to broaden the exploration of noble transition metal dichalcogenides for gas sensing., Competing Interests: The author declares no competing financial interest., (© 2023 The Author. Published by American Chemical Society.)

Based on density functional theory, this work first investigates the Pd-decorating property on the pristine WTe 2 monolayer and then simulates the adsorption performance of a Pd-decorated WTe 2 (Pd-WTe 2 ) monolayer on SO 2 and SOF 2 molecules, in order to explore its sensing potential for SF 6 decomposed species. It is found that the Pd atom can be stably anchored on the top of the W atom of the WTe 2 monolayer with a binding energy of -2.43 eV. The Pd-WTe 2 monolayer performs chemisorption on SO 2 and SOF 2 , with adsorption energies of -1.36 and -1.17 eV, respectively. The analyses of the band structure and density of states reveal the deformed electronic property of the WTe 2 monolayer by Pd-decoration, as well as that of the Pd-WTe 2 monolayer by gas adsorption. The bandgap of the Pd-Wte 2 monolayer is increased by 1.6% in the SO 2 system and is decreased by -3.9% in the SOF 2 system, accounting for the sensing response of 42.0 and -56.7% for the detection of two gases. Moreover, the changed work function (WF) in two gas systems in comparison with that of the pristine Pd-WTe 2 monolayer suggests its potential as a WF-based gas sensor for sensing two gases as well. This paper uncovers the gas sensing potential of the Pd-WTe 2 monolayer to evaluate the operation status of SF 6 insulation devices, which also illustrates the strong potential of WTe 2 -based materials for gas sensing applications in some other fields., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)